Banks DIH Field Trip Report

7/27/2019 Banks DIH Field Trip Report

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WASTEWATERTREATMENT FACILITY

FIELD TRIP REPORTWater Supply & Wastewater Engineering -

CIV 3202

24th

A ril, 2014

Steven Jackson13/0933/0919

Benedict Yhap12/0933/2562

Stephen Nascimento12/0933/2547

Dhanpaul Raghunandan12/0933/2573


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INTRODUCTION

Wastewater is any water that has been adversely affected in quality by anthropogenic influence.

Municipal and industrial wastewater is usually conveyed in a combined sewer or sanitary sewer,

and treated at a wastewater treatment plant. Treated wastewater is discharged into receiving

water via an effluent sewer or other forms of water ways. The reason wastewater is treated is

because it would be incredibly harmful to release it back into the environment. Wastewater

contains an incredible amount of pathogens, bacteria and other harmful substances that are

detrimental to an organisms well-being. Therefore it is imperative that wastewater be treated.

This document explains how wastewater is treated at Banks DIH Ltd. which is stipulated by

Coca Cola. The information was gained via a tour that the Civil Engineering third year class was

taken on and the following details the encounter.


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BANKS DIH WASTEWATER TREATMENT FACILITY FIELD TRIP REPORT

On the 10th April, 2014 the third year Civil Engineering class visited the Banks DIH Ltd.

Wastewater Treatment Facility. On this day class was given a tour of the facilities by Colin Wills

(Engineer in charge of the wastewater treatment facility), Mr. Roland (utility operator) and a

senior manager. Mr. Wills first explained to the class that the wastewater being treated by the

facility comes from the soft drinks factory, specifically Coca Cola, as it was mandatory in order

for Banks DIH Ltd. to maintain their Coca Cola franchise. He stated that the facility cost upward

of USD $1,000,000 to construct with Banks DIH Ltd. contributing half and Coca Cola the other

half. The facility costs approximately GYD $1,500,000 to maintain monthly, an expense bared

by Banks DIH Ltd.

At this point Mr. Wills handed over to Mr. Roland who then took us through the facility.

According to Mr. Roland the water that comes from the soft drinks factory first passes through a

solid separator which removes corks, plastics, oils etc. which may have gotten into the water. He

further stated that after the water passes through the solid separator certain parameters are then

tested, such as pH level, amount of nitrogen, phosphorous, chemical oxygen demand (COD),

biological oxygen demand (BOD) in order to know what parameters should be altered to

encourage the growth of the micro-organisms used to treat the water since the process employed

by this facility is a biological process. If the previously mentioned parameters need to be altered

certain chemicals such as caustic soda, phosphoric acid, sulphuric acid and urea are added to the

water by a dosing system. It should be noted that the urea introduced into the system is actually

the nutrients for the micro-organisms while the other chemicals are pH adjusters. This dosing

system monitors the levels of these chemicals and adjusts them automatically. It should be noted

that these chemicals are not used as part of the treatment system but rather to create a suitable


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environment for the growth and survival of the bacteria. There is a high oxygen demand since

this is an aerobic system. Oxygen is introduced into the water via blowers which sucks in air

from the atmosphere and injects it into the system also facilitating thorough mixing and

distribution of the chemicals. These air blowers are also part of the dosing system and are

regulated automatically. The entire dosing system is regulated from a control panel which has a

peristaltic function meaning it is self-controlled. The dosing of the water is done in the

equalizing tank. This is where the water is stored after passing through a secondary filter to

remove smaller solids.

After this the water is then pumped through a rotating sprinkler system into a trickling filter

(biological tower) which is large tank containing polypropylene discs. These discs provide a

larger surface area for the water to come into contact with the bacteria that grows on the discs as

slime. The bacteria break down 60% to 70% of the chemicals and BODs by the time the water

leaves the filter. From the top the slime cannot be seen on the discs since the tank is open and the

sunlight is harmful to the bacteria, but below the first layer of discs they are abundant. The tank

has to be open to the atmosphere since the process gives off carbon dioxide as a by-product and

therefore must be vented.

