Protection and utilization of groundwater resources

Jiaozuo City is located in the northwest of Henan Province, bordering Taihang Mountain in the north and Yellow River in the south, with a total area of 60 14km2 and a total population of 3.48 million. It has mineral resources such as coal, limestone, bauxite and iron ore, and its industries are mainly electric power, chemicals, machinery and coal. At present, it has developed into a new industrial city with energy and chemical industry as its main industry. The industrial, agricultural and domestic water in Jiaozuo mining area mainly depends on groundwater. The natural recharge of groundwater in Jiaozuo area is 10.583m3/s, in which the recharge of karst water is 8.86m3/s and the recharge of pore water is1.723m3/s. ..

I. Present situation of development and utilization of groundwater resources

The groundwater resources in Jiaozuo city are composed of karst water and pore water, mainly karst water, accounting for about 85% of all groundwater resources. The piedmont area of Jiaozuo mining area is a concentrated drainage area of karst water in Jiuli mountain spring area, and the groundwater resources are extremely rich. In recent years, with the development of cities, industry and agriculture and the extensive exploitation of coal mining areas, small-scale falling funnels have appeared in some areas, and the groundwater level has shown an obvious downward trend. Nevertheless, the range of the descending funnel and the water level in the center of the funnel are stable, and the groundwater level is basically in a dynamic equilibrium state for many years. In rainy season and wet year, due to the rise of groundwater level, the range of descending funnel decreases or even disappears [4].

At present, artificial mining has become the main way to discharge pore water and karst water. Groundwater exploitation methods include centralized and decentralized exploitation of self-provided water sources (wells) in factories and mines, centralized exploitation of water sources in Jiaozuo Water Supply Company, mine drainage and sporadic and decentralized exploitation of agriculture.

1. Groundwater exploitation status of self-provided water source (well)

1994, there were 234 * * * self-prepared wells in the city, and the annual groundwater exploitation was 6347.86× 104m3, with an average of 2.0 13m3/s, of which the annual groundwater exploitation was1939.36×/kloc-. The karst groundwater is 4408.50× 104m3, with an average of1.4000m3/s. Compared with 1994, 1993 has decreased by 5.77%, and the groundwater volume of 1993 is 6736.86. Self-provided water source wells are scattered except for the exploitation of groundwater in Jiaozuo Power Plant, Zhongzhou Aluminum Plant, Jiaozuo Aluminum Plant, Thermal Power Plant, Jiaozuo Cement Plant, No.1 Chemical Plant, Paper Mill and other factories and mines, and karst water is mostly used as the water supply source.

(1) Pore water exploitation: Due to the dual factors of climate and artificial exploitation, the pore water level in Jiaozuo City has shown a downward trend in recent years, forming a funnel of pore water level in the south of Jiaozuo City, and the water quality has deteriorated. In order to improve this situation, the exploitation of pore water has been restricted since 1990, and the exploitation of self-prepared wells has declined. 1992 decreased to 1466× 104m3, 1993 increased to 1765× 104m3, 19965438. 1994, the pore water production was 1989.36× 104m3, which was 173.86× 104m3 higher than 1993. The total groundwater exploitation of self-prepared wells changes greatly year by year, with the highest monthly exploitation of 566.092×104m3 (July) and the lowest monthly exploitation of 484.562×104m3 (June 65438+February).

(2) Karst water exploitation: Jiaozuo is rich in karst water resources with good water quality, which is the best water supply source for urban industry and residents' life. Most water users in Jiaozuo exploit karst water. 1994 The karst water produced by self-prepared wells was 4408.50× 104m3, accounting for 70% of the total groundwater produced by self-prepared wells. 1993, the exploitation of karst groundwater by self-prepared wells is 4972.438+0× 104m3, 1994, which is basically the same as 1993.

2. Exploitation of groundwater by Jiaozuo Water Supply Company

There are 6 waterworks in Jiaozuo Water Supply Company, among which the first waterworks and the fourth waterworks exploit karst groundwater, the second waterworks is jointly supplied by Xindong Company (mine drainage) and the self-provided water source in Gangzhuang of Jiaozuo Power Plant, and the third waterworks is jointly supplied by Jiaoxi Company (mine drainage) and Dong Xiaozhuang Water Source (exploitation of karst water). There are only three water sources for the exploitation of groundwater in Jiaozuo Water Supply Company: No.1 Water Plant, No.4 Water Plant and Dong Xiaozhuang Water Source (Gangzhuang Water Source belongs to Jiaozuo Power Plant, not included in it). 1994 The total water supply of Jiaozuo Water Supply Company is 5425.74× 104m3, of which the groundwater exploitation is 207 1.68× 104m3, accounting for 38.2% of the total water supply.

