Assessing current situation of wastewater from ha lam mine in ha long city, quang ninh province

ACKNOWLEDGEMENTS I would like to express my great appreciation to Msc.Nguyen Thi Bich Hao from Vietnam Forestry University, my research supervisor, for her enthusiastic encouragement and useful critiques on this research Without her thoughtful and patient guidance through every step of my research and her knowledge on how to correct and analyze the data I collected, this thesis could not be completed I also would like to say thanks to lecturers, who have taught us for more than years, and to the cooperation of Vietnam Forestry University and Colorado State University, especially, the faculty of Forest Resource and Environmental Management I would like to extend my gratefulness to Mr.Le Ngoc Hai, the Vice Director of environmental company - TKV- Vinacomin for accepting my research in his wastewater treatment station at Ha Lam mine And, I would like to express my gratefulness to Mrs Tran Thu Ha, the Deputy Head of Water Resources and Hydrometerology Section, Department of Natural Resources and Environment, Quang Ninh Province, Vietnam for providing information and documents on wastewater treatment station at Ha Lam mine Xuan Mai, 12th October, 2015 Student Nguyen Hoa Binh CONTENTS INTRODUCTION GOALS AND OBJECTIVES 2.1 Goals 2.2 Objectives 3 METHODS 3.1 Secondary data collections .4 3.2 Interviewing 3.3 Assessing the wastewater quality 3.3.1 Analyzed indicator selection 3.3.2 Sample locations and sites 3.3.3 Tools and sampling methods .7 3.3.4 Analysis Methods RESULTS AND DISCUSSION 13 4.1 Assessing the current situation of wastewater in Ha Lam 13 4.1.1 Mining activities at Ha Lam mine 13 4.1.2 Wastewater treatment systems 14 4.1.3 Analyzed results of some indicators for wastewater quality 18 Wastewater from mining before treatment at Ha Lam mine 18 Wastewater from mining after treatment at Ha Lam mine 20 4.2 Impacts of mining wastewater on surrounding environment at Ha Lam mine 23 4.2.1 Results of analyzing some water quality indicators at Ha Lam stream 24 Average values 24 4.2.2 Impact of wastewater from mining to Ha Lam stream 26 4.3 Solutions to improve effectiveness of the treatment systems 27 4.3.1 Reasons of ineffective operation of the wastewater treatment system 27 4.3.2 Solution to improve effective of treatment system 28 CONCLUSION 32 REFERENCES 34 APENDIXES 35 LISTS OF TABLE Table 3.1 Information on impacts of mining waste water on surrounding environment Table 4.1 Quantity of coal exploitation 13 Table 4.2 Characteristics of wastewater discharges at Ha Lam mine 16 Table 4.3 Quality of wastewater from mining activities at Ha Lam 19 Table 4.4 The results of analyzed indicators for treated water 21 Table 4.5 Analyzed results of surface water 24 Table 4.6 amount of chemicals used in treatment 27 LISTS OF FIGURE Diagram 3.1 Positions of taking water samples Diagram 4.1 Coal mining process 14 Diagram 4.2 Diagram of wastewater system at Ha Lam mine 16 Diagram 4.3 Wastewater treatment system I 18 Diagram 4.4 Diagram of new system 30 LIST OF DIAGRAM Map 3.1 Postision of Ha Lam mine Map 3.2 Sampling positions Graph 4.1 The analytical result of total concentration of Fe 22 Graph 4.2 The analytical results of total concentration of Mn 22 Graph 4.3 The analytical result of BOD5 25 Graph 4.4 The analytical result of COD 25 Graph 4.5 total of Fe 26 ABSTRACT Ha Lam mine locates in Ha long city, Quang Ninh province and belongs to Vinacomin As other coal mines in Vietnam, wastewater from this mine is causing some problems to the environment To assess the impacts of wastewater from activities of Ha Lam mine on the environment, the thesis applied various research methods which include field investigation method, wastewater quality assessment via some indicators, and methods of data processing The research results show that treated wastewater is severely polluted Almost all analytical results of BOD, COD, total concentration of Fe, and total concentration of Mn at four sampling sites are higher than the standards Investigating and analyzing results show that the wastewater treatment system is operating ineffectively Therefore, activities from this mine is negatively affecting on health of local people and the environment To contribute to improve the quality of wastewater, the thesis proposes some solutions such as replacing the old system by the new one with new technology INTRODUCTION Like all country in the world, Vietnam is facing various challenges related to water resource management, and water pollution, especially, pollution from mining activities Mining can have bad effects on surrounding surface and ground water if protective measures are not taken There is an obvious