Tài liệu Investigation on a combination of chemical and biological methods for the treatment of pulp and paper mill wastewater in Vientiane

TECHNICAL UNIVERSITY OF DRESDEN VNU UNIVERSITY OF SCIENCE Vienglasy Mangnomek INVESTIGATION ON A COMBINATION OF CHEMICAL AND BIOLOGICAL METHODS FOR THE TREATMENT OF PULP AND PAPER MILL WASTEWATER IN VIENTIANE MASTER THESIS Hanoi, November 2011 i TECHNICAL UNIVERSITY OF DRESDEN VNU UNIVERSITY OF SCIENCE Vienglasy Mangnomek INVESTIGATION ON A COMBINATION OF CHEMICAL AND BIOLOGICAL METHODS FOR THE TREATMENT OF PULP AND PAPER MILL WASTEWATER IN VIENTIANE Major: Waste Management and Contaminated Site Treatment MASTER THESIS SUPERVISOR: ASSOC. PROF. DR. BUI DUY CAM ASSOC. PROF. DR. DO QUANG TRUNG Hanoi, November 2011 ii Table of contents Abbreviations ......................................................................................................... iv List of tables ........................................................................................................... v List of figures .......................................................................................................... vi Abstracts ................................................................................................................. vii Acknowledgement ................................................................................................. viii Introduction .............................................................................................................. 1 CHAPTER I. LITERATURE STUDY .................................................................... 2 1.1.Status of environmental management in Vientiane ........................................... 2 1.1.1. Introduction of Vientiane ............................................................................. ..2 1.1.2. Environmental issues in Vientiane ................................................................ 3 1.1.3. Situation of pulp and paper mill in Vientiane ................................................ 7 1.2. The pulp and paper mill wastewater treatment technologies .......................... 11 1.2.1. Pulp and paper mill production .................................................................... 11 1.2.2. Sources of pollution in the production of pulp and paper mill .................... 12 1.3. Some methods commonly using to treat with the wastewater ........................ 15 1.3.1. Physicochemical treatment ........................................................................... 15 1.3.2. Membrane filtration..................................................................................... 19 1.3.3. Biological treatment .................................................................................... 21 CHAPTER II. EXPERIMENT ............................................................................... 25 2.1. Research objective........................................................................................... 25 2.2. Equipment and Chemicals…………………..……………………………… 26 iii 2.2.1. Equipments ................................................................................................... 26 2.2.2. Chemicals ..................................................................................................... 26 2.3. Analitycal methods in the study ...................................................................... 28 2.3.1. Determination of Chemical Oxygen Demand .............................................. 28 2.3.2. Determination of Biochemical Oxygen Demand………………………..…29 2.3.3. Analysis of Ammonia content ...................................................................... 30 2.3.4. Analysis of Nitrite and Nitrate ..................................................................... 31 2.3.5. Procedure for the determination of Phosphate ............................................. 33 2.4. Preparation of Pulp and paper mill samples .................................................... 34 2.5. Physicochemical method for the pretreatment of pulp and paper mill wastewater……………………………………………………………………… 35 2.5.1. Coagulation experiments for sample 1 and 2 .............................................. 35 2.5.2. Reduce of COD value by pH change for sample 3 ...................................... 35 2.6. Removal of COD in pulp and paper mill wastewater by combinated Aerobic and Anaerobic circulatory System ……………………………………………….35 2.7. Material filling in column ............................................................................... 36 CHAPTER III. RESULTS AND DISCUSSION ................................................... 39 3.1. Pretreatment of pulp and paper mill wastewater by physicochemical methods39 3.1.1. Coagulation experiments for sample 1 and 2 ............................................... 39 3.1.2. Effect of the pH and PAC doseage to the reduction of COD in sample 3 ... 41 3.2. Investigation of the biological treatment with activated sludge ..................... 