Rural Sewage Treatment Using A Biological-ecological Coupling Process Of UAF+SSFW

The domestic sewage in rural area is small amount, scattered, far away from the sewerage network. So usually it will flow into rivers and lakes directly without any treatment. And this can bring serious water pollution. Conventional wastewater treatment is expense, complex, so it is difficult to apply in rural area. For these reasons, it is import for rural area to develop a low investment, low running cost, simple operating method wastewater treatment.This study adopts UAF biologic technology and SSFW ecological technology aim to develop a Biological–ecological coupling treatment which is suit to rural area. And it uses the tracer response technique study water flow regime in artificial wetland reactors. Then operate coupling treatment to treat domestic sewage. Finally, observe the effect in different processing unit, different coupling treatment, different time and focus on improving the effect of nitrogen and phosphorus removal. The results prove that:1)The flow pattern in SSFW reactor is an imperfect non-uniform flow state. In the same HRT state, the height of layer of gravel has a little effect, so it is better that the layer of gravel a little higher than water intake.2)For UAF system the best HRT is 18 h, on this condition, in the output water the mean concentration of COD is 99.85 mg/L with a stabilization of water quality. The UAF system can’t remove ammonia nitrogen. What’s more, because the organic nitrogen hydrolyzes into ammonia nitrogen, the concentration of ammonia nitrogen increases in output water.3)For SSFW system the best HRT is 3d, on this condition, in the output water the mean concentration of COD, ammonia nitrogen, total nitrogen and total phosphorus is 46.84mg/L、11.08mg/L、17.54 mg/Land 1.77 mg/L, the related mean removal rate is 55.13%、69.25%、62.01% and 72.51% and with a stabilization of water quality. But, with a limited capability of nitrogen and phosphorus removal, Low plant density treat effect is difficult to reach a stable goal.4)With improving the plant density from 12/m2 to 24m2 the capability of nitrogen and phosphorus removal improved evidently. The removal rate of UAF+SSFW coupling treatment system for COD, ammonia nitrogen, total nitrogen and total phosphorus is 85.55%、88.48%、80.08% and 92.11%. And the mean concentration of COD, ammonia nitrogen, total nitrogen and total phosphorus in the output water is 44.07mg/L、4.25mg/L、13.36mg/L and 0.44mg/L. This could meet the requirements of First Grade Class A standard in discharge standard of pollutants for municipal wastewater treatment plant(GB18918-2002). At the same time, UAF+SSFW coupling treatment system is no power consumption, maintenance-free and that suit for rural area’s sewage treatment.