Study On The Technology Of High Concentration Domestic Sewage Treatmeng By Ecology Constructed Rapid Infiltration System (ECRI)

CRI, as a simple, low investment, and operation cost-effective process, has a significant effect in the treatment of municipal sewage and polluted surface water and has a good full-scale application. But the total nitrogen (TN) and total phosphorus (TP) removal efficiency of CRI system and the treatment effect under the low temperature are poor. Besides, the filter is easy to be blocked and ecological landscape is poor. Therefore, the enhancing requirements on water quality limit its application and promotion.To solve the above problems, this thesis intended to add plants on the surface of the CRI pool to create eco-CRI (Ecology Constructed Rapid Infiltration, called ECRI system). This thesis investigated the ECRI system treatment efficiency of high concentration domestic sewage. On the basis, the effect of denitrification by adding sustained release carbon sources to increase the TN removal was further studied. Moreover, the ECRI system adding sustained release carbon source operating in winter was conducted.Gynura was planted on the surface of pool of ECRI system with anterior micro-aeration pretreatment and post-denitrification section. The operating parameters was set as: a fixed 1:5 ratio of wet to dry rate (WDR), hydraulic loading 0.8 m/d, 4 HLC per day, an inlet last for 0.5 h, the drying time is 5.5 h, and stable operation for 3 months. The results showed that the removal efficiencies of CODCr, NH4-N and SS were 94.4%, 97.0%, and 96.9%, respectively, which can meet the requirements of Classâ… A of the National Wastewater Discharge Standard (GB 18918-2002). The effluent of TP meet the requirements of Classâ… B of the National Wastewater Discharge Standard (GB 18918-2002), and the TN removal was less effective, only 68.9% was removed.After adding the sustained release carbon source in the denitrification sector, the removal efficiency of TN significantly increased to 80.0%. The 40cm-thick slow-release carbon source didn't show obviously advantage than 20cm-thick, just with TN increasing from 88.0% to 89. 6 %. The increase of COD, NH4-N, and TP are not obvious. The scan electron microscopy (SEM) analysis showed that the surface of rotten branches dominated by filamentous bacteria and coccobacteria.The ECRI system can be operated under low temperature in winter using insulation layer outside the inlet pipe and film covering the ECRI pool to ensure that the system can be operated normally at about -10 oC in the north part of China. Nevertheless, the treatment effect was not as good as operating in summer. The removal of NH4-N, and TN most affected by the temperature, followed with COD, and TP was almost unaffected.The full-scale application of carbon source adding ECRI system was located in a highway service area in Anhui Province for treating domestic sewage. The entire system was operated stable with hydraulic loading rate 2.0 m/d. The effluent CODCr, NH4-N, and TN achieved the requirements of Classâ… A of the National Wastewater Discharge Standard (GB 18918-2002). As a new eco-processing technology, ECRI system has good technical and economic performance, which has a good application prospect for highway service area sewage treatment.