Ten domestic cases of coal chemical industry wastewater treatment projects

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Ten domestic cases of coal chemical industry wastewater treatment projects Author/Source: Date: 2016-01-13 Clicks: 2 1 Yuntianhua Group Project Name: Comprehensive solution for the water treatment system in Hulunbuir Jinxin Chemical Co., Ltd., a subsidiary of Yuntianhua Group Keywords: Model of comprehensive solutions for water treatment systems in the coal chemical industry Project Overview: Hulunbuir Jinxin Chemical Co., Ltd. is a subsidiary of Yuntianhua Group. The project is located deep in the Hulunbuir grasslands, where local regulations require that the environmental protection facilities for such chemical projects must achieve a \"zero emission\" standard. At the same time, this project is the first in Asia to use BGL reactors (British Gas-Lurgi reactors) for coal-to-gas conversion to produce ammonia and urea; the wastewater generated during the production process is complex in composition, highly polluted, and difficult to treat. This project has also become a model for comprehensive water system solutions in the domestic coal chemical industry. Project scale: Gas water: 80 m3/h; Sewage: 100 m3/h; Reused water: 500 m3/h; Desalinated water: 540 m3/h; Condensate: 100 m3/h. Main treatment processes: Gas water – oil removal + hydrolysis acidification + SBR + coagulation sedimentation + BAF + mechanically stirred clarifier + sand filtration; Sewage – air flotation + A/O; Desalinated water – raw water heat exchange + UF + RO + mixed bed; Condensate – heat exchange + iron removal filter + mixed bed; Reused water – clarifier + multi-media filtration + ultrafiltration + first-stage reverse osmosis + concentrated water reverse osmosis. EPC contractor: Botian Environment Group. Technical highlights: 1. The wastewater from gasification contains large amounts of oil, with a concentration as high as 500 mg/L, present in the forms of heavy oil, light oil, and emulsified oil. The project includes oil separation and air flotation units to remove this oil; the air flotation process makes use of nanobubble technology, with nanoscale bubbles having diameters of 30–500 nm. Compared to traditional dissolved air flotation, this approach results in more bubbles, a longer residence time for these bubbles, and a significantly higher utilization rate of the bubbles, thereby **improving the oil removal efficiency and overall treatment effectiveness. 2. The characteristics of gasification wastewater include high COD, high levels of phenols, and high salt content; its B/C ratio is low, and it contains a large amount of substances that are difficult to degrade. The hydrolysis-acidification process is used, as it does not produce methane. The microorganisms responsible for hydrolysis and acid production in the hydrolysis-acidification tanks enable the treatment of the wastewater with relatively low energy consumption and within a short retention time, in the subsequent biochemical treatment units. 3. Gas wastewater has high ammonia nitrogen levels; installing an SBR can achieve both nitrogen removal and carbon removal simultaneously. 4. The mature application of the dual-membrane process in desalinated water and recycled water treatment processes can effectively reduce the acid and alkali consumption per ton of water, and it is also easy to operate. After three years of operation, the current system’s desalination efficiency still reaches 98%. 2 Shaanxi Coal and Chemical Industry Group. Project name: EPC project for water treatment facilities at Shannxi Coal and Chemical Group Pucheng Clean Energy Chemical Co., Ltd. Keywords: The largest water treatment EPC project in the field of new coal chemical industries. Project overview: This project is located in Pucheng County, Weinan City, Shaanxi Province; it utilizes Texaco gasifiers as well as the DMTO second-generation olefin-to-methanol technology developed by Dalian Institute of Chemical Physics. Therefore, the wastewater mainly consists of vaporized wastewater and effluents from the DMTO unit, and is characterized by high ammonia nitrogen levels and high hardness. Botian Environment was tasked with designing the wastewater treatment systems, recycled water systems, and desalination systems for the company’s project aimed at producing 1.8 million tons of methanol and 700,000 tons of olefins per year; the total value of the EPC contract for water treatment amounted to 509 million yuan. Project scale: Sewage: 1300 m3/h; Reused water: 2400 m3/h; Concentrate treatment system: 600 m3/h; Desalinated water: First-stage desalinated water at 1600 m3/h; Process condensate: 600 m3/h; Turbine condensate: 1200 m3/h. Main processes: Sewage: Adjustment + Coagulation + Sedimentation + SBR; Reused water: BAF + Clarification + Activated carbon filtration + Dual-membrane system + Concentrate RO; Desalinated water: UF + Two-stage RO + Mixed-bed reactor; Concentrate treatment system: Heterogeneous catalytic oxidation; Process condensate: Filtration + Anion exchange resin bed + Mixed-bed reactor; Turbine condensate: Filtration + Mixed-bed reactor. Technical highlights: 1. The sewage treatment system combines multi-stage series technology with the SBR process, dividing the SBR reaction phase into multiple alternating anoxic and aerobic stages over time. In such an environment, sludge bulking caused by filamental bacteria is restricted, thereby improving the sludge settling rate ； At the same time, the duration of each separate reaction zone is optimized to match the microbial activity; this allows full utilization of the rapid denitrification phase, creating a favorable biological environment that promotes thorough completion of the nitrification and denitrification reactions, thereby improving the efficiency of organic matter removal and achieving the required treatment standards for wastewater containing high levels of ammonia nitrogen. 2. The concentrated wastewater is treated using heterogeneous catalytic oxidation technology; the highly active heterogeneous catalytic filler used reacts with the Fe3+ generated in the reaction to form FeOOH heterogeneous crystals, which catalyze the production of more hydroxyl radicals possessing strong oxidizing capabilities. This approach reduces the amount of chemicals required as well as the amount of sludge generated. 3 Shenhua Group Project Name: Advanced Wastewater Treatment Project for Shenhua Ordos Coal Direct Liquefaction Keywords: World’s first commercial coal direct liquefaction project Project Overview: The Shenhua Ordos coal-to-oil project is the world’s first commercial project for coal direct liquefaction, and it was one of the key projects under the 10th Five-Year Plan. Among them, the coal liquefaction plants generate large volumes of wastewater with high concentrations, while other sources of wastewater are diverse; there is no similar wastewater treatment experience available for reference either domestically or internationally. This project employs the MBR process; after 9 months of pilot testing on wastewater from various sources, an economically viable process model was developed, enabling the treatment of wastewater with different quality and volumes to meet the required standards. Project scale: Product water purification system: 300 m3/h; Advanced treatment system: 410 m3/h. Main processes: Product water purification system – UF+RO; Advanced treatment system – A/O+MBR+UF+RO. Technical highlights: 1. The advanced treatment stage uses the A/O process for nitrogen and carbon removal. In Pool A, denitrifying bacteria use the organic matter in the wastewater as a carbon source to reduce the large amounts of NO3-N and NO2-N present in the recycled mixture and recycled sludge to N2, which is then released into the air. The soluble organic matter is absorbed by microorganisms, resulting in a decrease in the BOD5 concentration in the wastewater, as well as a significant reduction in the NO3-N concentration ； In Pool O, organic matter is biologically broken down by microorganisms, causing the BOD5 concentration to continue decreasing. Organic nitrogen and ammonia are subsequently nitrified, leading to a significant drop in the NH3-N concentration. 2. The advanced MBR treatment process provides enhanced treatment of COD, significantly reducing the level of organic contamination on the membranes in subsequent reuse processes. Additionally, the turbidity of the treated water is lower compared to traditional advanced treatment methods, which ensures the long-term stable operation of the membrane treatment system while maintaining a high recovery rate. **This reduces the amount of concentrated wastewater discharged, creating the conditions for achieving ‘zero discharge’ in the plant. 3. Given the limited space available at the project site, the advanced treatment and reuse system employs a dual-membrane process. This process features a simple flow structure, compact design, small footprint, high level of automation, and easy operation; it requires no large amounts of chemical agents, resulting in low operating costs ； 4. The ultrafiltration unit retains tiny particles, reducing suspended solids, bacteria, and turbidity; it also partially removes organic pollutants, thereby improving and stabilizing water quality. 5. The reverse osmosis system is primarily used to remove dissolved salts, small molecular organic substances, and pollutants such as silica from water; it can eliminate over 98% of the electrolytes (salts) present in water. 4 Jutai Group Project Name: Concentrated brine recovery unit and wastewater treatment unit for Jutai Energy (Jungar) Co., Ltd.’s methanol deep processing project Keywords: Concentrated brine recovery Project Overview: Jutai Energy (Jungar) Co., Ltd.’s methanol deep processing project is primarily used to produce olefins, polyethylene, polypropylene, and other products. The wastewater flow rate is 600 m3/h. Due to the significant differences in the characteristics of the various water sources, this wastewater treatment facility handles wastewater generated in the oxidation-dehydrogenation process for butadiene production, MTO production, as well as domestic and laboratory wastewater from various units, along with wastewater resulting from system failures. The treated water is then reused in the C4 unit and the plant’s reclaimed water system. Project scale: Brine: 600 m³/h; Wastewater: 600 m³/h. Main processes: For brine: high-efficiency clarifier + V-type filter + UF + sodium bed + cation exchange bed + RO; for wastewater: pretreatment + A/O process + ozone oxidation + BAF. Technical highlights: Brine reuse: 1. To address contaminants such as suspended solids, hardness, and COD in the raw water, flocculants, coagulants, lime, soda ash, and other chemicals are added at the front end of the high-efficiency clarifier to effectively remove these impurities. 