The No.1 Water Plant is located in Xinhua Street in the center of Jiaozuo, and uses abandoned No.2 and No.3 mines to supply water. It is increased by160.53x104m3 and 1994 * * compared with 1993.

The fourth water plant is located near the northern piedmont of Jiaozuo City, with 22 mining wells. This water plant is the main water supply source of Jiaozuo Water Supply Company, with groundwater as the water source, accounting for 53.68% of the groundwater exploitation of Jiaozuo Water Supply Company and 20.46% of the water supply of Jiaozuo Water Supply Company. 1994, * * mined karst water112×104m3, with an average of 0.3527m3/s.

Dong Xiaozhuang water source is located in Dong Xiaozhuang, west of Jiaozuo City. There are 0/9 wells/kloc-0, and the annual karst groundwater exploitation is 649.00× 104m3, with an average of 0.2058m3/s, which is about 15.89% higher than last year.

3. Mine drainage and utilization

(1) Mine drainage: divided into Jiaodong mining area and Jiaoxi mining area.

Yanmazhuang Mine and Jiulishan Mine in Jiaodong Mining Area have moved to the top of all mines, and the mine displacement has been above 1.0m3/s for many years. In contrast, the hydrogeological conditions of Zhongmacun Mine, Xiaomacun Mine, Feng Ying Company and Fangzhuang Mine are relatively simple, and the mine drainage is small. The average annual drainage of seven mines in Jiaodong mining area during 1994 is 3.3778m3/s, which is slightly lower than before 1993. The seasonal variation of total mine drainage in Jiaodong mining area is not obvious, but it is relatively stable.

1994, the mine drainage of yanmazhuang mine in Jiaodong mining area still ranks first among all mines, which is1.0847m3/s. In recent years, there have been two water inrush disasters in the floor of malignant coal seam in this mine, and the mine drainage is relatively stable. The average displacement of Jiulishan Coal Mine is 0.7903 m3/s. Since May, the mine drainage has been reduced due to the grouting at the water inrush point of the coal seam floor and the grouting transformation of the coal seam floor in the working face. Other mines, such as Hanwang Company, Feng Ying Company, Xiaomacun Mine and Zhongmacun Mine. There is a relatively stable displacement, and there has been no obvious change for many years. 1994, the average mine drainage of Hanwang company was 0.3840m3/s, that of Feng Ying company was 0.3098m3/s, that of Xiaomacun mine was 0. 1248m3/s, that of Zhongmacun mine was 0.6535m3/s and that of Weicun mine was 0.0307m3/s.

Wangfeng Company in Jiaoxi mining area stopped production due to mine closure, and the mine drainage decreased and gradually stabilized. 1989 has an average displacement of 1.50m3/s, 1.25m3/s in 990 and 1 year has an average displacement of 19 1. The mine drainage of Wangfeng Company changed obviously during the year, with the highest monthly drainage of 1. 1605m3/s and the lowest monthly drainage of 1.0 182m3/s ... Due to the scrapping of the mine, the mine water inflow of Jiaodong Company gradually stabilized. It is 0.38m3/s in 199 1, 0.35m3/s in 1992, and 0.3033m3/s in 1994 ... The mine drainage in Zhucun Mine is relatively large and increasing year by year. 0.80m3/s in 1990, 0.84m3/s in199/kloc-0, 0.90 13m3/s in 1994. The mine drainage of Jiaoxi Company 1994 is 0.5970m3/s, which is slightly higher than that of 1993. Jiaodong Company and Wangfeng Company in Jiaoxi Mining Area have closed and stopped coal mining, and no new working face has been mined. The mine drainage in the whole mining area is decreasing year by year and tends to be stable. The water inrush point of the original coal seam floor has been used as the water source of the water supply well. 1989 with an average displacement of 3.25m3/s; 1990 decreased to 3.09m3/s; At 199 1, it is further reduced to 2.85m3/s; 1994 increased slightly, reaching 2.8931m3/s.

