Inaugural Ir. Ahmad (i).indd 1 2/23/14 9:48 AM

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Wastewater Treatment Technology: A Green Application in Aquaculture

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Published in Malaysia by / Diterbitkan oleh Penerbit UMT, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia.

http://www.umt.edu.my/penerbitumt E-maill: [email protected]

Perpustakaan Negara Malaysia Cataloguing-in-Publication Data

Ahmad Jusoh, 1955- WASTEWATER TRAETMENT TECHNOLOGY: A GREEN APPLICATION

IN AQUACULTURE : INAUGURAL LECTURE UNIVERSITI MALAYSIA TERENGGANU / Ahmad Jusoh.

Bibliografi: ms. 39 ISBN 978-967-0524-52-8 1. Sewage--Purification. 2. Water--Purification. I. Title. 628.3

Set in Arial

Reka bentuk: Penerbit UMTReka letak: Penerbit UMT


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Contents

WASTEWATER TREATMENT TECHNOLOGY: A GREEN APPLICATION IN AQUACULTURE 1Abstract 1Introduction of Water 2Properties of Water 3Hydrologic Cycle 6Source of Water 7 Surface Water 7 Groundwater 9

A GREEN TECHNOLOGY OF WASTEWATER TREATMENT IN AQUACULTURE 11Physico-chemical Treatment 11 Filtration 12 Adsorption 16 Membrane Filtration 18 Ion Exchange 20 Ultra-violet and Ozonation 22 Solar Distillation 24Biological Treatment 25 Trickling Filter and Bio-tower 26 Rotating Biological Contactor 28 Fluidized Bed Filters 29 Reed Bed and Constructed Wetland 30 Microalgae Phytoremediation 33 Bio-floc Technology 37Electrochemical Technology 39 Electrochemical Reduction of Nitrate 40 Electrochemical Oxidation of Organic Compound 41Bio-electrochemical Technology 42 Bio-electrochemical Reduction of Nitrate 43 Bio-electrochemical Oxidation of Organic Compound 44

WATER MONITORING AND CONTROL SYSTEM 47

CONCLUSION 51

References 53


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List of Tables

Table 1: Typical types of contaminants found in water (McKinney et al., 2012) 7

Table 2: BET surface area analysis of CSAC and PSAC (Jusoh et al., 2011) 18

Table 3: Specifications and properties of UF and MF membranes (Lee et al., 2004) 19

Table 4: Uptake data for ammonium ion onto clinoptilolite in the presence of magnesium, calcium and potassium ions (Weatherley & Miladinovic, 2004) 21Table 5: Second-order rate constants of pharmaceuticals

oxidation and pathogen inactivation at pH 8 and T = 20°C (Huber et al., 2005; von Gunten, 2003) 23


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List of Figures

Figure 1: Distribution of Earth Water (Gleick, 1993) 3Figure 2: Triple point of water 4Figure 3: Flow diagram of hydrologic cycle (Sylvan

Source, 2013) 6Figure 4: Confined and unconfined aquifers (NGWA, 2007) 9Figure 5: Saltwater intrusion due to overpumping

of ground water at coastal area 10Figure 6: Transport mechanism in filtration

(Jusoh et al., 2011) 12Figure 7: Production of BOPS from oil palm

(Jusoh et al., 2009) 13Figure 8: A schematic diagram of deep-bed filtration

system (Jusoh et al., 2007a) 14Figure 9: Progress of specific deposit and head loss

in a dual-media BOPS-sand filter with effective size of 0.6:0.5 mm. 15

Figure 10: Pore structure of activated carbon particle consist of macropore, mesopore and micropore 17

Figure 11: Ammonium ion uptake equilibria onto clinoptilolite 22

Figure 12: Schematic diagram of typical complete trickling filter system 27

Figure 13: Isometric view of RAS prototype (Endut et al., 2011; Endut et al., 2010) 31

Figure 14: Theoretical scheme of ammonia in RAS 31Figure 15: Nitrogen mass balance for production system

based on the mass fraction of nitrogen composition relative to the culture feed input 32

Figure 16: Upscale procedure for microalgae cultivation. 33Figure 17: Aquaculture wastewater treatment using immobilized microalgae (de-Bashan

& Bashan, 2010) 34


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Figure 18: Eight different species of microalgae isolated from the South China Sea 35

Figure 19: Microalgae technology transfer with Kerapu Online Hatchery, Besut, Terengganu 36Figure 20: Cultivation of Chlorella sp. for outdoor mass

cultivation at Kerapu Online Hatchery, Besut, Terengganu 37

Figure 21: Symbiotic relationship of microorganism in biofloc technology 38

Figure 22: Induction of bio-flocs formation at Freshwater Hatchery, Faculty of Science and Technology UMT 39

Figure 23: Mechanism of nitrate electro-reduction using zinc and copper electrodes 41

Figure 24: Mechanism of bio-electrochemical reduction of nitrate 44

Figure 25: Mechanism of bio-electrochemical oxidation of organic matter 45

Figure 26: A real-time control system for recirculation aquaculture (Ali, 2010) 48

Figure 27: Remote monitoring system based on 3G networks and ARM-Android embedded

system (Wang et al., 2012) 49


1

WASTEWATER TREATMENT TECHNOLOGY: A GREEN APPLICATION

IN AQUACULTURE

Abstract

Nowadays, it is well understood that we must make every possible

effort to protect the environment. The most viable and effective

approach for that purpose is the utilization of green technology. The

main challenge that green technology had to face is the operational

quest for sustainability. Sustainability of the green technology

means the way of running aquaculture industry that can continue

indefinitely into the future without damaging or depleting natural

resources. In addition, green technology could reduce the waste

and pollution by optimizing patterns of aquaculture production

and consumption of the resources. For instance, by facilitating

direct water reuse that reduce the use of hazardous chemicals

require less non-renewable energy source as well as to remove

contaminant. Aquaculture technology could be developed based

on alternatives which is based on renewable energy and materials

which caused insignificant damage to the health and environment.

Among them the most important are physic-chemical, biological,

electrochemical and bio-electrochemical technologies. Normally,

the aquaculture wastewater is physically treated as it runs

through channels or columns of charcoal (activated carbon) and

sand filters. The water ends in final sedimentation tank prior to

fish tank or discharging to water body. Biological treatment using

microorganisms would produce biomass and excess biological

sludge simultaneously with the treatment of the wastewater.

Thus, the sludge handling and disposal process would also have

strong influence on the overall environmental impact. Proper

Inaugural Ir. Ahmad.indd 1 2/25/14 12:21 PM


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management of the produced biomass is vital for the sustainability

of green technology. By proper management, the produced

biomass would contribute greatly to the production of biodiesel,

pharmaceutical precursors and bio-fertilizers whereas poor

management leads to contamination of the environment. Thus,

the use of organic coagulant such as Moringa oleifera, biofloc and

auto-flocculating microalgae Ankistrodesmus sp. were utilized in

the flocculation and biomass harvesting process which is highly

potential and energy efficient approach which could spearhead

the development of renewable energy in this third world country.

This means looking for strategies where water management is

combine with energy and nutrient recovery. As a conclusion,

engineers could provide the insights for better understanding of the

green technology treatment system development which leading

towards a sustainable standards of living to protect environment,

animal and human health especially in Malaysia.

