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 Table of contents Abbreviations iv List of tables v List of figures vi Abstracts .vii Acknowledgement viii Introduction CHAPTER I LITERATURE STUDY Status of environmental management in Vientiane 1.1 1.1.1 Introduction of Vientiane 1.1.2 Environmental issues in Vientiane 1.1.3 Situation of pulp and paper mill in Vientiane 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 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 and .35 2.5.2 Reduce of COD value by pH change for sample 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 and 39 3.1.2 Effect of the pH and PAC doseage to the reduction of COD in sample 41 3.2 Investigation of the biological treatment with activated sludge 43 3.2.1 Effect of retention time on COD removal for sample 43 3.2.2 Effect of retention time on COD removal for sample 44 3.2.3 Effect of retention time on COD removal for sample 45 3.3 Primary investigation on the treatment of pulp and paper mill wastewater by the combination of circulatory aerobic and anaerobic system .46 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 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 List of tables Table Wastewater Quality in Vientiane Capital Jan-Dec 2000[2]… Table Industrial Growth in Lao PDR [2]… .6 Table 3.Pollutants in the wastewater in the factory’s ponds[8]… Table Typical efficiencies of aerobic systems [9]… 22 Table Anaerobic degradability of pulp and paper mill wastewater[19]… .23 Table Data of standard curve 30 Table Data of ammonia standard curve 32 Table Data of nitrite standard curve making 33 Table 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 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 Table 22 Data of effection of CSOCA&A to Phosphorus due to times… 53 List of figures Figure Map of Lao PDR… Figure2 Source flowchart from the production line in KPS paper mill in Laos [8]… 10 Figure Process description for pulp and paper mill factory[10] 12 Figure Pollutants from various sources of pulping and papermaking [11] … 15 Figure Diagram of Flocculate w11 27 Figure Diagram of Aerobic system W11 27 Fignure COD standard curve 30 Figure Ammonia standard curve 32 Figure 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 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 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 H 2SO4 acid at pH = 3; and by the coagulation with poly aluminum chloride (PAC) The COD removal from 74.21% of sample and 62.16% of sample 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 adding PAC over mL, the line graph tented to go down However, the trend fluctuated slightly, nearly 1%, so we could consider as a stable trend The optimal dosage of PAC is mL of 10% solution per 100 mL of wastewater, or 2000 mg PAC per liter of wastewater After using PAC with volume of 2.0 mL, COD was decreased to 503.11 mg/L Table 12 Effect of PAC dosage on COD removal for sample COD removal(%) VPAC(mL) COD (mg/L) Removal Efficiency (%) VPAC(mL) COD (mg/L) Removal Efficiency (%) 2140 3.0 506.07 76.35 1.0 566.01 73.55 3.5 506.07 76.35 1.5 515.53 75.90 4.0 518.69 75.76 2.0 503.11 76.49 4.5 512.38 76.05 2.5 506.07 76.35 5.0 515.53 75.91 77 76.5 76 75.5 75 74.5 74 73.5 73 VPAC(mL) Figure 17 Diagram of effect of PAC dosage on COD removal 3.1.2 Effect of the pH and PAC dosage on the reduction of COD in sample 3.1.2.1 Effect of the pH to the reduction of COD The sample had initial black color, pH value of 13.5 and COD value of 161740.36 mg/L Firstly, sample was diluted to the COD value of 6469.61 mg/L This solution was used to investigate the effect of pH on the reduction of COD content in the solution Diluted sulfuric acid solution was added to three wastewater samples to reduce the pH of solution, stirred in 2-3 minutes at 40 rpm and settled for hours The solution was separated into two phases; the liquid phase was taken to determine the COD value The