July 2010, Volume 1, No. 1 International Journal of Chemical and Environmental Engineering

Onsite Greywater Treatment Using Septic Tank Followed by Intermittent Sand Filter- A Case Study of Abu Al Farth Village in Jordan Almoayied K. Assayed*, Sahar S. Dalahmeh, Wael T. Suleiman Royal Scientific Society-Environmental Research Centre Al-Jubaiha Jordan * Corresponding Author email: a.assayed@surrey.ac.uk Abstract This paper aims at presenting a case study of onsite greywater treatment in small rural community in Jordan using septic tank followed by intermittent sand filter. A 1 m3 septic tank followed by 6m2 intermittent sand filter of 1m in depth were used to treat an average flow of 150L/Day of greywater effluent from single household in Abu Al Farth Village in the Badia of Jordan. The raw greywater has a total BOD5 of about 1149mg/L, total suspended solids TSS of 606mg/L, COD of 1952mg/L and E.coli of 9400MPN/100mL. The treatment efficiency of BOD5, COD, total suspended solids and E.coli were 95%, 93%, 95% and 90% respectively. The treated greywater has average BOD5 of 59 mg/L, TSS of 31 mg/L, COD of 161 mg/L and E.coli of 227 MPN/100mL. The quality of treated greywater complies with the Jordanian Standards JS (893/2006) for the Reclaimed Wastewater reuse for restricted irrigation. 1. Introduction

Greywater is commonly defined as wastewater without input from toilets and kitchen. Separation of domestic wastewater at source is wide spread practice in many of the rural communities in Jordan; blackwater from toilets discharged to cesspools and septic tanks, while greywater is directly discharged to the environment or used for irrigation without treatment [1]. This indigenous practice of source separation provides a potential for development of sustainable greywater management systems [2] based on the principle of ecological sanitation or what so called "Ecosan" [3].

Greywater can be considered an alternative that provides non-potable water for household usage, and thus reduces the per capita water use by 50% [4]. For this reason it provides an attractive and sustainable low cost water source especially in the arid and semiarid areas due to the water scarcity and fluctuation in the rainfall patterns [5].

The issue of greywater management is gaining importance especially in low and middle income countries where inadequate wastewater management has detrimental impacts on public health and environment. In the recent years, greywater has been linked not only to environmental degradation and serious health risks, but has also been increasingly identified as a valuable source of water that if properly used for irrigation can reduce the

agricultural use of freshwater and increased food security as well as improves public health [6].

In 1997 reclaimed wastewater was officially approved in the national strategy of Jordan as a non conventional water source that shall be managed and treated to a standard level that allows its use for non domestic use [7].

Greywater management is a critical issue that not only depends on the technical feasibility of the treatment system, but also depends on human issues such as public perceptions and health [8]. According to Nolde (1999) and (2005), greywater reuse after treatment shall satisfy four criteria: Hygienic safety, aesthetics, environmental tolerance and technical and economical feasibility [9, 10].

Treatment technologies for making greywater safe for indoor use or for irrigation are many and diverse and they vary from simple systems in single household to advanced systems for large scale reuse. Course filtration with disinfection represents the most common technology used for greywater treatment in many places in the world [8]. Septic tank followed by sand filter is an alternative for greywater treatment [11]. Septic tank, acts as a settling basin for the wastewater in which heavy materials settle down to the bottom of the tank whereas water and other materials are found above the sludge, while soap and grease form a floating scum layer [12]. Intermittent sand filters provide unsaturated downward flow of wastewater

Onsite Greywater Treatment Using Septic Tank Followed by Intermittent Sand Filter-

68

through mineral sand, so as to provide biodegradation or decomposition of wastewater constituents by bringing the wastewater into close contact with a well developed aerobic biological community attached to the surfaces of the filter media [12].

Intermittent sand filters are proposed as an efficient and economic treatment technology for domestic-strength wastewater, and can produce an effluent with low organic and pathogenic content [13]. 1.1 Study area

Integrated wastewater management policies and technologies in the marginal communities on Jordan, 2003-2007" is a development research project focuses on greywater management in the rural communities in the North-eastern Badia of Jordan. Two pilot scale treatment units were constructed in two villages in the North-eastern Badia of Jordan. Selection of villages where the treatment plants were constructed based on a selection criteria took into consideration: 1. current wastewater management practices (existing greywater separation and household agriculture), 2. social acceptance & favourability for treatment, operation and maintenance of the treatment system and 3. potential for replication in other similar communities in terms of environmental conditions, practices, and building/housing style [11].