(2) Utilization of mine water: At present, the main methods of groundwater exploitation in Jiaozuo City are mine drainage and agricultural irrigation, and the mine drainage is 6.2707m3/s. Comprehensive utilization of mine drainage is an effective way to develop and utilize groundwater. The utilization of mine water in Jiaozuo city has three aspects:

The first is the utilization of mine water by Jiaozuo Water Supply Company. The fifth and sixth waterworks affiliated to Jiaozuo Water Supply Company all use mine water as the water supply source, and the second and third waterworks partially use mine water as the water supply source. 1994, the No.4 Water Plant of Jiaozuo Water Supply Company used 3363.04× 104m3 of mine water, accounting for 6 1.8% of the total water supply of Jiaozuo Water Supply Company.

The second water plant is located in the northeast of Jiaozuo City, with the well drainage of Jiaodong Company as the water supply source, and the water supply amount in 1456× 104m3 and1571.66× in 1994. Because Jiaodong Company has closed down, the utilization of mine water will be restricted. At present, the second water plant is building a new water source.

The third water plant is located in Jiefang West Road, which mainly uses the mine drainage of Jiaoxi Company. The water supply is1821×104m3, 1994 is1288.50x104m3, which is 65438.

The Fifth Water Plant is located in macun district, Jiaozuo City, and takes the mine water of Zhongmacun Mine as the water supply source to provide domestic water for macun district residents. The water supply of 1993 is 239× 104m3, and that of 1994 is 297.68× 104m3, which is 24.55% higher than that of 1993.

The Sixth Water Plant is located in zhongzhan district, Jiaozuo City, and uses the mine drainage of Li Feng Company to supply water to zhongzhan district, Jiaozuo City. 1993, the total water supply was 13 1× 104m3, and 1994 was 196.2× 104m3, which was 65438.

1994, the total utilization of mines in various water plants of Jiaozuo Water Supply Company reached 3363.04× 104m3, with an average annual utilization of 1.0664m3/s and 1993, which was 3570× 104m3, compared with 6570.

Second, Jiaozuo Coal Industry Group Company's own mine water inflow. Zhucun Mine, Jiulishan Mine and Yanmazhuang Mine of Jiaozuo Coal Industry Group Company all or partially depend on mine water for production and life. According to the investigation of 1994, the water consumption of each mine is 0.282m3/s. ..

Agricultural irrigation in Jiaozuo City leads to mine drainage. Part of the mine drainage is used by Jiaozuo Water Supply Company, Jiaozuo Coal Industry Group Company, Jiaozuo Power Plant, Jiaozuo No.3 Chemical Plant and other factories and mines, and the rest is discharged from the mine through rivers. The part of mine drainage flowing out of the mine is used as the water source for farmland irrigation in this area, and the rest flows out of the mining area. According to the data of Jiaozuo Water Conservancy Bureau,1971.0×104m3 used mine water in Jiaodong irrigation area and Jiaoxi irrigation area in 1994, with an average of 0.625m3/s ... After comprehensive calculation, the average total utilization of mine level is1.977. Therefore, the utilization degree of mine water resources is low.

4. Agricultural development of groundwater in Jiaozuo City

The existing cultivated land in Jiaozuo City is167,000 mu, including 67,000 mu in well irrigation area. According to the data of Jiaozuo Water Conservancy Bureau 1994, the crops are irrigated seven times, and the irrigation quota is generally 75m3/ mu. Therefore, it is calculated that the pore water for urban agricultural exploitation in Jiaozuo City is 35 17.5×65438+. In addition, the pore water for agricultural irrigation in Fangzhuang Township, Zhouzhuang Township, Liwan Township and Wuliyuan Township of Xiuwu County in Jiaozuo City is 0.7746m3/s, and the average shallow groundwater for agriculture in the whole region is1.89m3/s. ..

5. The total amount of groundwater exploitation in Jiaozuo City.

To sum up, 1994 * * underground water is exploited for industrial and agricultural production and life in the whole region14379.73x104m3, with an average of 4.56m3/s, of which karst water is 6480.07x104m3, with an average of 2.055m3/. With an average of 2.505m3/s, the karst water exploited by Jiaozuo Water Supply Company is 207 1.68× 104m3, with an average of 0.6569m3/s, and the total groundwater exploited by self-prepared wells is 6347.86× 104m3, with an average of 2.013.

