(Luận văn thạc sĩ) evaluation of the efficiency of the liquid waste treatment system in coal mining at khanh hoa coal mine

THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN THI HANG EVALUATION OF THE EFFICIENCY OF THE LIQUID WASTE TREATMENT SYSTEM IN COAL MINING AT KHANH HOA COAL MINE BACHELOR THESIS Study Mode: Full-time Major: Environmental science and management Faculty: International Programs Office Batch: 2015 - 2020 Thai Nguyen, 20/11/2020 ACKNOWLEDGEMENT Over the internship at Khanh Hoa-VVMI Coal Company where it is very suitable for the environment industry Here, we have initially grasped: - Diagram of coal mining process; - Discharge from coal mining; - Methods of wastewater treatment during coal mining; During my internship, I have strictly follow all the rules of the company set out, try, actively study, grasp the labor safety process During my internship, I have strictly follow all the rules of the company set out, try, actively study, grasp the labor safety process With the knowledge learned on the school chair combined with practical observation, through this internship has helped me to add knowledge and learn experience working for myself With the knowledge learned on the school chair combined with practical observation, through this internship has helped me to add knowledge and learn experience working for myself In order to complete this internship report, in addition to my efforts, I would like to express my deep gratitude to: In order to complete this internship report, in addition to my efforts, I would like to express my deep gratitude to: - The teachers of the advanced program have dedicatedly taught in the past semesters, especially thanking the instructor Mr Nguyen Huu Tho for dedicatedly guiding me to complete this internship iv - The board of directors and employees of Khanh Hoa-VVMI Coal Company have dedicatedly guided and facilitated me to complete this internship Due to the short internship time, my ability is limited and initially approaching the reality is still very difficult, so I can not avoid mistakes, I look forward to receiving the sympathy and suggestions of teachers and friends Thank you very much! v PART I INTRODUCTION 1.1 Research rationale Natural resources are material assets available in nature that humans can exploit, process, use and serve human life (forests, animals, plants, mineral deposits, water, oil, and gas, ) It is an essential part of the environment and has a close relationship with the environment Natural resources bring a lot of benefits to people, but the exploitation and use of resources are not reasonable, the management is not strict and ineffective, leading to the loss and waste of natural resources countries in general and Vietnam in particular In the trend of integration and development, our country's industries are interested in investing and promoting Among them are activities of the mining and mineral processing industry Coal mining is an activity that has been interested in investment and development for a long time Coal provides fuel sources for many economic sectors such as thermal power, cement, metallurgy, The demand for coal is increasing, coal mining and processing activities are therefore continuously increasing Besides the economic benefits that the coal mining industry brings, this activity causes coal reserves to decline, but coal is a non-renewable resource and it also causes negative impacts on the environment requires investors to have appropriate management solutions, technology solutions, and treatment solutions to minimize negative impacts on the environment Thai Nguyen is a province with large coal reserves, with many coal mines being exploited such as the Khanh Hoa coal mine, Phan Me coal mine, Nui Hong coal mine Khanh Hoa is a large coal mine located in the North of Thai Nguyen city Originally, coal mining activities here have brought many economic benefits, created jobs for local people, contributed to promoting the development of the market economy However, besides that, coal mining has been adversely affecting the surrounding environment In addition to the benefits brought by the coal mining and processing industry to Thai Nguyen province, the current environmental impacts are not small: Land erosion problem, air pollution, environmental pollution land and in particular, water pollution such as lowering the groundwater level, polluting irrigation water sources are increasingly causing frustration among the people Therefore, the assessment of the current water environment in coal mining activities in Thai Nguyen is necessary Stemming from the above reality, with the guidance of the teachers, I carried out the topic: "Report on assessment of the current state of water environment in coal mining of Khanh Hoa coal mine" to apply the Theoretical knowledge you have learned in school to apply in practice Propose measures to manage and improve wastewater treatment technology for factories to improve environmental quality 1.2 Introduction of Khanh Hoa coal company- VVMI Figure 1.1: Khanh Hoa Coal company 1.2.1 Geographical location Khanh Hoa coal mine is km west of Thai Nguyen city center The west of the mine is adjacent to Ba Son coal mine, the Southeast is adjacent to Quan Trieu station The East of the mine is adjacent to Highway Thai Nguyen - Bac Kan - Tuyen Quang Adjacent to communes: + An Khanh commune (Dai Tu district) + Son Cam commune (Phu Luong district) + Phuc Ha commune (Thai Nguyen city) Figure 1.2: Topographic map of Khanh Hoa coal mine The quarry's infrastructure has been built relatively fully, the communication routes from the quarry to the villages and to the city center are all concrete roads with a roadbed width of> 5m 1.2.2 Type of exploitation Open-pit mining and underground mining, in which open-pit mining is the main type Figure 1.3: Open-pit mining At Khanh Hoa coal mine 1.2.3 Target - Meeting coal consumption demand for coal consumers in Thai Nguyen province, especially supplying coal for thermal power plants of An Khanh and Cao Ngan - To make the fullest use of the reserves in the mines to enrich the country 1.2.4 Organizational structure Table 1.1: Current number of employees at the mine No Occupation Quantity I Direct labor 621 II Management department 90 Whole mine 721 The company's organizational structure includes: director, deputy directors Departments: departments Workshops: workshops 1.2.5 Capacity and mine life The estimated mine capacity is 800,000 tons/year The expected life span of mine is 25 years (from 2013 to 2037) 1.3 Research’s objectives - Determine the source of generation and main components in the wastewater of Khanh Hoa coal mine - Assess the status of management and wastewater treatment of Khanh Hoa coal mine - Some solutions to improve the efficiency of wastewater management and treatment to contribute to environmental protection 1.4 Research questions and hypotheses 1.4.1 Research questions - What is the current situation of wastewater in coal mining in Khanh Hoa coal mine? Đánh giá hiệu hệ thống xử lý chất thải lỏng khai thác than mỏ than khánh hịa để đảm bảo mơi trường nước bên xung quanh mỏ than an toàn - Wastewater management and treatment like? - What is the impact of coal mine wastewater on the environment and people living around the coal company? 