2. The ion exchange system is used as a pre-treatment step in the brine concentration process; its main function is to further remove ionic and structural ions from the water obtained after pretreatment, so as to ensure that the water fed to the reverse osmosis membranes contains virtually no structural ions. 3. By using UF technology, it effectively traps small particles, reduces turbidity, removes bacteria and certain organic pollutants, thereby improving and stabilizing the quality of the treated water. 4. This process effectively reduces the contamination of the membrane by organic substances in concentrated brine, enabling the system to operate stably over the long term. Wastewater treatment: 1. To address the issue of oily wastewater from PP and PE plants, air flotation units are installed to prevent oils from affecting subsequent biochemical treatment units. 2. For the oil-containing, hard-to-degrade and poorly biodegradable COD substances in wastewater, a longer retention time in the biochemical tank is employed; for the large-molecule COD that remains difficult to degrade after biochemical treatment, ozone oxidation is used, followed by removal through BAF biological treatment. 3. To improve the efficiency of ozone oxidation, a coagulation and sedimentation unit is added before oxidation to reduce ozone consumption. 5 Yankuang Group Project Name: EPC Project for Sewage Treatment and Reused Water Treatment at Yankuang Yulin Project, Shaanxi Future Energy Chemicals, Yankuang Group Keywords: China’s first million-ton-scale coal indirect liquefaction project Project Overview: The 1 million tons per year coal indirect liquefaction demonstration project carried out by Shaanxi Future Energy Chemicals Co., Ltd. at Yankuang Yulin is one of the key projects during the 12th Five-Year Plan period, and it represents China’s first million-ton-scale coal indirect liquefaction project. Using coal as raw material, this project primarily produces chemical products such as diesel, naphtha, and LPG. This time, it mainly introduces the wastewater treatment plant and recycled water treatment project of this project. The wastewater from this project includes gasification wastewater, low-temperature methanol washing wastewater, high-concentration synthesis wastewater, oily wastewater, and domestic wastewater. Project scale: Sewage: 820 m3/h; Reused water: 1300 m3/h. Main treatment processes: For combined sewage 1: flotation + A/B tanks + sedimentation; for combined sewage 2: flotation (primary sedimentation tank + UASB) + OAAO + MBR tank. For combined reused water: high-efficiency clarifier + V-type filter + UF + RO process; for concentrated reused water: high-efficiency clarifier + quartz sand filtration + UF + RO process. Technical highlights: 1. Based on the inlet conditions and outlet requirements, the time ratio and operating conditions of the biochemical treatment system are artificially controlled. As long as there is an adequate supply of carbon sources, a relatively high nitrogen removal rate and organic matter removal can be achieved as needed; therefore, the OAAO process is used as the main biochemical treatment method. 2. The aerator uses a high-efficiency swirl aerator; its cylinder features large-pore channels, and combined with a swirl mixing structure, it offers advantages such as a large service area, low resistance, stable and reliable operation, resistance to clogging, and a long service life. 3. MBR integrates membrane separation technology from separation processes with traditional biological wastewater treatment techniques, **improving the efficiency of solid-liquid separation ； Furthermore, the increased concentration of activated sludge in the aeration tank, along with the presence of specific bacteria within the sludge (especially the dominant bacterial communities), led to an increase in the rate of biochemical reactions ； At the same time, by reducing the F/M ratio, the amount of excess sludge generated is decreased, thereby essentially resolving many of the prominent problems associated with the conventional activated sludge process. 4. The organic matter concentration in the synthetic wastewater exceeds 15,000 mg/L, and it also contains a large amount of toxic and harmful substances ； A two-stage anaerobic process is employed, along with a dual-circulation system in the anaerobic stage, to reduce the impact of high concentrations of organic matter on the system while maintaining an upward flow rate within the reactor. 