Influence Of Nitrogen And Phosphorus Removal By Integral Side-ditch OCO Process

Integrated wastewater treatment process becomes a hot research in recent years for its high efficiency, economy, ease of management, etc. OCO sewage treatment process was developed by the company of Danish Puritek A/S in 1980s, which has small floor area, clearly divided zones, and low cost compared with conventional oxidation ditch. And OCO sewage treatment process is popular in the Nordic region. Based on the classic OCO and oxidation ditch process, a novel integrated OCO process has been developed. It combines the bio-chemical reactor with the secondary clarifier and its sludge refluxing is automatic. The side-ditch sedimentation tank is not in the main channel, so that has little influence on the hydraulic conditions of the main channel. It is an efficient, economy, new sewage treatment process.Using manual simulated domestic sewage as the treatment media, the treatment efficiency by integral side-ditch OCO process is studied. The followings are mainly studied:The hydraulic mixing characteristics of integral OCO process. The hydraulic mixing characteristics of integral OCO process is similar to completely mixed process and the ratio is 84.7%.Influences of different DO on nitrogen and phosphorus removal by integral side-ditch OCO process. DO has little effect on the COD removal efficiencies, and the COD removal efficiencies are more than 80%. The optimal TN and TP removal efficiencies are 82% and 76% respectively when DO is about 2.0mg/L. Influences of different HRT and C/N on Nitrogen and phosphorus removal by integral side-ditch OCO process.HRT has little effect on the COD removal efficiencies, the COD removal efficiencies are more than 87%. But the TN and TP average removal efficiency increases first and then decreases along with the decrease of HRT. HRT of 12h is about the most suitable hydraulic retention time. The optimal COD, TN and TP removal efficiencies are 95%, 83% and 79% respectively when HRT is 12h. C/N has little effect on COD removal efficiencies. The COD removal efficiencies are more than 80%. The optimal TN and TP removal efficiencies are 82% and 77% respectively when C/N is about 8.The microbial community structure of integral side-ditch OCO process.The diversity of microbial communities of activated sludge by integral side-ditch OCO process is very rich. The microbial community succession of different zone is not obvious and microbial community structure is relatively stable.