Introduction of water

Water is known as a chemical substance with the formula of

H2O which is also known as dihydrogen monoxide. Water is the

only common substance found naturally in three common states

as solid, liquid and gaseous. Water exist as liquid at ambient

conditions, however, it often co-exists with its solid and gaseous

state as water vapor. A dynamic equilibrium where solid, liquid

and gaseous state of water coexist at specified standard

temperature and pressure is known as the triple point.

Water is the most abundant compound, covering about

two-third (71%) of the Earth’s surface. The waters of the earth

are found on land, in the ocean, and in the atmosphere. The



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distribution of water resources of the earth is shown in Figure 1.

The vast majority of the earth’s water of about 96.5% is available

in the ocean as saltwater, 1.7% in ground water (0.93% saline

and 0.75% freshwater) and 0.001% of the atmospheric water as

vapor, cloud and precipitation (mainly rainfall, only about 2.5%

of the Earth’s water is freshwater). Most of the freshwater is

available as polar ice and ground water.

Figure 1: Distribution of Earth Water (Gleick, 1993).

Properties of Water

Water is a tasteless and odorless liquid and appears colorless in

small quantities even though it has very slight blue hue. Water

vapor is invisible as a gas. Water is relatively transparent in the

visible light, near ultraviolet light and far-red light electromagnetic

spectrum. However, water absorbs most ultraviolet light, infrared

light and microwaves. The aquatic plant can live in water due to

sunlight can penetrate in a transparent water. Pure water has

a neutral pH of 7.0 which is neither basic nor acidic. Initially

rainwater is neutral. However, rainwater falling on earth is



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potentially acidic due to the dissolved carbon dioxide and sulfur

dioxide in the atmosphere.

In addition, other unique physical properties of water are the

triple point. As shown in Figure 2, the temperature and pressure

at which solid, liquid and gaseous water coexist in equilibrium is

called the triple point of water. Thus, the triple point of water is

rather a prescribed value than a measured quantity.

Figure 2: Triple point of water.

Water has relatively high melting and boiling points.

Water also has a very high specific heat capacity and heat of

vaporization. Therefore, it can absorb a huge amount of heat or

energy before it becomes hot. On the contrary, water releases

heat slowly during cooling process. The special conditions

of a high specific heat of water help organisms to regulate or

acclimatized effectively their body temperature with respect to

the surrounding. On top of that, these two unique properties of

water contribute to moderate the Earth’s temperature.



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Water is an excellent solvent which is also known as the

universal solvent. It can dissolve numerous substances or

chemical compounds such as sugars, salts, alkalis, acids and

some gases. A large water bodies such as river and ocean can

dilute specific amount of pollutants. However, there are still many

compounds that are partially or totally insoluble in water. The

soluble properties enable water to carry substances together

during surface runoff, infiltration, ground water flow as well as

water transportation in living organisms.

Water is miscible with some liquids producing the homogenous

liquid. On the other hand, water is also immiscible with some

liquids such as oil and grease, which forming distinctive layers

between liquids and water. Some substances that dissolve in

water are referred as hydrophilic or water loving substances, on

the other hand substances that do not dissolve are known as

hydrophobic or water fear substances.

Pure water functions as an excellent insulator because it

contains no ions. Since water is such a good solvent, it easily

undergoes auto-ionization especially when some solute is

dissolved. A small amount of impurities such as salt readily

separate into various ions in aqueous solution that generate

an electric current. Generally, pure water has a relatively low

electrical conductivity and it increases significantly with the

increasing of dissolved ionic material. Due to water easily

conducts heat than any other liquid (except mercury), large

water bodies such as oceans and lakes have a relatively uniform

vertical temperature profile.



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Hydrologic Cycle

Hydrology is the science of water, which involved with the

occurrence, circulation, and distribution of water on the surface

of the earth and underground as well as in the atmosphere. The

hydrologic cycle is defined as a series of processes of water

as it moves in various phases through the atmosphere, over

and through the land, such as to the river, lake and ocean, and

back to the atmosphere. In this cycle, water is conserved where

there is no water gained or lost, however the water quantity may

fluctuate due to the variations in the source and the changes

encountered during delivery.

Figure 3: Flow diagram of hydrologic cycle (Sylvan Source, 2013).

The major hydrologic processes and their flow path are

illustrated in Figure 3. Assume that the hydrologic cycle may

begin with the evaporation of water from water bodies driven by

energy from the sun. Transpiration is the biological which water

is transferred from the plant to the atmosphere as water vapor

through the leaves opening. The combinations of the evaporation

and transpiration are also known as evapo-transpiration (ET).



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The evaporated vapor, rises by convection to form clouds;

condenses at the dew point in the atmosphere and precipitates

as rain or snow onto the land and ocean surfaces. The quality of

water varies considerably as it moves through the hydrological

phases. Types of contaminants commonly found in water, follow

with some examples are illustrated in Table 1.

Table 1: Typical types of contaminants found in water (McKinney et al., 2012).

Source of Water

Surface Water

Surface water is water collecting on the ground or in a stream,

river, lake, wetland, or the ocean; it is related to water collecting

as ground water or atmospheric water. Surface water is naturally

replenished by precipitation and naturally lost through discharge

to evaporation and sub-surface seepage into the ground.

Contaminant class Types of contaminantsOxygen-demanding waste Plant and animal material

Infective agents Bacteria and viruses

Plant nutrients Fertilizer such as nitrates and phosphates

Organic chemicals Pesticides, such as DDT, detergent molecules

Inorganic chemicals Acids from coal mine drainage, inorganic chemicals such as iron from steel plant

Sediment from land erosion

Clay silt from the stream bed

Radioactive substances Waste product from mining and processing of radioactive material, radioactive isotopes after use

Heat from industry Cooling water used in steam generation of electricity



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Lakes are natural depressions of the land which are filled up

with water. The water in lakes is supplied by a direct rainfall on

the surface of the lake, by surface run-off from the catchment, or

by ground water that seeps through the soil. Fresh water lakes

have a natural outlet through which the excess water discharg-

es. On the other hand, lakes lose water through surface evapo-

ration, via the lake’s natural outlet, or through percolation from

the bottom or side of the lake to the ground water.

Rivers served its purpose around the world as a source

of irrigation and drinking water. The most typical characteristic

defining a river is a flow and not like a reservoir that contains

a fixed amount of water. A new quantity of water is passing at

any given time and location along the river. However, the flow of

river fluctuates over time, which depend on the precipitation. The

flows of some rivers fluctuate greatly especially small rivers in a

small catchment. The water quality of rivers directly influenced

by surface erosion which depend on the land use or activities in

the catchment area. Therefore, the surface water may contain

higher suspended solids as compared to ground water. Even

rainwater has traces of substances dissolved in it that were

picked up during passage through the atmosphere. Much of this

material that washes out of the atmosphere today is pollution,

but there are also natural substances present.

As rainwater passes through soil and percolates through

rocks, it dissolves some of the minerals. This process is known

as weathering. Eventually, this water with its small load of

dissolved minerals or salts reaches a stream and finally flows

into the ocean. The annual addition of dissolved salts by rivers

is only a tiny fraction of the total salt in the ocean. The dissolved

salts carried by all the world’s rivers in the ocean had happened



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for millions of years. The evaporation process only transfers

pure water to the atmosphere and left the minerals or salt in the

ocean. Another example of this phenomenon is the Great Salt

Lake and the Dead Sea. Unlike other freshwater lakes that has

an outlet, these lakes have no outlet and water escapes only by

evaporation. In addition, the hydrothermal vents also contributed

to the salinity of the where water has seeped into the rocks of the

oceanic crust and dissolved some of the minerals from the crust.