6 Sichuan Chemical Industry Group. Project name: Sichuan Chemical Industry Group’s Ningxia Jiemefengyou Chemical Wastewater Treatment Facility Project. Keywords: Typical coal-based chemical wastewater treatment project. Project description: This project utilizes coal as a raw material to produce fertilizers and methanol among other products, employing the water-coal slurry gasification technology developed by Northwest Thermal Engineering Institute. It has an annual production capacity of 400,000 tons of ammonia, 700,000 tons of urea, and 200,000 tons of methanol. The sources of wastewater mainly include gasification wastewater, synthetic ammonia wastewater, initial rainwater, and wastewater from other production processes. This wastewater has high COD and NH3-N levels and a low C/N ratio, making it a typical case for coal chemical industry wastewater treatment. Project scale: Integrated wastewater: 3600 m3/d. Main treatment process: Hydrolysis acidification + A/O technology. Key features: 1. This wastewater treatment plant is used to treat the wastewater generated by the gasification unit, the production wastewater from the ammonia synthesis (methanol) and urea production areas, the domestic wastewater from the entire plant, as well as the accident discharge water and polluted fire-fighting water from the production units. 2. The main treatment process for this project is a multi-stage A/O process, which is used to remove COD and ammonia nitrogen; as a result, the COD removal rate for wastewater in this project reaches 95%, while the ammonia nitrogen removal rate reaches 92%. 7 Shenhua Group Project Name: Shenhua Baotou Coal-to-Olefins Wastewater Treatment Project Keywords: World’s first operational MTO unit Project Overview: The Shenhua Baotou Coal-to-Olefins project is the world’s first operational MTO unit. The wastewater treatment plant for this project has a processing capacity of 9,600 tons per day. The wastewater includes effluents generated by units such as gasification, purification, methanol to olefins, olefin separation, polyethylene, sulfur recovery, methanol production, recycled water generation, and flaring systems, as well as water used for cleaning the plant’s floors, polluted rainwater, and domestic sewage. The main pollutants in wastewater are various organic pollutants and ammonia nitrogen ； The wastewater has good biodegradability, but its ammonia nitrogen concentration is high and the carbon-to-nitrogen ratio is low, making treatment challenging. Project scale: Comprehensive wastewater: 9,600 m3/d. Main process: A/O + BAF. Technical highlights: The aerobic tank uses high-efficiency swirl aerators patented by Botian Environment; these aerators are of the type with perforated channels, and combined with a swirl mixing structure, they offer advantages such as a large service area, low resistance, stable and reliable operation, resistance to clogging, and a long service life. This solves the problem of aerator scaling and clogging caused by the high hardness of the wastewater. 8. China National Coal Group Project Name: CNCC Shaanxi Yulin Energy and Chemical Methanol and Acetic Acid Deep Processing and Comprehensive Utilization Project Keywords: The largest circulating cooling water system in China’s chemical industry Project Overview: The first phase of CNCC Shaanxi’s 3.6 million tons per year methanol and deep processing project consists of three relatively independent circulating water stations, namely the thermal power and air separation circulating water station (I), the coal chemical industry circulating water station (I), and the petrochemical industry circulating water station (I). This project is one of the largest in the world in terms of the scale of circulating cooling water treatment, and it is also the largest EPC project for circulating cooling water in China. Project scale: Thermal power and air separation circulating water station (I): 131.33×104 m3/d; Coal chemical industry circulating water station (I): 105.80×104 m3/d; Petrochemical industry circulating water station (I): 117.25×104 m3/d. Main processes: Thermal power and air separation circulating water station (I): Cooling tower + side filtration + chemical dosing; Coal chemical industry circulating water station (I): Cooling tower + side filtration + chemical dosing; Petrochemical industry circulating water station (I): Cooling tower + side filtration + chemical dosing. Technical highlights: 1. In view of the cold winters in Yulin, multiple anti-freezing measures have been incorporated into the design of the cooling towers and pipelines to ensure that the system remains functional during winter ； 2. Use the excess steam in the plant to drive water pumps, thereby achieving energy savings ； 3. The seamless design technology for ultra-long reinforced concrete water tank structures exceeds standard requirements. It ensures the integrity and stability of the tank structure, guarantees tight interconnections between all structural components, and enhances the overall structural stiffness of the tank itself. This technology effectively addresses issues associated with expansion joint designs, such as poor integrity and seismic performance, susceptibility to leaks, and difficulties in repair ； 4. By adopting cooling tower steam recovery technology, the steam from cooling towers can be recovered. It reduces the amount of water evaporated and recovers distilled water, resulting in significant economic benefits. In cold regions, the vapor recovery rate can exceed 30%. 