43 3.2.1. Effect of retention time on COD removal for sample 1 ............................... 43 3.2.2. Effect of retention time on COD removal for sample 2…………………...44 3.2.3. Effect of retention time on COD removal for sample 3 ………….……….45 3.3. Primary investigation on the treatment of pulp and paper mill wastewater by the combination of circulatory aerobic and anaerobic system ............................... 46 iv 3.3.1. The reduction of COD .................................................................................. 47 3.3.2. The change of Ammonia .............................................................................. 48 3.3.3. The change of Nitrite.................................................................................... 49 3.3.4. The change of Nitrate……………………………………………………...50 3.3.5. The change of Phosphrus ............................................................................. 51 3.3.6. A proposed model for pulp and paper mill wastewater treatment for Vientaine factories .................................................................................................. 52 Conclusions ............................................................................................................ 54 References ……………………………………………………………………….55 v Abbreviations AC Anaerobic Contact process AF Anaerobic Filter AOX Adsorbable organic halogens BOD Biological Oxygen Demand COD Chemical Oxygen Demand CSOCA&A Circulatory system of combination of Aerobic and Anaerobic DO Dissolved Oxygen MLSS Mixed Liquor Suspended Solids PAC Poly Aluminum Chloride TSS Total suspended solids vi List of tables Table 1. Wastewater Quality in Vientiane Capital Jan-Dec 2000[2]…………..…5 Table 2. Industrial Growth in Lao PDR [2]…………………………………..……6 Table 3.Pollutants in the wastewater in the factory’s ponds[8]…………………..8 Table 4. Typical efficiencies of aerobic systems [9]……………………………..22 Table 5. Anaerobic degradability of pulp and paper mill wastewater[19]…...…..23 Table 6. Data of standard curve..............................................................................30 Table 7. Data of ammonia standard curve……………………………………….32 Table 8. Data of nitrite standard curve making…………………………………..33 Table 9. Data of nitrate standard curve………………………………………..…34 Table 10. Data of phosphorus standard curve…………………………………....35 Table 11. Effect of PAC dosage to COD reduction for sample 1…………….….41 Table 12. Effection of coagulant PAC to COD removal ……………………...…42 Table 13. Effection of pH changed to COD removal……………………………44 Table 14. Effection of coagulant PAC to COD removal ………………………...44 Table 15. Data of effection of aerobic to COD removal ………………………...46 Table 16. Data of effection of aerobic to COD removal…………………………47 Table 17. Data of effection of aerobic to COD removal…………………………48 Table 18. Data of effection of CSOCA&A to COD removal…………………….49 Table 19. Data of effection of CSOCA&A to NH4+ due to times………………..51 Table 20. Data of effection of CSOCA&A to NO22- due to times………………..51 Table 21. Data of effection of CSOCA&A to Nitrate due to times………………52 vii Table 22. Data of effection of CSOCA&A to Phosphorus due to times………....53 List of figures Figure 1. Map of Lao PDR…………………………………………………...….2 Figure2 . Source flowchart from the production line in KPS paper mill in Laos [8]………………………………………………………………….………..10 Figure 3. Process description for pulp and paper mill factory[10]………….… 12 Figure 4. Pollutants from various sources of pulping and papermaking [11]…………………………………………………………………………….….15 Figure 5. Diagram of Flocculate w11…………………………………………....27 Figure 6. Diagram of Aerobic system W11………………………………………27 Fignure 7. COD standard curve..............................................................................30 Figure 8. Ammonia standard curve…………………………………….………....32 Figure 9. Nitrite standard curve………………………………………………..…33 Figure 10. Nitrate standard curve………………………………………….……..34 Figure 11. Phosphorus standard curve……………………….…………….…….35 Figure12. Diagram of combining Anaerobic and Aerobic system…………..…..38 Figure 13 : Surface of porous material…………………………………………...39 Figure14. Microorganism layer………………………………………………..…38 Figure 15. Membrane of porous material after three times circularly pumping water containing nutrient………………………………………………………....38 Figure 16. Diagram of effection of PAC dosage to COD removal…………..…38 Figure 17 Diagram of effection of coagulant PAC to COD removal…………….41 Figure 18. Diagram of effection of pH changed to COD removal….....................42 Figure 19. Diagram of effection of coagulant PAC to COD removal…………....43 viii Figure 20. Diagram of effection of aerobic to COD removal…………….…..…..44 Figure 21. Diagram of effection of aerobic to COD removal……………….……45 Figure 22. Diagram of effection of aerobic to COD removal……………….……46 Figure 23. Diagram of effection of aerobic to COD…………………………..…48 Figure 24. Diagram of effection of aerobic to Ammonia………………….……..49 Figure 25. Diagram of effection of aerobic to Nitrite…………………………....50 Figure 26. Diagram of effection of aerobic to Nitrate……………………………51 Figure 27. Diagram of effection of aerobic to Phosphrus……………………..