Comparison and analysis of various processes for t

2022-10-15
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Comparison and analysis of various processes for the treatment of highly salty wastewater

highly salty wastewater is the most common type of circular arc synchronous gear belt in the process of chemical production, so what are its treatment processes? With the increasingly stringent requirements of environmental protection, we need to know more about the treatment process of various wastewater! Here are three treatment methods for high salinity wastewater

high salinity wastewater refers to wastewater containing organic matter and at least 3.5% TDS (total dissolved solid), including high salinity domestic wastewater and high salinity industrial wastewater

it mainly comes from industrial production, domestic water and food processing plants, chemical plants that directly use seawater, and the collection and processing of oil and natural gas

in addition to organic pollutants, these wastewater also contains a large number of inorganic salts, such as cl-, so42-, na+, ca2+ plasma. These high salt and high organic wastewater

if discharged directly without treatment, it is bound to do great harm to water organisms, domestic drinking water and industrial and agricultural production water production

however, the concentration of brine in conventional treatment methods should not be too high, and it is urgent to develop technology to treat higher concentration and high salinity wastewater

low temperature multi effect plate evaporation, concentration and desalination of high salt wastewater

1 principle of low temperature multi effect evaporation, concentration and crystallization technology

low temperature multi effect evaporation, concentration and crystallization system is composed of multiple evaporators in series. Low temperature (about 90 ℃) heating steam is introduced into the first effect to heat the feed liquid, so that the feed liquid produces almost equal evaporation with lower temperature than the steam. The generated steam is introduced into the second effect as heating steam, so that the feed liquid of the second effect evaporates at a lower temperature than that of the first effect. This process is repeated until the last effect

the condensate of the first effect returns to the heat source, and the condensate of other effects is collected and output as desalinated water. A share of steam input can evaporate multiple times of water. At the same time, the feed liquid is concentrated from the first effect to the last effect, and crystallizes when the tensile strength, constant elongation, constant elongation force value and yield strength of the last effect reach supersaturation. Thus, the solid-liquid separation of material and liquid is realized

low temperature multi effect evaporation, concentration and crystallization system can be applied not only to the concentration process and crystallization process of chemical production, but also to the evaporation, concentration and crystallization process of industrial saline wastewater

during the treatment of industrial saline wastewater, the industrial saline wastewater enters the low-temperature multi effect concentration and crystallization device, and is separated into desalinated water (the desalinated water may contain trace low boiling point organic matter) and concentrated crystal slurry waste liquid through the concentration and crystallization process of effective evaporation and condensation; Inorganic salts and some organic substances can be crystallized and separated, and incinerated into inorganic salt waste residue; The concentrated waste liquid of organic substances that cannot be crystallized can be incinerated by drum evaporator to form solid waste residue; Desalinated water can be returned to the production system to replace softened water for utilization

its main technical parameters are as follows:

① desalination water salt content (TDS) 10ppm (may contain trace low boiling point organics with steam)

② ton desalination water steam consumption = (1/efficiency)/90% t/T

③ ton desalination water power consumption 2-4 kW h/t (depending on efficiency and device size)

2 device structure scheme:

⑴ low temperature multi effect plate evaporator + tubular evaporative crystallizer

⑵ condenser: tubular condenser

⑶ defoaming type: each effect adopts a three-stage composite defoaming system of "corner baffle + cyclone re baffle + wire" to ensure that the secondary steam (diluted water) is clean

⑷ the vacuum pump is a self cooling water ring pump

(5) system control:

the temperature, pressure, liquid level and flow of the device are automatically controlled and adjusted by the system

3 technical characteristics of low temperature multi effect concentration and crystallization device:

process characteristics:

① the device adopts mixed process water supply, so that the water and electricity consumption per ton of the same water making tonnage device is reduced by 40% - 50% compared with foreign processes

② due to the mixed process water supply, the wastewater flows from high temperature effect to low temperature effect, and the concentration gradually increases and the temperature gradually decreases. It avoids the increase of feed water concentration in high temperature effect caused by circulating feed water from low temperature effect to high temperature effect in foreign processes, and effectively reduces the scaling and corrosion of high temperature effect

③ the water volume is evenly distributed on the evaporator, avoiding the disadvantage that the sprinkler type water supply of the existing device is uneven and easy to be blocked

④ the vacuum system adopts a differential pressure pumping device, and the design differential pressure is accurately formed between the effects, making the device operate stably and reliably

structural features:

① drawer structure is adopted, which is convenient for manufacturing, assembly, overhaul and maintenance; Plate evaporator, disassembly and cleaning

② plate evaporator can realize high concentration of wastewater and crystallization separation of inorganic salts

③ adopt plate evaporator and modular design, which is convenient for mass production. Low cost

④ the device has simple structure and good manufacturing technology

⑤ all supporting electromechanical equipment of the device are localized

the manufacturing cost of ⑥ ton water plant is 30-40% lower than that of foreign companies

biological method

biological treatment is one of the most commonly used methods for wastewater treatment at present. It has the characteristics of wide application range and strong adaptability

chemical wastewater, such as dye, agricultural Yao, pharmaceutical intermediates and other wastewater with high salt content, brings certain difficulties to biological treatment. This kind of wastewater has high salt content and serious pollution, which must be treated before being discharged

moreover, this kind of wastewater is complex in composition, has no recycling value, and the cost of adopting other treatment methods is high, so biological treatment is still the method chosen by Shou

inorganic salts play an important role in promoting enzyme reaction, maintaining membrane balance and regulating osmotic pressure in the process of microbial growth. However, high salt concentration will inhibit the growth of microorganisms

the main reasons for inhibition are:

when the salt concentration is too high, the osmotic pressure is high, which dehydrates the microbial cells and causes the separation of cell protoplasm

under the condition of high salt content, the activity of dehydrogenase decreases due to salting out

high chloride ion concentration has toxic effect on bacteria

due to the increase of water density, activated sludge is easy to float and lose

therefore, the biological treatment of high salinity wastewater needs to be diluted. It usually operates at low salt concentration (salt concentration is less than 1%), resulting in waste of water resources, huge treatment facilities, increased investment and increased operating costs

with the increasing tension of water resources, the implementation of various regulations and charges for the protection of water resources issued by the state has brought a burden to enterprises dealing with high salinity wastewater, and introduced in detail the utilization of various materials in Great Wall Motors

biological treatment method has the characteristics of economy, efficiency and harmlessness. When it is widely increased from 0 to 30g/l, it can no longer increase after loading a certain load in the domesticated system. The removal rate of organic matter (in the form of COD) is reduced from 97% to 60%, and the removal rate of nitrogen (n) is reduced from 88% to 68%; In the domesticated system, when the mass concentration of salt is increased from 5g/l to 30g/l, the removal rate of COD is reduced from 90% to 71%, and the removal rate of n is reduced from 85% to 70%

sbr process for the treatment of salty wastewater

acclimated high salt tolerant activated sludge by gradually increasing the salinity. Sequencing batch biofilm process (SBBR) was used to simulate the treatment of high salt wastewater. The high salt wastewater with salinity of 0 and 2% and COD of 300 mg/l was studied

the results showed that under the conditions of 12 hours per cycle, aeration rate of 0.6 l/min, average sludge mass concentration of 2000-3500 mg/l, and sludge age of 18 days, the COD removal rate of effluent changed little, 97% and 93% respectively, while the corresponding nh4+-n removal rate of effluent decreased from 93% to 72%, indicating that the salinity of wastewater increased, which had a great impact on the nitrification capacity of the system

changing the influent organic load has little effect on the removal of effluent COD, and the system has strong resistance to the impact of organic load

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