Groundwater

Ground water is defined as the water below the land surface in

soil pore spaces and in the fracture of rock formation. An aquifer

is a layer of porous media which contains and transmits water.

The upper layer of an aquifer is considered unconfined when the

water can flow directly between the surface and the saturated

zone. As shown in Figure 4, The upper level of the saturated

zone of an unconfined aquifer is known as the water table. An

aquifer that is overlain by an impermeable layer or clay is called

confined aquifer.

Figure 4: Confined and unconfined aquifers (NGWA, 2007).



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Groundwater is eventually flow to and recharged from, the

surface naturally; natural discharge often occurs at springs

and seeps, and can form oases or wetland or as the beginning

point of a stream and river. Ground water is a major source of

freshwater and serve as a natural reservoir of the water cycle.

It is protected and relatively free of pollution. The hardness in

ground water may be higher as it passes through a limestone

area.

Saltwater intrusion is the movement of saline water into

freshwater aquifers, which can lead to contamination of drinking

water sources (Figure 5). Saltwater intrusion occurs naturally

in most coastal aquifers. Since saltwater has a higher mineral

content than freshwater, it is denser and has a higher water

pressure. Water extraction or ground water pumping from

coastal freshwater wells contribute to the increase of saltwater

intrusion in coastal areas. This activity reduces the level of fresh

ground water and its pressure, thus allowing saltwater to flow

further inland. Furthermore, saltwater intrusion may also include

agricultural and drainage channels, which provide conduits for

saltwater to move inland. The phenomenon of saltwater intrusion

can be mitigated by providing recharge wells or conduit.

Figure 5: Saltwater intrusion due to overpumping of ground water at coastal area.


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A GREEN TECHNOLOGY OF WASTEWATER TREATMENT

IN AQUACULTURE

Water and wastewater treatment is very important in the

aquaculture industries. The level of water treatment depends on

the quality of the source of water. Water treatment is defined as

the processing of the source of water to achieve a water quality

standard that suitable for the specific purpose of aquaculture

requirement. The recent challenges in water treatments are the

elimination of water borne diseases. The main focus shifted from

the acute illnesses to the chronic health effects of trace quantities

of organic, inorganic and microbiological contaminants.

In the aquaculture system, the effluent wastewater must

be treated in accordance to the Department of Environment

(DOE) before discharging to the water bodies. In the case of

recirculation aquaculture system, the wastewater must be

treated up to the influent water quality before entering the

rearing tank. The water and wastewater commonly shared a

similar technology of treatment which include physico-chemical,

biological, electrochemical and bio-electrochemical treatments.

Physico-chemical Treatment

Physico-chemical treatment may include filtration, activated

carbon adsorption, ion exchange, membrane filtration and electro-

dialysis. In certain industrial wastewater treatment processes

strong or undesirable wastes are sometimes produced over

short periods of time (MECC, 2010). Since the periodic inputs

of such wastes would damage a biological treatment process,

these wastes are sometimes held, mixed with other wastewaters,



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and gradually released, thus eliminating shocks to the treatment

plant. This type of process is call equalization. Another type of

equalization can be used to even out wide variations in flow rates.

In addition, physico-chemical treatment is employed to reduce

the fluctuation of waste concentration such as organic loading

and toxic to the following biological and chemical treatments.

Filtration

Filtration is a physical process that commonly used for the

removing particulate matter in water and wastewater treatment.

Granular filter media has been found effective for removing

particulate of a wide range of sizes up to 50 µm that readily exist

in water (Osmak et al., 1997). Most surface waters may contain

high suspended solid contributed by sediment, clay, colloidal

humic compound, other organic and inorganic particulate

matter and microorganism such as algae, viruses, pathogens.

Even though much progress has been made in the aspect of

filtration modelling, there are still no reliable and comprehensive

applicable models of the filtration process (Jusoh et al., 2009).


A Green Technology of Wastewater Treatment in Aquaculture

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Figure 6: Transport mechanism in filtration (Jusoh et al., 2011).

As shown in Figure 6, suspended particles deposited within

a filter increases with time and alters the structure of the filter

media and the nature of the surface interactions between

particles and the filter media (Jusoh et al., 2011). Moreover, the

attachment process is dependent upon the interaction forces

condition, contributed by the charge of the particles, filter grains

and ionic chemicals being used in the influent. Therefore, the

filtration efficiency and the permeability of the media changes

with the operation time. The usage dual-media filter of burned

oil palm shell granule and sand will enhanced the operation

time up to five times compared to a conventional single media

sand (Jusoh et al., 2011). The production of BOPS, filtration

configuration and the results of dual-media are shown in Figure

7, Figure 8 and Figure 9.



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Figure 7: Production of BOPS from oil palm (Jusoh et al., 2009).

Figure 8: A schematic diagram of deep-bed filtration system (Jusoh et al., 2007a).



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Figure 9: Progress of specific deposit and head loss in a dual-media BOPS-sand filter with effective size of 0.6:0.5 mm. (a) filtration velocity, V = 3.62 m/hr and (b) V = 5.81 m/hr; and effective size of 0.8:0.5 mm (c) V = 3.62 m/hr and (d) V = 5.81 m/hr (Jusoh et al., 2009).



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Adsorption

Adsorption is the adhesion of atoms, ions, or molecules from

a dissolved solid that form a film on the adsorbent surface.

Activated carbon adsorption has been extensively used in

potable water and wastewater treatment. The most important

criteria of the activated carbon are the high porosity and surface

area. Activated carbon, also known as porous, has been widely

used as an adsorbent in the separation and purification of liquid.

As shown in Figure 10, activated carbon particle consist of

various structures of pores. Adsorption process has been also

adopted in aquaculture wastewater treatment to remove organic

chemicals and dissolved organic carbon (DOC) (Wang, 1993).

Aitcheson et al. (2001) studied on aquaculture therapeutants

and dissolved organic carbon onto the coal-based granular

activated carbon. They found that the therapeutants Malachite

Green, Chloramine-T and Oxytetracycline were generally

more strongly adsorbed than the dissolved organic carbon.

This therapeutants compounds were utilized in controlling fish

parasites and diseases.



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Figure 10: Pore structure of activated carbon particle consist of macropore (width greater than 50nm), mesopore (between 2 - 50nm) and micropore (less than 2nm).

According to Mostofa et al. (2005) the main components of

dissolved organic carbon in aquaculture wastewater are fulvic

acids, humic acids, carbohydrates, protein-like substance,

phenols, organic peroxides and low molecular weight aldehydes.

The author also had compared the characteristics between

coconut shell activated carbon (CSAC) and palm shell activated

carbon (PSAC) in term of surface area analysis (Jusoh et

al., 2011; Jusoh et al., 2009). As shown in Table 2, Brunauer,

Emmett and Teller (BET) was performed for the activated carbon

prior to the absorption experiments on various contaminants and

toxic compounds. In addition, Jusoh et al. (2011) and Jusoh et al.