…51 Figure 28 : A purposed model wastewater treatment process using activated sludge…………………………………………………………………….…….. 54 ix Abstract Lao PDR is a country rich in natural resources and its water resources are vital in providing the basic needs for its people, socio-economic development of the country. The scale and extent of environment problems in the urban areas of Vientiane is relatively small compared to other cities in the region due to its relatively small size and population, low population density, and relatively low level of industrial activity. However, there are some water pollution problems in major urban areas caused by various water uses by communities (households, hotels, hospitals and entertainment centers). In addition, the actions of the agricultural and industrial sectors have resulted in water pollution, including mineral exploitation, pulp and paper mills factories and hydropower generation. Therefore, in accordance with the Millennium Development Goals, the government set targets in order to improve the local people’s access to safe drinking water by the years 2015. For in Vientiane is one looking for manage methods for treatment wastewater discharges. In this study, the situation of environmental pollution in Vientiane in general and from the pulp and paper mill wastewater in particularly was evaluated. These are recognized that the environmental issues in Vientiane having problem. The wastewater samples were collected from pulp and paper mill factories in Laos and Vietnam for the experiments in laboratory of Environmental Chemistry, Hanoi University of Science. The physicochemical and biological methods for the treatment of wastewater were investigated. The results shown that, the pulp and paper mill wastewater can be pretreated by the reduction of pH with dilute H2SO4 acid at pH = 3; and by the coagulation with poly aluminum chloride (PAC). The COD removal from 74.21% of sample 1 and 62.16% of sample 3. Then the wastewater samples can be treated by using combined aerobic and anaerobic system with efficiency of COD removal 94.99% of anaerobic and 90% for aerobic x alone the reduction of the COD. For the wastewater sample 2 (taken from tissues paper factory in Vientiane), the coagulation and follwing by biological treatment with activated sludge are suitable methods. Acknowledgement The time of doing thesis in HUS is very special to me. It is the time for to harvest my knowledge and to meet interesting Vietnamese friends. Thank you for accepting the long hours, weekends and holidays I have spent working, for taking good care of me during this time and for pushing just hard enough to make sure I finally completed my thesis. I would like to express my utmost appreciation and thanks to Prof. Dr. Bui Duy Cam and Assoc. Prof. Dr. Do Quang Trung for them valuable guidance, endurance, encouragement and support throughout this research. Several people have given me assistance with the work in this thesis. I thank Mr. Mai Xuan Thang and the late Mrs. Hoang Thu Trang for assistance in the laboratory, and for assistance with the experimental set up. Special thanks are extending to Prof. Bernd Bilitewski, Prof. Nguyen Thi Diem Trang for your role in this circumstance. Finally, the generous financial support by the DAAD. Also the support of the Hanoi University of Science and Dresden University of Technology is acknowledged. xi Introduction Water are vital element for both of demand’s people and socio-economic development of the country. As the population has grown, demand is also incresed and has had to travel further in search of good quality water, marginal and polluted sources have started being tapped. Therefore, investigation of the water quality in Vientaine is very important because Laos is one of developing country looking for the suitable system for wastewater treatment. The amount and characteristics of the pulp and paper mill wastewater depend highly on raw materials and processing conditions. The pulp and paper mill wastewater may cause oxygen deficiency, acute or chronic toxicity, mutagenicity in recipient water bodies. In some countries the discharge standands for pulp and paper mills include conventional biochemical oxygen demand (BOD), chemical oxygen demand (COD) and suspended solide also nutrients and organochlorine compounds expressed as adsorbable organic halide (AOX). There are number of technique to reduce the discharged pulp and paper mill wastewater. The mechanical treatment method with primary clarifies is usually applied to remove the wastewater solids and the organic load while dissolved organics are removed in aerated lagoons and/or activated sludge system, the most commonly applied biological processes. However, these processes are expensive and none is consider to be economically viable when this is done as standard process. Biological method have been found to be more effective and eco-friendly since they are capable of