Table 3- 18 1993 and 1994 Groundwater Discharge (unit: 1000m3)

Second, the main factors affecting groundwater resources in Jiaozuo area

1. Groundwater recharge decreases and discharge increases.

Groundwater resources in Jiaozuo area are seriously affected by mine drainage and groundwater pollution, and groundwater is mainly replenished by atmospheric precipitation infiltration and river leakage. Therefore, precipitation and river flow are the direct factors affecting groundwater resources.

The amount of precipitation directly affects the amount of groundwater resources, and precipitation infiltration is the main source of groundwater recharge in Jiaozuo area. Since the founding of New China, with the rapid development of industry and agriculture, groundwater exploitation has been increasing, groundwater level has been getting lower and lower, surface water resources have been exhausted, rivers have been cut off, water circulation system has been seriously damaged, and atmospheric precipitation has tended to decline. The average precipitation of 1952 ~ 1964 is 826. 1 mm, and that of 1965 ~ 1977 is 68 1.56 mm,1977.

There are four steps in the groundwater table decline in Jiaozuo, the first step is 1952 ~ 1964, the second step is 105m, 1965 ~ 1977, and the third step is 91~ 977. The main reason is that due to the decrease of precipitation and the increase of exploitation, the relationship between groundwater level and precipitation and exploitation is shown in Figure 3-36.

Figure 3-36 Relationship between Groundwater Level and Precipitation and Exploitation

Danhe River, Xishi River, Shanmen River, Zhifanggou River, Xinhe River and Wengjian River all flow through Jiaozuo mining area. Due to the development of surface karst, the river leakage is relatively large. For example, in 1994, the flow of the Danhe River was measured twice from the 480 power plant to the post-Chen Zhuang section in the dry season and the high season, and the average river leakage from the 480 power plant to the post-Chen Zhuang section was1.7338m3/s. In recent ten years, although the flow of the Danhe River has decreased year by year, the Xinhe River and Wengjian River are sewage rivers, and all other rivers have been drained.

The coal seam in Jiaozuo mining area is Carboniferous and Permian coal seam, and its direct water filling source is mainly Carboniferous thin limestone, and the karst water at the bottom of Ordovician limestone is indirect water filling source. This layer is rich in water and has a large water supply, which seriously threatens the safe production of coal. Therefore, thin-layer limestone of Carboniferous should be drained and depressurized, and fault waterproof coal pillar should be used for O2 limestone, and the water prevention policy of "mine-oriented, prevention first, dredging and plugging combined, and classified treatment" should be implemented. With the increase of mining depth, the frequency of water inrush from the floor of Carboniferous thin limestone coal seam increases, and O2 limestone water participates in the occurrence of malignant water inrush from the floor of coal seam, and the water displacement is also increasing. From the point of view of water use, the exploitation of O2 limestone water is also increasing. For example, in 1952 ~ 1964, the water yield of O2 limestone is 1.50 1m3/s, and in 1965 ~ 1977, the water yield of O2 limestone is 4.964m3/m3. According to incomplete statistics, water inrush from coal seam floor has reached 1000 times over the years, and the maximum water inrush from coal seam floor has reached 320m3/min. Therefore, water inrush from coal seam floor is another factor leading to the depletion of groundwater resources.

2. Groundwater pollution status

Among the rivers in Jiaozuo area, the water quality of Danhe River, Xishi River, Shanmen River and Zhifanggou is good and meets the drinking water standard. The chemical types, total hardness and chloride of Wengjian River exceeded the standard; The salinity of Xinhe River is 2782.99mg/L, the total hardness 1669.63mg/L and the Cl- content 149.5438+0 mg/L, all of which have exceeded the standard. Therefore, both Wengjian River and Xinhe River are polluted to varying degrees. According to the data of monitoring station in Jiaozuo City, Henan Province, the non-ionic ammonia, permanganate index, biological oxygen consumption, chemical oxygen consumption and hexavalent chromium in Wengjian River all exceeded the standard. Wengjian River and Xinhe River have become serious pollution sources of rivers and groundwater.