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(2005) also reported that GAC could be used to effectively adsorb

pesticide (malathion) from agricultural surface water runoff. This

would reduce the risk of water contamination in the aquaculture

ponds. In the case of heavy metal treatment from water source,

Jusoh et al. (2007b) had predicted the breakthrough curve and

obtain the adsorption capacity of cadmium and lead on GAC.

Table 2: BET surface area analysis of CSAC and PSAC (Jusoh et al., 2011).

Membrane Filtration

Membrane filtration such as reverse osmosis (RO) has potential

to remove proteins, organic chemical and ions in brackish water

and sea water (Afonso et al., 2004; Hilal et al., 2004; Kim et

al., 2009). RO has high efficiency performance in permeability

of selective ion, unchanged molecular structure at room

temperature, no product accumulation in the membrane and

environmental friendly. However, the capital and operation cost

of RO are more expensive. Lee et al. (2004) had reported the

comparison of the physical properties of Ultrafiltration (UF)

and Microfiltration (MF) membranes (Table 3). Moreover, the

UF and nanofiltration (NF) membrane technology are potential

in removing ammonia–nitrogen from the aquaculture system

(Noráaini et al., 2009).

Type of Granular Activated Carbon

Surface Area(m2/g)

Pore Volume(cc/g)

Median Pore Radius

(A)CSAC 850 281 21.78PSAC 788 261 17.27



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Table 3: Specifications and properties of UF and MF membranes (Lee et al., 2004).

* At pH 7.0 and 5mM KCl.

The detail studies aimed to investigate the effect of polymer

concentration on the morphology and perfor mance of an

asymmetric UF membrane for bovine serum albumin (BSA)

separation was reported by Ali et al. (2011). BSA representative

the excreted fish proteins, ammonia and faeces. This research

also proved that polymer concentration would greatly affect the

membrane performance and structural properties, consecutively

enhancing the membranes ability for BSA separation (Ali et al.,

2005). Further investigation has been conducted on the potential

of nano-filtration membrane technology in removing ammonia–

nitrogen from the aquaculture system (Ali et al., 2010). Membrane

productivity and separation performance were assessed via pure

water, salt and ammonia–nitrogen permeation experiments. The

Membrane type

Ultrafiltration (UF) Microfiltration (MF)

Hydrophobic Hydrophilic Hydrophobic Hydrophilic

Membrane code PES, Orelis

YM100, Millipore

GVHP, Millipore

GSWP, Millipore

Pore size 100 kDa 100 kDa 0.22 µm 0.22 µm

Materials PES Regenerated cellulose PVDFMixed

cellulose ester

Pure water permeability

5.15 (gal/ft2 day

psi)

5.15 (gal/ft2 day

psi)

5.15 (gal/ft2 day

psi)

5.15 (gal/ft2 day

psi)

122(L/m2 h bar)

122(L/m2 h bar)

122(L/m2 h bar)

122(L/m2 h bar)

Contact angle 58° 18° 83° 19°

Zeta potential

(mV)*-32 -3 -7 +20

Roughness 6.4 22.9 94.1 96.7



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study managed to remove about 68% of ammonia–nitrogen

and proved nano-membrane technology as a potential in the

treatment of aquaculture wastewater.

Ion Exchange

Ion exchange is the process where ions in solution are transferred

to a solid matrix which, in turn releases ions of a different type

with the same polarity. In other words the ions in solutions

are substituted by different ions originally exist in the solid. Ion

exchange is used in the purification and decontamination of

aqueous solutions solid polymeric or mineral as ion exchangers.

Typical ion exchangers are resins, zeolites, montmorillonite and

soil humus (GATCO, 2012). In fact, ion exchangers are widely

used for water softening by exchanging calcium and magnesium

cations with sodium or hydrogen cations. In aquaculture

wastewater, ammonium ions are normally accompanied with

organic pollutant. Heterotrophic bacteria, which utilize the organic

species, inhibit the growth of nitrifying bacteria to consume

ammonia. Thus, ion exchangers offer an alternative method to

remove ammonia in aquaculture wastewater. Weatherley and

Miladinovic (2004) had carried out experiment to compare the

ion exchange uptake of ammonium ion onto naturally available

minerals, clinoptolite and mordenite. Clinoptilolite is a zeolite

occurring in abundance, especially in volcanic areas and it is

known to have high affinity for ammonium ions. Table 4 shows

the ammonia, magnesium, calcium and potassium ions uptake

on the clinoptilotile via ion exchange mechanism.



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Table 4: Uptake data for ammonium ion onto clinoptilolite in the presence of magnesium, calcium and potassium ions (Weatherley & Miladinovic, 2004).

Jorgensen and Weatherley (2003) investigated on ammonia

removal from wastewater by ion exchange clinoptilolite in

the presence of organic contaminants. In the experiment,

the ammonium ion uptake equilibria onto clinoptilolite was

successfully determined (Figure 11). It was also found that in

most of the cases studied, the presence of organic compounds

enhances the uptake of ammonium ion onto the ion exchangers.

On top of that, ion exchange offer more flexible system, which

can responds rapidly to changes in feed water concentration or

organic loading that associated with flow rate. It can operate

on-line as it immediate responds and offer significantly greater

turndown flexibility compared with bio-filtration. Another

advantage of ion exchange is that the water treatment can

be maintained over a wider range of concentrations and

temperatures. Therefore, ion exchange technique is more

appropriate to be applied to aquaculture systems for water

treatment during fish transportation and as a backup system to

biological filtration system.

Initial ammonia

concentration (N-mg/L)

Percentage of removed ammonia (%)

NH4+ Mg Ca K

10 98.82 94.73 93.66 95.95

40 92.37 86.68 84.78 89.25

70 83.61 79.45 75.65 80.18

90 75.97 71.76 68.50 71.30

150 57.45 54.43 50.40 52.17

200 46.28 42.69 40.09 41.99



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Figure 11: Ammonium ion uptake equilibria onto clinoptilolite (Jorgensen & Weatherley, 2003).

Ultra-violet and Ozonation

Higher stocking density would result in greater stress and related

health implication on fish stock. Common disinfection methods

used in treating water and wastewater are chlorination, ozonation

and ultra-violet (UV) light facilities. However, chlorination is not

suitable for recirculation aquaculture system since this method

produces residual chlorine in the treated water which is harmful

to the aquatic lives. Therefore, RAS commonly utilized UV light

or ozone to destroy any pathogens, parasites and diseases

that may exist in water. Ozone is also helping in oxidizing nitrite

to nitrate, organic matter and total ammonia nitrogen (Aloui et

al., 2009; Bullock et al., 1997). UV light is used together with

ozone treatment because it will destroy excess ozone residuals

(Summerfelt, 2003). UV consists of electromagnetic radiation

of wavelengths ranging from 10 to 400 nanometer (nm). For

instance, UV light at wavelength of 254 nm penetrates the cell

wall of the microorganism. The UV energy permanently alters

the DNA structure of the microorganism. Thus, this inactivates

the microorganism and renders it unable to reproduce or infect.



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The main advantage is that the UV light triggers inactivation

process in a very short time.

