Applied Research On Pvc Centrifugal Mother Liquid Treatment And Recovery Technology

Biochemical methods and membrane separation technology are two effective ways in the contemporary wastewater treatment industry. The process of calcium carbide production of PVC (Polyvinyl Chloride, referred to as PVC) is associated with the generation of large amount of the mother liquor by centrifugation. CODcr, ammonia, suspended solids and other parameters in the PVC centrifugal mother liquor are not high, so the mother liquor possesses some biochemical properties. However, the residual additives (such as PVA) in the wastewater on the one hand limit the biochemical effects, on the other hand, they are prone to block the membrane pores and affect the separation efficiency. Consequently, it is difficult to achieve long-term and stable wastewater treatment effects by biochemical methods or membrane separation technology alone.According to the real condition, Hybrid Biological Fixed Film process (referred to as HBF) and double membrane method, which is the combination of Microfiltration (referred to as MF) and Reverse Osmosis (referred to as RO), were used to treat the PVC centrifugal mother liquor as a whole in the pilot production process. The paper mainly illustrates the experimental technology and the process, and further summarizes the experimental results as well as discusses the various factors affecting the experimental results.The results of the six-month pilot experiment revealed that the amount of water production from HBF system stably reached50mg·L-1when the treatment capacity of the device in the field amounted to10m3per day. After MF+RO, the average yield of CODcr was only2.6mg·L-1, the average water production of ammonia was0.33mg·L-1, the index of turbidity was less than0.1NTU, and the average conductivity rate of water decreased from100.0μ s·cm-1of the mother liquor to8.0μ s·cm-1. The data collected from30consecutive days showed that with the basic maintenance of operation pressure, the attenuation rate of water production in the microfiltration and reverse osmosis unit in the double membrane system was respectively2.6%and3.4%. The attenuation rate was predicted to be7.8%and10.2%with linear estimation, respectively. Overall, the condition met the chemical cleaning requirements every three months.In the paper, the main factors in the experiment were discussed and researched, involving hydraulic loading, organic loading, gas-water ratio and temperature. Furthermore, a series of data and charts illustrated the effects of these experimental conditions on the biofilm growth conditions and the treatment effects of HBF system. In the end, data obtained from material balance indicated that the recovery rate of centrifugal liquor which was deeply treated and achieved reuse in water reactor was about33%after the described process.