Pore water pollution is mainly manifested in the runoff and drainage area of pore water in the south of Jiaozuo city. This area is characterized by fine lithology, poor permeability, shallow groundwater level, long-term evaporation and concentration, increased ion content in water, especially Cl-, K++Na+, and increased salinity. More seriously, agriculture in this area is irrigated by mine water and industrial domestic sewage, which leads to the deterioration of pore water quality. The pore water quality in the area from Dongwangchu to Encun in the south of Jiaozuo City and Qiuhuazhuang in the southeast of Jiaozuo City to Xiuwu Yang Lou and Dagao Village in Jiaozuo City is Class I, Mg2+ and Class II, and the water quality is the worst. Among the 18 items detected in this area, the items exceeding the drinking water standard include total hardness, salinity, chloride, sulfide, nitrate and fluoride. See Table 3-65433 for the over-standard rate of each pollution component.

Table 3- 19 Statistical Table of Pore Water Quality

According to the monitoring and research in recent years, the water quality of karst water is deteriorating gradually, and the rate of deterioration is getting faster and faster. The main manifestations are the increase of Cl- ions, the salinization of water quality, and the loss of drinking value of individual well water. According to previous studies, the background value of Cl- in karst water in this area is 26.69 mg/L. When it reaches 1998, Cl- in karst water has reached 40 ~ 75 mg/L, with the highest value of128.73 mg/L. In 2000, at least three karst water sources exceeded the national drinking water standard (≤ 250 mg/L). Although the water source wells with excessive Cl- in karst water are individual, the karst groundwater in Jiaozuo area belongs to the same karst water system. If the water quality continues to deteriorate at the current rate, the karst water in Jiaozuo mining area will be seriously polluted in the future. The causes of Cl- pollution in karst water are: surface sewage leakage in karst water recharge area; Pore water and mine drainage pollute karst water through O2 limestone "skylight"; The polluted river water leaks to replenish karst water [2 1].

Three. Countermeasures of groundwater protection and utilization

1. Water pollution prevention and sewage recycling.

For factories and mines that have no treatment capacity, sewage treatment fees shall be paid, which shall be handled by the relevant municipal departments in a unified manner. In accordance with the national industrial structure adjustment policy and the requirements of eliminating backward production processes, technologies and equipment, we will focus on the structural adjustment of heavily polluting industries such as metallurgy, chemical industry, cement, electric power and mining and dressing. Sewage can be regarded as a "waiting resource". For sewage treatment, enterprises should build their own small sewage treatment plants based on the principle that whoever discharges will treat them, and the treated water can be reused to save water resources. Jiaozuo is a heavy industrial city with energy and chemical industry as its pillars. The sewage discharge is quite large, which pollutes the groundwater to varying degrees and reduces the available water resources. Implement the system of total pollutant discharge control, strictly control the examination and approval of construction projects, implement the system of treatment within a time limit, and adhere to the policy of "closing, stopping, prohibiting, changing and transferring".

2. Trinity of drainage, water supply and environmental protection

Professor Wu Qiang believes that the optimal management of drainage and environmental protection not only considers the drainage effect and safe operation of the drainage system, but also the water supply demand of the water supply system and the quality guarantee of the environmental system are important constraints for the design of the optimal model. At the same time, it is necessary to make full use of mine drainage and treat the discharged mine water with a certain quality to replace all or part of the water supply sources for different purposes in the mining area [27, 9, 26]. For the sake of safe production, a large amount of groundwater is drained in Jiaozuo mining area, and the mine drainage is 6.2707m3/s, accounting for 58% of the total exploitation 10.8 134m3/s, while the utilization rate of mine water is only 3 1.47%.

The trinity optimization model of drainage, water supply and environmental protection involves not only the management of groundwater hydraulic technology, but also the management of economic evaluation, environmental protection and industrial structure planning. The trinity of drainage and environmental protection refers to providing a certain amount of water resources to mines and their surrounding areas on the premise of ensuring environmental quality and mine safety, which can be used for domestic, industrial and agricultural water supply. The trinity model of drainage, water supply and environmental protection not only realizes the purpose of ensuring the environmental quality of water supply by using mine drainage and ground pumping, but also completes the use of a model by selecting the objective function with the greatest economic benefit generated by various water supply users and appropriate constraints, and at the same time, comprehensively formulates the concrete water resources optimization management scheme of the trinity of drainage, water supply and environmental protection. This model has been applied to Jiulishan Mine in Jiaozuo Mining Area [27].