Ozone has been successfully improved water quality

in recirculation aquaculture system by reducing parameter

such as carbonaceous oxygen demand, nitrogenous waste,

total suspended solid and color (Summerfelt et al., 1997;

Summerfelt et al., 2004). As shown in Table 5, Buffle et al. 2006)

reported the effectiveness of ozone for the oxidation of harmful

pharmaceutical effluent and pathogen inactivation. In fact, the

main function of ozone in the recirculation aquaculture system

is to eliminate bacteria levels and any fish pathogen (Sharrer

& Summerfelt, 2007; Summerfelt et al., 2009), (Buffle et al.,

2006). Furthermore, Park et al. (2011) evaluated the effects of

two different ozone doses on seawater recirculating systems for

black sea bream Acanthopagrus schlegeli (Bleeker): They found

that ozonation improved the removal efficiency of heterotrophic

bacteria, even at the lowest concentration.

Table 5: Second-order rate constants of pharmaceuticals oxidation and pathogens inactivation at pH 8 and T = 20°C (Huber et al., 2005; von Gunten, 2003).

Pharmaceuticals oxidation

K’’Ozone(M-1 s-1)

K’’Hydroxide(M-1 s-1)

Pathogens inactivation

K’’Ozone(M-1 s-1)

17α-ethinylestradiol 3.16 x 107 9.8 x 109 Escherichia coli 1.04 x 105

Sulfamethoxazol 2.4 x 106 5.5 x 109 Escherichia coli 6 x 104

Diclofenac 105 7.5 x 109 Escherichia coli 2.3 x 104

Carbamazepine 3 x 105 8.8 x 109 Escherichia coli 1.2 x 104

Bezafibrate 5.9 x 102 7.4 x 109 Escherichia coli 6.7 x 102



24

Solar Distillation

Solar water distillation is a natural phenomenon on earth that

heats water from water bodies such as rivers, lakes and seas,

evaporates it to water vapor, and condenses it as cloud to

fall back on earth as precipitation. Thus, solar still distillation

represent this natural phenomenon on a small scale. Distillation

is one of many processes that commonly used in laboratory as

well as in community to obtain such pure water. It functions by

evaporating the water from a mixture (or saline) solution and

subsequent condensation of the mineral-free vapor.

Aybar et al. (2005) have investigated on an inclined solar

water distillation system. The results found that the wicks plate

increased the water generation about three times as compared

to bare plate. Therefore, solar distillation process succeed to

remove impurities such as salts, heavy metals and eliminate

microbiological organisms. The end result is a relatively pure

water and in fact cleaner than the purest rainwater. Various

active distillation systems have been developed to overcome

such a lower distillate output in passive solar stills. The solar

distillation proves to be an economical and eco-friendly

technique particularly in suburban areas (Sampathkumar et al.,

2010). In the recent report, Mokhtar et al. (2012) have studied on

the techno-economic assessment for a case study in New South

Wales, Australia using actual weather and wholesale electricity

price data. It is shown that the proposed technology can be

economically viable for solar collector at current retail electricity

prices This is one of the promising technologies for reducing

carbon dioxide from existing fossil fuel power plant.



25

Biological Treatment

There are commonly five types of biological treatment used in

aquaculture system including trickling filter, fluidized bed reactor,

rotating biological contactor (RBC) and reedbed (constructed

wetland). These bio-filters have the ability to remove ammonia,

nitrites and dissolved organic solids. Fish produce ammonia,

nitrites and uneaten food as toxic metabolic waste products.

These waste materials need to be treated or converted to less

harmful compound such as nitrate. Normally, three types of

aerobic microorganism colonized bio-filters for aquaculture that

are heteretrophic bacteria, Nitrosomonas sp. and Nitrospira

sp.. Heterotrophic bacteria utilized the dissolved carbonaceous

material as their food source. Nitrosomonas sp. bacteria convert

ammonia to nitrite whereas Nitrospira sp. utilize nitrite to produce

nitrates as a waste product. In order to have a more effective

treatment in removing ammonia, the carbonaceous BOD have

to be removed prior to the bio-filter system.

Bio-filter bacteria (such as Pseudomonas sp. and Nitrobacter

sp.) convert ammonia to nitrite and then nitrate in the nitrification

process as illustrated in Eqn. 2.1 and 2.2.

Ammonia, NH3 + O2 → Nitrite, NO2 (2.1)

Nitrite, NO2 + O2 → Nitrate, NO3 (2.2)

The appropriate materials used in the bio-filter should be

inert material, non-corrodible, UV-resistant, resistant to decay

and impervious to chemical attack. The bio-filter should be

inexpensive to build and easy in operation and maintenance.

Moreover, the bio-filter should be tough enough to withstand the

wear and tear of the aquacultural environment. The energy cost

to operate the bio-filter should be minimal, especially in terms



26

of running operation cost. The bio-filter should normally be self

cleaning and does not have any inherent dangers to the aquatic

species and operator.

Trickling Filter and Bio-tower

Trickling filters are one of the most conventional fixed film

biological filters. As shown in Figure 12, rickling filters commonly

filled with packed media of rock, coal or porous media for effluent

wastewater treatment. The high surface area of media provides

the substrate enhancing the growth of a bio-film. In some cases,

air is forced into the filter media to increase the amount of

oxygen for the effective oxidation. Since trickling filters are an

aerobic process, additional oxygen supply is required. Trickling

filters also act as effective strippers to remove carbon dioxide,

hydrogen sulfide, nitrogen or other undesirable volatile gases.

The major drawback of this filter is the energy cost especially in

terms of pumps, aerators and compressors. Thus, trickling filters

is rather rugged, easy to operate and low maintenance cost. A

trickling filter can be upgraded to a bio-tower by supplying extra

capacity (surface area) in the bio-filter to allow a huge number of

bacteria to grow. On top of that, this method helps in making a

longer plug flow path through the bio-filter.



27

Figure 12: Schematic diagram of typical complete trickling filter system (Chowdhury et al., 2010).

Asaduzzaman (2006) have been studied on design and

development of a steady state close-cycle aquaculture system

that equipped with trickling filter for intensive culture of

freshwater fish species at Universiti Malaysia Terengganu. Their

findings showed that the density of Oreochromis niloticus (red

tilapia) of about 76 kg/m3 produced a better performance in

terms specific growth rate (SGR), feed conversion ratio (FCR)

and protein efficiency rato (PER) with the ratio of volume of the

rearing unit and the volume of the biological filter of 5:1 compared

to other ratio of 45:1, 23:1 and 10:1. The biomass yield was 5.36,

24.36 and 42.05 kg/m3 for the ratio of the 45:1, 23:1 and 10:1,

respectively. The efficiency of the trickling filter was 37, 54, 70

and 70%, for the ratio of 45:1, 23:1, 10:1 and 5:1, respectively.

On top of that, this system was producing TAN at the rate of

255.90, 454.35, 308.12 and 548.35 g/day, respectively, and at



28

the same time the removing of TAN was at the rate of 226.87,

400.78, 284.80 and 527.62 g/day, respectively.

Rotating Biological Contactor

Rotating Biological Contactors (RBC) were commonly used

in domestic wastewater treatment and later being used in

aquaculture wastewater. The RBC reactor is utilizing a unique

attached-growth of bio-film, similar to the trickling filter. A typical

design consist of a bundle of plastic packing that are installed

to a horizontal rotating shaft. Several modules are normally

arranged in parallel and/or in series to accommodate with the

flow and treatment requirements. The disks are about 40 to 50

percent submerged in the wastewater with a very slow speed of

1 to 5 rpm (Brazil, 2006). Alternating exposure to nutrient in the

wastewater and oxygen during rotation is similar concept to the

trickling filter with rotating distributor. Microorganisms growing on

the disks surface treat the nutrient from wastewater and absorb

oxygen from the air to sustain their aerobic metabolic processes.

