CN116789246A

CN116789246A - Quality and efficiency improving method for sewage system

Info

Publication number: CN116789246A
Application number: CN202310875424.1A
Authority: CN
Inventors: 刘轶文; 郭海晓; 王玉芬; 李一鸣; 朱婷婷
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2023-07-17
Filing date: 2023-07-17
Publication date: 2023-09-22

Abstract

The invention belongs to the technical field of sewage treatment, and discloses a quality improvement and efficiency improvement method for a sewage system, which comprises the following steps: the invention adopts solid acid source to reduce the risk of transportation and storage process, intermittent dosing reduces the cost, realizes the dephosphorization efficiency of sewage through pipe network dosing at the downstream, improves the quality of methane by anaerobic digestion of sludge, reduces the production of greenhouse gas nitrous oxide in the dosing process compared with the prior art, reduces the loss of microorganisms on sewage organic carbon in the sewage transmission process by killing pipe network microorganisms, improves the carbon-nitrogen ratio of the sewage in the downstream sewage plant, and reduces the additional carbon source supplement cost in the quality improvement and synergy process of the sewage plant.

Description

Quality and efficiency improving method for sewage system

Technical Field

The invention relates to the technical field of sewage treatment, in particular to a quality improvement and synergy method of a sewage system.

Background

The sewage pipe network is an important sanitary infrastructure of the modern society, plays a role in collecting and transmitting household water to a sewage treatment plant for treatment, and with the development of the society, urban population is gradually dense, urban sewage discharge is rapidly increased, and the scale of the sewage pipe network system is also increased. Bacteria in sewage are attached to the pipe wall to form a biological film in the sewage transmission process, natural anaerobic conditions in the pipeline cause enrichment of sulfate reducing bacteria and methanogenic archaea, sewage matrixes are utilized for biochemical reaction to generate sulfides and methane, and the sulfides are formed not only to cause malodor and health problems, but also to seriously corrode the pipeline, so that expensive repair cost is caused. Methane is produced as a highly potent greenhouse gas (28 times higher global warming potential than carbon dioxide for 100 years), the production of pipe network methane contributes significantly to carbon emissions, and the explosion limit of methane is about 5% vol lower, and the closed environment accumulated in the sewer has explosion hazards, so sulfide and methane production can be controlled from the source by killing sulfate reducing bacteria and methanogenic archaea on the pipe wall. In addition, the pipe network belongs to a part of the sewage system, and cannot be split with the strategic targets of pollution reduction, carbon reduction, quality improvement and efficiency improvement of the sewage system.

At present, related chemical agents for inactivating microorganisms in sewage pipelines are divided into two types, wherein one type has little influence on the environment, but chemical agents such as sodium hydroxide, nitrate, oxygen and the like need to be continuously added; the microbial agent has high biocidal effect, and can kill pipeline microbes, such as glutaraldehyde, polyoxometallate, sodium nitroprusside, etc. through intermittent addition, sulfide and methane rebound need regeneration of biomembrane, and pipeline malodor and methane can be obviously controlled. However, no method for controlling the sulfide and methane in a pipe network in a lower concentration range by intermittent feeding without continuous feeding is available, so that the chemical feeding cost is greatly reduced, the environmental risk is avoided, and the beneficial effect is brought to the whole sewage system. Although the patent CN102939013a discloses a method of killing sulfate reducing bacteria and methanogenic archaea of a pipe network by combining hydrochloric acid with nitrite to control the production of sulfide and methane in the pipe, the acid source is liquid 37% (w/w) hydrochloric acid, which cannot provide any other beneficial effect except lowering the pH, and has high volatility to corrode equipment, and is inconvenient in liquid transportation and high in price.

Therefore, the research results in a sewage system quality improvement gain method which can control sulfide and methane production in a sewage pipe network and has additional beneficial effects on the whole sewage system.

Disclosure of Invention

In view of the above, the invention provides a quality improvement and synergy method for a sewage system, which aims to solve the technical problems of higher cost, environmental pollution and complex process in the prior art.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention provides a quality improvement and efficiency improvement method for a sewage system, which comprises the following steps: and sequentially adding ferric salt and nitrite into the sewage pipe network system, and exposing to obtain the treated sewage pipe network system.