Abu Al Farth village is one of the two villages that met community selection criteria where septic tank followed by intermittent sand filter pilot unit was constructed to serve single household in the village. The household is inhibited by 9 people with the monthly income ranges from US$ 185 to US$420. The blackwater of the household is diverted to cesspool while the greywater is used to irrigate the olive trees. The average consumptive use of water of this family is about 40L/Capita.day [1].

2. Materials and Method 2.1Quality and Quantity Measurements

Greywater quality and quantity was monitored for seven months before the construction of the septic tank-Intermittent sand filter system, from March 2005 to September 2005. 14 greywater samples were collected and analyzed from three sampling points in the household; kitchen sink, washing machine & bath tub and hand washing basin & moping basin. Composite greywater samples were collected over 24 hrs using barrels that were previously graduated over the height for the purpose of flow measurement. Contents of the barrels were mixed thoroughly before sampling. Collected samples were transferred to Royal Scientific Society RSS labs and analyzed for pH, Electrical Conductivity (EC), Total Suspended Solids (TSS), Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Phosphorus (T-P), Ammonia (NH4), Fat, Oil and Grease (FOG), total and faecal coliform and E.coli. All chemical analyses were carried out according to the

Standard Methods for the Examination of Water and Wastewater [14]. 2.2Design Calculations a. Septic tank Vliq = Q× HRT

Vscum = Hscum × AST VST = (Vliq + Vsl. + Vscum) + 0.2 × (Vliq + Vsl. + Vscum)

Where: Vliq is the volume needed for the liquid (m3); Q is the flow rate (m3/d); HRT is the hydraulic retention time (d); Vsl is the volume needed for the sludge (m3); CTSS is the concentration of TSS (kg/m3); RTSS is the percentage removal of the TSS; Csl. is the concentration of the sludge (kg/m3); Vscum is the volume needed for the scum (m3); Hscum is the height of the scum layer (m); AST is the surface area of the septic tank (m2); VST is the volume of the septic tank (m3); OLR is the organic loading rate [15]. Intermittent sand filter Area (A) = Flow (Q) / Organic Application rate

dmkgBODBODQ

A./024.0 2

5

5×=

Table (1) shows the design criteria of the sand filter.

Filter Media Sieve analysis of the filter media was done to find the

effective size and uniformity coefficient. The sieve analysis was done According to ASTM procedures C136, 2006 and C117 2004.

2.3 Layout and Effluent Distribution System The sand filter was laid out based on the area, length

and width of the sand filter. Number of lateral pipes was decided taking into consideration the spacing requirements based on design criteria in Table (1). Spacing between orifices was designed based on design criteria in Table (1). Flow /dose = Daily Flow/ Dosing Frequency Flow /Lateral /Dose = (Flow /Dose) / Number of Laterals Number of Orifices = (Flow/Lateral/Dose) / Flow in Orifices Flow in Orifice = 2.45 C (D2) (2ghn) 1/2 (Metcalf, 1991)

Where 2.45 is a conversion factor, C is an orifice discharge coefficient, D is diameter of orifice (m), g is gravitation acceleration (m/s2), and hn is the head loss in orifice (m).

2.4 Head Loss in Laterals Hlfp = 10.5 L (Q/C) 1.85 D –4.87 (Metcalf, 1991) Where Hlfp is the head loss in pipe through orifice (m), Q

.

365

sl

TSSTSSsl C

RCQV ×××=

Onsite Greywater Treatment Using Septic Tank Followed by Intermittent Sand Filter-

69

is the pipe discharge (m3/s), C is Hazen Williams discharge coefficient (150 for plastic pipes) and D is the diameter of the pipe (m). 2.5 Efficiency & Performance of the Treatment System

Efficiency of treatment system was measured by analyzing greywater samples from three locations:

1. Collection tank: Gives the quality of untreated greywater,

2. Outlet of septic tank: Gives the quality of greywater treated in septic tank

3. Outlet of Sand Filter: Gives the quality of greywater treated in the sand filter.

19 samples from the each of the above mentioned three sampling points were collected over 14 months from March 2006 to May 2007. The samples were analyzed for the physical, chemical and microbiological parameters mentioned earlier according to the Standard Methods for the Examination of Water and Wastewater [14]. Table 1 Design criteria of sand filter

Treatment components

Parameters Value/criteria Ref.