A treatment system begins with primary sedimentation

preceding the RBC reactor and finally followed by secondary

sedimentation. Waste sludge is mainly withdrawn from the

primary and secondary clarifiers for disposal. RBC units are

preferably protected either under separate plastic covers lined

with insulation or in a building with adequate ventilation. The

main advantages of RBC are high specific surface area, low

energy requirement, less chances of clogging, relatively short

hydraulic retention time and higher tolerance to toxic substrate

(Chowdhury et al., 2010).



29

Fluidized Bed Filters

Regular sand filter used for potable water filters are inappropriate

to be used as a biofilter for aquaculture. This is due to the rapid

bio-film buildup in the void spaces between the grains and

produce higher head losses or pressure drop across the filter.

Therefore, more frequent back washing is required and the

beneficial active bio-film is removed each time. On the other

hand, fluidized bed filter can overcome these problems and have

been successfully adapted for aquaculture wastewater filtrations

(Crab et al., 2007; Summerfelt, 2006). A sand filter becomes

fluidized when the sufficient water upflow velocity raise the

grains up. This means that the drag on each particle is sufficient

to overcome the weight of the grain particle and the particle is

suspended in the stream of water.

Fluidized bed filters have several advantages over any other

types of biofilter because they packed higher biologically active

surface area in such a tall column. Thus, it has a small footprint

and alse develop self cleaning as well as higher tolerance with

different nutrient loadings. In contrast, fluidized bed filters have

several disadvantages since they required relatively high energy

requirement to overcome high pressure drop. Furthermore, they

required an additional aeration system to enhance the treatment

performance (Summerfelt, 2006). (Guerdat et al., 2011) have

evaluated the effect of organic carbon on biological filtration

performance in a large scale RAS. The system contained three

types of filters: fluidized sand, floating bead, and moving bed.

The study was based on a 60m3 tilapia with average daily feed

rates of 45 kg using a 40% protein feed and an average biomass

of 6750 kg. The effect of elevated organic carbon concentrations



30

on total ammoniacal nitrogen (TAN) removal rates was

evaluated and determined based on biofilter media volume. The

performance of fluidized bed filter is comparable to floating bead

and moving bed.

Reed Bed and Constructed Wetland

The combination of aquaculture and hydroponics are known

as Aquaponics aquaculture systems. In addition to commercial

terrestrial plant grown in a hydroponics system, aquatic plants

such as water hyacinths and duckweed can be used to absorb

nitrates and phosphorus from the aquaculture wastewater.

Emergent plants required water for their root support while their

stems and leaves shoot up above the water surface. The most

common emergent plants locally available with high economic

value are water spinach (Ipomea aquatica) and Watercress

(Nasturtium officinale). Substrates that are normally used are

sand and gravel. The main advantage of the water spinach and

watercress are rapidly growing and can be regularly harvested.

Submerged plants grow completely under water with their

root system attach into substrates such as sand. For example,

submerged aquarium plants like eel grass (Vallisneria sp.) can

be grown in RAS (Figure 13). Furthermore, they also useful

in mitigating the growth of phytoplankton and enhancing the

production of dissolved oxygen in water. The major nutrients

which are required in relatively large quantities to support

the plant growth may include nitrate, phosphate, potassium,

calcium, sulfur oxide and magnesium. Hydroponic plants may

require 10 to 20 percent of total nitrogen as ammonium to

stimulate vegetative growth. Theoretical scheme of ammonia in

recirculation aquaculture system is shown in Figure 14. However,



31

a sufficient nitrogen requirement can be produced by the fish in

aquaponic systems and thus no additional nitrogen required.

Figure 13: Isometric view of RAS prototype (Endut et al., 2011; Endut et al., 2010).

Figure 14: Theoretical scheme of ammonia in RAS.



32

Nutrient removal is essential for aquaculture wastewater

treatment to protect receiving water from eutrophication and for

potential reuse of the treated water. Figure 15 shows the nitrogen

composition from nitrogen mass balance of the production

system of aquaculture pond. The integration of aquaculture

with agri culture appears to be an excellent way of saving water,

disposing aquaculture wastewater and pro viding fertilizer to the

agricultural crop.

Endut et al. (2011) evaluated aquaponic recirculation

system (ARS) performance in removing inorganic nitrogen and

phosphate from aquaculture wastewater using water spinach

(Ipomoea aquatica) and mustard green (Brassica juncea) in

Universiti Malaysia Terengganu. Overall results suggest that

water spinach is better than mustard green in nutrient removal in

the aquaponics system used due to its root structures provided

more microbial attachment sites, sufficient wastewater residence

time, trapping and settlement of sus pended particles, surface

area for pollutant adsorption, uptake, and assimilation in plant

tissues (Endut et al., 2011).

Figure 15: Nitrogen mass balance for production system based on the mass fraction of nitrogen composition relative to the culture feed input.



33

Microalgae Phytoremediation

Microalgae provide a very promising alternative for wastewater

treatment. Its population will be co-propagated as a result of

organic matter bioconversion and incorporation of inorganic

carbon such from carbon dioxide into the cell biomass (Jeong

et al., 2003). Consequently, microalgae phytoremediation also

act in producing microalgae biomass to fulfil the demand for

biofuel productions (Brennan & Owende, 2010; Sharif Hossain

et al., 2008). In addition, microalgae technology also reported to

significantly contribute to the environmental conservation. With

moderate technology and expertise, maintenance and cultivation

of pure culture microalgae could be carried out without any

difficulties. As shown in Figure 16, the upscale of Chlorella sp.

from primary stock culture to 30L mass culture was performed

at the Institute of Tropical Aquaculture by the author’s research

team which focused on the removal of ammonia and phosphate

from aquaculture wastewater.

Figure 16: Upscale procedure for microalgae cultivation. (a) Colony isolation on agar plate, (b) Subculture in 250 mL sterile medium, (c) and (d) Cultivation in 5000 mL and 30 L acrylic tank.



34

Nowadays, phytoremediation using microalgae mainly

focused on the use of immobilized culture. Efforts on the

application of suspended microalgae phytoremediation became

less apparent due to the difficulties in biomass separation and

culture maintenance. In immobilized culture, the microalgae

is embedded within the thin film of permeable membrane or

within porous alginate beads. Thus, the microalgae biomass

are immobilized or trapped within the fibrous structure of the

agar preventing free microalgae cell from being suspended in

the water column. Figure 17 shows the utilization of immobilized

microalgae culture in phytoremediating aquaculture wastewater.

Once the treatment had been completed, alginate beads or

membrane is discarded using nets leaving clear treated water.

Its advantage is the easiness of separating microalgae biomass

from the treated with the expense of valuable alginates and

agarose membrane.

Figure 17: Aquaculture wastewater treatment using immobilized microalgae. (a) Nannochloropsis sp. is immobilized in alginate beads, (b) Alginate beads turns into darker green due to microalgae growth (de-Bashan & Bashan, 2010).

In the other hand, the author focused on the utilization of

suspended microalgae in the believe of unlimited absorption

capability and growth performance promised by the



35

characteristics of large surface area per volume as compared

to the immobilized culture. Prior to the further researches

on the potential of microalgae as aquaculture wastewater

phytoremediator, the author had screened the best microalgae

species from those isolated from the South China Sea as shown

in Figure 18 with highest ammonia and phosphate removal

efficiency, tolerance to wide range of salinity, temperature

fluctuations and illumination irregularity (Ahmad et al., 2013;

Fathurrahman et al., 2013).

