Shanghai International Nutrition Co., Ltd.
 Shanghai International Nutrition Co., Ltd is a company that produces Dumax milk power, UNO yoghurt and other brands of milk. A complete set of wastewater treatment system was built in 1994. This system operated well during the early time near construction and the effluent can meet the standard. In order to save water resource, this company planed to make use of the effluent as cooling water, washing water, etc. after reclamation. So the original wastewater treatment system needs reconstruction and a new water recycling system needs to be added.
The design scale is 1000m3/d.
Process flow chart
The original process and equipment from water collecting tank and contact aerator is still adopted. The effluent from contact aerator flows into CAF system after flowing through the mixing tank (mechanical reaction, agitator attached) . The floatation tank is transformed from the original DAF tank. The effluent from CAF system partly drained into the municipal wastewater system, partly flows into the sandflo filter system for further treatment. After disinfection process, the water is reused as the compensated water of the cooling system, the washing water of sludge dewatering machine, the irrigation water or the service water.
The backwashing water of sandflo filter system is drained into the adjusting tank by gravity. The sludge from the flotation tank is drained into the sludge tank, then lifted by the screw pump to the mixing tank to confect, finally dewatered by the belt filter press. The cake is delivered to the qualified sludge treating company.
The indexes of the recycling water are as follows.
The effluent of the contact aerator: COD Cr: 200 ¡« 300mg/l; SS: 60 ¡« 70mg/l.
The effluent of the sandflo filter system: COD Cr: <50mg/l; SS: <10mg/l.
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