Preferably, the pH value of the sewage after adding ferric salt is 5.5-6.

Preferably, the ferric salt comprises one or more of ferric chloride, ferric nitrate, ferric sulfate and water supply plant sludge.

Preferably, the nitrite comprises sodium nitrite, potassium nitrite or nitrified wastewater containing high ammonia nitrogen.

Preferably, the concentration of nitrogen in the nitrite is 100-200 mg/L, and the concentration of free nitrous acid is 0.26-0.81 mg/L.

Preferably, the sewage system is further added with an oxidant after adding ferric salt and nitrite.

Preferably, the oxidant comprises one or more of calcium peroxide, sodium percarbonate, hydrogen peroxide, peracetic acid, potassium ferrate, potassium permanganate, periodate, peroxymonosulfate and peroxydisulfate.

Preferably, the exposure time is 12 to 24 hours.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts solid acid source, reduces the risk in transportation and storage processes, improves the dephosphorization efficiency of sewage through pipe network dosing at the downstream, anaerobically digests the biogas quality by sludge, reduces the generation of greenhouse gas nitrous oxide in the dosing process compared with the prior art, reduces the loss of microorganisms on organic carbon of sewage in the sewage transmission process by killing pipe network microorganisms, improves the carbon-nitrogen ratio of the sewage in the downstream sewage plant, and reduces the additional carbon source supplementing cost in the quality improving and efficiency enhancing process of the sewage plant. The related chemicals can be obtained from the recycled waste, so that the administration cost is further reduced. Therefore, the invention provides a green and economic strategy, and simultaneously has a plurality of additional beneficial side effects on the whole sewage system, and has excellent application prospect; the invention can effectively kill pipe network microorganisms, prolong the rebound period of sulfides and methane, reduce the dosage, the dosage frequency and the dosage cost, and bring beneficial effects to the whole sewage system while not generating environmental risks by providing a single and intermittent dosage mode.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of the quality improvement and synergy method of the sewage system of the invention;

FIG. 2 is a graph showing the comparison of the morphology of the pipe network biofilm before and after administration in example 4, wherein a1 is the morphology of the pipe network biofilm before administration and a2 is the morphology of the pipe network biofilm after administration;

FIG. 3 is a graph showing the comparative graph of the leakage of metal elements in the cells of the pipe network biofilm before and after the administration of the drug in example 4, wherein a1 is the relative content of iron and sodium elements in the cells of the pipe network biofilm before and a2 is the relative content of iron and sodium elements in the cells of the pipe network biofilm after the drug administration;

FIG. 4 is a schematic diagram of the inactivation of the pipe network biofilm by two different free nitrous acids in example 5, wherein a1 is a schematic diagram of the inactivation of the pipe network biofilm by free nitrous acid prepared from sodium nitrite and ferric trichloride, and a2 is a schematic diagram of the inactivation of the pipe network biofilm by free nitrous acid prepared from the acidity provided by hydrolysis of iron flocculated sludge in a water supply plant in combination with nitrite;

FIG. 5 is a graph showing the composition of active oxygen generated in situ in example 6.

Detailed Description

In the invention, the adding position of the ferric salt and the nitrite is preferably upstream of a sewage system, and further preferably a pump station, a wet well, a manhole or a pipeline to be treated.

In the present invention, the pH of the sewage after adding the ferric salt is preferably 5.5 to 6, more preferably 5.6 to 5.9, and still more preferably 5.7 to 5.8.

In the present invention, the ferric salt preferably comprises one or more of ferric trichloride, ferric nitrate, ferric sulfate and water supply plant sludge.

In the invention, the water supply plant sludge is preferably sludge produced by a water supply plant using ferric trichloride as a flocculant.

In the invention, ferric salt is added to a pump station, a wet well, a manhole or a pipeline to be treated; nitrite is added to a pump station, a wetwell, a manhole or a pipeline to be treated, to which ferric salt is added.

In the invention, the ferric salt is transmitted to a downstream sewage treatment unit along with sewage, iron ions are combined with phosphorus in the sewage to form precipitation, so that the phosphorus concentration of the effluent of a sewage treatment plant is reduced, the content of hydrogen sulfide in methane in the recycling process of residual sludge is reduced, and the quality of the methane is improved.

