In China, plastic products are already a part of our lives. While it brings convenience, it will cause a lot of plastic wastes. But thankfully, plastics can be recycled. The recycling processes generally include crushing, washing (cleaning) and granulation. During the cleaning process, a large amount of wastewater will be generated. If directly discharged, it will not only waste our water resources, but also will pollute the environment. In fact, plastic waste water is easy to be recycled.
The plastic waste water mainly contains sediment (sludge, sands etc.), so the treatment is relatively simple. Generally, after adding the flocculant to settle, the effluent will be very clear. In addition, it will contain a certain amount of organics and other suspended matters. Depending on its use, the COD and SS values in the sewage will also be quite different. Generally, the popular process adopts is "Grid + Adjustment + Coagulation with air floatation + AO + Filtering + Disinfection".
Specifically, the sewage first flows through the grid to remove big impurities and enters into the conditioning tank. Then, the effluent is disposed in the air floatation tank. At the same time, the coagulant is added. The small particles in it are flocculated into larger particles and overflow. The water from the DAF tank is further biologically treated to remove most organics, ammonia nitrogen and other substances. Later sludge and water will be separated in the secondary sedimentation tank. Finally, the water is recovered and sludge will be dewatered by plate and frame filter press.