Figure 18: Eight different species of microalgae isolated from the South China Sea.

In addition, field study involving the use of marine microalgae,

Chlorella sp. and Chaetoceros sp. was also performed by the

author and the research team. The biological treatment of

aquaculture wastewater incorporating microalgae is reported

to be successfully adopted in the open pond and enclosed

photobioreactor system (Acién Fernández et al., 2003; Arbib

et al., 2012; Christenson & Sims, 2011). A knowledge transfer

program involving the technique in maintaining and upscaling

microalgae culture was done between the research team with

Kerapu Online Hatchery, Besut on January 2013. Maintenance



36

of indoor culture and upscaling of outdoor with very economical

cost was pioneered for the adoption of the technology for the

industry (Figure 19).

Figure 19: Microalgae technology transfer with Kerapu Online Hatchery, Besut, Terengganu. (a) Maintenance of stock culture in control room condition, (b) Cultivation of Chlorella sp. under direct sunlight, (c) Outdoor low-cost cultivation of microalgae.

Marine microalgae were cultivated at community-based

hatchery located at Kampung Air Tawar, Besut, Terengganu

for the purpose of wastewater treatment and live feeds to

fish hatchlings and zooplanktons. In this project, the hatchery

manage to maintain the microalgae production with regular

advice from the university. Figure 20 shows the potential of

marine microalgae mass cultivation to be adopted and practiced

by the community.



37

Figure 20: Cultivation of Chlorella sp. for outdoor mass cultivation at Kerapu Online Hatchery, Besut, Terengganu. (a) Inoculation of microalgae on Day 1, (b and c) Growth and increase of biomass density on Day 3 - 5, (d) Microalgae ready for feeding.

Bio-floc Technology

Bio-floc encourages the development a microbial community

in the pond or raceway. Once bio-floc community established,

microbial-dominated areas are more stable than algae-

dominated areas. The microbial accumulate in flocs and

consume the nitrogenous waste more effectively than algae.

Microbial community continuously convert nitrogenous waste

into high protein feed source for the aquatic organism (Crab

et al., 2009). This conversion processes enhanced in a well

balanced of carbon and nitrogen composition as shown in Figure

21. As shown in Figure 22, bio-flocs consist of variety of bacteria,

microalgae (phytoplankton), fungi, aggregates of living and dead

particulate organic matter suspend in water. These bio-flocs

capable of absorbing dissolved and organic particulate waste



38

and convert it into microbial biomass. Thus, bio-flocs assist in

reducing feed and disposal waste cost. In order to measure

the amount of bioflocs, Imhoff cones is use as a simple tool as

shown in Figure 22. The following procedure is recommended:

transfer a water sample from the pond to the Imhoff cone and

let it stand for 15-20 minutes and then measure the volume of

settled bioflocs.

Figure 21: Symbiotic relationship of microorganism in biofloc technology (Peavy et al., 1985).

In the case of shrimp farming in pond with intensive aeration,

the recycling of waste is commonly carried out in the following

tank that equipped with bio-flocs reactor. Microorganisms are kept

in suspension in the bio-reactor where flocs is provided. Organic

material and nitrogenous waste are absorbed and assimilated

by the bio-flocs. The uptake of inorganic nitrogen by bacteria



39

is reported to be effective when the C/N ratio is greater than 10

(Burford et al., 2003). According to Zhu and Chen (2001), further

addition of organic carbon contributed to heterotrophic bacteria

growth and resulting in limitation of the denitrification process.

Figure 22: Induction of bio-flocs formation at Freshwater Hatchery, Faculty of Science and Technology UMT. (a) Formation of bio-flocs in catfish tank, (b) Measurement of bio-flocs in imhoff cones, (c) Microorganism composition in bio-flocs complex.

Electrochemical Technology

Electrochemical is applying electro-chemical processes in

any types of industrial application such as nanotechnologies,

synthesis of pharmaceutical products, wastewater treatment and

heavy metal recovery. One of the most relevant applications of

(a)

(b) (c)



40

the electrochemical technology in aquaculture is the treatment

of wastewater with high organic compounds. Electro-chemical

technologies have several advantages over biological treatments

such as the ability in treating high toxic waste, operation at

ambient temperature and environmental friendly. Electrochemical

concept can be used in water and wastewater treatment in terms

of deposition for heavy metal recovery, coagulation of suspended

solid, floatation in generating gas bubbles attaching to flocs,

oxidation of chlorine and ozone and microbial disinfection.

Electrochemical Reduction of Nitrate

Electrochemical technology can be adopted to induce the

reduction of nitrate and nitrite ions to nitrogen on the cathode

(Figure 23). Li et al. (2009) studied on the simultaneous reduction

of nitrate and oxidation using electro chemical technology. They

achieved nitrate removal of about 90% a current density of 40

mA/cm2. A further improvement made by Li et al. (2010) on the

nitrate removal by adopting iron and titanium as cathode and

anode, respectively. They found out the nitrate removals are about

93 and 87% with the absence and presence of 500 mg/L NaCl,

respectively. Yunqing and Jianwei (2011) investigated regarding

the electrochemical process found that ammonia and nitrite

were indirectly oxidized by electro generating hyperchlorous

acid, whereas organic compounds were directly oxidized at the

anode surface. They found out in order to achieve simultaneous

removal of total ammonia nitrogen, nitrite and chemical oxygen

demand, the current had to be controlled over 23.4 A/m2.



41

Figure 23: Mechanism of nitrate electro-reduction using zinc and copper electrodes.

Electrochemical Oxidation of Organic Compound

Electrochemical oxidation of organic method is highly efficient

and economical for wastewater that contains toxic or non-

biodegradable organic pollutants. The wastewater may oxidize

with ozone, which is a powerful oxidant however the total organic

carbon removal was quite low (less than 30%). The oxidation by

using hydrogen peroxide in the presence of iron as a catalyst is

also given the same result of the lower total organic removal.

Therefore, research on the electrochemical oxidation of organic

compounds from wastewater has been carried out. Diaz et al.

(2011) have investigated the kinetics of electro-oxidation of

ammonia, nitrites and COD from a marine RAS using boron doped

diamond (BDD) anodes. They used current density in the range

of 5 to 50 A m-2 and kinetic constants for the anodic oxidation.

Furthermore, the formation of free chlorine and trihalomethanes

by-products (THMs) was monitored during the electro-oxidation



42

process. However, a hybrid process that combines an adsorption

step onto activated carbon to the electro oxidation cell in order to

remove the generated THMS and residual chlorine is currently

being studied.

Bio-electrochemical Technology

The utilization of microorganisms in catalyzing an oxidation and/

or reduction reaction at an anode and cathode is known as bio-

electrochemical system (BES). The anode and the cathode are

installed and connected through an electrical circuit. BES can

be divided into two major groups which are microbial fuel cell

(MFC), where the electrical power is generated from the circuit

and microbial electrolysis cell (MEC). This BES is also known as

bio-energy and bio-fuel cell (Mook et al., 2012; Rabaey, 2010).