In the invention, the nitrite preferably comprises sodium nitrite, potassium nitrite or nitrified wastewater containing high ammonia nitrogen.

In the invention, the wastewater containing high ammonia nitrogen is preferably urine and sludge fermentation liquor.

In the invention, the addition of ferric salt and nitrite can reduce the generation of greenhouse gas nitrous oxide in a sewage pipe network.

In the invention, ferric salt added into the pipe network can control the generation of sulfide in the pipe network, and the ferric salt accumulated in the sludge can reduce the content of hydrogen sulfide in the biogas generated by anaerobic digestion of the sludge, thereby improving the quality of the biogas.

In the present invention, the concentration of nitrogen in the nitrite is preferably 100 to 200mg/L, more preferably 120 to 180mg/L, still more preferably 140 to 160mg/L, and the concentration of Free Nitrous Acid (FNA) is preferably 0.26 to 0.81mg/L, still more preferably 0.32 to 0.64mg/L, still more preferably 0.42 to 0.58mg/L.

In the invention, the concentration of the free nitrous acid and the nitrous nitrogen are related to pH and temperature, and the calculation formula of the concentration of the free nitrous acid is as follows: c (C) _FNA ＝C _NO2 ^- _-N /(K _a ×10 ^pH ) Wherein K is _a ＝e ^{-2300/(273+T)} In the formula, C _FNA The unit is mg-N/L, C _NO2 ^- _-N The unit is mg-N/L, K _a The pH is the pH of the wastewater as a function of temperature T (. Degree.C.).

In the invention, the free nitrous acid has the effect of killing pipe network microorganisms.

In the invention, the sewage pipe network system is preferably added with an oxidant after adding ferric salt and nitrite.

In the present invention, the addition of the oxidizing agent can further kill those microorganisms that are resistant to the free nitrous acid produced.

In the present invention, the oxidizing agent preferably includes one or more of calcium peroxide, sodium percarbonate, hydrogen peroxide, peracetic acid, potassium ferrate, potassium permanganate, periodate, peroxymonosulfate, and peroxydisulfate.

In the invention, the oxidant can kill sulfide-producing bacteria and methanogenic archaea which are resistant to free nitrous acid, and the investment of chemical cost is reduced.

In the invention, the oxidant can be activated in situ to generate active oxygen species, has nonselective biocidal property, improves the control efficiency of pipe network sulfides and methane, reduces the loss of organic carbon in the sewage transmission process, further improves the inlet carbon nitrogen ratio of a sewage treatment plant, and reduces the cost of adding additional carbon sources.

In the invention, the oxidant is preferably added intermittently or in a short time in a pulse step-by-step manner so as to improve the inactivation efficiency of the microorganisms in the pipe network.

In the present invention, the exposure time is preferably 12 to 24 hours, more preferably 16 to 22 hours, and still more preferably 18 to 20 hours.

In the invention, the exposure is chemical agent to treat the pipe network system.

In the present invention, the chemical agent comprises two schemes, one of which is trivalent iron salt and nitrite, and the other of which is trivalent iron salt, nitrite and oxidant.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

In the embodiment of the invention, the structure of the applied simulated sewage pipe network reactor is as follows:

the simulated sewage pipe network reactor is an acrylic cylindrical reactor with the diameter of 80mm, the height of 149mm and the effective volume of 750 mL; the side wall of the reactor is provided with a sampling port for collecting a water sample to detect sulfide and methane; the top of the reactor is provided with a reactor cover, three stainless steel bars are arranged on a detachable screw cap on the reactor cover, and K2 type circular biomembrane plastic carriers with the diameter of 1.5mm are fixed on the steel bars, so that biomembrane is conveniently attached; the reactor cover comprises a cylindrical reservoir with an effective volume of 100mL in addition to the water inlet and outlet, so as to avoid affecting the measurement of sulfides and methane due to the ingress of air during water sampling.

