| Swine wastewater has high concentration organic pollutants, ammonia nitrogen and floaters. It is difficult for swine wastewater to meet national environmental emission standard on a single water handle approach, and the wastewater treatment cost is so high that most breeding enterprise can't bear. The advantages of constructed wetland, such as high removal efficiency for N and P from Wastewater, project construction and operation cost is low, the operation maintenance convenient and strong ability to adapt to load change etc, make it become an ideal choice for the deep treatment of swine wastewater.This research has studied the treatment of anaerobic digested swine wastewater by Improved Wavy Subsurface Flow Constructed Wetland. Research conclusions are as follows:1. The static adsorption test of ash brick substrate to nitrogen and Phosphorus. This study examined nitrogen and phosphorus adsorption performance of ash brick, which is construction waste. Ash brick is a construction waste; it has high removal capability of phosphorus. The data obtained in these experiments were in accordance with Freundlich and Langmuir isotherms. Maximum adsorption capacity of ash brick calculated from Langmuir Equation was 5.382mg/g; the ammonia adsorption performance of ash brick is stronger than sand and volcanic cinder's. So ash brick can be used to make a wetland system packing.2. COD/N of the influent affects the removal efficiency of horizontal subsurface flow constructed wetland treating swine wastewater. There set three COD/N values:2, 5 and 7. The results show that:the constructed wetland system has better nitrogen removal efficiency when COD/N of influent was five.3. In this experiment, wavy subsurface flow constructed wetland (Wavy Subsurface Flow Constructed Wetland, referred to as W-SFCW) served as controls and improved wavy subsurface flow constructed wetland (Improved Wavy Subsurface Flow Constructed Wetland, referred to as IW-SFCW) was studied at the removal efficiency of pollutants in swine wastewater at different hydraulic retention time. The results showed that:IW-SFCW has good removal efficiency for treating swine wastewater. In the HRT 4d, COD, TN, NH4+-N, TP concentrations of influent were 511mg/L,120mg/L, 110mg/L, 10mg/L or so, the removal rate of COD, NH4+-N, TN and TP was 86.0%,54.4%,70.1% and 91.6%, respectively. It shows that this wetland system can be used to deal with swine wastewater; the removal efficiency of COD and TP improves gradually with the HRT extension. In the best adapt HRT 8d, the removal rate of COD and TP reached 92.7% and 96.8% respectively. But the removal efficiency of TN and NH4+-N was first increased and then decreased with the HRT extension. In the best adapt HRT 4d, the removal rate of TN and NH4+-N in the wetland system was 54.4% and 70.1% respectively.4. After continuous aeration, ORP in the wetland system has greatly changed; explaining aeration can obviously improve dissolved oxygen levels in the wetland bed body. Dissolved oxygen increasing Helps COD, NH4+-N removal, however, it is to the disadvantage of TN removal. May be increasing dissolved oxygen in the wetland system restraining the denitrifying function smoothly, causing effluent TN concentrations rise and decreasing TN removal efficiency.5.The advantage of strong COD removal ability causing carbon source lacked in constructed wetland system back-end. In this experiment, adding carbon source at constructed wetland system central or back-end to enhance the effect of the denitrification in constructed wetland system. The results showed that:this measures is used to enhance the TN effect of wetland system, it can improved TN removal efficiency about 14%. |
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