results of experiments are shown in table 13 and figure 18 The diagram shows that, at pH = 2, the COD removal efficiency is the highest and attained 62.16% However, at pH of 3, the COD removal was lower 0.15% (62.01%) than at pH of 2; therefore the pH of was selected for the next experiments Table 13 Effect of pH on COD removal pH COD (mg/L) 2507.62 2448.1 2457.8 61.24 62.16 62.01 COD removal(%) Efficiency (%) 62.5 62 61.5 61 60.5 60 59.5 59 0.5 1.5 p2H 2.5 3.5 Figure 18 Diagram of effect of pH on COD removal 3.1.2.2 Effect of the PAC dosage to the reduction of COD After pretreatment by adjusting the pH to 3, the COD value was 2457.8 mg/L and the sample was taken to the next step of coagulation by PAC The experiments were carried out as follows: six samples were adjusted to the pH of 6, then added 0.5 to 3.0 ml of 10% PAC solution, stirred for 15 minutes at 40 rpm and settled in 30 minutes The results are showed in table 14 and figure 18 The optimal dosage was 2ml of 10% PAC solution Table 14 Effect of coagulant PAC on COD removal VPAC(mL) COD (mg/L) Efficiency (%) 2457.8 0.5 941.17 61.55 1.0 1024.00 58.17 1.5 995.33 59.34 2.0 922.06 62.33 2.5 931.61 61.94 3.0 934.79 61.82 COD removal(%) 64 62 60 58 56 54 52 50 0.5 1.5 VPAC(mL) 2.5 3.5 Figure 19 Diagram of effect of coagulant PAC on COD removal According to the diagram above, when added PAC with the volume of 2mL, the highest COD removal gained is 62.33% Thus, the volume of PAC solution is chosen at 2mL to be the optimal condition for coagulation method When adding PAC over 2mL, the line graph tented to go down However, the trend fluctuated slightly, nearly 1%, so we could consider as a stable trend Similar to sample and 2, the optimal dosage of PAC to the COD removal of sample is 2000mg PAC/ L 3.2 Investigation of the biological treatment with activated sludge 3.2.1 Effect of retention time on COD removal for sample After pretreatment with coagulation process, the COD value of sample was 846.76 mg/L and the value gained after days of BOD or BOD5 was 450.00 mg/L As a result, the ratio BOD/COD was 0.53 This ratio was rather suitable for using aerobic treatment The table 15 below showed the COD removal efficiency versus retention time of treatment Table 15 Data of effect of retention time on COD removal Time (Hour) COD(mg/L) Removal Efficiency (%) Time COD (mg/L) Removal Efficiency (%) 846.76 268.84 68.25 624.57 26.24 244.21 71.16 540.57 36.16 234.30 72.33 303.49 64.16 199.66 76.42 COD removal (%) 90 80 70 60 50 40 30 20 10 0 Time (hours) Figure 20 Diagram of effect of retention time on COD removal The line graph of diagram above indicated the trend of treatment, the COD removal went up during the time of reaction At the time of t = hours the COD value tested was 199.66 mg/L The wastewater sample should go to further treatment 3.2.2 Effect of retention time on COD removal for sample The COD value of sample after coagulation step was 503.11mg/L After days, BOD5 gained the result of 297.00 mg/L The BOD/COD (297 / 503.11) ratio was 0.59; therefore it was suitable for applying aerobic treatment to this sample (according to Rodriguez et al (2007)) The effect of retention time on COD removal of sample is shown in table 16 and figure 21 Table 16 Data of effect of retention time to COD removal Time (hours) COD (mg/L) Removal Efficiency (%) 503.11 468.22 8.05 310.49 39.02 209.54 58.85 121.21 76.19 80.20 84.24 48.66 90 COD removal(%) 100 90 80 70 60 50 40 30 20 10 0 Time (hours) Figure 21 Diagram of effect retention time on COD removal The line graph of diagram above indicated the trend of treatment; COD removal went up during the time remaining reaction After hours, the COD value tested was 48.66 mg/L The color, the COD value and the pH of have met the standard to release to the environment (according to Lao and Vietnam industrial wastewater quality 2005) 3.2.3 Effect of retention time on COD removal for sample In order