9 China Coal Group Project Name: EPC Project for Demineralized Water and Condensate Treatment Facilities in China Coal Mengda New Energy Chemical Project Keywords: Demineralized water Project Overview: This project involves the construction of demineralized water and condensate treatment plants for China Coal Mengda New Energy Chemical Co., Ltd.’s project aimed at producing 500,000 tons of engineering plastics per year. Once completed, these plants will supply qualified demineralized water to various process units and power stations, while also treating and recycling clean condensate as well as oil-containing condensate. Project scale: Clean condensate: 160 m3/h; Oily condensate: 300 m3/h; Deionized water: 600 m3/h. Main processes: Clean condensate – heat exchange + iron removal filter + mixed-bed reactor for condensate water; Oily condensate – heat exchange + surface condensation filter + activated carbon filter + mixed-bed reactor for condensate water; Deionized water – UF + RO + cation exchange resin bed + anion exchange resin bed + mixed-bed reactor. Technical highlights: 1. Effective utilization of heat from condensate – the heat recovered from the condensate is used to heat raw water and the resulting deionized water, thereby achieving efficient use of thermal energy. 2. Application of surface condensate filters: These are backwashable filter elements that ensure effective iron removal without the need for frequent replacement, resulting in low operating costs. 3. Application of the double-membrane method: The mature use of this method in desalination processes enables effective reduction in the amount of acid and alkali required per ton of water produced; it is simple to operate and easy to maintain. 4. Application of high-efficiency floating beds: Floating beds also offer advantages such as good water quality in the effluent, low consumption of regenerants, minimal amount of waste liquid discharged, small equipment size, high water output, and simple operation. 10. Yangmei Group Project Name: Sulfonic Acid Wastewater Treatment Project of Taiyuan Chemical New Materials Co., Ltd. under Yangmei Group Keywords: Characteristics of typical chemical wastewater Project Overview: The Qingxu Chemical New Materials Park project of Yangmei Group is a supporting project for the overall relocation of Taihua Group. The wastewater sources for this project mainly include wastewater from the adipic acid plant, the gasification plant, the crude benzene hydrogenation plant, the caprolactam plant, plant washing water, initially polluted rainwater, and domestic wastewater. This time, it mainly introduces the treatment projects for the wastewater from the adipic acid plant, the wastewater from the crude benzene hydrogenation plant, and the wastewater from the **/alcohol plant. In this project, the quality and quantity of a portion of the wastewater fluctuate significantly; its pollutant composition is complex, exhibiting typical characteristics of chemical industrial wastewater ； The wastewater contains dibasic and polybasic acids; it is acidic in nature and contains small amounts of CU2+/V5+ ； The wastewater has a high COD level and good biodegradability, but it still contains a small amount of organic substances that are difficult or hard to biodegrade. Currently, the project is being implemented. Project scale: Adipic acid production wastewater: 260 m3/h; Cyclohexanol/related wastewater: 196 m3/h; Crude benzene hydrogenation wastewater: 17 m3/h. Main treatment processes: UASB + A/O + ozone oxidation + BAF + sand filtration. Technical highlights: 1. Pre-treatment and adjustment are carried out using neutralization, coagulation, and sedimentation to address issues such as the low pH value of the raw water. 2. Due to the high COD level and the presence of components such as benzene, toluene, and xylene, a biochemical treatment process involving UASB, anaerobic sedimentation tank, A/O process, and secondary sedimentation tank is employed. 3. Ozone is used to further break down biodegradably difficult large-molecule organic substances, thereby improving their biodegradability; BAF combined with sand filtration is employed for advanced treatment. Conclusion: It has only been in recent years that attention has been paid to wastewater treatment in the coal chemical industry. Due to the varying compositions of this wastewater, there are few existing project examples available for reference, both domestically and internationally. To this day, many project owners still do not know which companies in the industry are skilled at handling coal chemical wastewater; the cases mentioned above may provide some useful insights for these owners! http://www.nmtech.com.cn/*nwen_mhg_xx.asp?id=174818