Intermittent sand filter

BOD loading rate 24 g/m2.d [16] Hydraulic loading rate

44 L/m2.d.

BOD removal efficiency

90%

COD removal efficiency

80%

Dosing rate 12 times/day Media Specifications

Filter medium Material

Washed durable granular material

[12]

Effective size 0.25-0.75 mm Uniformity coefficient

<0.4

Depth 450-900 mm Application Rate 80-200 L/m2/day Pipe size 25- 50 mm

Distribution system

Orifice size 3-6 mm [12] Head on orifice 1-2 m Lateral spacing 0.3- 1.2 m Orifice spacing 0.3- 1.2 m

Dosing

Frequency 12- 48 times/day [12]

Volume/orifice 0.6- 1 L/orifice/dose

3. Results and discussion 3.1Greywater Characteristics

Greywater generation in the targeted household fluctuates from day to day according to the indoor activities. Hence, it varied from 52L/day to 345L/day, with average flow of 150L/day; Average of 60L/day was generated in the kitchen basin, 80L/day was from washing machine and bath tub and 10L/day was from hand washing basin.

The average values of BOD5, COD and TSS of the total generated greywater were 1149 mg/L, 1952 mg/L,

and 797 mg/L respectively. These concentrations are very high, and attributed to the low consumptive use of water in the household (<40L/ca.day) as well as to hygienic behaviours of household inhabitants, types of detergent used by households (locally manufactured), amount of detergent used, food style and meals patterns.

Average BOD5/COD ratio was 0.48 and BOD5 Filtered /BOD5 ratio was about 0.3 which means that most of the suspended solid in the greywater was organic. Thus, pre-treatment using septic tank is necessary and will considerably enhance the quality of the greywater.

In addition, high pathogenic counts at 2.85× 104 MPN/100 ml were found for greywater samples. Faecal input from hand washing after defecation and babies washing in hand washing basin were the key factors for this high numbers of E.coli. Table (2) shows greywater quality parameters of the household in which septic tank and sand filter treatment unit was constructed. 3.2 Size of Septic Tank and Sand Filter

1 m3 septic tank with retention time of 5 days was designed and constructed. A sand filter with overall surface area of 6 m2 (2x3) and 1m depth was designed and constructed. The filter media consisted of 3 layers; top layer of 10 cm of (11 mm) gravel, intermediate layer of 10 cm of (5mm) fine gravel and filtering sand of 60 cm of effective size of (0.32 mm). The sand layer was under laid by 10 cm fine gravel and another 10 cm of under drain. Greywater was distributed over the sand filter using 5 laterals each of 12 orifices. Fig. 1 shows schematic diagram of the septic tank and sand filter units.

Table .2 Greywater Quality Parameters of greywater effluent from household subject of the study

Parameter

Washing machine & Bath Tub (1)

Hand washing basin & Moping

basin (2)

Kitchen sink (3)

weighted average

(1) & (2)

weighted average

(1), (2) & (3)

PH 7.30 8.30 5.60 7.41 8.29 EC 1286 2812 1357 1456 1756 TSS 810 698 410 798 797 TDS 793 1271 918 TSS 1603 1969 1328 1517 TS (g/d.ca) 14.3 2.2 8.8 25.29 BOD5 657 650 1092 656 1030 BOD5Filtered 298 168 551 284 391 COD 1466 1906 2039 1515 2138 BOD/COD 0.45 0.34 0.53 0.43 0.48 NO3 2.20 2.10 2.70 2.19 2.97 NH3 76 152 82 84 103 MBAS 53.0 43.0 36.0 51.9 56.4 E.coli 2.30E+04 4.70E+04 1.90E+04 2.57E+04 2.85E+04

Onsite Greywater Treatment Using Septic Tank Followed by Intermittent Sand Filter-

70

a. Top view

Fig 1 (a&b). Schematic diagram of septic tank and sand filter treatment unit

b. Sectional view 3.3Performance of Septic Tank and Sand Filter

The performance data of BOD5, COD, TSS, Fat-Oil-Grease (FOG), NO3, NH4, T-P and E.coli for both septic tank and sand filter are shown in Table (3).