to compare the COD removal efficiency by activated sludge process with two samples from Laos, the experiments of sample were carried out and the results are shown in table 17 and figure 22 Table 17 Data of effect of aerobic on COD removal COD removal(%) Time ( hours) COD (mg/L) Efficiency (%) Time ( hours) COD (mg/L) Efficiency (%) 922.2 524.55 43.12 884.92 4.04 518.34 43.79 878.7 4.71 437.57 52.55 580.47 37.05 10 418.93 54.57 561.83 39.07 11 363.93 60.63 555.62 39.75 12 338.15 63.33 543.19 41.09 - 100 80 60 40 20 0 10 20 30 40 50 60 time( hours) Figure 22 Diagram of effect of aerobic on COD removal At the time of hours the COD value was 524.55mg/L The wastewater sample should go to further treatment methods 3.3 Primary investigation on the treatment of pulp and paper mill wastewater by the combination of circulatory aerobic and anaerobic system The wastewater sample after pretreatment by pH change and coagulation in the above experiments (3.1.2.2) getting COD value of 922.2mg/L was used to test the treatment efficiency by circulatory aerobic and anaerobic system 60 liters of wastewater were adjusted to pH of 7-8 and pumped to the first column which is filled with porous film The organic compounds were degraded by the microorganisms living in the porous film The analytical samples were taken and determined the values of COD, NH4, NO2-, NO3-, and PO43- 3.3.1 The reduction of COD The results showed that after 57 hours the COD removal was 94.99% which reduced COD value from 922.20 mg/L to 46.2 mg/L The gained COD value was good for outflow standard When comparing aerobic using alone with the circulatory system of combination of aerobic and anaerobic (CSOCA&A), it is clear that, the CSOCA&A gained the higher efficiency (94.99%) than aerobic system (90%) In anaerobic column, without oxygen, the persistent organic chemicals were broken down to other chemicals forms which are then easy to treat by aerobic method Table 18 Data of effect of CSOCA&A on COD removal 24 25 26 28 COD (mg/L) 922.22 915.98 829.01 505.91 487.27 481.06 462.42 Efficiency (%) 4.04 4.71 45.47 47.16 47.83 49.85 Time ( hours) 29 31 46 47 56 57 - COD (mg/L) 462.42 394.07 300.88 288.45 52.45 46.13 - Efficiency (%) 49.85 57.26 67.37 68.72 94.32 94.99 - COD removal(%) Time (hours) 100 90 80 70 60 50 40 30 20 10 0 10 20 30 40 time( hours) Figure 23 Diagram of effect of aerobic to COD 3.3.2 The change of ammonia concentration 50 60 Monitoring the change of ammonia concentration, it was seen that ammonia reduced to 3.02 mg/L after 57 hours treated by CSOCA&A This is suitable for the output standard required Table 19 Data of effect of CSOCA&A to NH4+ due to time Amonia Concentration(mg/L) Time( hour) NH4+concentration(mg/L) Time( hour) NH4+concentration(mg/L) 13.30 28 5.41 11.50 46 3.17 8.23 47 3.12 24 6.69 56 3.16 25 5.73 57 3.02 26 5.54 - 14 12 10 0 10 20 30 40 50 time( hour) Figure 24 Diagram of effect of aerobic to Ammonia 3.3.3 The change of nitrite concentration Nitrite and nitrate concentrations were also measured to determine the amount of nitrogen and how nitrogen compounds work under CSOCA&A Over hours, the diagram reached the highest peak with the value of 12.46 mg/L of nitrite The reduction over 46 hours was 94.6% Table 20 Data of effect of CSOCA&A on NO2- due to time Time(hours) NO2Concentration (mg/L) 9.46 12.09 10.47 24 25 26 28 29 31 4.71 2.62 1.61 1.36 1.17 0.97 46 0.51 Nitrite Concentration(mg/L) 14 12 10 10 20 30 Time( hours) 40 50 Figure 25 Diagram of effect of aerobic on Nitrite concentration 3.3.4 The change of nitrate concentration Nitrate Concentration(mg/L) Over 46 hours the nitrate reduction was 77.4% and the output standard for nitrate was hopeful to release Table 21 Data of effect of CSOCA&A on Nitrate due to time Time(hours) Concentration Nitrate(mg/L) Time(hours) Concentration Nitrate(mg/L) 7.89 26 2.10 4.31 28 2.06 20 Ti me (hour) 30 2.42 29 2.01 24 2.13 31 2.07 25 2.23 46 1.78 