Standard reaching to ground surface water grade IV water urban sewage treatment process

Abstract

The invention discloses a standard reaching to ground surface water grade IV water urban sewage treatment process, which comprises the following treatment steps that the urban sewage is subjected to pretreatment so as to remove sand, stone and big particle materials in the sewage; after the pretreatment, different-point water feeding is performed to a pre-denitrification and anoxic pool; outlet water subjected to pre-denitrification sequentially passes through an anaerobic pool, the anoxic pool, an aerobic pool, a secondary sedimentation tank, a magnetic or sand loading flocculation deep dephosphorization settling pool and a reaction unit for sterilizing and oxidizing rest organic matters and improving dissolved oxygen in water, and is discharged after the standard reaching; mud water in the secondary sedimentation tank flows back to the pre-denitrification pool; mud water in the aerobic pool flows back to the anoxic pool; a carbon source can be additionally fed into the anoxic pool; the preferable carbon source and the carbon source precise control mode are favorable for the target realization; the problem of the conventional grade IV water standard reaching is solved through oxidization, sterilization and oxygen charging measures. The process has the advantages that the multiple regions are used for reasonably allocating the inlet water; the carbon source is sufficiently utilized; the sludge age is more reasonable; various conventional problems and the practical problem that the grade IV water standard is difficult to reach are solved; each outlet water index is enabled to stably reach the grade IV water standard.

Description

technical field [0001] The invention relates to the technical field of environmental protection, in particular to a process for treating urban sewage up to the standard of Class IV surface water. Background technique [0002] With the increasingly prominent problem of water pollution in our country, the improvement of urban sewage treatment and discharge standards has become the general trend. Judging from the current requirements for improving the quality of the water environment, the effluent treated by many urban sewage treatment plants is often discharged into urban rivers and becomes the water body of the river. For the effluent of my country's existing sewage treatment plants, the discharge standards mostly refer to Class I A in the "GB18918-2002 Pollutant Discharge Standards for Urban Sewage Treatment Plants". However, for the first-class A standard, its water quality is only equivalent to the inferior V-class water of surface water. This kind of water quality is di...

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Problems solved by technology

However, the following core problems still exist in the existing Class IV water treatment process: (1) Part of the design of the secondary biological treatment process is unreasonable, and it is difficult to control the mud age and dominant bacterial flora of various functions; the organic carbon source in the influent is not fully utilized ; The organic carbon source in the influent water is not fully utilized, and the denitrification efficiency is low; the nitrification is incomplete, and when the temperature is low in winter, the NH in the effluent 4 + -N is difficult to control below 1.5mg / L; effluent TP is generally higher than 1.0mg / L; (2) The traditional chemical phosphorus removal technology uses a large amount of chemicals, the treatment effect is poor, the surface load is low, and the floor area is large , can not guarantee to meet the standard of Class IV water stably; (3) The traditional denitrification denitrification biofilter is often used in the traditional fine denitrification, and there are the following problems: 1) It is well known in the industry that due to the compaction between the biological fillers in the anoxic / anaerobic denitrification environment , short flow and other effects, the effluent COD of the denitrification biological filter after adding carbon source Cr COD Cr High about -10 ~ 25mg / L, Class A and Class IV water COD Cr The difference is only 20mg / L, BOD 5 The difference is only 4mg / L, and the effluent COD of Class Ⅳ water Cr and BOD 5 Extremely unstable; 2) The selection of carbon source type and the precise dosage control of carbon source in the denitrification filter are very critical. For BOD 5 The difference between Class A and Class IV water is only 4mg / L, which directly affects the COD of the effluent Cr How much to increase, the utilization rate of denitrification carbon source and whether it can reach the standard are the core key, which must be precisely controlled; (4) The concentration of organic matter in the effluent of the denitrification and denitrification biological filter increases, and the subsequent treatment units do not reduce COD Cr and BOD 5 (5) Since denitrification and denitrification occur in anoxic / anaerobic environment, the dissolved oxygen (DO) of wastewater after deep denitrification of denitrification is generally lower than 0.2mg / L, while the level of Class IV water Dissolved oxygen should not be lower than 3mg / L, so other measures are needed to further increase the dissolved oxygen (DO) of sewage, but the existing Class IV water treatment process does not take this key indicator into consideration

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