3 TABLE OF CONTENTS TABLE OF CONTENTS 1 ABBREVIATIONS 3 LIST OF FIGURES 4 LIST OF TABLES 5 LIST OF DIAGRAMS / FLOWCHARTS 5 ACKNOWLEDMENTS 6 INTRODUCTION 7 CHAPTER 1- OVERVIEW 10 1.1. Water Sources and Quality Requirements for Drinking Purpose 10 1.1.1. Water sources: 10 1.1.2. Groundwater Quality Requirements for Drinking Purpose 10 1.2. Current Status of Ammonia and Arsenic Contamination of Groundwater 11 1.2.1. Arsenic Contamination of Groundwater: 11 1.2.2. Ammonia Contamination of Groundwater: 16 1.3. Treatment Technologies 17 1.3.1. Arsenic Removal Treatment: 17 1.3.2. Ammonia Removal from Groundwater 19 1.4. Phytofiltration Systems 21 1.4.1. Characteristics of Phytofiltration Systems 21 1.4.2. Principles of Phytofiltration Systems 23 CHAPTER 2 - MATERIALS AND METHODS 28 2.1. Plant Selection: 28 2.2. Soil Selection for Rooting Media: 29 2.3. Setup and Operation of Phytofiltration Systems: 29 2.3.1. Plant Cultivation: 29 4 2.3.2. Operation: 29 2.3.3. Preparation of Ammonia and Arsenic Solutions 31 2.4. Sampling: 31 2.5. Chemical analysis of samples [APHS, 1970]: 31 2.5.1. pH-value measurement 31 2.5.2. Alkalinity determination 31 2.5.3. Ammonia-nitrogen analysis 32 2.5.4. Nitrite-nitrogen analysis 34 2.5.5. Nitrate-nitrogen analysis 36 2.5.6. Arsenic analysis 37 CHAPTER 3 - RESULTS AND DISCUSSIONS 40 3.1. Biomass Accretion of Cattails (Typha spp.) 40 3.2. Arsenic Removal Effectiveness 42 3.3. Ammonia Removal Effectiveness 44 3.3.1. Ammonium-Nitrogen: 44 3.3.2. Nitrite-Nitrogen: 48 3.3.3. Nitrate-Nitrogen: 49 CONCLUSIONS 51 RECOMMENDATION AND PROSPECT 53 REFERENCES 56 APPENDIX 61 5 ABBREVIATION APHA American Public Health Association ATSDR Agency for Toxic Substances and Disease Registry CETASD Center for Environmental Technology and Sustainable Development FAO Food and Agriculture Organization HUS Hanoi University of Science MCL Maximum Concentration Limit MONRE Ministry of Natural Resource and Environment NRC National Research Council TCVN The Vietnamese Standard US EPA The United Stated Environmental Protection Agency WEPA Water Environment Partnership in Asia WHO World Health Organization 6 LIST OF FIGURES Figure 1.1 Tentative risk map of arsenic concentrations in groundwater of the Red River Delta 13 Figure 1.2 Expressions of the black foot disease 15 Figure 1.3 Situation of ammonia contamination of groundwater in Hanoi City 16 Figure 1.4 Arsenic Removal Mechanisms in a Phytofiltration System 25 Figure 2.1 Cattails (Typha spp.) 28 Figure 2.2 Cross section of an phytofiltration system with cattails (Typha spp.) cultivation. 30 Figure 3.1 Biomass accretion of cattails after periods of transplanting time 40 Figure 3.2 Root accretion of cattails after periods of transplanting time 41 Figure 3.3 Loading rates on arsenic 42 Figure 3.4 [As] in outflows after periods of treatment time 43 Figure 3.5 Loading rates on ammonia (mg/d) 45 Figure 3.6 [NH 4 + -N] in inflows and outflows after periods of treatment time 47 Figure 3.7 [NO 2 - -N] in outflows after periods of treatment time 49 Figure 3.8 [NO 3 - -N] in outflows after periods of treatment time 50 Figure 5.1 Sequentially assembled phytofiltration systems with cattails (Typha spp.) cultivation. 54 Figure 8.1 Distribution of documented world problems with arsenic in groundwater in major aquifers as well as water and environmental problems related to mining and geothermal sources. 61 Figure 8.2 Evaluation of simultaneous removal of arsenic and ammonia via hydroponically transplanted plants 64 7 LIST OF TABLES Table 1.1 MCL values for arsenic in drinking water 10 Table 1.2 Average arsenic concentrations and ranges in sample collected in rural districts in the Red River Delta in 2001 13 Table 1.3 Average arsenic concentrations and ranges in sample collected in the Mekong Delta on July, 2004 (n = 112) 14 Table 1.4 Average NH 4 + -N and NO 2 - -N concentrations and ranges in samples collected in 2004 in the Mekong River Delta 17 Table 1.5 The seven states of oxidation in which nitrogen can exist 19 Table 2.1 Initial concentrations of ammonia and arsenic in inflows 31 Table 2.2 Daily-taken volumes of outflow samples 31 Table 3.1 Front accretion of cattails after periods of transplanting time (n=6) 41 Table 8.1 Classification of nitrogen compounds pollution levels in groundwater in general 61 Table 8.2 Major arsenic minerals occurring in nature 62 Table 8.3 Ammonium-Nitrogen Concentrations in several rivers in the North of Vietnam (in 2004) 33 Table 8.4 Values of K a (Ionization constant in the ammonia and ammonium equilibrium) dependent on Temperature 33 Table 8.5 Loading rates on arsenic and