Common methods of sewage treatment

2020-10-12 11:42:53 rtchem 2

Common methods of sewage treatment


Industrial wastewater treatment method

A method for treating industrial sewage belongs to the technical field of sewage treatment. It is to take the sewage to the collecting basin, adjust the pH to the end of the collecting tank, and raise it to the first-stage pressure dissolved gas tank with the first-stage dissolved gas pump, while inhaling the air and the polycondensation decolorizing agent, which will be in the first-stage pressure dissolved gas tank. The first-stage saturated dissolved gas water is suddenly released to the first-stage air-floating tank to form the first-stage treatment water; the first-stage treated water overflows into the buffer pool, and then the primary treatment water is raised to the secondary pressure by the secondary dissolved air pump at the pH control. In the dissolved gas tank, the air and the polycondensation decoloring agent are simultaneously sucked, and the second-stage saturated dissolved gas water in the secondary pressure dissolved gas tank is suddenly released to the secondary air floating pool to form secondary treated water and discharged from the overflow to the sedimentation tank for sedimentation. The floating mud in the first and second air floatation tanks is put into the floating mud pool, and is filtered into a filter cake, and the filtrate is led back to the collecting tank. The removal rate of CODcr, decolorization rate, SS and BOD5 of the industrial sewage treated by the method is 80-90%, 95%, 90% or more, and 75-80%, respectively, and meets the first-class water discharge standard of GB8978-1996. Biogas power generation is a new energy comprehensive utilization technology that integrates environmental protection and energy conservation. It utilizes biogas produced by anaerobic fermentation of industrial wastewater to drive biogas generators to generate electricity, and can make full use of the waste heat of the generator set for biogas production, so that the comprehensive thermal efficiency is about 80%, which is much higher than the average 30-40%. Efficiency, the user's economic benefits are a good way to deal with industrial wastewater.

Domestic sewage treatment

1. Rural domestic sewage treatment methods

Domestic sewage septic tank anaerobic pond constructed wetland (planted with canned roots, wet, and absorbable canna, scallions, calamus, etc.) is treated by filteringand is mainly used for rural dispersion. Domestic sewage treatment, after running, the operating cost is basically zero, and the service life is more than 10 years.

2. Urban domestic sewage treatment methods

The urban domestic sewage is transported to the rural areas around the city, and the vast rural land is used to purify the urban domestic sewage. It will be a good way to do it once and for all. Take the large and medium-sized cities that supply 100W cubic meters of tap water for daily use as an example: the average sewage treatment facility costs 1,000 yuan/cubic. The construction cost is 1 billion, and the annual operating cost is 100W cubic/day × 365 × 0.5 yuan / cubic = 180 million. The construction cost of the soil purification method is 1,000 yuan/cubic, and the annual operating cost is 100W cubic/day×365×0.1 yuan/cubic=0.4 billion. At the same time, it saves 360 million cubic meters of agricultural water resources, saves about 10,000 tons of chemical fertilizers per year, and reduces the amount of pesticides by 5 tons per year. The comprehensive benefits are considerable.

3. New technology for domestic sewage treatment: decentralized treatment

The domestic sewage decentralized biological integrated treatment system is a new type of economical and environmentally friendly treatment system for domestic sewage. The system has the advantages of low equipment investment, low operating cost and easy installation. The bio-enhancement technology can effectively degrade pollutants, and can realize the treatment of domestic sewage on the spot and nearby, and achieve the purpose of recycling and utilization of water resources. As an effective supplement to the sewage treatment of traditional sewage treatment plants, the system has been widely used in urban residential communities, hotels, tourist attractions, new rural communities and other fields.

The decentralized sewage treatment technology has the characteristics of small equipment, no need to lay pipe network, and high equipment integration. Therefore, infrastructure costs and civil construction costs account for a small proportion of the overall investment, only about 30%, and about 70% of the investment. Mainly used for the procurement and installation of sewage treatment equipment.

