CN-122010376-A - Method for realizing DNRA based on ferrate sludge wall breaking and carbon utilization

CN122010376ACN 122010376 ACN122010376 ACN 122010376ACN-122010376-A

Abstract

The invention discloses a method for realizing DNRA based on ferrate sludge wall breaking and carbon source utilization, belonging to the technical field of sewage treatment and recycling. The method comprises the steps of S1, adding ferrate into residual sludge under a strict anaerobic environment, rapidly stirring to break walls of the sludge and release intracellular organic matters, S2, carrying out solid-liquid separation on a mixture after reaction, collecting supernatant and diluting to a specific Chemical Oxygen Demand (COD) concentration to obtain a recovered carbon source liquid, S3, adding the recovered carbon source liquid into nitrate nitrogen-containing wastewater, regulating and controlling the carbon nitrogen ratio and Oxidation Reduction Potential (ORP) of a system, and reducing nitrate nitrogen into ammonia nitrogen by utilizing functional microorganisms under an anaerobic condition to realize ammonia nitrogen accumulation and recovery. The method utilizes the ferrate to release the high-concentration carbon source through high-efficiency wall breaking, solves the problem of lack of the traditional denitrification carbon source, converts low-concentration nitrate nitrogen into recoverable ammonia nitrogen through the process of directionally inducing the reduction of the dissimilated nitrate into ammonium (DNRA) through the regulation and control of environmental parameters, avoids nitrogen loss, has the advantages of high-efficiency denitrification and resource recovery, and is environment-friendly.

Inventors

LI MENGQING
WEI DONG
YANG ZHIXIANG
QIN YIJIE
XIE JUNXIN

Assignees

济南大学

Dates

Publication Date: 20260512
Application Date: 20260309

Claims (7)

1. A method for realizing DNRA based on ferrate sludge wall breaking and carbon source utilization is characterized by comprising the following steps: S1, anaerobic wall breaking and carbon releasing, namely taking residual sludge of a sewage treatment plant, adding ferrate into the sludge according to the adding amount of 20-150 mg Fe (VI)/g SS under the anaerobic environment with the dissolved oxygen concentration of less than or equal to 0.5 mg/L, controlling the sludge concentration to be 25 g/L, and carrying out rapid stirring reaction for 30-60 min so as to realize cell wall cracking of the sludge and release intracellular organic matters; S2, carbon source recovery and domestication, namely performing solid-liquid separation on the sludge mixture after the reaction in the step S1, collecting supernatant rich in soluble organic matters, diluting the supernatant to the concentration of Chemical Oxygen Demand (COD) of 180-220 mg/L, and obtaining recovered carbon source liquid; and S3, DNRA, namely adding the recovered carbon source liquid obtained in the step S2 into the wastewater to be treated, wherein the concentration of nitrate nitrogen is 15-25 mg/L, regulating and controlling the carbon nitrogen ratio (COD: NO 3 - -N) of the mixed system to be 8:1-12:1, and reducing the nitrate nitrogen into ammonia nitrogen by utilizing functional microorganisms under the anaerobic condition that the oxidation-reduction potential (ORP) is-150 mV to-100 mV and the Hydraulic Retention Time (HRT) is 4-8 h so as to realize accumulation and recovery of the ammonia nitrogen.
2. The method according to claim 1, wherein in the step S1, the condition of the rapid stirring reaction is that the stirring speed is 300-500 rpm and the reaction time is 1-3 h.
3. The method of claim 1, wherein in step S1, the ferrate is selected from the group consisting of potassium ferrate and sodium ferrate.
4. The method of claim 1, wherein in the step S2, the COD release amount of the sludge supernatant obtained after solid-liquid separation is more than or equal to 1500 mg/L, and the degradation rate of the Extracellular Polymer (EPS) of the sludge is more than or equal to 60%.
5. The method of claim 1, wherein in step S3, the activity of methanogen and the denitrification gas production side reaction are inhibited by regulating and controlling ORP to be more than or equal to-150 mV, so that the DNRA metabolic pathway is ensured to be dominant in the nitrate reduction process.
6. The method of claim 1, wherein in the step S3, after DNRA reaction, the ammonia nitrogen accumulation concentration in the system is 8-15 mg/L, so that the recycling of ammonia nitrogen in the low-concentration nitrogen-containing wastewater is realized.
7. The method according to claim 1, wherein in the step S1, the surplus sludge is sourced from a sludge recirculation tank or an aerobic tank end of a sewage treatment plant.