ammonia of some plants transplanted hydroponically in arsenic- and ammonia- contaminated water 64 Table 8.6 Experimental Results 65 LIST OF DIAGRAMS / FLOWCHARTS Flowchart 5.1 Potential applications of phytofiltration for arsenic- contaminated soil and water 55 9 INTRODUCTION Groundwater in Vietnam is abundant; however, it is often polluted by different contaminants, especially by arsenic and ammonia [WB, 2002]. The frequency of ammonia-contaminated groundwater demonstration in the Red River Delta areas is approximately 80% - 90% with average ammonia concentrations ranging from 10 mg/L – 30 mg/L [Le Van Cat, Tran Mai Phuong, 2005]. In the Mekong River Delta, ammonia contamination of groundwater is also alarming with average ammonia concentrations ranging from 0.1 - 35 mg/L [M. Berg, 2006]. Ammonia does not directly cause poisoning, but unfortunately, its transformed products (such as nitrite NO 2 - , nitrate NO 3 - ) can cause health risks to human beings [US EPA, 2000]. Besides, groundwater in Vietnam is significantly polluted by arsenic [WB, 2002]. The levels of arsenic contamination were examined and varied from 1 µg/L to 3050 µg/L (48% above 50 µg/L and 20% above 150 µg/L) in groundwater samples from domestic shallow tube-wells in rural areas in the Red River Delta. Particularly, of which, the groundwater used directly as drinking water source had an average concentration of 430 µg/L in several highly affected rural areas [Tran Hong Con, 2006]. In the Mekong River Delta, arsenic concentrations in groundwater are also high in range from 1 µg/L to 845 µg/L [M. Berg et al., 2006] Actually, such high arsenic- and ammonia-contaminated groundwater indicates that millions of people, especially who are living in the Red River Delta and in the Mekong River Delta daily consuming untreated groundwater, might be at high considerable health risks of poisoning caused by such contaminated groundwater. Treatment technologies for arsenic and/or ammonia removal from contaminated groundwater have been paid much attention and concern. There are several current treatment technologies for ammonia removal from groundwater such as Breakpoint Chlorination, Ion Exchange by Clinoptilolite, Air-stripping [Le Van Cat, 2007]. Main methodologies for arsenic removal include Precipitation, Adsorption, Ion 10 Exchange by Activated γ-Al 2 O 3 [US EPA, 2000]. However, selection of an optimal treatment technology depends on both objective and subjective factors, for example, contaminant contents, economic conditions, treatment scales, availability While precipitation is the most common among such methods, the disadvantage is that it only reduces the dissolved metal concentration to the solubility product level, which is frequently out of compliance with rigorous discharge permit standards and thus requires additional cleaning stages. These aforementioned techniques are all generally expensive and might possibly generate by-products dangerous to human health [US EPA, 2000]. Regarding to rural areas conditions, the priority factors which should be much taken into account are costs and treatment scales. Applications of these technologies for small-scale treatments are certainly more difficult in comparison to those for large-scales in point of views of financial problems, operation and maintenance conditions. In Vietnam, several studies on removal of arsenic and ammonia from contaminated groundwater have been researched and implemented in recent years. However, applications of the above-mentioned technologies often faces difficulties and disadvantages such as high costs, complicated operation and maintenance skills In addition, each of these treatment technologies can be compatible for partially removing one contaminant. Thus, simultaneous removal of contaminants requires a series of sophisticatedly combined treatment systems. An optimal treatment technology which can be broadly applied in rural areas must be considered in terms of low cost, small-scale treatment, simple operation and maintenance Moreover, requirements of simultaneous removal of both arsenic and ammonia should necessarily be taken into account. Phytofiltration system, a plant-based technology for the removal of toxic contaminants from soil and water, has been receiving renewed attention. A great deal of research in decades that plants have the genetic potential to remove many toxic contaminants from water and soil [R.L. Chaney et al., 2000]. Plants can 11 uptake nutrients for their biomass development and growth. Moreover, plants can transport oxygen from the air through their leaves, their shoots and finally