After this the water is then pumped into a clarifier where heavy organic matter settles to the

bottom of the tank. This is facilitated by churning caused by two mechanical arms that rotate at a

slow rate. The churning encourages flocculation of the particles in the water that then become

heavier and sink. The arms also scrape the sides of the tank and removes particles that have

adhered to the walls of the tank. The sludge bed formed at the bottom of the clarifier is

monitored and is removed when there is a large build up.


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From the clarifier the water is pumped into an aeration tank. Air is pumped into the tank via

three rows of air diffusers at the bottom. This encourages mixing and provides oxygen to aid in

the return of bacteria since bacteria is added to the aeration tank and oxygen is need for their

growth and survival. At this stage volatile suspended tests are carried out to test the food to

micro-organism ratio. Since a surplus of nutrients would cause the water to have a high

chemical oxygen demand and a shortage would cause under performance of the bacteria. From

the aeration tank the water enters a second but smaller clarifier.

The liquid sludge that is removed from the two clarifiers is placed into a sludge tank. This is

where the sludge is compressed under a pressure of approximately 5000 psi in order to separate

the water from the sludge. The sludge is transformed into a solid cake like substance.

Samples are taken from all along the process and are tested in a laboratory that is housed in the

dosing chamber. This is done to ensure that the quality is up to standard. Samples are also sent to

Puerto Rico for third party analysis to ensure that the water being treated corresponds to the

standards implemented by Coca Cola. The samples are tested for coliforms, heavy metals etc.

and once they have passed the tests then the cake like sludge can be used for landfills,

agriculture, etc.

The treated water from the clarifier travels along an underground pipe and is discharged into the

Demerara River. To demonstrate the purity of the water after treatment, the facility has an

aquarium in the dosing chamber containing fishes living in the treated water. This serves to

demonstrate that the waste water being disposed of into the Demerara River poses minimum treat

to the environment and aquatic life.


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CONCLUSION

After the tour of Banks DIH Ltd. wastewater treatment facility, the researchers of this group

firmly believe the treatment plant is an effective one since it removes up to 95% of the impurities

from the wastewater. The process is entirely biological and the open air system in place

compliments the aerobic reactions taking place. The tour was indeed educational since it gave

the researchers a better appreciation of the wastewater treatment process, for learning about it is

one thing but actually seeing it taking place cements your understanding.


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APPENDIX

INCOMING WASTEWATER

(FROM COCA COLA PLANT)

SOLIDS SEPARATOR

SECONDARY FILTER

EQUALIZING TANK

TRICKLING FILTER

FIRST CLARIFIER

AERATION TANK

SECOND CLARIFIER SLUDGE TANK

DISCHARGE INTO DEMERARA

RIVERSOLID SLUDGE

LANDFILL,

FERTILIZER, ETC

SCHEMATIC OF THE WASTEWATER TREATMENT PROCESS AT BANKS DIH LTD.


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PHOTOGRAPH TAKEN BY ANTHONY STEPHENS ON APRIL 10, 2014 SHOWING LAYOUT OF FACILITY

PHOTOGRAPH TAKEN BY ANTHONY STEPHENS ON APRIL 10, 2014 SHOWING THE SECONDARY

FILTER AND EQUALIZING TANK


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PHOTOGRAPH TAKEN BY ANTHONY STEPHENS ON APRIL 10, 2014 SHOWING THE TRICKLING

FILTER TANK

PHOTOGRAPH TAKEN BY ANTHONY STEPHENS ON APRIL 10, 2014 SHOWING THE FIRST

SEDIMENTATION (CLARIFIER) TANK


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PHOTOGRAPH TAKEN BY ANTHONY STEPHENS ON APRIL 10, 2014 SHOWING THE AERATION TANK

AND SLUDGE DIGESTER TANK

Banks DIH Field Trip Report

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