Chemical wastewater:

It refers to the wastewater produced during the production process of chemical plants, such as oily wastewater from the production of ethylene, polyethylene, rubber, polyester, methanol, ethylene glycol, oil tank areas, air separation and compression stations, etc. After biochemical treatment, it can generally meet the national secondary discharge standards. Due to the shortage of water resources, the water that meets the discharge standards needs to be further treated to meet the requirements of industrial water replenishment and reused. As a major water user, chemical plants generally consume several million cubic meters of fresh water annually, with low water reuse rates. At the same time, they discharge several million cubic meters of sewage, which not only wastes a large amount of water resources but also causes environmental pollution. Moreover, the shortage of water resources has posed a threat to the production of these industrial water users. To maintain the sustainable development of the enterprise, reduce water waste, lower production costs, and improve the economic and social benefits of the enterprise. Chemical wastewater needs to undergo advanced treatment (tertiary treatment) as makeup water for circulating water or power desalinated water to achieve wastewater reuse. Due to the fact that impurities in water are mainly suspended particles and fine fibers, mechanical filtration principle is used to remove impurities through microporous filtration technology. The working condition of the filter equipment is controlled by PLC or time relay to achieve automatic backwashing and operation, and the water pump is raised to provide the required water head for the filter. The effluent is directly introduced into the production system.

Main characteristics of chemical wastewater:

1. Chemical wastewater has complex components, and the reaction raw materials are often solvent based substances or cyclic compounds, which increases the difficulty of wastewater treatment;

2. The wastewater contains a large amount of pollutants, mainly due to incomplete reaction of raw materials and the use of a large amount of solvents in raw materials or production;

3. There are many toxic and harmful substances, and there are many organic pollutants in fine chemical wastewater that are toxic and harmful to microorganisms, such as halogen compounds, nitro compounds, dispersants or surfactants with bactericidal effects, etc;

4. There are many biologically recalcitrant substances, with B being lower than C and having poor biodegradability.

The nature of wastewater in the production process of chemical products is characterized by large discharge volume, high toxicity, high concentration of organic matter, high salt content, high chromaticity, high content of difficult to degrade compounds, and difficult treatment. However, at the same time, wastewater also contains many available resources, and membrane technology plays an important role as a high-tech in the production and processing, energy conservation and consumption reduction, and clean production of chemical products.

Recommended physical and chemical processes for chemical wastewater pretreatment:

1. Catalytic microelectrolysis treatment technology

【 Technical Background 】

The treatment of organic wastewater, especially high salt and high concentration organic wastewater, has always been a problem of concern for many environmental protection workers and management departments in China. With the rapid development of China's chemical industry, various new types of chemical products have been applied to various industries, especially in heavy polluting industries such as pharmaceuticals, chemicals, electroplating, printing and dyeing. While improving product quality, it has also brought increasingly serious environmental pollution problems, mainly manifested as high concentration of organic pollutants in wastewater, stable structure, poor biodegradability, difficulty in achieving standard discharge by conventional processes, and high treatment costs, which bring great pressure to energy conservation and emission reduction for enterprises.

[Technical Overview]

Micro electrolysis technology is an ideal process for treating high concentration organic wastewater. This process is used for the treatment of high salt, difficult to degrade, and high color wastewater, which not only significantly reduces COD and color, but also greatly improves the biodegradability of the wastewater. This technology utilizes micro electrolysis fillers filled in micro electrolysis equipment to generate the "primary battery" effect for wastewater treatment without power supply. After the water is supplied, countless "primary batteries" with a potential difference of 1.2V will be formed inside the equipment.