0 10 40 Figure 26 Diagram of effect of aerobic on Nitrate 3.3.5 The change of phosphorus concentration 50 The amount of phosphorus over 46 hours was reduced from 23.10 mg/L to 9.3 mg/L This concentration has met the standard to release to the environment (wastewater discharge standard 2005 VN) Table 22 Data of effect of CSOCA&A on phosphorus due to time 24 25 Phosphorus Concentration (mg/L) 23.10 21.74 17.71 14.37 14.37 Time (hours) 26 28 29 31 46 Phosphorus Concentration (mg/L) 14.21 14.07 13.39 13.15 9.31 Concentration(mg/L) Phosphorus Time (hours) 25 20 15 10 0 10 20 30 40 50 Time( hours) Figure 27 Diagram of effect of aerobic on phosphorus From the results of COD values and sum amount of nitrogen and phosphorus concentration it is possible to conclude that the quality of effluent after treatment is suitable to release into the environment (according to Lao and Vietnam industrial wastewater quality standard 2005) 3.3.6 A proposed model for pulp and paper mill wastewater treatment for Vientiane factories From the experimental results above, a model for pulp and paper mill wastewater treatment of Vientiane factories was proposed as in figure 28 Firstly, pulp and paper mill wastewater is equalized and diluted to suitable conditions, then the pH of solution is adjusted to by diluted sulfuric acid The sludge is converted to solid form for further treatment The liquid phase is adjusted to the pH of and coagulated by 10% PAC solution to remove suspended matters and also reduce COD The sludge of this stage also goes to solid form for further treatment and the liquid phase comes to the next treatment step Finally, all so used above wastewater samples were pumped to combined anaerobic and aerobic system Pulp and paper mill wastewate r H2 SO4 Equalization Precipitation (pH=3) Sludge Sludge press Wastewater Solid waste Coagulation (pH=6) PAC Sludge press Solid waste Wastewater Aerobic Anaerobic Figure 28 A proposed models for pulp and paper mill wastewater treatment system Discharge Vientiane ctories for Conclusions During the time of doing master thesis at Lab of Environmental Chemistry, Hanoi University of Science I have some conclusions as follows: The current environmental issues in Vientiane in general and the pulp and paper mill wastewater in particularly were evaluated It is obvious that the environmental issues in Vientiane are becoming serious and urgently require the attention of the government as well as relative agencies The selected analytical methods are suitable for monitoring the value of COD, BOD and NH4+, NO2-, NO3-, PO43- contents in pulp and paper mill wastewater in Vientiane The application of physicochemical method to pretreat pulp and paper mill wastewater by adjusting the pH value to and coagulating high suspended solids with 10% PAC solution is suitable for tissues paper factory in Vientiane The preliminary results of using the combined Aerobic and Anaerobic circulatory system for the pretreatment of pulp and paper mill wastewater have shown that the combined system gets higher efficiency of COD removal (94.99%) and than the aerobic one (90%) A model for the wastewater management of pulp and paper mill industry in Vientiane is proposed and will be evaluated for further application References [1] Environmental protection law (1999), Lao people’s democratic republic, 20, 10- 16 [2] Lao PDR Environment Monitoring (2005), 67, viii - ix [3] National water resources profile (June 2008), Department of Water Resources and Environment Administration (WREA), 81, 47- 66 [4] Mekong River Commission (2010), The Mekong River Report Card On Water Quality, Assessment of potential Human Impacts on 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industry... treatment of pulp and paper mill wastewater by the combination of circulatory aerobic and anaerobic system The wastewater sample after pretreatment by pH change and coagulation in the above experiments