Mode of operation of the sewage pipe network reactor: feeding the actual sewage retrieved by the actual municipal sewage pipe network, filling the same actual sewage as the reactor in a reservoir, intermittently feeding water into the reactor through a peristaltic pump according to the flow rate of the actual pipe network in different time periods of one day, wherein the water feeding flow rate is 0.6m/s, the water feeding is 16 times per day, the hydraulic retention time is 2-10.5 h, placing the reactor on a magnetic stirrer, providing a rotating speed of 200rpm, and simulating the hydraulic shear force of water flow. The simulated sewage pipe network reactor is operated for half a year, so that the activity of generating sulfide and methane is kept relatively stable, and the simulated sewage pipe network reactor is used in the following examples 1-3.

In the embodiment of the invention, the step of gradient dehydration of the biological film is included before the scanning electron microscope observation: the biofilm was first immersed in 50mM phosphate buffer solution containing 2.5% pentanediol at 4℃where Na ₂ HPO ₄ ·12H ₂ The concentration of O is 11.55g/L, naH ₂ PO ₄ ·2H ₂ The concentration of O is 2.77g/L, the concentration of KCl is 0.13g/L, and NH ₄ Cl concentration of 0.31 g/L) for 12h, washing the cells twice with the same phosphate buffer solution to obtain cell particles, dehydrating the cell particles with ethanol solutions with mass concentrations of 50%,70%,80%,90% and 100% for 15min, and finally drying the dehydrated cell particles at room temperature for 24h for observation.

In the embodiment of the invention, the determination of the active oxygen comprises the following steps: filtering 1mL of the solution to be detected with a filter membrane with the diameter of 0.22 mu m to obtain a supernatant, dispersing the supernatant in a methanol solution, and determining whether the solution contains superoxide radicals or not by taking tetramethyl piperidinol (TEMP) as a capturing agent; dispersing the supernatant in water, and measuring hydroxyl radical and singlet oxygen by using 5, 5-dimethyl-1-pyrroline-N-oxide (DMPO) as a capturing agent, and measuring the characteristic peak of the generated active species by using an electron spin resonance spectrometer.

Example 1

And (3) evacuating the sewage in the sewage pipe network simulating reactor reaching a steady state through a water outlet, pumping the actual sewage into a reactor volume by a peristaltic pump, adding ferric trichloride powder to enable the pH value of the sewage to be equal to 6.0, adding sodium nitrite with the nitrogen concentration of 100mg/L, enabling the concentration of free nitrous acid generated in the reactor to be 0.26mg/L, and exposing for 12 hours to obtain the treated sewage pipe network system.

Evacuating the sewage in the treated sewage pipe network system, injecting fresh actual wastewater, and immediately measuring sulfide and methane generation activity; then the reactor is operated for one month according to the operation mode, so that the pipe network enters the recovery period after the drug administration; sulfide and methane producing activity was measured every two days during the recovery period, and once every other week for the rest.

Example 2

And (3) evacuating sewage in the sewage pipe network simulation reactor reaching a steady state through a water outlet, pumping the actual sewage into a reactor volume by a peristaltic pump, adding ferric nitrate powder to enable the pH value of the sewage to be equal to 6.0, adding potassium nitrite with the nitrogen concentration of 100mg/L, enabling the concentration of free nitrous acid generated in the reactor to be 0.26mg/L, and exposing for 24 hours to obtain the treated sewage pipe network system.

Example 3

And (3) evacuating the sewage in the sewage pipe network simulating reactor reaching a steady state through a water outlet, pumping the actual sewage into a reactor volume by a peristaltic pump, adding ferric sulfate powder to enable the pH value of the sewage to be equal to 5.5, adding sodium nitrite with the nitrogen concentration of 100mg/L, enabling the concentration of free nitrous acid generated in the reactor to be 0.81mg/L, and exposing for 12 hours to obtain the treated sewage pipe network system.