to their root-zones for aerobic microorganisms to carry out nitrification and denitrification, with presence of ammonia as a preferable nutrient source. Ammonia will be transformed to gaseous nitrogen (non-toxic) and to escape to the air. In addition, plants have metals-accumulating ability to build their own cellular matters via uptake process. Consequently, arsenic and ammonia will be removed from groundwater after periods of time. Phytofiltration has been proposed as a cost-effective, environmental-friendly alternative technology. A number of plants have been identified for the phytofiltration, and some have been used in practical applications. In this study, cattails (Typha spp.) were chosen as a model plant for the phytofiltration systems because of its high arsenic-accumulating ability coupled with its rapid growth and generation of high biomass yields. This finding may open a door for phytofiltration of ammonia and arsenic-contaminated groundwater in Vietnam. This study aims at: 1. Examining simultaneous removal ability of ammonia and arsenic from contaminated water by three pilot phytofiltration systems with cattails (Typha spp.) cultivation; 2. Constructing and developing an optimal treatment technology for simultaneous removal of ammonia and arsenic (and other contaminants) from groundwater for drinking uses. 12 CHAPTER 1 - OVERVIEW 1.1. Water Sources and Quality Requirements for Drinking Purpose 1.1.1. Water sources: In Vietnam, the water sources exploited and used for domestic purposes are mainly from surface water and groundwater. Surface water source is abundant, mainly from rivers, lakes, ponds It is commonly recharged with rainwater, shallow-level groundwater, and wastewater. Moreover, surface water quality is often affected by human life activities such as agriculture, industries. Nowadays, surface water does gradually not meet basic requirements for domestic purposes if it is not treated before use. Besides, groundwater quality is somewhat better than that of surface water in general. However, groundwater sources are also gradually polluted by both natural and anthropogenic contamination sources. 1.1.2. Groundwater Quality Requirements for Drinking Purpose a/ Arsenic MCL Standard for Drinking Water: The MCL for arsenic in drinking water according to several standards are shown in Table 1.1: Table 1.1 - MCL values for arsenic in drinking water [J. Matschullat, 2000] Standard WHO* EU NL TVO-D DVGW TCVN [As] (µg/L) 10 50 10 - 60 10 10 - 30 10 ▪ WHO: World Health Organization, drinking water guidelines for arsenic; ▪ EU: European Union; ▪ NL: Dutch drinking water guidelines for arsenic (the first numbers refer to reference values, the second to maximum permissible levels); ▪ TVO-D: German drinking water standards for arsenic; 13 ▪ DVGW: German surface water (raw water) guidelines (for ranges see NL); ▪ TCVN: Vietnamese Standards b/ Ammonia MCL Standard for Drinking Water: Ammonia MCL standards for drinking water in somewhere around the world are different. The WHO and EU standards for ammonia MCL in drinking water is of 0.5 mg/L. Whereas, Vietnamese standard has set a limit for ammonia-nitrogen MCL in drinking water is 3 mg/L according to new TCVN 5520-2003 [TCVN, 2003]. 1.2. Current Status of Ammonia and Arsenic Contamination of Groundwater 1.2.1. Arsenic Contamination of Groundwater: a/ Arsenic Contamination: Arsenic, a significant contaminant of groundwater, has been found in many regions around the world [P.L. Smedley and D.G. Kinniburgh, 2002]. Arsenic is widely known for its adverse effects on human health, affecting millions of people. High concentrations of arsenic (above 50 g/L) in groundwater used as drinking water source have been reported in several countries such as Bangladesh, India, China, Mexico, Nepal, Taiwan, Vietnam… In some Asian countries, arsenic in groundwater is a major health concern and the risks from using shallow tube-wells (STWs) for drinking water are well-known. As part of the green revolution, millions of STWs have been installed throughout Asia over the last three decades. This has resulted in a sharp increase of groundwater extraction for irrigation. The direct consumption of groundwater through tube-wells in an attempt to replace polluted surface water supplies has resulted in widespread arsenic poisoning. a1/ Sources of arsenic contamination: Arsenic is one of the most toxic elements encountered in the environment. Arsenic can enter groundwater through both natural geologic processes (geogenic) and [...]... 