potential for massive contamination of the area surrounding mines due to a large amount of various chemicals used in the mining process as well as the potentially damaging compounds and metals removed from the ground with the ore Large amounts of water produced from mine drainage, mine cooling, aqueous extraction and other mining processes increases the potential for these chemicals to contaminate ground and surface water The result can be unnaturally high concentrations of some chemicals, such as arsenic, sulfuric acid, and mercury over a significant area of surface or subsurface Locating in the northeast of Vietnam, Quang Ninh is known as a miniature Vietnam with different terrain types of plain, midland, mountainous regions, sea, islands, and borders Quang Ninh is also internationally popular with the presence of the world's natural wonder of Ha Long Bay Additionally, this is also the main coal mining centre in Vietnam Every year, all mines in Quang Ninh discharge about 70 million cubic meters of wastewater to the environment Many mining areas have caused serious water contamination by untreated wastewater during mining and mineral processing The wastewater from these sources may contain acidic and alkaline compounds, heavy metals and other toxic substances If this type of water is not treated, it will inevitably affect the living environment of the local community In the long time, it can become an environment disaster Ha Lam mine locates in Ha long city, Quang Ninh province With reserve of about 171 million tons of coal in 2008 and the highest yield of 2,400,000m3/year, the volume of daily discharged waste will be significant, particularly, wastewater However, according to the information from the annual report of Environment Department, the wastewater treatment system of the Mine is not effective So, the pollution level of this mine is increasing and threatening water resource for social and livelihood needs of local people Determining the causes and proposing solutions for pollution situation of Ha Lam Mine are necessary and urgent these days Therefore, I chose topic “Assessing current situation of wastewater from Ha Lam mine in Ha Long city, Quang Ninh province” 2 GOALS AND OBJECTIVES 2.1 Goals Goals of this project are to assess the wastewater from Ha Lam mine in Ha Long city and propose solutions to improve the efficiency of wastewater treatment systems for Ha Lam mine 2.2 Objectives Main objectives of the thesis are as follows: Assessing the current situation of wastewater in Ha Lam mine by investigating wastewater treatment systems, analyzing wastewater by some major indicators; Assessing impacts on surrounding environment caused by wastewater from Ha Lam mine; Proposing solutions to improve the effectiveness of wastewater treatment for Ha Lam mine and protect surrounding environment 3 METHODS 3.1 Secondary data collections To achieve the objectives, the thesis investigated the information on Ha Lam mine to support for assessing wastewater The information collected includes: Mining activities in Ha Lam mines (mining capacity, coal reserves…); Production technology and manufacturing diagrams; Sources of wastewater, characteristic and quality of wastewater; Characteristic of wastewater treatment system and treatment diagram; Impacts on surrounding environment 3.2 Interviewing From the results of investigating the study area, the thesis interviewed the people who live near the Ha Lam mine Thesis uses interview method to investigate information shown in table 3.1 Table 3.1 Information on impacts of mining waste water on surrounding environment Name Address Their knowledge Activities Activities of Impacts of about wastewater of the people to Ha mining from mine mine Lam stream wastewater Nguyen Van A Nguyen Van B … 3.3 Assessing the wastewater quality 3.3.1 Analyzed indicator selection Based on the purposes of the research and analysis conditions, the thesis chooses the following criteria to analyze and assess: 4.2 Impacts of mining wastewater on surrounding environment at Ha Lam mine Wastewater after being treated at system will be discharged into Ha Lam stream through gate CX2 Treated water runs to Dien Vong river and approaches the coastal area of Ha Long Bay through Cua Luc river Currently, Ha Lam stream is considered as a place to drain rainwater and domestic wastewater of local people inhabiting along the banks of the stream Ha Lam stream originates from the southern slopes of Ha Trung ward, Ha Long, which is a small stream with short and relatively wide stream bed, and low flow Ha Lam stream flows through five (05) wards such as, Ha Trung, Ha Lam, Cao Thang, Cao Xanh, Ha Khanh 23 4.2.1 Results of analyzing some water quality indicators at Ha Lam stream Table 