degrading not only lignin but also chloro-oganics contributing to AOX. In my study, the overview of the wastewater treatment technologies for pulp and paper mill factories are conducted for the purpose of applying to Laos and both methods of chemical and biological ones are investigated for the treatment of pulp and paper mill wastewater in Vientiane. The real samples from Laos, Vietnam pulp and paper mill wastewater have been tested. CHAPTER I. LITERATURE STUDY 1.1. Status of environmental management in Vientiane 1.1.1. Introduction of Vientiane The Lao People’s Democratic Republic (Lao PDR) is near to Myanmar, Cambodia, the People’s Republic of China , Thailand, and Viet Nam. The total land area of the country is 236,800 square kilometers (km2) with a largely mountainous xii topography. The capital, Vientiane (See picture 1 - Map of Lao PDR), however lies on a plain. The country is bordered on the west by the Mekong River, making the river an important artery for transportation, communications, and trade with other countries sharing tributaries of the Mekong River. Set in the heart of Vientiane, Laos from the north latitude 17 45'50 - 22'38 18 09'37 5'40 and 102 - 103 east longitude and the natural area 3.920 km2. Vientiane is the 9 District: Chanthabuly, Sikottabong, Xaysettha, Sisattanak, Naxaythong, Saythany, Hatsaiphong, Saengthong Phakngum area and population density level of economic development of each district is different. Entire Vientiane has 500 villages, of which urban area accounts for 76% of villages, rural areas account for only 24%. Population Vientiane has highest level of culture, a spirit of hard-working, patriotic tradition and unyielding will to revolution [1]. Figure 1. Map of Lao PDR Lao PDR is a rich country in natural resources and its water resources are vital in providing the basic needs for its people, for socio-economic development of the country and for the ecological systems. The availability of water resources has created favourable conditions for the Laos and for the socio-economic development of the country, but it is essential that the country protects and manages water and water resources in a sustainable way. Despite this a scarcity of water for both drinking and irrigation purposes is common in some provinces particularly in remote areas. As the population has grown, and has had to travel further in search of good quality water, marginal and polluted sources have started being tapped. The major surface water resources are from rivers, streams and via xiii gravity fed systems and through the protection of spring water. Groundwater is sourced from boreholes with hand pumps and from protected dug wells. Rainwater is also harvested in reservoirs or tanks and individual collection jars [2]. 1.1.2. Environmental issues in Vientiane The scale and extent of environment problems in the urban areas of Vientiane is relatively small compared to other cities in the region due to its relatively small size and population, low population density, and relatively low level of industrial activity. However, despite recent investments, there remain few systems in place to ensure that all, and in particular the poor, benefit from environmental improvements and environmental problems can be controlled in the future (EPL, 1999). The Water Quality Laboratory of the Ministry of Agriculture and Forestry reported that the quality of water in Lao PDR has generally been good according to the past 15 years of monitoring data. However, there are some water pollution problems in major urban areas caused by various water used by communities (households, hotels, hospitals and entertainment centers). In addition, the actions of the agricultural and industrial sectors have resulted in water pollution, including mineral exploitation and hydropower generation. The degradation of water bodies and catchments due to sedimentation, land erosion and drying out continues [3],[4]. Poverty and Access to Clean Water and Sanitation throughout Lao PDR, there is a high incidence of diarrhea and dysentery caused in part by inadequate water supply, poor sanitation and sewerage, and absence of wastewater treatment facilities. With rising populations in urban and upland areas, water pollution is getting worse. Also the poorest districts have less than half the national average of daily water use, due to less access to water for either personal use or irrigation purposes. For this reason, various challenges exist in the field of water quality monitoring, modeling and other technical strengthening; however, there is a need for a more systematic approach. Currently, some ministries and departments are responsible for water resources independently carry out water quality management, such as water quality monitoring and analysis. The Water Resources and Environment Administration (WREA) needs to play an active and leading role in water quality management in line with its mandate on water resources and environment. Also, stronger water quality policies and strategies