1.4.2 Hypotheses Null Hypothesis (Ho): - Water is observed flowing around coal production areas The water quality around the coal company is polluted Water quality parameters are higher than permitted standards - Liquid waste treatment system at Khanh Hoa coal mine does not operate effectively, wastewater after treatment are not allowed to discharge into the environment - The surrounding household and surrounding landscape area may be polluted with water due to the factory's production activities Alternative hypothesis (Ha): - Although wastewater discharged from coal production areas, the parameters of elements in the country are lower than the permitted level The water quality around the coal mine is safe - Liquid waste treatment system in Khanh Hoa coal mine operates effectively, wastewater after treatment is allowed to discharge into the environment - The household area and surrounding landscape are not polluted with water because wastewater is treated efficiently before being discharged into the environment 1.5 Limitations • Collection and disposal issues All wastewater generated from the open pit and pit mining area is led to the pit bed, preliminary settling before being pumped to the centralized wastewater treatment station for treatment Currently, the wastewater collection and treatment of Khanh Hoa Coal Company are relatively stable However, there are still possible problems that affect wastewater treatment such as Failure of equipment, high push height, water quality fluctuations in flow, and concentration The expansion and increase in the capacity of coal mines in recent years have had a significant impact on the surrounding environment Mining is one of the activities that generate a large amount of wastewater, wastewater from Khanh Hoa coal mine is basically treated through a sedimentation tank using chemical sedimentation, the treated water meets the discharge standards Discharge into surface water The open-pit mine of Khanh Hoa coal mine is currently exploited at a depth of ≥-225m, greatly affecting the surrounding groundwater level, leading to the risk of lowering the groundwater level 1.6 Definitions Liquid waste: is all waste that exists as a liquid rather than either a gas or a solid It includes both waste produced as a liquid and waste that has been converted into a liquid for handling Wastewater: is broken into two categories (gray and black water) Gray water is from showers, baths, whirlpool tubs, washing machines, dishwashers and sinks other than the kitchen sink Black water is from toilets and kitchen sinks 10 Figure 4.3 Pump system At the flocculation compartment, the flocculation solution and the PAC, PAM deposition aid are pumped into and mixed with wastewater by a stirrer, then water flows itself into the reaction compartment The powdered PAC and PAM deposition agent are prepared at the operator into a solution of 0.1% concentration The flocculation solution is pumped quantitatively from the preparation tank to the flocculation compartment First, add PAC to reduce viscosity, increase the absorption between small particles to form larger particles, then add PAM to increase convergence of particles when in contact with each other form a large flocculation, speed up deposition - The flocculation solution is mixed with wastewater by a stirrer installed in the flocculation compartment to have the effect of distributing, distributing upstream, swirling to speed up flocculation and deposition 39 Figure 4.4: Location of Wastewater through the mixing compartment PAC and PAM deposition aid At the reaction compartment, Wastewater through the mixing compartment PAC and PAM deposition aid, continues to be passed through the slow stirring compartment to help the flocculants and deposition aids disperse into the water and make the Small sized suspended solid particles stick together to form colloidal cotton - these colloidal flakes will settle by gravity, the faster and more efficiently they settle thanks to the sloped slabs due to the water from the reactor in the sedimentation tank, it will move from the bottom up according to the slanted slab of lamella in the process of moving the colloidal cotton will collide and stick to the surface of the lamenlla settling plate When the colloidal cotton sticks together on the surface of the lamella settling plate is heavy enough and can overcome the repulsion of moving water, the colloidal cotton will slide 40 down in the opposite direction and fall to the bottom of the settling tank After sedimentation, wastewater is taken to a tank containing clean water and discharged into the stream Sludge from regulating tanks to settling tanks is transported to sludge tanks and by sludge pumping system respectively Figure 4.5 Exhaust door, installation of automatic monitoring system Flow monitoring parameters of TSS and iron The sludge stored in the sludge tank is compressed naturally, then dumped by a dedicated sludge truck at the disposal site (sludge composition is mainly non-toxic inorganic substances) 41 Figure 4.6: Sludge storage tank The wastewater treatment station is controlled by a semi-automatic form 4.3.2 For ground water Groundwater in the project area exists and moves in the fracture zone of the sandstone and grit layers while the clay, coal clay and coal layers are the water insulation layers Groundwater is poor, the permeability coefficient K 5m 1.2.2 Type of exploitation Open-pit mining and underground mining, in which open-pit mining is the main type Figure 1.3: Open-pit mining At Khanh Hoa coal mine 1.2.3 Target - Meeting coal