4.5 Analyzed results of surface water QCVN Results No Indicators 18th Unit 19th 08: 20th Average 2008/BTN V1 V2 V1 V2 V1 V2 values C 29.5 29 30.5 30.3 31 31.2 30.3 - MT Temperature pH - 7.55 7.2 7.01 7.1 7.8 7.5 7.4 5.5-9 Turbidity NTU 22 28 22 25 30 35 27 - TSS mg/l 23.4 25.6 20.2 21.1 24.8 29.3 24.1 100 TDS mg/l 1105 1198 1452 1343 1408 1567 1345 - DO mg/l 4.2 3.6 3.2 2.6 2.5 3.6 3.3 >2 BOD mg/l 25.3 28.6 30.7 34.3 28.8 33.3 30.2 25 COD mg/l 51.3 54.2 55.7 60.8 52.7 58.4 55.5 50 Fe mg/l 5.56 5.93 5.09 6.67 4.23 6.33 5.6 10 Mn mg/l 1.92 2.01 2.13 2.37 1.82 2.56 2.1 - The results show that:  BOD, COD: the analyzed results of these indicators are slightly higher than the standard of QCVN 08:2008/BTNMT Values of COD in waster range from 51.3 mg/l to 60.8 mg/l which are about 1.2 times higher than the standard The results for BOD range from 25.3 mg/l to 34.3 mg/l which are about 1.37 times higher than the standard 24 BOD 40 35 30 25 25 25 25 V1 V2 20 Average 15 QCVN 08:2011/BTNMT 10 18th 19th 20th Graph 4.3 The analytical results of BOD5 COD 70 60 50 50 50 50 V1 40 V2 30 Average 20 QCVN 08:2011/BTNMT 10 18th 19th 20th Graph 4.4 The analytical results of COD  Fe: Total concentrations of Fe in water are still high At sampling site of V1 which is above the discharge point of 200m, the analyzed results of Fe are 2.1-2.7 times higher than the standard And at sampling site of V2 which is below the discharge point of 300m, total concentrations of Fe are about 2.96-3.33 times higher than the standard  There is no limit for Mn in surface water 25 Total of Fe V1 V2 Average 2 2 QCVN 08:2011/BTNMT 18th 19th 20th Graph 4.5 Total concentrations of Fe 4.2.2 Impact of wastewater from mining to Ha Lam stream Ha Lam stream has become the source receiving wastewater for a long times Water quality in Ha Lam stream is not uniform Water in some sections is dirty and has bad smells By interviewing some local people, their knowledge on the wastewater from mines is limited Local people can identify the mining activities which include surface mining and underground mining They just know that wastewater has many toxic substances, and it may be harmful to the environment All of the interviewed residents reported that water in Ha Lam stream is dirty and smelly However, they were not able to indentify how wastewater influences to the environment and their life And, local people Water flow in Ha Lam stream changes following season, high flow in rainy season which is from April to November In dry season, from December to March, water flow is low Water in Ha Lam stream is not used to water supply, water transportation and aquaculture It is used to drain rain water and domestic wastewater of local people So, currently, wastewater is not impact to the health of people It makes loss of aesthetics, bad smell in some section But, wastewater in Ha Lam stream will discharges to the coastal area of Ha Long bay So, in the long time, it will harmful to the water quality and environment in Ha Long bay 26 4.3 Solutions to improve effectiveness of the treatment systems 4.3.1 Reasons of ineffective operation of the wastewater treatment system Follow the result survey, there are main reasons for wastewater is not satisfied the standard QCVN 40:2011/BTNMT before discharges to environment:  Treatment capacity: Follow designed capacity of system 1, treatment capacity can processed 2400 m3/day So, with the average industrial wastewater from mining is 625m3/day, and the largest wastewater is 2333m3/day, system can still processed wastewater with this quantity  The operation and management of worker in the system: In field survey, follow tracking and assess the record of worker at the treatment station Amount of chemicals used in treatment: Table 4.6 amount of chemicals used in treatment Chemical Quantities (kg/m3) Ca(OH)2 0.09 PAA 0.0004 PAC 0.00016 So, amount of chemicals are calculated to processed the wastewater is satisfied the requirement  Technology of treatment system: Through field survey, in the system, wastewater was led through trash-shields Then water ran into conditional tanks, with the volume about 300 m3 So, with the largest flow, and the special characteristic of wastewater from mining, water will continuous run into the tank So, with the short time in tank, the effective of the tank is not satisfied Then, wastewater run to reaction-tank, added the chemical PAA, PAC, Ca(OH)2, and continuous run to the sedimentation tanks Both of tanks have volume about 250 m3 After that, wastewater was discharge to the environment So, follow my opinion, this 27 is the main reason for wastewater is unsatisfied The treatment system is very simple, with the small volume in the tanks, so the effective of treatment is not