Improved process for primary treatment of sewage in urban area

Abstract

An improved process of one-stage treatment of city sewage is characterized by that on the basis of biologic-chemical adsorption and flocculation method, the deposited mud is separated and activated by aeration and the activated mud is used for reflux, adsorption and flocculation, so greatly removing COD, ammoniacal nitrogen and SS, and saving chemical flocculant. Its advantages are high effect and low cost.

Description

technical field [0001] The invention relates to urban sewage treatment, in particular to the improvement of a method for strengthening the primary treatment of urban sewage. Background technique [0002] For urban sewage treatment, secondary treatment requires large investment and high operating costs, so it is limited to a certain extent. Although the primary treatment has a low investment, it is less effective in removing pollutants, so it is rarely used. Emerged at the historic moment are various types of low investment, and enhanced primary treatment process with higher efficiency for pollutant removal, such as chemical flocculation enhanced primary treatment process (flocculation - precipitation - effluent), through the sedimentation Pre-dosing chemical flocculants improves the efficiency of sedimentation and separation, and its disadvantages are: for dissolved organic pollutants (such as dissolved COD, NH 3 -N) The removal efficiency is very low, and the dosage of ch...

AI Technical Summary

Problems solved by technology

[0002] Urban sewage treatment, secondary treatment has large investment and high treatment operation cost, so it is subject to certain restrictions

Although the primary treatment has a low investment, it is less effective in removing pollutants, so it is rarely used.

Emerged at the historic moment are various types of low investment, and enhanced primary treatment process with higher efficiency for pollutant removal, such as chemical flocculation enhanced primary treatment process (flocculation - precipitation - effluent), through the sedimentation Pre-dosing chemical flocculants improves the efficiency of sedimentation and separation. The disadvantages are: for dissolved organic pollutants (such as dissolved COD, NH 3 -N) The removal efficiency is very low, and the dosage of the agent is large, usually up to 200-300ppm, and the treatment cost is relatively high

Bioflocculation and adsorption enhanced primary treatment process (reflux sludge - flocculation and adsorption - precipitation - effluent), through the mixed reaction with the return sludge before sedimentation, through the adsorption and flocculation of sludge to improve the removal efficiency of pollutants , but its disadvantages are: the removal rate of total phosphorus is low, and the sludge return flow is large, and the power consumption is high. Generally, the return ratio of sewage sludge varies from 100-300% according to different sewage sludge

However, since the return sludge is a mixed sludge of biological sludge and chemical sludge discharged from the sedimentation tank, and the process does not sort or activate the return sludge, the inactive chemical sludge in the return sludge gradually increases. As a result, the microbial activity of the return sludge is not high, and the adsorption performance is poor, so that the treatment effect is still not ideal, the removal rate of dissolved COD and dissolved ammonia nitrogen is still not high, and the unactivated sludge flocs are small, SS The removal rate is also low

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