WASTEWATER TREATMENT SYSTEM FOR CASSAVA STARCH
1. Overview of the cassava starch processing industry
- Cassava starch processing contributes a significant part to economic development. The production of tapioca starch will generate waste in the form of wastewater, waste gas and solid waste. In which, wastewater is the most polluting form. The need to use water for 1 ton of powdered product is about 25-40m3 and the waste is about 20 - 38m3.
- On the other hand, due to a considerable amount of starch released, the wastewater is more polluted. Therefore, it is necessary to build a cassava starch wastewater treatment system to ensure everyones health.
2. Origin of wastewater treatment system for cassava starch
- According to statistics, every year, the cassava starch industry discharges into the environment about 240-300 million m3 of wastewater / year. In which, only about 10% of the total amount of wastewater has been treated, the rest is discharged directly to the receiving source. Because the wastewater from the cassava industry contains a lot of starch, organic acids, fibers, and sediments, most of the wastewater from tapioca facilities has a high concentration of organic matter, total solids and is acidic.
3. Technology scheme of wastewater treatment system for cassava starch
- Sedimentation tank: Responsible for removing sand, metal arrays, etc in raw materials, in factory sanitary wastewater. Wastewater from production areas under separate drainage network flows into sand settling tanks of treatment plants. Here, in order to protect the equipment and the technological pipeline system behind, raw waste screens are installed in front of the sand settling tanks to remove large-volume wastes from the wastewater.
- Waste water, after being led through a net of pure garbage, will be led into the biogas cellar. The biogas tunnel is an aerobic treatment area that helps to reduce a large amount of COD, BOD5 concentrations and release energy for other activities.
- Conditioning tanks: The fluctuation of the concentration and flow of wastewater will affect the working regime of the network and treatment facilities, especially important for physical, physical and biological works. Stabilizing wastewater concentrations will help reduce the size of physical and chemical treatment facilities, simplify treatment technology and increase efficiency of wastewater treatment in treatment facilities.
- Neutralization tank: Wastewater in tapioca processing technology has low pH due to starch acid fermentation.
- Reaction Tank: Chemical flocculation is added to the tank at standard dosage. And is strictly controlled by chemical dosing pump.
- Cotton flocculation tank: Helps to form floss with size, volume many times larger than the original cotton residue. Facilitate the sedimentation process in sedimentation tanks.
- Sedimentation tank 1: The sedimentation tank has the function of removing sediments that can cause sedimentation in the receiving source, separating grease and other floating substances, reducing the organic load for the back treatment works.
- Biofilter: The aerobic biological membrane is an arbitrary microorganism system, the outermost layer of the membrane is the aerobic bacteria layer, the inner layer is the anaerobic bacteria. Waste water after going through the treatment system meeting QCVN 24: 2009 standards, Class B will be discharged into the receiving source.
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