Description

Method for realizing DNRA based on ferrate sludge wall breaking and carbon utilization Technical Field The invention belongs to the technical field of sewage treatment and recycling, and particularly relates to a method for carrying out wall breaking treatment on residual sludge by utilizing ferrate, recovering an intracellular carbon source, and realizing deep denitrification and ammonia nitrogen resource recovery of low-concentration nitrogen-containing wastewater through DNRA paths. Background With the increasing strictness of environmental regulations, town sewage treatment plants face higher nitrogen emission standards. The traditional biological denitrification process mainly relies on a nitrification-denitrification process, and the process can effectively remove total nitrogen, but a large amount of easily degradable carbon sources (such as methanol, acetic acid and the like) are consumed in the denitrification process, and the carbon nitrogen ratio (C/N) of municipal sewage is generally low, so that expensive external carbon sources are required to be additionally added in the denitrification process, and the operation cost is obviously increased. And the final electron acceptor of the denitrification process is nitrate, the final product of which is nitrogen (N 2), which not only causes a permanent loss of nitrogen resources, but under certain conditions (e.g. short-cut denitrification) may produce the powerful greenhouse gas nitrous oxide (N 2 O). In addition, the treatment and disposal costs of a large amount of excess sludge generated in the sewage treatment process often occupy 30% -50% of the running cost of the whole sewage treatment plant. The current mainstream sludge treatment technology (such as anaerobic digestion, incineration, landfill) has the problems of high energy consumption, secondary pollution or low resource utilization rate and the like. On the other hand, in recent years, the reduction of differentiated nitrate to ammonium (DNRA) is distinguished from denitrification due to the development of isotope technology. Under anaerobic conditions, DNRA transfers more electrons than denitrification per 1mol of nitrate, and DNRA acts as a final reduction product for ammonia nitrogen (NH 4+ -N), which does not involve the emission of nitrous oxide (N 2 O), and ammonia nitrogen (NH 4+ -N) is more readily utilized by plants and other microorganisms. Compared with the traditional denitrification process, DNRA converts inorganic nitrogen into available ammonia nitrogen, avoids volatilization loss of nitrogen, and provides possibility for subsequent nitrogen recovery (such as struvite precipitation, stripping method and the like) or directly as slow-release nitrogen fertilizer for recycling. Meanwhile, the final product of DNRA is ammonium ion, N 2 O is not generated, and the carbon footprint in the sewage treatment process is reduced. DNRA and denitrification are two competing microbiological processes. Under the environment of low oxygen and high COD, DNRA bacteria can utilize complex organic matters as electron donors. Therefore, if a proper environment can be constructed, the nitrate flow DNRA way can be induced, and the difficult denitrification problem under the low-carbon source condition can be solved. However, the rate of DNRA reactions is slow in the prior art and is extremely sensitive to environmental conditions (such as pH, ORP, carbon source type and concentration). In addition, the conventional anaerobic sludge fermentation technology can produce Volatile Fatty Acids (VFAs) as a carbon source, but the fermentation period is long (usually 10-20 days), and the produced VFAs are easily utilized by methanogens, resulting in low and unstable actual recovery of the carbon source. Therefore, how to develop a method for rapidly and efficiently releasing a high-activity carbon source from residual sludge and directing the method for deep denitrification and resource recovery of low-concentration nitrogen-containing wastewater is a technical problem to be solved in the current sewage treatment field. Disclosure of Invention 1. Technical problem to be solved The invention aims to overcome the defects of the prior art and provides a method for realizing DNRA based on wall breaking of ferrate sludge and carbon source utilization. According to the method, the waste residual sludge in the sewage treatment plant can be used as an internal carbon source, high-concentration soluble organic matters are quickly released through the efficient wall breaking effect of ferrate, and the process of DNRA is driven by the organic matters, so that the deep removal of nitrate in the low-concentration nitrogen-containing wastewater and the recycling recovery of ammonia nitrogen are realized. 2. Technical proposal In order to solve the problems, the invention provides a method for realizing DNRA based on wall breaking of ferrate sludge and carbon source utilization, which comprises the following steps: S1,