The "primary battery" uses wastewater as an electrolyte and generates an electric current through discharge to perform electrolytic oxidation and reduction treatment on the wastewater, in order to achieve the goal of degrading organic pollutants. The new ecology generated during the treatment process, such as [• OH], [H], [O], Fe2+, Fe3+, can undergo redox reactions with many components in the wastewater, such as the ability to destroy the chromophore or chromophore groups of colored substances in the wastewater, and even break the chain, achieving the effect of degradation and decolorization; The generated Fe2+is further oxidized to Fe3+, and their hydrates have strong adsorption flocculation activity, especially after adjusting the pH value with alkali to generate ferrous hydroxide and iron hydroxide colloidal flocculants. Their flocculation ability is much higher than that of iron hydroxide colloids obtained by general chemical hydrolysis, and they can flocculate a large number of dispersed small particles, metal particles, and organic macromolecules in water Its working principle is based on the combined effects of electrochemistry, oxidation-reduction, physics, and flocculation precipitation. This process has the advantages of wide applicability, good treatment effect, low cost, short treatment time, convenient operation and maintenance, and low power consumption. It can be widely used in the pretreatment and deep treatment of industrial wastewater.

[Technical Features]

(1) Fast reaction rate, generally industrial wastewater only takes half an hour to several hours;

(2) The scope of organic pollutants is wide, such as difficult to remove and degrade organic substances containing even fluorine, carbon double bonds, nitro groups, and halogenated structures, which have good degradation effects;

(3) The process flow is simple, the service life is long, the investment cost is low, the operation and maintenance are convenient, the operating cost is low, and the treatment effect is stable. Only a small amount of microelectrolyte filler is consumed during the processing. The filler only needs to be added regularly without replacement, and can be directly added when adding.

(4) After microelectrolysis treatment, wastewater will form native ferrous or iron ions in the water, which have better coagulation effect than ordinary coagulants. There is no need to add coagulants such as iron salts, and the COD removal rate is high, without causing secondary pollution to the water;

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

(6) This method can achieve the effect of chemical precipitation for phosphorus removal and can also remove heavy metals through reduction;

(7) For high concentration organic wastewater treatment projects that have been built but have not yet met the standards, using this technology as a pre-treatment for the wastewater of the existing projects can ensure stable and compliant discharge after wastewater treatment. Alternatively, the high concentration portion of the production wastewater can be separately extracted for microelectrolysis treatment.

(8) Each unit of this technology can be used as a separate treatment method or as a pre-treatment process for biological treatment, which is beneficial for sludge settling and biofilm formation.

[Applicable types of wastewater]

⑴ Dye, chemical, and pharmaceutical wastewater; Coking and petroleum wastewater—— The BOD/COD values of the treated wastewater have significantly increased.

⑵ Printing and dyeing wastewater; Leather wastewater; Paper making wastewater and wood processing wastewater—— It has good application in decolorization and effectively removes COD and ammonia nitrogen.

⑶ Electroplating wastewater; Printing wastewater; Mining wastewater; Other wastewater containing heavy metals—— Heavy metals can be removed from the aforementioned wastewater.

⑷ Organic phosphorus agricultural wastewater; Organic chlorine agricultural wastewater—— Greatly improve the biodegradability of the above-mentioned wastewater, and remove phosphorus and sulfides.

2. New type of catalytic microelectrolysis filler

[Technical Overview]

It is produced by fusing multiple metal alloys with catalysts and using high-temperature microporous activation technology, and belongs to a new type of additive non plate micro electrolytic filler. Applied to wastewater, it can efficiently remove COD, reduce chromaticity, improve biodegradability, and achieve stable and long-lasting treatment effects. At the same time, it can avoid phenomena such as filler passivation and compaction during operation. This filler is an important guarantee for the continuous action of microelectrolysis reaction, bringing new vitality to the treatment of current chemical wastewater.

Key innovation points of the product

(1) By fusing multiple metals and catalysts through high-temperature melting, an integrated alloy is formed to ensure the sustained and efficient "primary battery" effect. It will not cause anode cathode separation like physical mixing, which affects the reaction of the primary battery.

(2) The architectural microporous structure provides a large specific surface area and uniform water and gas flow channels, providing higher current density and better catalytic reaction effect for wastewater treatment.

(3) Strong activity, light specific gravity, no passivation or hardening, fast reaction rate, stable and effective long-term operation.

(4) Adjusting different proportions of catalytic components for different wastewater has improved reaction efficiency and expanded the application scope of wastewater treatment.