high and unsatisfied Total of Fe and Mn in water is still higher In all result of survey wastewater, total of Fe and Mn is higher than the standard QCVN 40:2011/BTNMT 4.3.2 Solution to improve effective of treatment system Under this situation, the urgent solution is the plan to improve effective treatment of system station I, or changes treatment system to suitable with the conditions of the wastewater from mining at Ha Lam mine So, i give two solutions to improve efficiency:  Temporary solution: Upgrade equipment, add more chemicals in treatment system  Long-term solution: Changes the technology of treatment system, replace complete the treatment system 4.5.2.1 Temporary solution Reconstruction the capacity of the tank, upgrade and add more machine in the system In the system I, there are 12 pressure filters, pumps, air blower So, to improve the efficiency, we need add more machines And, about the tanks in the system, we need increase the capacity Wastewater treatment system was built since 2004, volume of water always is higher So, when heavy rain happens in the long time, wastewater in the tanks will rise and spill out Solutions to improve capacity of the tanks in the system are essential Testing, recalculate the amount of chemicals (Ca(OH)2, PAC, PAC) to increase efficiency Beside using Ca(OH)2, we can add NaOH to increase pH of wastewater, combines more chemicals to increase the efficiency of the systems Using lamellar packs in the tanks, it improve the efficient of sedimentation in the tanks In fact, the lamellar packs increase the sedimentation surfaces of all new tanks and the performance of existing systems, while reducing the overall space and costs of civil engineering works 28 4.5.2.2 Long-term solution To solve completely the problem of wastewater quality, we need to replace the treatment system, changes by new technology to improve wastewater quality after release to environment So, I would like to propose a solution to replace the system in Ha Lam mine This is the methods combines between neutralize the acid and sedimentation-filtration, constructs the continuous treatment tanks, calculate the chemicals add to the systems The essences of new system are: Construct the new continuous treatment tanks, with higher capacity, can be used for a long time, avoid the negative impact from weather( heavy rain happens in long times) Using alkaline chemicals (Ca(OH)2, NaOH ) to neutralize acid, raise the pH, oxidized the heavy metal (Fe, Mn…) Using deposition aid chemicals (PAA, PAC, PAM) to increase precipitated of suspended solids available in wastewater, or remove suspended solids Using active materials coated with Mn oxide for oxidized Mn and retaining Mn in process Using mechanical methods to dry the sludge (solid mixture in wastewater and water 29 Wastewater Conditional tank and Trash- shield Wastewater run back to reprocesses Neutralized tank Ca(OH)2 NaOH, aeration Sludge drying tank PAC Flocculation tank PAM Lamella tank Manganese filter tank Discharges to Ha Lam Stream Diagram 4.4 Diagram of new system All the process are: add Ca(OH)2 to neutralized acid, raise pH, aeration to oxidize iron and a part of manganese, next is flocculation and the tanks with lamellar packs separated and filtering suspended solids Manganese filter tank with active material coated with Mn processing section Mn remaining in the wastewater This is method has many companies applied in Quang Ninh province 30 The processes are: Conditioning flow: The wastewater is flow to conditional tanks, to control the flows and remove a part of sediment, the large-sized coal particles in wastewater Neutralized acid, oxidation Fe and Mn: in neutralized tank, we add Ca(OH)2 and NaOH to wastewater to raising pH, and aeration air to oxidize Fe and apart of Mn In here, the wastewater is removed suspended particles, and precipitate Fe, other metal part Iron often exists as the divalent ions, and part of the soluble salts, such as bicarbonate (Fe (HCO3)2; sulfate FeSO4… The reaction in tank are:  Wastewater is added Ca(OH)2: Fe(HCO3)3 + O2+ 2H2O + 4Ca(OH)2 -> 4Fe(OH)3 + 4Ca(HCO3)2  Fe (OH)3 is precipitate and retained in the sedimentation tanks The compound is created in the form of suspensions: Fe(HCO3)2 + Ca(OH)2 -> FeCO3 + CaCO3 + 2H2O Flocculation: After neutralization tanks, sewage will be directed to the flocculation tank In here, PAA, PAM are added, mixed by agitators The chemicals make the suspended solids in the wastewater is flocculation, then the water will flow into the lamella sedimentation tanks Lamellar tank: suspended solid in the large sized form In the process of water moving, lamellar packs filtering suspended solids, deposit in the bottom, water will flow from lamella sedimentation