The activity of the sulfide and methane production in examples 1 to 3 is shown in Table 1:

TABLE 1 sulfide and methane production Activity of examples 1 to 3

As can be seen from table 1, in example 1, the sulfide-producing activity after administration was close to 0, indicating that sulfide production was completely inhibited; after two weeks of recovery, sulfide production activity rebounded to 95% prior to dosing and methane production activity rebounded to 100% prior to dosing. In example 2, the activity of sulfide production after administration was close to 0, indicating complete inhibition of sulfide production; after two weeks of recovery, sulfide production activity rebounded to 98% prior to dosing and methane production activity rebounded to 100% prior to dosing. In example 3, the activity of sulfide production after administration was close to 0, indicating complete inhibition of sulfide production; after two weeks of recovery, sulfide activity rebound to 57% before dosing, after recovery, sulfide activity rebound to 86% before dosing, and methane activity rebound to 76% after recovery. It can be seen that control of the biofilm sulphide and methanogenic activity of the pipeline network is not positively correlated with exposure time, and that merely increasing exposure time without changing the dosing concentration does not significantly enhance control efficiency.

Example 4

2 plastic carriers with complete biological membranes attached are taken out from a reactor in a sewage pipe network system treated in example 1, the plastic carriers are placed in a centrifuge tube (50 mL) containing 45mL of phosphoric acid buffer solution (50 mM) after high-pressure steam sterilization, the centrifuge tube is placed on a vortex oscillator (25 Hz,2500 rpm) for oscillating for 1min, the biological membranes are completely separated from the plastic carriers, the biological membrane cell particles are obtained by centrifugation at 8000rpm for 10min, the biological membrane cell particles are washed twice by the phosphoric acid buffer solution and then centrifuged at 8000rpm for 10min, and products are collected into a 2mL sterile centrifuge tube for scanning electron microscopy, and the results are shown in FIG. 2 and FIG. 3.

Example 5

Taking out 2 plastic carriers attached with complete biological membranes from a reactor in the sewage pipe network system treated in the embodiment 1, respectively transferring the plastic carriers into two anaerobic bottles containing 50mL of actual sewage after high-pressure steam sterilization, adding sodium nitrite and ferric trichloride into one bottle, and sealing, wherein the concentration of the sodium nitrite is 100mg-N/L, the concentration of the ferric trichloride is 15mg-Fe/L, the pH value is 6, and the concentration of the generated free nitrous acid is 0.26mg/L and is marked as a1; the other flask was charged with sodium nitrite and recycled ferric flocculated sludge to pH 6 and sealed, wherein the concentration of sodium nitrite was 100mg-N/L, designated as a2. The two anaerobic bottles are placed in an oscillator (the running speed is 50 rpm) to slowly oscillate, so that the medicament is fully contacted with the biological film, and the plastic carrier is taken out after the exposure is carried out for 12 hours.

The two removed plastic carriers were independently subjected to the following operations: placing a plastic carrier into a 50mL centrifuge tube filled with 45mL of sodium chloride solution with the volume fraction of 0.85%, oscillating for 1min by a vortex oscillator (25 Hz,2500 rpm), separating a biological film from the plastic carrier, centrifuging for 10min at 8000rpm to obtain cell particles, washing the obtained cell particles with the sodium chloride solution with the volume fraction of 0.85% three times, re-suspending the cell particles in the 50mL centrifuge tube filled with 45mL of sodium chloride solution (with the volume fraction of 0.85%), sucking 0.1mL of suspension, transferring the suspension into a 2mL sterile centrifuge tube containing 100 mu L of green coloring agent (N01) and 100 mu L of red coloring agent (PI), standing the obtained mixed solution at room temperature for 15min, washing twice with the sodium chloride solution with the volume fraction of 0.85% to remove free coloring agent, and mixing the washed cell particles with 40mL of sodium chloride solution with the volume fraction of 0.85% to obtain a sample. Finally, 5. Mu.L of the sample was smeared uniformly on a microscope slide, and fluorescence microscopy was performed using a 100X objective.

Of these, N01 is able to stain all bacteria, while PI can stain only dead bacteria. The resulting pictures were quantified for the proportion of death of biofilm cells by determining the relative abundance of green and red fluorescence intensities using ImageJ software, the results of which are shown in fig. 4.

Example 6

In the sewage pipe network system after 12h exposure in example 1, 2 plastic carriers with complete biological films attached (black particles attached to the biological films are ferrous sulfide precipitates) were taken out from the pipe network reactor, the plastic carriers were respectively placed in 50mL centrifuge tubes containing 45mL of 50mM phosphoric acid buffer solution after high-pressure steam sterilization, sodium periodate powder was added into one of the centrifuge tubes to make the concentration of sodium periodate be 50mg/L, no substance was added into the other centrifuge tube as a control, the two separate pipes were respectively left stand for 10min, and were then placed on vortex oscillators (25 Hz,2500 rpm) to oscillate for 1min, so that the biological films were completely detached from the plastic carriers, and then active oxygen measurement was performed, with the result shown in FIG. 5.

