Method for forcibly removing nitrogen and phosphorus by means of in-situ enrichment of nitrifying bacteria coupled with sludge hydrolysis

Abstract

The invention discloses a method for forcibly removing nitrogen and phosphorus from a sewage plant by means of in-situ enrichment of nitrifying bacteria coupled with sludge hydrolysis, and belongs to the field of sewage treatment. Specific to the defects of the conventional mainstream nitrogen and phosphorus removing process, two independent serial or parallel reaction tanks namely, an S-NDN tank and an S-HY tank, are arranged on a sludge return line; sludge returning from a sludge return pump room is shunted into the S-NDN tank and the S-HY tank respectively; the other part of return sludge directly returns into a main biological tank; a nitrogen-rich supernatant generated on a sludge treatment segment of the sewage plant is introduced into the S-NDN tank for serving as a nitrogen source for use in a nitration process, and is applied to in-situ enrichment culture of the nitrifying bacteria; active sludge in the S-HY tank undergoes anaerobic hydrolysis and generates soluble chemical oxygen demand (SCOD); and a mud-water mixed solution which is subjected to the biochemical process in the two reaction tanks returns into a main biological tank respectively. By adopting the method, the nitrogen and phosphorus removing efficiencies can be increased remarkably, and sludge reduction can be realized.

Description

technical field [0001] The invention relates to a sewage treatment method, which belongs to the field of environmental protection, in particular to a method for in-situ enrichment of nitrifying bacteria coupled with sludge hydrolysis to strengthen nitrogen and phosphorus removal in sewage plants. Background technique [0002] At present, China's environmental problems are frequent, surface water eutrophication is serious, and the water quality of some waters even loses the function of drinking water source. Strengthening nitrogen and phosphorus removal will become an important task for a long time in the future. At the same time, the existing conventional treatment processes, such as the deformation process of various activated sludge methods, AAO, oxidation ditch, SBR, etc., are affected by factors such as influent water quality and sludge age control, and have poor nitrogen and phosphorus removal effects. Stability issues, the effluent nitrogen and phosphorus indicators ar...

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Problems solved by technology

[0003] The internal factors that affect the effect of simultaneous nitrogen and phosphorus removal are mainly restricted by two factors. One is the influence of sludge age (SRT). For a specific water temperature, nitrifying bacteria require a theoretical minimum SRT min , the activated sludge system requires the actual operating SRT ≥ SRT in order to satisfy sufficient nitrification min , the lower the water temperature, the longer the SRT is required; and the phosphorus removal process requires the shorter the SRT, the shorter the SRT often means the discharge of more excess sludge (WAS), therefore, for the same sewage treatment system, the existing It is often difficult to find a relatively reliable SRT in operation practice, which can not only meet the requirements of nitrification, but also efficiently remove phosphorus, and take into account the effect of nitrogen and phosphorus removal. It is often in a dilemma

[0004] There are similar lateral flow sludge bioaugmentation technologies in foreign countries, such as process, AT-3 process, etc., the main purpose is to strengthen the nitrification process, but the operating conditions and control of these processes are relatively cumbersome, such as The water temperature of the process operation needs to be controlled at 25-30°C, and the intermittent operation mode (water intake, mixing, aeration, sedimentation, decanting) is adopted, and the effect is difficult to control

[0005] At the same time, another important factor affecting the effect of nitrogen and phosphorus removal is the problem of influent water quality. As we all know, the main problems faced by China's sewage plants are insufficient carbon sources in influent water and poor nitrogen and phosphorus removal effects. This is because denitrification Both biological processes of nitrogen removal and anaerobic phosphorus release require sufficient dissolved readily biodegradable organic matter (SCOD), especially low molecular weight volatile fatty acids (VFAs) in wastewater, in order to achieve reliable enhanced biological phosphorus removal (EBPR ), often requires VFAs / TP≥10, which means that for a sewage plant with influent TP=4mg / L, the VFA concentration in the influent water must reach at least 40mg / L to achieve reliable EBPR. However, many sewage plants in my country Plant influent VFAs is less than 10mg / L

In order to make full use of activated sludge carbon sources, some technologies have been developed in recent years, such as ultrasonic cracking, alkaline sludge hydrolysis technology, etc., but these technologies have shortcomings such as high energy consumption, high chemical consumption, and destruction of sludge biological activity. Not a sustainable green process, difficult to apply on a large scale in production practice

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