The ETP is made up of different stages that ensure that the effluent from the company is well treated before sending out to the environment. The stages are listed below and its diagram.
The stages are:
· Static point
· Self clearing device (strainer Device )
· Oil separation tank
· Equalization tank
· Biological tank A
· Sedimentation Tank
· Biological tank (B)
· Final clarification
Firstly, the Nigerian bottling company has a well organized, functional plant that is used to treat the effluent from the company and safety procedure are followed from the entrance of the gate to the plant location which is done by a yellow marked line that allows for a walkway to the plant.
The various components of a effluent treatment plant have been derived from unit operations. Every unit operation aims at the removal or reduction of specific objectionable substances to the desired degree. Depending upon the kinds and magnitudes of the treatment required, proper unit operations are selected and arranged in the proper sequential order for the purpose of modifying the quality of raw water to meet desired standards.
The company flowrate of effluent into the plant is 200m3 /hr and the discharge ratio of influent to the environment is 65 to 70m3 /hr and the rest 130m3 /hr is recycled and surface aerators are used in the tank to remove the odours and colour from the tank.
The two process used in these pant is : the constant flow pump and valve
– The constant flow /buffer tank: Help to checkmate the rate of flow of the effluent in the tank while
– the valve act as an aid for serving there by passing a less concentrated effluent a flow directly to the biological tank B when serving and maintenance are needed
The effluent from the Nigerian bottling company contains pieces of broken bottles, oil, chemical and pipes which are screen at the unit operation section known as the static point.
The screening removes or hold back the floating matter. The NaOH (costic soda) or Sodium Hydroxide in the effluent which is poisonous and its basic in nature and will be neutralized by an acid (HCL) thereby forming salt and water.
While the screening of the floating matter are holdback, the rest flows down to the self clearing device where plain sedimentation take place
Plain sedimentation: Simply means that sedimentation is not effected by the addition of chemical or other processed in a relatively quiescent state, solids having specific gravity greater than that of the liquid containing them settle while solids with specific gravity lower than that of the liquid tends to rise. Though the debris are removed but the effluent still contain sand and oil. But on reaching the strainer device some of the debris that escaped are been trapped by the screen at the strainer device which is 3mm apart each other. It is normally taken as a batch separation process where some of the sand which where unable to pass the hole are retain but rest are sent to the oil separation unit but due to the fact that pressure of effluent entering into the oil separation tank is on high pressure it tends to push and missed with the oil that is meant to settle after the first process tank but on the third process tank the separation takes place settling the sand and floating the oil at the surface of the third process tank of the oil separation tank which is scoop out with net, the water in-between the oil and sand flows into the fourth stage known as the equalization tanks. After the separation of sand and oil the treatment of the effluent start properly at these stage, the water that flows into the equalization tank still contain chemical known as sodium hydroxide which is transferred into the tank. The moment you start agitation in the equalization tank it helps to reduce the concentration of sodium hydroxide (NaOH) which is base in nature then manually by hand hydrochloric acid is coagulated by allowing it to dozed into the equalization tank. To determine or know the quantity of HCL. (hydrochloric acid) to be applied in the equalization tanks is by simply dipping in a meter reader in the tank at the ratio of 1000m3 water you apply 600 liter of hydrochloric acid which is a standard but can be changed depending the among of sodium hydroxide present in the equalization tank. Micro–organisms that are present in the effluent are enriched in the Biological Process A with urea and decomposition process take place producing water, biomass and carbon iv oxide. carbon iv oxide easily escape to the atmosphere and leaving behind biomass and water which either sent to sedimentation tank for separation or to the belt press room where sludge is abstracted from biomass and it is pressed to a sludge cake which is use as a manure in agriculture. Before the sludge cake is produced it pass through a ploymaker unit where polyelectrolyte coagulate with biomass before sending it to the sludge belt press at the sedimentation tank which is the sixth stage, normally defined as a separation of wanted from unwanted.
Sedimentation tank may be considered to consist of four part
· inlet zone where influent flow and suspended solids disperse over
· A settling zone where suspended solid settle
· A bottom zone where settled particles accumulate and are withdrawn
· An outlet zone through which the effluent flow out
In the sedimentation tank there is a cylindrical scaper bridge machine that rotate and collect the scum to pit then the sludge (Biomass) to sludge tank and it take maximum of 6 month/ one year for a sludge to be matured before sending it to belt press room for sludge cake.
The effluent is then sent to the biological tank B which is the seventh stage and a surface aerator is turned on to stirs, by removing the odours. The final stage which is the final classification tank where chlorine is added before send it fish pond or to the lake /river around the company known as the AJARI RIVER.
Below is the data log for Nigerian bottling company production record is attached and it shows the weekly report and necessary precaution obtained if need be.
The following are the challenges and precautions taken in the effluent treatment plant
CHALLENGES:
– At the static point the effluent discharged was overflowing it channel reason being that the pipe was not wide enough to accommodate the flow
– At the time of inspection the (HCL) hydrochloric acid needed to prevent the odour from the effluent was not available whereby causing un-conducive environment.
PRECAUTION
– A wire gaze was constructed to reduce the flow rate coming into the pipes
– Place order for the replacement of (HCL)hydrochloric acid which was not enough to neutralized the base (NaOH) sodium hydroxide
Be the first to comment