Micro-electrolysis for industrial water treatment

1. Technical Overview:

Micro-electrolysis technology is an ideal process for treating high-concentration organic wastewater, also known as internal electrolysis. It is to use the micro-electrolytic material filled in the wastewater to generate a 1.2V potential difference to electrolyze the wastewater in the absence of electricity, so as to achieve the purpose of degrading organic pollutants. When the system is flooded, numerous micro-battery systems are formed in the device, forming an electric field in its working space. The new ecology [H], Fe2+, etc. produced during the treatment can undergo redox reactions with many components in the wastewater, such as chromophores or color-promoting groups that can destroy colored substances in colored wastewater, and even chain scission. The degradation of decolorization is achieved; the formed Fe2+ is further oxidized to Fe3+, and their hydrates have strong adsorption-flocculation activity, especially after adding alkali to adjust the pH value to form ferrous hydroxide and ferric hydroxide colloidal flocculant. Their adsorption capacity is much higher than that of the iron hydroxide colloid obtained by the hydrolysis of the general agent, and it can adsorb a large amount of fine particles, metal particles and organic macromolecules dispersed in water. Its working principle is based on the combination of electrochemistry,oxidation-reduction,physical adsorption and flocculation and precipitation to treat wastewater. The method has the advantages of wide application range, good processing effect, low cost, convenient operation and maintenance, and no need to consume power resources. The process for the treatment of refractory high-concentration wastewater can greatly reduce COD and chromaticity, improve the biodegradability of wastewater, and at the same time have a good effect on the removal of ammonia nitrogen. Traditionally, the micro-electrolytic materials used in the micro-electrolysis process are generally iron filings and charcoal. It is activated by acid and alkali before use. It is easy to passivate the knot during use, and it is easy to form because iron and carbon are in physical contact. The isolation layer makes microelectrolysis unable to continue and loses its effect, which leads to frequent replacement of the micro-electrolytic material, which not only affects the high cost and high efficiency but also affects the treatment effect and efficiency of the wastewater. In addition, the surface area of the traditional micro-electrolytic material is too small, which requires a long time for wastewater treatment and increases the investment cost of tons of water, which seriously affects the utilization and promotion of the micro-electrolysis process.

2. Reaction formula:

Anode: Fe-2eFe2+E(Fe/Fe2+)=0.44V

Cathode: 2H++2eH2E(H+/H2)=0.00V

When aerobic is present, the cathodic reaction is as follows:



3. Technical characteristics:

(1) The reaction rate is fast, and the general industrial wastewater only takes half an hour to several hours;

(2) A wide range of organic pollutants, such as: difficult to remove organic matter containing fluoro, carbon double bonds, nitro, halogenated structures, etc. have a good degradation effect;

(3) Simple process flow, long service life, low investment cost, convenient operation and maintenance, low operating cost and stable treatment effect. Only a small amount of microelectrolytic reactant is consumed during the treatment. The micro-electrolytic agent only needs to be added periodically without replacement, and it can be added directly without activation.

(4) After the micro-electrolysis treatment, the wastewater will form the original ferrous or iron ions in the water, which has better coagulation than the common coagulant. It does not need to add coagulant such as iron salt, and the COD removal rate is high, and Secondary pollution to water;

(5) It has good coagulation effect, high chroma and COD removal rate, and the same amount can greatly improve the biodegradability of wastewater;

(6) The method can achieve the effect of chemical precipitation and phosphorus removal, and can also remove heavy metals by reduction;

(7) For the high-concentration organic wastewater treatment project that has not been completed, this technology is used as the pretreatment of the wastewater of the built project, which can improve the biodegradability of wastewater while degrading COD, and ensure the stable discharge of wastewater after treatment. It is also possible to carry out advanced treatment on the process of micro-electrolysis or micro-electrolysis combined with biological filter bed after biochemical wastewater;

(8) Each unit of the technology can be used as a separate treatment method, and can also be used as a pretreatment process for biological treatment, which is beneficial to sludge sedimentation and biofilming.

4. Applicable wastewater types:

The technology is particularly targeted at the treatment of organic matter concentration, high toxicity, high chroma, and difficult biochemical wastewater, which can greatly reduce the color and COD of wastewater, and improve the B/C ratio, that is, improve the biodegradability of wastewater; Printing and dyeing, chemical, electroplating, pulp and paper, pharmaceutical, scouring, pesticides, alcohol and other industrial wastewater treatment and treatment water reuse projects.

(1) Dyestuff, printing and dyeing wastewater; coking wastewater; petrochemical wastewater;

------The above wastewater is decolorized, and the BOD/COD value in the treated water is significantly increased.

(2) petroleum wastewater; leather wastewater; papermaking wastewater, wood processing wastewater;

------The BOD/COD value of the above wastewater treatment water is greatly improved.

(3) electroplating wastewater; printing wastewater; mining wastewater; other wastewater containing heavy metals;

------ Heavy metals can be removed from the above wastewater.

(4) Organic phosphorus agricultural wastewater; organic chlorine agricultural wastewater;

------ greatly improve the biodegradability of the above wastewater, and can remove phosphorus and sulfides.