tanks into manganese removal tanks Manganese removal tanks: Manganese exists in the wastewater as ions Mn2+ Manganese exists in the wastewater as Mn2+ ions When the water through the filter active material coated with Mn, ions Mn2+ are oxidized to form a precipitate and retained on the surface layer of filter material However, the active material coated with Mn need to replace in periodic times Because, for a long time, precipitated on the surface will reduce the ability 31 of materials in process Next, wastewater is satisfied the standard will be released to environment Sludge tank: The sludge are dried naturally, and treated The wastewater in the sludge tanks will flow to conditional tank to reprocesses The new system has some advantages and disadvantages as follows Positve Negative Initial investment costs are not high, can upgrade from existing conditions Automatic control During regular operation, system needs staff to check and supervision Use a variety of chemicals, affecting The tanks have the ability to the health of workers if exposed withstand high pressure of water, regularly resistant to corrosion of low pH and the effects of chemicals Systems must to conduct regular maintenance easy to operate 4.4 Discussion  To assess more accurately, the thesis need more time for collecting data and sample to analysis wastewater quality follow the time and season  The contamination in Ha Lam streams is due to a part of human activities living around  Require more treatment recommendations, to help for improving the system more efficient CONCLUSION 32 Follow the result of the thesis, wastewater from mining at Ha Lam mines discharge to environment is not satisfied Wastewater is not thoroughly treated before being discharged The total of Fe and Mn in wastewater after treatments is still high The result shows the total of Fe is 1.95-2.11 times higher than the standard QCVN 40:2011/BTNMT, efficiencies of treatment are 67.4-70% And total of Mn is 2.23-3.34 times higher than standard, the efficiencies of treatment are 56-74.8% Water in Ha Lam stream is not satisfied the standards of QCVN 08: 2008/BTNMT in terms of BOD, COD, Fe And, in the environment surrounding Ha Lam mine, at V1 and V2 position, the indicators are higher than the standard QCVN 08:2008/BTNMT At the V1, above discharge point 200m, total of Fe is 2.1-2.7 times higher than standard And at the V2, below discharge point 300m, total of Fe is 2.96-3.33 times higher than standard And total of Mn in water still very high At V1, it’s 1.82- 2.13 mg/l, and at V2, it’s 2.01-2.56 mg/l The amount of wastewater was discharged to Ha Lam stream, affected to a part of local people And, wastewater follow Ha Lam stream will be released to Ha Long Bay If this situation continues for a long times, it will reduces water quality in coastal area of Ha Long bay, destroy aquatic systems To increases quality wastewater before discharging it into the environment, the critical requirement is improve processing efficiency of treatment systems In short-term, the system needs to renovate and upgrade the system, equipment, recalculate and add more chemicals to increase process efficiency In long- term, Ha Lam mine needs to replace the old system by the new one, with higher efficiency 33 REFERENCES Bui Thanh Hoang (2008), "the the wastewater treatment underground mine in Ha Lam Coal Company - TKV" Science and Technology Information mines, No 8/2008 Ha Lam Coal Joint Stock Company - Vinacomin, "Report to discharge wastewater into water sources in 2014” JSC Ha Lam Coal Vinacomin (2009-2015), "Annual eport on the results of production and business" Nam Mau Coal Company (2014), "Report on the discharge of the wastewater treatment station” The Natural Resources and Environment Department - Quang Ninh province (2011): "Management and the wastewater treatment in the coal industry" Coal Industry Group - Minerals of Vietnam (2013), "Environmental Protection Scheme Quang Ninh coal region until 2020 and orientations towards 2030" Mine Institute of Science and Technology (2013), "Management and the wastewater treatment in the coal industry" QCVN 02: 2009/BYT: National technical regulation on domestic water quality QCVN 38:2011/BTNMT: National technical regulation on Surface Water Quality for protection of aquatic life 10 QCVN 39:2011/ 11 BTNMT: National technical regulation on Water Quality for irrigated agriculture 12 QCVN 40: 2011/BTNMT: National Technical Regulation on Industrial Wastewater 34 APENDIXES  Picture about research process Figures 1: Trash-shield Figure 2: sedimentation tank 35 Figure 4: Waste water pipes from underground Figure 3: Conditional tank Figure 6: Discharges gate Figure 5: Path of untreated wastewater 36 Figure 8: Ha Lam stream 37