Bio-electrochemical systems applied biological capacities of

microbes, enzymes and plants for the catalysis of electrochemical

reactions. Emerging systems biology approaches to the study

of microorganisms interacting with electrodes are expected to

contribute to improved microbial fuel cells (Clauwaert et al., 2008).

Only recently, electron transfer in both anodes and cathodes has

been described without the external addition of artificial electron

mediators (Bond & Lovley, 2003; Clauwaert et al., 2007; Rabaey

et al., 2005). Among typical application of BES are Plant-

Microbial Fuel Cell, Enzymatic Fuel Cells, Microbial Fuel Cells,

Microbial Electrolysis Cells, Microbial Electrosynthesis Cells and

Microbial Desalination Cells (Rozendal et al., 2008).

BES have recently emerged as a promising technology for

an alternative or renewable energy as well as for providing many

valuable products such as ethanol, hydrogen and other organic



43

compounds. On top of that BES appear as an alternative for

treating various types wastewaters and simultaneously fit within

the biorefinery purposes. BES have been effectively removed of

organic materials as anodic oxidation with a lower sludge yield

compared to a common aerobic activated sludge processes.

Bio-electrochemical Reduction of Nitrate

Biological denitrification is capable of reducing inorganic nitrate

compounds to harmless nitrogen gas (Figure 24). Based

on numerous studies in biological denitrification of nitrate in

aquaculture wastewater, it was confirmed that potential of BES

towards the remediation of different concentrations of nitrate

is highly potential. BES can be utilized to eliminate nitrate

through a cathodic reduction process. Denitrifying bacteria are

accommodated to enhance nitrate removing efficiency. Review

of heterotrophic and autotrophic denitrifications with different

food and energy sources concluded that autotrophic denitrifiers

are more efficient in denitrification (Ghafari et al., 2008). For

instance, autotrophic denitrifying microorganisms use hydrogen

gas as the electron donor that is produced on the cathode

surface by electrolysis of water (Zhang et al., 2006). Hydrogen

gas is used to reduce nitrate to nitrite which further reacts with

hydrogen to form nitric oxide. Then, this compound continues to

be reduced to nitrous oxide and finally forms nitrogen gas.



44

Figure 24: Mechanism of bio-electrochemical reduction of nitrate. (a) Interaction between biofilm and cathode, (b) Nitrate bio-electroduction reaction steps.

Bio-electrochemical Oxidation of Organic Compound

Microbial production of electricity may become a newly potential

form of bio-energy since it offers the possibility of extracting

electrical current from a wide range of complex organic wastes

and renewable biomass. However, the limitation of microbial fuel

cells as an alternative energy source is that the power densities

are still low for most regular applications. It is important to

understand the range of microorganisms that known to function

either as electrode-reducing at the anode or as electrode-

oxidizing microorganisms at the cathode. Microorganisms that

can completely oxidize organic compounds with an electrode

serving as the sole electron acceptor are expected to be the

primary contributors to power production (Figure 25).

Current practical applications are sediment microbial fuel cells

that extract electrons from organic matter in marine sediments



45

to power electronic monitoring devices and possibly sediment

fuel cells which can serve as a light source or battery charger

in off-grid areas (Lovley, 2008). Substantial improvements will

be required before other commonly projected uses of microbial

fuel cells, such as large-scale conversion of organic wastes and

biomass to electricity, or powering vehicles, mobile electronic

devices, or households with suitably scaled microbial fuel cells

will be possible.

Figure 25: Mechanism of bio-electrochemical oxidation of organic matter.


47

WATER MONITORING AND CONTROL SYSTEM

The implementation of process control system technique into

the monitoring and control will assist in the efficient execution

and management of the water quality for the aquaculture system

and finally contribute to the increase in aquaculture production.

Control system can be applied in various aquaculture facilities

such as water quality monitoring, water flow, aerators, pumps,

alarms and communication devices. In addition, these systems

can be customized to serve from the simplest to the most

complex aquaculture system.

Ali (2010) had developed the remote monitoring and

control system for aquaculture system in Universiti Malaysia

Terengganu. The developed system is connected to the sensors

(temperature, pH and dissolved oxygen), data acquisition

module, monitoring software and water quality database system.

The system was developed by connecting water quality sensors

with Remote Terminal Unit (RTU) which acts as an interfacing

device between these sensors and a host computer. Within the

system development as shown in Figure 26, it is intended that

database system provides the platform to record water quality

data so that operators will be able to study and analyses the

water quality related data for optimizing the aquaculture system.



48

Figure 26: A real-time control system for recirculation aquaculture (Ali, 2010).

Another new technology of monitoring and control system

was developed by Qi et al. (2011) based on wireless sensor

network for RAS. With the advance of communication technology,

the recent progress of remote monitoring system for aquaculture

system was developed based on 3G networks and ARM-Android

embedded system (Wang et al., 2012). Structure of the remote

monitoring system is as shown on Figure 27. Automatic control

module and detecting module of aquaculture detecting terminal

can get real time water quality parameters and video information,

which is saved to storage module, compressed by the CPU of the

control module, and later sent to the portable monitor terminal

through the wireless network of 3G module.


Water Monitoring and Control System

49

Figure 27: Remote monitoring system based on 3G networks and ARM-Android embedded system (Wang et al., 2012).


51

CONCLUSION

Aquaculture industry could be dependent on the surface and

ground water as its water source. The selection of water source

is typically based on the quality and quantity of water that can be

provided. Aquaculture industry should possess water source with

a very minimal treatment and the most cost effective. Selection

of aquaculture technology commonly based on the availability

of water source, economic affordability and the technological

know-how of the industry. Various types of aquaculture system

range from a high water requirement system as a flow through

raceway to a very low water usage as in high-tech recirculating

aquaculture systems.

Thus, various types of aquaculture wastewater treatment

available that focused on specific aquaculture system. There is a

variety of water and wastewater treatment technologies could be

accommodated in providing such a high quality of water source

and to render the wastewater reusable or safely discharged into

the environment. However, the most important consideration

for the aquaculture wastewater treatment system should be

based on green technology of physico-chemical and biological

treatments.

Phytoremediation is a biological or green technology

in removing nutrient and organic pollutant in aquaculture.

Aquaponics is a kind of green technology used in the same

principle of constructed wetlands that can be used as

recirculation aquaculture system. Subsurface flow constructed

wetland is the effective green technology in removing

Escherichia coli and total coliforms. Current trends of research



52

focused on the electrochemical and bio-electrochemical which

is a green technology for water and wastewater treatment.

Several alternative wastewater treatment is the use of plant

and microorganism such as Moringa oleifera, biofloc and auto-

flocculating microalgae Ankistrodesmus sp. to absorb the

pollutant from the generated wastewater.

Activated sludge has been the most frequently used

biological process in wastewater treatment. Biological treatment

using microorganisms would produce biomass simultaneously

with the treatment of the wastewater. Thus, proper management

of the biomass is crucial for the sustainability of green technology.

The biomass would contribute greatly to the production of

biodiesel, pharmaceutical precursors and bio-fertilizers however

mismanagement of it would leads to the contamination of the

environment. Therefore, the use of organic coagulant and

innovative biomass harvesting process would be highly potential

and energy efficient approach which could spearhead the

development of renewable energy in Malaysia.


53

References

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Inaugural Ir. Ahmad (i).indd 1 2/23/14 9:48 AM - Universiti Malaysia Terengganu · 2017. 1. 26. ·...

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