The septic tank allowed solids to separate from liquid, while encouraged oils and fats to float at the surface of liquid. The accumulated solids have undergone into biological degradation that resulted in reducing the BOD5, COD and TSS by 63%, 58% and 66% respectively. FOG was reduced 89% by floating on the surface of water in septic tank. The anaerobic condition in the septic tank has resulted in de-nitrification of 95% NO3-N into (NH4-N); as a result, higher concentrations of NH4-N were measured at the outlet of the septic tank than in raw greywater. Storage of greywater and presence of organic materials in the septic tank has resulted in the reproduction of E.coli in the septic tank by 2.4 logs.

The partially clarified greywater in septic tank was vertically distributed into the sand filter on intermittent bases. 87% of the BOD5, 83% of the COD and 85% of TSS were removed by both physical and biological processes within the filter media. 50% of NH4 entering the sand filter was removed by being assimilated into cell tissues of the biomass in the top layer of the sand filters. 68% of synthetic detergents (MBAS) were removed by biodegradation. 3.4 log reduction in E.coli was estimated in the sand filter which was accomplished by physical filtration in the sand bed.

The septic tank-sand filter overall removal efficiencies of BOD5, COD, TSS, FOG, NO3, NH4,

MBAS and E.coli were 95%, 93%, 95%, 95%, 53%, 98%, 5% and 90% respectively with concentration of 59mg/L, 161mg/L, 31 mg/L, 8mg/L, 12 mg/L, 1mg/L, 50 mg/L and 227MPN/100 ml in the same order.

The septic tank followed by intermittent sand filter has achieved a level of treatment that exceeded the requirement of Jordanian standards JS (893/2006) for the reclaimed wastewater reuse for fodder, industrial crops and vegetable eaten cooked.

The septic tank-sand filter overall removal efficiencies of BOD5, COD, TSS, FOG, NO3, NH4, MBAS and E.coli were 95%, 93%, 95%, 95%, 53%, 98%, 5% and 90% respectively with concentration of 59mg/L, 161mg/L, 31 mg/L, 8mg/L, 12 mg/L, 1mg/L, 50 mg/L and 227MPN/100 ml in the same order.

The septic tank followed by intermittent sand filter has achieved a level of treatment that exceeded the requirement of Jordanian standards JS (893/2006) for the reclaimed wastewater reuse for fodder, industrial crops and vegetable eaten cooked.

Table.3 Performance of Septic tank/sand filter treatment unit

Parameter A B C D E F BOD5 mg/l 1182 438 59 63 87 95 COD mg/l 2248 951 161 58 83 93 TSS mg/l 609 206 31 66 85 95 FOG mg/l 159 17 8 89 53 95 MBAS mg/l 27 39 12 ** 68 53 NO3-N mg/l 47 2 1 95 58 98 NH3-N mg/l 53 100 50 ** 50 5 E.coli MPN/100ml 2172

5.86 E+05 227 ** 90 90

A: Raw greywater B: Effluent from septic tank C: Effluent from sand filter D: Efficiency of septic tank % E: Efficiency of sand filter % F: Overall efficiency %

Greywater is generated by the use of soap products

and detergent, and it contains organic materials, suspended solids and pathogens. Organic content of the raw generated greywater from the household is higher than raw greywater quality mentioned in literature. The type of local manufactured detergent used by households, amount of detergent used, food style and meals patterns as well as the low consumptive of water are the key factors that lead to the high organic loadings which all reflected on the performance of the treatment system used [17]

Clogging of sand is still a problem in the sand filtration processes. A risk of clogging was expected and happened once after one year of operation. The clogging depth of the sand layer was about 50 cm whereas the sand layer depth is 60 cm. Therefore, depth of sand layer of less than 60 cm will lead to more frequent clogging events.

Onsite Greywater Treatment Using Septic Tank Followed by Intermittent Sand Filter-

71

The high concentration of TSS in greywater entering the sand filter is the main factor of clogging. Colonization and growth of bacteria within the sand grains enhances the removal of SS but at the same time it may increase the risk of sand’s pores clogging.

4. Conclusion 1. The low consumption rate of water in the

household has resulted in high pollution loads of the generated greywater, and this pollution requires the greywater to be treated before use to conserve environment and to protect health.