8.2 and Table 8.5), cattails (Typha spp.) demonstrated as the most feasible plant and chosen for evaluation of its removal capacity to arsenic and ammonia from contaminated water in the phytofiltration systems in this study Figure 2.1 - Cattails (Typha spp.) 30 2.2 Soil Selection for Rooting Media: Soil substrate for rooting media plays an important role in phytofiltration systems because the type and. .. simultaneously Cattails (Typha spp.) Inflow Tap volume control Open air (3-4 cm) Water layer (3-5 cm) Outflow Sandy soil layer (35-40 cm) Small pebble layer (6-8 cm) Figure 2.2 - Cross section of an phytofiltration system with cattails (Typha spp.) cultivation 32 2.3.3 Preparation of Ammonia and Arsenic Solutions Ammonia was supplied as a solution of NH4Cl in running-tap water to produce initial ammonia concentration... 28.4oC) When fronds of the cattails reached 0.8-1.0 m high (equivalent to 0.2-0.3 kg/cattail body), the cattails were ready to be used for phytofiltration evaluation of these pilot systems 2.3.2 Operation: The three phytofiltration systems were fed with tap water pickled with 30 mg/L of ammonia and 300 µg/L of arsenic (initial concentrations) (see Table 2.1) Volumes of inflows and outflows were always... anthropogenic contributions of arsenic to groundwater are from application of arsenical pesticides, irrigation, mining and smelting of arsenic- containing ores, combustion of fossil fuels (especially coal), land filling of industrial wastes, release or disposal of chemical warfare agents [K.H Goh and T.T Lim, 2005], manufacturing of metals and alloys, petroleum refining, and pharmaceutical manufacturing... outflow from being blocked by fine sands 2.3 Setup and Operation of Phytofiltration Systems: 2.3.1 Plant Cultivation: Cattails (Typha spp.) were collected in nature Then, the cattails were washed in running-tap water to remove medium from the root zones and immediately transplanted into three identical 80-litter volumetric PVC plastic pots, surface area of each pot was at 0.16 m2 Each pot consisted of four... Dembitsky and T Rezanka, 2003] Fe-coprecipitation under oxic conditions Uptake by plants (predominantly in roots) Filtration and Sedimentation of suspended particles) Precipitation (as effect of microbial transformations) Sorption Figure 1.4 – Arsenic Removal Mechanisms in a Phytofiltration System c/ Mechanisms of Ammonia Uptake and Accumulation in Plants Nitrogen-compound removal processes in phytofiltration. .. groundwater in several sites of Hanoi City is strongly affected with high ammonia concentrations, especially in Ha Dinh and Phap Van areas with ammonia concentrations of higher 10 mg/L (shown in red color) In the Mekong River Delta, ammonia contamination of groundwater is also alarming M Berg et al., 2006 researched and found demonstrations of ammonia contaminations of groundwater as shown in Table... textile of soil affect physical, chemical, and biological mechanisms regulating the removal of contaminants from water and soil Sandy soil, which has high spongy textile and supports for penetration, was selected to apply in this phytofiltration system The sandy soil was washed by running water several times before being used for rooting media in the phytofiltration systems The soil layer was upper-lain by. .. Phytofiltration Systems a/ Phytofiltration: Phytofiltration, the use of plant with extensive root systems and high accumulation capacity for contaminants, to absorb and adsorb pollutants from water and streams, is gaining a lot of importance in recent times since it is a cost-effective, promising and environmentally-friendly technology [D.E Salt et al., 1995] b/ Main Components of Phytofiltration Systems:... components of a phytofiltration system are hydrology, soils/sediments, and vegetation The interactions of these components dictate the overall contaminant removal efficiency of the phytofiltration systems 1 Hydrology: Hydrologic regime is the major regulating factor of all phytofiltration systems used for water treatment Hydrologic characteristics depend on configuration or geometry of phytofiltration . 1.4 Arsenic Removal Mechanisms in a Phytofiltration System 25 Figure 2.1 Cattails (Typha spp. ) 28 Figure 2.2 Cross section of an phytofiltration system with cattails (Typha spp. ) cultivation. . Examining simultaneous removal ability of ammonia and arsenic from contaminated water by three pilot phytofiltration systems with cattails (Typha spp. ) cultivation; 2. Constructing and developing. contaminants ) 1.4. Phytofiltration Systems 1.4.1. Characteristics of Phytofiltration Systems a/ Phytofiltration: Phytofiltration, the use of plant with extensive root systems and high accumulation