3. Strengthen water price and water price reform.

Adjust the water price according to the requirements of the National Development and Reform Commission's Notice on Guiding Opinions on Reforming Water Price to Promote Water Conservation, otherwise the problem of wasting water cannot be fundamentally solved. Gradually increase the project water price (tap water price, water supply price of water conservancy projects), water resource fee (resource water price) and water pollution control fee (environmental water price). Taking water as the main raw material and means of production, a higher water price should be set. The water price of water conservancy projects should be gradually put in place, and the water resources fee should be adjusted in a timely manner. According to different industries, different basic water prices and different stepped water price standards are implemented, and domestic water should have a minimum guaranteed amount. Industrial water should refer to the advanced water quota at home and abroad to determine the water quota suitable for different regions, different industries and different industrial products, and the water exceeding the quota should be increased, and the equipment should be ordered to be reformed within a time limit to reduce the water quota. The collection of agricultural water resources fee will make the most potential users raise their awareness of water saving, promote well irrigation and save water, and nourish water with water [33]. Using economic lever to adjust water demand and promote water saving. Adjusting water price and water resource fee is the most important means to save water.

Please?Save?Water

Improve the reuse rate, save water, and gradually achieve "zero" emissions. Accelerate the development and research of new industrial water-saving technologies, new processes and wastewater recycling, as well as the research and manufacture of urban water-saving facilities; Formulate industry water-saving planning and water standard quota, continuously reduce water consumption and displacement, and improve water utilization rate; Comprehensive utilization of wastewater and recycling of wastewater are important measures to improve the reuse rate of water resources. Through the adjustment of product structure, industrial structure, enterprise organizational structure and industrial layout, saving water and realizing the balance between supply and demand of water resources are also the focus of water pollution prevention and control. These are several important aspects that should be considered in urban industrial water saving.

Large-scale development of high-efficiency water-saving forms suitable for intensive cultivation, mainly sprinkler irrigation. Take various water-saving measures such as pipe irrigation, canal irrigation, drip irrigation and sprinkler irrigation according to local conditions. Do a good job in comprehensive water-saving measures for surface water irrigation channels and develop double irrigation for wells and channels. Popularize agronomic water-saving measures such as straw returning, plastic film mulching cultivation, rainwater harvesting and water saving. Both dry farming and irrigated agriculture must adopt agronomic water-saving measures to improve the utilization rate of water resources. Agronomic measures and engineering measures of agricultural water saving should be combined with scientific management.

Saving water is a long-term fundamental measure, which is related to the sustainable development of society. Focusing on the development of agricultural water-saving irrigation and industrial water-saving, we have taken various administrative, economic, legal and management measures to do everything possible to improve the utilization rate and efficiency of water.

Four, mine water quality treatment technology

Coal mine roadway is the main place of coal mining. The pollutants in the roadway mainly include waste engine oil, waste acid solution, coal dust, debris particles and pathogenic bacteria, as well as underground artificial garbage and feces. If some old kiln water is connected with the roadway, mine water is easy to acidify. If the mine is replenished by surface water, it may be polluted by various pesticide solutions and industrial wastewater, most of which contain toxic substances such as organophosphorus, phenol and aldehyde. A large amount of groundwater flows into the roadway, which will inevitably be polluted to varying degrees by this coal mining environment.

Therefore, the comprehensive utilization of mine water must first solve the water quality problem, which is a very important link in the combination of drainage and environmental protection. In order to solve this problem, it is necessary to pretreat the water quality of mine water on the ground according to different pollution types and different water supply objects for comprehensive utilization, provide water supply users with mine drainage resources that meet their specific water quality requirements, and pay attention to the diversion of clean water to minimize the pollution degree of mine water. Practical mine water treatment technologies and methods mainly include the following categories:

1. Purification of turbid water in mine

Impurities contained in mine water can be roughly divided into three categories, namely suspended matter, colloidal matter and dissolved matter [5]. The main removal objects of mine turbid water purification treatment are suspended solids and colloids, which are the main factors causing mine turbid water. The general purification process of turbid water is as follows:

(1) clarification: clarification refers to the process of removing impurities such as suspended solids and colloids that cause water turbidity, which can generally be divided into three steps, namely coagulation, precipitation and filtration.