(5) During the reaction process, the active iron contained in the filler continuously provides electrons as the anode and dissolves into the water, while the cathode carbon flows out in the form of extremely small particles with the water. After a certain period of use, the filling material can be supplemented directly by adding it, which can restore the stability of the system in a timely manner and greatly reduce the workload of workers.

(6) The treatment of wastewater with fillers integrates multiple functions such as oxidation, reduction, electrodeposition, flocculation, adsorption, bridging, sweeping, and co precipitation.

(7) Low processing cost, while significantly removing organic pollutants, can greatly improve the biodegradability of wastewater.

(8) Supporting facilities can be structured and equipped according to scale and user requirements, meeting various needs.

(9) Specification: 1cm * 3cm (there are various forms of fillers, including spherical particles, porous columns, and others, and sizes can be customized).

(10) Technical parameters: Specific gravity: 1.0 ton/cubic meter, specific surface area: 1.2 square meters/gram, porosity: 65%, physical strength: ≥ 1000KG/CM2.

3. Multiphase catalytic oxidation treatment technology

[Technical Overview]

This treatment technology is a newly developed technology in the field of environment, mainly using strong oxidants with hydroxyl radicals as the core to quickly, non selectively, and thoroughly oxidize various organic pollutants in the environment. Hydroxyl radicals react with soluble organic compounds in water to form hydroxyl radicals; Under the catalysis of catalysts, hydroxyl radicals oxidize and decompose organic matter in wastewater. This technology has significant effects on CODcr removal, decolorization, and improving the biodegradability of wastewater. Its chromaticity and CODcr removal rate can reach 75% -99%. In the practical application of pesticide wastewater, chemical wastewater, and pharmaceutical wastewater, this technology has demonstrated excellent application effects.

[Scope of Application]

Mainly applicable to: nitrobenzene, nitrophenol, nitrotoluene, phenol, aniline wastewater, and benzyl ether wastewater; Wastewater containing dispersed dyes, cationic dyes, and weakly acidic dyes; Synthetic pharmaceutical and pesticide wastewater; Veterinary wastewater; Fine chemical wastewater; Synthetic resin wastewater; Cyanide containing wastewater; Fluorinated wastewater; Anthracene containing wastewater; Coking wastewater and electroplating wastewater, etc.

Optimization combination process for water reuse in advanced treatment of chemical wastewater:

(1) Pre treatment+UF+RO/NF treatment process

(2) MBR+UF/RO/NF treatment process

Advantages of process system:

Advantages of ultrafiltration system: Hollow fiber membranes made of polymer materials are used, which have high pressure resistance, pollution resistance, long service life, small footprint, high degree of automation, strong separation ability, good effluent quality, and ensure the normal operation of subsequent RO/NF systems.

Advantages of RO/NF membrane treatment system:

The RO system adopts anti pollution reverse osmosis membrane with long service life; Effective interception of salt, organic matter, and recalcitrant compounds; The effluent quality is suitable for all production processes; High degree of automation and low operating costs.

Membrane bioreactor process (MBR process) is a new wastewater treatment technology that combines membrane separation technology with biotechnology. It uses membrane separation equipment to capture activated sludge and large molecular organic matter in the biochemical reaction tank, separate clean water, and achieve synchronous biochemical reaction and clean water separation, eliminating the need for a secondary sedimentation tank.

The compact and concise unit structure of MBR is particularly suitable for treating printing and dyeing wastewater with complex components and high pollutant concentrations.

Advantages of MBR process:

High processing efficiency, good effluent quality, and minimal sludge; Short hydraulic retention time and small footprint; Easy to clean, easy to replace, stable operation, and low operating costs; Strong impact resistance, high COD and chromaticity removal efficiency.

Application areas: high concentration chemical wastewater, chlor alkali industry wastewater, pesticide wastewater, chemical industrial parks and sewage treatment plants, phosphorus containing wastewater treatment, formaldehyde containing wastewater treatment.

This article is compiled by chemical wastewater treatment equipment and does not represent the views of this website.