| This paper introduced the waste water pollution from livestocks and the related research progress in our country, and discussed the current technology used by waste water treatment plants. Poultry breeding wastewater treatment plant in Ya’an campus has been investigated. In order to determine the processing effect of wastewater of every processing unit, indicators of water samples, for example, CODCr and SS, PH, ammonia nitrogen, TP and other indicators had been tested using the scientific monitoring technology. This paper has analysed and summarized the reasons from poor treatment situation. The improvement project for waste water treatment has been put forward. This paper also introduced the improved technological process, design parameters, equipment allocation and design characteristics. The technical feasibility and economic rationality of improved process analysis had been evaluated. Main research results are as follows:1、Through research and analysis, the original designing volume of waste water treatment per day was260m3/d in ya’an campus. With the continuous expansion of aquaculture farms, however, the quality of waste water has changed greatly, and the volume of waste water was360m3/d. The quality of inflow waste water are as follows: CODcr=2000-8000mg/L, SS=1000～1500mg/L, NH3-N=300～500mg/L, TN=400～600mg/L, TP=100～150mg/L.2、Through field investigation and experimental analysis, the possible reason for poor original treatment effect are as follows:(1) The management and operation are not qualified. Grille failed to clear slag on time. With the increasing waste water and the flow, the hydraulic retention period of every processing unit being shorter than before, what is more, the aeration and etc all have effects on water quality. Heavy rains in summer will even overflow to the oxidation pond system directly, which has serious impact on water quality.(2) The maintenance in every processing unit was not enough, which weakened the processing efficiency of construction unit. The ABR anaerobic pool leaked Occasionally, which indicated that the sealing of the anaerobic pool was not good enough, since too much oxygen has a bad influence on the treatment effeciency. According to the monitoring of the waste water quality from the constructed wetland, the wetland system almost lost its processing capabilities. The removal rate of nitrogen and phosphorus was very low, and CODcr even increased slightly. Wetland system lacked proper management for a long time and the underlying base failed to timely clean and dredge, and what is more, the bed debris consolidation increased waste water infiltration head loss. The waste water only flow through the bed surface, and at the mean time wetland plant residues rot may release some pollutants, which makes whole wetland system failed to achieve the actual processing effect.(3) Waste water enters the ABR anaerobic pool through Air flotation pool, the dissolved oxygen content in the floating process of wastewater treatment is higher. If the water went directly into anaerobic pool, the growth of anaerobic microorganisms would be affected, which in turn, affected the anaerobic pool treatment effect.3、In order to expand treatment water quantity and improve water quality, based on the above analysis of existing problems, combined with the engineering examples, this paper puts forward the following suggestions and improvement projects:(1) To strengthen the management and maintenance of each processing unit, try to be the "best", and play its proper role. (2) The regulating pool should be built between Air flotation pool and ABR pool. The waste water should be led to the regulating pool to consume dissolved oxygen in waste water after air flotation treatment, then the ABR pool, in order to decrease the impact on anaerobic microorganisms. In addition, regulating pool can equilibrate and dilute water quality, and enhance the system’s ability to fight water quantity and quality impact load.(3) The diving aeration device should be added as the improved oxidation pond area in the original oxidation pond. Aeration pond system combined with ABR-CASS system should be able to form two kinds of response to sudden increasing water quantity,(such as heavy rains in the summer) into the system expansion and parallel operation. It can also guarantee the ABR and CASS system can run normally under special cases.The aeration pond and ABR-CASS systems should be series operated in order to help to improve water quality.(4) Having some filter feeding, Silver carp, omnivorous crucian carp, grass carp and etc into the pond, can dispose some of the residue such as organic matter, microorganism, suspended sludge, sediment and etc in water, which can also bring certain economic benefits.(5) Excessive sludge should be composted to fermentate and used as agricultural green fertilizer.4、Above all, this system will have fine social, economic and educational values after improvement. |
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