The Research Of Integrative OCO Process Dispose Urban Domestic Wastewater

Traditional biological nitrogen and phosphorous removal processes either needseveral separated tanks with different DO concentrations, or need sequential aerobicand anoxic environment in turn in a single reactor. Thus these processes have manyshortcomings, such as high-cost removal efficiency of facility and high-costconstruction, large consumption of energy, low nitrogen removal efficiency. As tothese shortcomings, an integrative OCO reactor is designed which combines thebio-chemical reactor with the secondary clarifier. Compared with the traditionalOCO process, it has strong function of nitrogen and phosphorous removal and cansaves floor area and capital expenditure. Self-driven reflux of sludge has been carriedout.First, research is carried out on carbon and nitrogen and phosphorous removal indomestic wastewater with the modified reactor. Second, mechanism of the reactorand also effects of operating conditions, such as influent organic load and hydraulicload and DO and aeration rate on the reactor's removal efficiencies are investigatedwith synthetic wastewater. The following conclusions can be obtained.(1) Anaerobic and oxic and anoxic environment can be created simultaneously inthe integrative, it combines the bio-chemical reactor with the secondary clarifier,which saves floor area and power and the cost of facility construction could bereduced.(2) The research results of domestic wastewater show that the COD removalefficiency is about 93%, nitrification rate and TN removal efficiency reach 93% and80% when HRT is 24hr and temperature is at 24-30℃,The effluent concentration ofNH3-N and TN are about 3mg/L and 8.4mg/L respectively.(3) Carbon is benefit for denitrification, but is disadvantageous to nitrification. The experiment results indicate that the reactor's nitrification ability anddenitrification ability could match each other best when the ratio of influentCOD/TN is about 7.(4) The removal rate of ammonia nitrogen rate is up when the dissolved oxygenof oxic area is up. The nitrification and denitrification of the reactor would beoptimal when the dissolved oxygen of oxic area is about 2mg/L, the effluentconcentration of ammonia nitrogen and total nitrogen are 0.5mg/and 8mg/L, theremoval rate of ammonia nitrogen and total nitrogen are 99% and 80%. Theconcentration of TP is always below 0.6mg/L and the removal rate is above 91%.Dissolved oxygen of the oxic area' variation has no obvious influence to the removalrate of total phosphorous.(5)The integral OCO reactor's nitrogen removal process is based on the followingtwo aspects. One is that nitrification is mainly displayed in the oxic section anddenitrification is dominantly carried out in the anoxic section and they harmonizewith each other by circulation. And the other is that nitrification and denitrificationcould be displayed simultaneously in each section.