(2) Disinfection: Mine turbid water can be disinfected after coagulation, sedimentation and filtration (or disinfected before filtration).

The general purification process of mine turbid water is shown in Figure 3-37. For some special types of mine turbid water or water supply users with special requirements, they can be treated flexibly according to their specific conditions, and it is not necessary to completely copy all the above purification treatment processes.

Figure 3-37 Schematic Diagram of Mine Turbid Water Purification Process

For example, if the turbidity of mine drainage is low and there is no algae propagation, the turbidity is often below 100 degrees. After adding coagulant, it can be directly filtered at one time without coagulation and sedimentation. The filtered mine water is disinfected with chlorine gas and then sent to the water supply network through the pumping station.

For another example, if the turbidity of mine water is high, we should try our best to achieve the expected purification purpose and save the dosage of coagulant. Before coagulation and sedimentation, natural sedimentation can be used to pre-precipitate a part of the larger precipitation particles in the original high-turbidity mine water, and the structures used can be pre-sedimentation tanks or grit chambers. Finally, coagulation, sedimentation, filtration and disinfection are carried out.

2. Softening treatment of mine high hardness water

The hardness of water mainly refers to the content of Ca2+ and Mg2+ ions dissolved in it, and Fe2+, Mn2+ and Sr2+ ions dissolved in water are also a factor affecting the hardness of water. Here are three commonly used softening methods:

(1) Microbial method: This method includes desulfurization by sulfate reducing bacteria and iron removal by iron bacteria.

(2) Chemical method: chemical softening treatment includes neutralization of lime and lime milk and softening of lime and soda.

(3) Physical method: This softening treatment method includes distillation, electrodialysis and dilution.

3. Neutralization treatment of mine acid water

The coal seam or its roof and floor often contains sulfide minerals, which form sulfuric acid compounds under oxidation conditions. Once these sulfuric acid compounds are dissolved in mine water, their ion content will increase and become acidic mine water.

The formation of acidic water in mining area is gradually formed with the extension of coal mining time, and most acidic water is very destructive. However, some acidic water has been enriched before coal mining, that is, in the oxidation zone of sulfide deposits.

The harm of acidic water is very serious. In the exploration of Bria mining area in Russia, due to the corrosion of acid water, the diameter of drill pipe decreased by 1mm within 8 hours, and the casing was partially corroded. In the area where strongly acidic water is distributed, the casing wall is corroded and perforated by 12 day and night. When the mine is connected with the old kiln and goaf where acidic water is stored, acidic water can enter the mine along the passage, so acidic water will pollute the underground production environment.

For the formed acidic water and the mine polluted by it, limestone neutralization method or microbial method should be adopted for treatment. For acidic old kiln water, waterproof coal pillars and other projects should be set up to completely isolate it from the mine system; For sulfur-bearing coal seams, the water-filled and oxygen-filled environment should be eliminated as far as possible to make it closed and lose the environment for forming acidic water. In order to eliminate the pollution of acid mine water, prevention and control must be carried out simultaneously.

4. Treatment of high-iron and high-manganese water in mine

When treating1100m3 high-iron and high-manganese water on the same day, the filter can be a steel circular two-stage pressurized filter, which is divided into an upper chamber and a lower chamber, and the upper and lower chambers are made of manganese sand. In order to achieve sufficient aeration, disperse the free CO2 in the water as much as possible and improve the pH value, an impeller surface aeration device can be used, and the aeration tank can be made into a rectangle, and the residence time of water in the aeration tank is about 20 minutes. The process of removing iron and manganese by surface aeration two-stage filter is an economical and effective technical method.

There are two main methods to remove iron, one is shower head aeration, quartz sand filtration, or river sand, pebble and carbon pebble layer filtration, and the other is natural manganese sand contact oxidation to remove iron. This method is simple, economical and effective, and has been widely used. These processes can achieve the expected purpose of iron removal and make the iron content in water reach the national drinking water standard.

At the end of 1970s, a two-stage filtration treatment system was developed. After aeration and two-stage filtration, the contents of iron and manganese in general water can be controlled below the national drinking water standard. The content of iron and manganese ions in water can be eliminated at the same time. The technological process is as follows: firstly, fully aerate the water, then remove iron through the primary filter, and then remove manganese through the secondary filter. In terms of manganese removal technology, the contact oxidation process was initially adopted, and the effect was also good.