are needed to deal with the rapid development of water resources and possible impacts on water quality and ecosystems. The updating of the National Water Resources Policy and Strategy and the possible review of the Law on Water and Water Resources will provide the opportunity for this policy and strategy development. Reviewing and setting coordinated water xiv quality monitoring standards and procedures need to be considered. Furthermore, capacity and systematic coordination procedures and mechanisms among agencies responsible for overall and sectored water quality monitoring and management need to be built [4]. Environmental measures used in solid waste management in Vientiane, including market and non-market instruments as well as public education and training programmers (moral suasion). Under pressure from rapid demographic growth, socio-economic development and urbanization, however, water quality is deteriorating. In urban areas, pollutants from roads, commercial and industrial areas, and private properties wash into drains and watercourses. Litter, dust and dirt, oil and grease, particles of rubber compounds from tires, particles of metal, glass and plastic from vehicles, and lead are common pollutants. Residential properties and open spaces contribute sediments and nutrients [5]. Urban drains also act as secondary sewers carrying industrial discharges, septic tank seepage and overflows in wet weather. It is common practice to dispose of sewage to surface drains and drainage channels. As a result, wastewater is invariably contaminated with faecal matter from latrines and coli-form septic tank effluent. Wastewater monitoring was conducted in Vientiane in 2002. Samples were collected from 15 monitoring stations. Parameters were measured: pH, conductivity, alkalinity, BOD5, COD and temperature. The monitoring results showed that the average of all parameters were within acceptable limits, although certain samples exceeded standards for Class A wastewater discharge, issued by the Government in 1994 [2]. Table 1. Wastewater Quality in Vientiane Capital Jan-Dec 2000 [2] Parameters Unit pH Range of Avg Results Standard 6.38-8.44 7.34 6 – 9.5 Conductivity us/cm 110 - 782 362.62 Alkalinity mg/l 57 – 250 (CaCo3) 175.56 BOD5 mg/l 5 – 35 (O2) 14.09 < 20 COD mg/l 70 – 200 (O2) 115.93 < 120 12.2 - 30 24.42 Temperature 0 C Lao PDR has taken significant step to ensure that the country’s environment and natural resources, particularly the forests and use are sustainable management. Since xv 1993, the institutional framework has been established and followed up by a place of legal framework for instances: Environmental law, land law, forestry law, water and water resources law, and others [3]. However, the growing number of industries has increased the risk of pollution. The larger mills and industries of concern in Lao PDR are pulp and paper, timber, food processing and garment manufacturing. Most of these have only limited wastewater treatment systems for reducing waste concentrations and loads in the final effluents to waterways. Likewise, the increasingly large number of smaller industries also produces an increasing risk of pollution. There has been an increase in the output of in the industrial sector from 8 percent of GDP in 1999 to 11.3 percent in 2003. The total number of industries has grown nearly four-fold from 1994 to 2003 (Table 2). Therefore, in accordance with the Millennium Development Goals, the government set targets in oder to improve the local people’s access to safe drinking water by the years 2015. Table 2. Industrial Growth in Lao PDR [2] Large(>100 employees) Medium(10-100 employees) Small(<10 employees) Total 1994 80 343 5.523 5.946 1995 89 363 10.374 10.826 1996 112 408 14.134 14.654 1997 119 437 15.375 15.931 1998 99 462 15.953 16.514 1999 94 493 19.806 20.393 2000 95 512 20.962 21.569 2001 116 542 22.916 23.574 2002 112 604 24.026 24.742 2003 119 614 24.874 25.607 For this reason, the government set targets in the Socio-Economic Development Strategy up to the year 2020 for the five years plans. For the National Growth and Poverty Eradication Strategy, the National Environment Strategy up to the year 2020 and the Action Plan 2006–2010 highlight the importance of the sustainable use and management of natural resources, specifically water. Moreover, the Environment Protection Law (EPL), the Water and Water Resources Law and the regulation on wastewater discharge forbid any water pollution and propose that the personal sector be responsible for the environmental damage and the related social and economic effects that result from their industrial activities, specifically from wastewater and air emissions. xvi The Government’s increasing focus on the importance of the private sector, in particular small and medium-sized enterprises (SMEs), is commendable. It needs, however, more strongly emphasize the importance of export orientation and move away from import substitution by various means of protection, a policy that most countries