Example 4 a graph of the morphology of the network biofilm before and after administration is shown in fig. 2, wherein a1 is the morphology of the network biofilm before administration, and a2 is the morphology of the network biofilm after administration. As can be seen from FIG. 2, the cell morphology of the network biofilm changed from smooth, full, regular without administration, shrinkage, invagination of cell membranes, irregular cell membranes, rough cell surfaces with cracks, severe damage to the cells of the network biofilm, and outflow of intracellular substances.

Example 4 a graph of the comparative graph of the leakage of metal elements in the pipe network biofilm cells before and after administration is shown in fig. 3, wherein a1 is the relative content of iron and sodium elements in the pipe network biofilm cells before and after feeding, and a2 is the relative content of iron and sodium elements in the pipe network biofilm cells after feeding. From fig. 3, it is understood that the metal elements of the microorganisms that maintain normal vital activities leak to the outside, and the iron and sodium elements in the inside of the cells are reduced.

In example 5, two different inactivation schemes of free nitrous acid on pipe network biological membranes are shown in fig. 4, wherein a1 is an inactivation scheme of free nitrous acid prepared by sodium nitrite and ferric trichloride on pipe network biological membranes, and a2 is an inactivation scheme of free nitrous acid prepared by combining acidity provided by hydrolysis of iron flocculated sludge in a water supply plant with nitrite on pipe network biological membranes. As can be seen from FIG. 4, the biological inactivation efficiency of free nitrous acid prepared from sodium nitrite and ferric trichloride is close to that of free nitrous acid generated by combining nitrite with acidity provided by hydrolysis of iron flocculation sludge in water supply plants, and the biological inactivation efficiency of free nitrous acid prepared from sodium nitrite and ferric trichloride has good pipe network microorganism killing efficiency.

Example 6 an in situ generated active oxygen composition diagram is shown in figure 5. As can be seen from fig. 5, in the control group to which periodate was not added, there was no signal peak of the active species, but in the experimental group to which periodate was added, characteristic peaks of superoxide radical, hydroxyl radical, and singlet oxygen were generated. The periodate can be activated by ferrous sulfide precipitation attached to a biological film after being added to form active oxygen species with strong biocidal effect, including hydroxyl free radicals, superoxide free radicals and singlet oxygen, so that the biological film of a pipe network is killed, long-acting control of sulfides and methane in the pipe network is realized, and the loss of organic carbon in sewage is reduced.

The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims

1. The quality and efficiency improving method for the sewage system is characterized by comprising the following steps of: and sequentially adding ferric salt and nitrite into the sewage pipe network system, and exposing to obtain the treated sewage pipe network system.

2. The method for improving quality and efficiency of a sewage system according to claim 1, wherein the pH value of the sewage after adding ferric salt is 5.5-6.

3. The method for upgrading a wastewater system according to claim 2, wherein the ferric salt comprises one or more of ferric trichloride, ferric nitrate, ferric sulfate, and water plant sludge.

4. A method for upgrading a wastewater system according to claim 3 wherein the nitrite comprises sodium nitrite, potassium nitrite or nitrified wastewater containing high ammonia nitrogen.

5. A method for upgrading a sewage system according to claim 2 or 3, wherein the concentration of nitrogen in the nitrite is 100-200 mg/L and the concentration of free nitrous acid is 0.26-0.81 mg/L.

6. The method for improving quality and efficiency of a sewage system according to claim 1, wherein an oxidant is added after ferric salt and nitrite are added into the sewage system.

7. The method for upgrading a wastewater system according to claim 6, wherein the oxidizing agent comprises one or more of calcium peroxide, sodium percarbonate, hydrogen peroxide, peracetic acid, potassium ferrate, potassium permanganate, periodate, peroxymonosulfate, and peroxydisulfate.

8. The method for improving quality and efficiency of a sewage system according to claim 1, wherein the exposure time is 12-24 hours.