2. The composition and characteristics of greywater significantly vary and very dependant on the practices of household's inhabitants.

3. Septic tank followed by intermittent sand filter was found very effective treatment system for the highly polluted greywater with overall efficiency of more than 90%.

4. The quality of the treated greywater is in compliance with Jordanian standards for the reclaimed wastewater reuse in restricted irrigation.

5. Failure of sand filter due to clogging is the main concern in the long term operation of the treatment system.

Acknowledgment Authors would like to express their deep thanks for the International Development Research Centre IDRC/ Canada, Ottawa for their financial support for the project "Integrated wastewater management policies and technologies of the marginal communities in Jordan", under which this research has been done by Environmental Research Centre of Royal Scientific Society.

References [1] Sulieman. W., Dalahmeh, S., Mashaqba. O., 2004,.

Technical reports of integrated Wastewater management policies and technologies of the marginal communities of Jordan. 2nd interim technical report. Royal Scientific Society.

[2] Dallas, S., Scheffe, B., Ho, G., 2004. Reedbeds for Greywater treatment- case study in Santa Elena- Montverde, Costa Rica, Central America. Ecological Engineering Vol 23 (2004) pp 55- 61.

[3] Esry, S.A., Gouch, J., Rapaport, D., Sawyers, R., Simpson-Hebert, M., Vargas, J., 1998. Ecological Sanitation, Swedish International Development Cooperation Agency (SIDA), Stockholm, Sweden.

[4] Oschmann, N., Nghiem, L.D., Scafer, A. 2005, Fouling mechanisms of submerged ultra filtration membranes in greywater recycling. Desalination, Vol 179 (2005) pp 215-223.

[5] Al- Jayyousi. OR. 2003. Greywater reuse: towards sustainable water management. Desalination, vol. 156, pp 181- 192.

[6] Eawag aquatic research, 2006. Greywater management in Low and Middle Income countries. Sandec Department of Water and Sanitation in Developing Countries.

[7] Al-Jayyousi, O.R. 2002. Focused environmental analysis for greywater reuse in Jordan. Environmental Engineering Policy, Vol 3, pp 67-74.

[8] Jefferson, B., Palmer, A., Jrffrey, P., Sturtz, R. and Judd, S., 2004. Grey water characterization and its impact on the selection and operation of technologies for urban reuse. Water Science Technology Vol. 50 No. 2 pp 157 – 164.

[9] Nolde, E., 2005. Greywater recycling systems in Germany- results, experiences and guidelines. Water Science & Technology Vol 51 No 10 pp 203-210.

[10] Nolde, E. 1999. Greywater reuse for toilet flushing in Multi-storey buildings-over ten years experience in Berlin. Urban Water, Vol 1 pp 275-284.

[11] Dalahmeh, S., Assayed, M., Sulieman. W. 2006,. Technical reports of integrated Wastewater management policies and technologies of the marginal communities of Jordan. 4th, 5th interim technical report. Royal Scientific Society.

[12] Metcalf and Eddy (1991) Wastewater Engineering, Treatment, Disposal, Reuse, 3rd ed., Mc-Graw Hill Inc, New York.

[13] Healy, M.G., Rodgers, M., Mulqueen, J., 2007. Performance of a stratified sand filter in removal of chemical oxygen demand, total suspended solids, and ammonia nitrogen from high-strength wastewaters. Journal of Environmental management, 83 (4):409-415.

[14] APHA, 1995. Standard methods for the examination of water and wastewater.

[15] Bounds, T.R., 1997. Design and performance of septic tanks: site characterization and design of onsite septic systems. ASTM STP 901, M.S. Bedinger, A.I. Johnson, and J.S. Fleming, Eds., American Society of Testing Materials, Philadelphia.

[16] Sabbah, I., Ghattas, B., Hayeek, A., Omari, J., Haj, Y., Admon, S. and Green, M.,2003. Intermittent sand filtration for wastewater treatment in rural areas of the Middle East- a pilot study. Water Science Technology. Vol. 48 No 11-12 pp 147-152.

[17] Halalsheh, M, Dalahmeh, S., Sayed, M., Suleiman, W., Shareef, M., Mansour, M., Safi, M. 2008. Grey water characteristics and treatment options for rural areas in Jordan. Bioresource technology. 99 (14): 6635-41.