in the world, often after having experienced costly mistakes, have abandoned [6]. Finally, in according by the presentment of the Minister of Industry and Commerce, in 2005 has regulation issued of the main condition on the industrial factories [7] are follows : a) To prohibit discharging directly or indirectly into public water that may have adverse impacts on ecology of water body, health of people or use of water, b) To require getting approval on wastewater treatment system before starting construction of factories from Director of Industry Department of the Ministry or Province as well as submit a treatment approach, waste management system plan. c) To rein stalling wastewater treatment system, volume measurement equipment, and other necessary facilities for monitoring, and sample analysis, d) To require frequently monitoring monitoring and analyzing the wastewater, and report the analysis results to Director of Industry Department of the Ministry or Province, e) To require recording the daily use of chemical substances and explaining the purpose of their use. 1.1.3. Situation of pulp and paper mill in Vientiane There are six pulp and paper mills in which five factory located in Vientiane Capital City and one in Vientiane Province. For pulp and paper mills factories were processed as to less than 200 tones of output per day, and small scale have to compared with in near countries. KPS Paper mill is one factory in Vientiane Capital, this is factory using water from stored in three underground buffer tanks and from supply water to the manufacture process. The raw material processed is bamboo, which is reduced to chips by a cutter. For delignification, the chips are immersed in a sequence of five tanks containing caustic soda, an alkaline solution. Sulfur is also added. After concentration, the chips are removed manually and placed in a grinder. The pulp produced in the grinder station is mixed with recycled paper (which includes rejected and surplus paper) in a water tank. The flow chart of the production line is shown in figure 2. After screening, the mixture is transferred into the paper-making machines. The finished paper is then xvii colored, cut and stamped before being packed for export. The plant uses sodium carbonate (Na2CO3) or sodium hydroxide (NaOH) (or cold soda) mixed with sulfur (S) amount 1,688 tones/year to deepen of the paper it manufactures and exports. In the factory is general discharged effluent water amount 600 m3/day. Wastewater discharges from the factory has not installed any effluent treatment system even though it is pre-determined in the factory’s project document. Therefore, the wastewater from the factory are two types of first black wastewater from the delignification stage of the pulping process, and second white wastewater from the paper making process. The black wastewater is discharged directly addicted to the local steam and a series of ponds in the factory through two separated pipeline systems according [8] is shown in table1. xviii Table 3.Pollutants in the wastewater in the factory’s ponds [8] Parameter Unit White wastewater discharged Black wastewater discharged Maximum allowed (industrial wastewater Discharge regulation 326/MIH ) pH - 10 9.23 6-9.5 Color CU 160 14,000 - BOD5 mg/l 135 475 90 COD mg/l 3,238 7,040 - TSS mg/l 292 6,435 60 TDS mg/l 2,572 15,548 3,500 Cl- mg/l 404.9 1,410 500 Bamboo Bamboo surplue Dust Chipping NaOH + water Pulping Process Water Delignification Black wastewater Grinding Solid waste Mixing Screening xix Recycling Wastewater Figure 2 . Source flowchart from the production line in KPS paper mill in Laos [8] 1.2. The pulp and paper mill wastewater treatment technologies 1.2.1. Pulp and paper mill production The characteristics of the wastewater generated from various processes of the pulp and paper industry depend upon the type of process, type of the wood materials, process technology applied, management practices, internal recirculation of the effluent for recovery, and the amount of water to be used in the particular process. That the load of chlorinated phenols and acids in the wastewaters of hardwood kraft mill was three to eight times lower than it was in the soft wood kraft mill. The pulping and paper making process is prominent compound in the produce pollutants at various stages. The wastewater pollution load from individual pulping and papermaking process. There have 1. Mechanical forces in the presence of water (mechanical pulping). The process involves passing a block of wood, usually debarked, through a rotating grindstone where the fires are stripped of and suspended in water. 2. Chemical pulping which utilizes significantly large amounts of chemicals to break down the wood in the presence of heat and pressure. The spent liquor is then either recycled or disposed of by burning for heat recovery. 3. A combination of the two (chemical thermo-mechanical pulping). The wood is first partially softened by chemicals and the remainder of the pulping proceeds with xx