Experimental Study Of Cyclic Activated Sludge System For Treatment Of Village And Township Domestic Wastewater

The treatment of domestic sewage is related to people’s livelihood and is also a hot topic in the field of environmental research.The economic conditions in the village areas are more backward,and it is necessary to develop low-cost and efficient wastewater treatment technology suitable for the village areas in the Central Plains.CASS process is widely used in domestic sewage treatment plants due to its many advantages.Currently,most of the papers focus on the exploration of the impact of specific factors on the CASS process,lacking a comprehensive study of more factors.Therefore,this experiment self-made CASS reactor,manually prepared domestic sewage,optimized the operating parameters of CASS reactor,investigated the impact of various factors,and analyzed the microorganisms in the operating stage to achieve effective sewage treatment.According to the experimental results,an HRT of 8 h or 12 h makes the sewage treatment achieve the standard,and 8 h is the most suitable for comprehensive consideration.The enrichment of microorganisms was completed with the extension of HRT.Among them,Proteobacteria,Bacteroidetes and Candidatus Saccharibacteria were the main phyla,and Gaproteobacteria,Sphingobacterias were the main phyla.Gaproteobacteria,Sphingobacteriia,and Betaproteobacteria were the main phylum-level groups.The prediction of microbial functions showed that the HRT was 8 h and the anoxic section was treated well with carbon source while the abundance of metabolic functions was large.Both high and low organic loads in the influent water resulted in poor nitrogen removal.The microbial community Proteobacteria reached a relative abundance of 77% in the T2 sample,which corresponds to a good organic removal effect in the T2 stage.The genus Thiothrix,under the phylum Proteobacteria,had a relative abundance of 46% in the T2 sample,and this genus was associated with phosphorus removal,corresponding to the excellent phosphorus removal at this stage.The influence of influent pH is small,and the influence of temperature on TN and COD is large.although the low temperature weakens the microbial activity,but the 8h HRT is enough to make the effluent meet the standard discharge.C/N mainly affects the TN removal rate,and the TN effluent concentration gradually decreases as the C/N rises.Therefore,a certain amount of carbon source needs to be added at low C/N.Due to the price of sodium acetate,it needs to be considered carefully for carbon source.The glucose-sodium acetate mixture can be used as the carbon source to improve the effluent treatment effect and reduce the cost.The results of this experiment provide a reference for the treatment of village and township domestic wastewater by CASS process in the central plains.