Department of Civil Engineering, Vellore Institute of Technology, Deemed University, Vellore 632014, Tamil Nadu.
Fluoride is a naturally occurring toxic mineral present in drinking water and the root cause of many diseases and disorders. Present international drinking water standard set by World Health Organisation (WHO) for fluoride is 1.5 ppm. In order to find the wide spread concentration of fluoride in drinking water of fluoride contaminated aquifer, 30 bore well water samples have been collected from different villages of Natrampalli Union which comes under Tiruvannamalai Circle, Tamil Nadu, India. In the present work, an attempt to remove fluoride by the use of coagulant, Poly Aluminium Chloride (PAC) was made and is compared with the most common existing technique "Nalgonda Technique" where there was a reversible reaction. The coagulant used in Nalgonda technique is Alum [(Al2SO4)3]. Results of the present work show that Poly Aluminium Chloride (PAC) can be an effective coagulant for the removal of fluoride from water with a higher removal efficiency of about 75 - 85% in less detention time and also observed that the fluoride removal was dependent on initial fluoride concentration and dose of coagulants.
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The title compound, C(21)H(20)O(2)S(2), forms a propeller-shaped structure with the tetra-hedral C atom as the central hub and meth-oxy-benzene and phenyl residues as radiating blades. Short C-H⋯π contacts are observed.
In the title compound, C(15)H(17)BrN(2)O(2), both pyrrolidinone rings adopt envelope conformations. The crystal packing is characterized by short C-Br⋯O=C inter-actions [Br⋯O = 3.1730 (13) Å], leading to supra-molecular dimers. Inter-molecular C-H⋯O and C-H⋯π inter-actions are also observed.
Effect of potential electron acceptors on anoxic ammonia oxidation in the presence of organic carbon.
Environmental Engineering Division, School of Mechanical & Building Sciences, VIT University, Vellore 632014, India. email@example.com
A novel route of anoxic ammonia removal in the presence of organic carbon was identified recently from ecosystems contaminated with ammonia. Sequencing batch reactor (SBR) studies were carried out in anoxic condition at oxidation-reduction potential varied from -185 to -275 mV for anoxic ammonia oxidation with adapted biomass (mixed culture). SBR studies were carried out in absence and in the presence of externally added organic carbon and/or in the presence of inorganic electron acceptors like NO2(-), NO3(-) and SO4(2-). The results showed anoxic ammonia oxidation to nitrate (in contrast to reported anammox process) in the presence of organic carbon available through endogenous respiration whereas anoxic ammonia oxidation was effective in the presence of externally added organic compound for nitrogen removal. The presence of externally added inorganic electron acceptors like NO2(-), NO3(-) and SO4(2-) was effective in anoxic ammonia oxidation, but failed to follow the reported anammox reaction's stoichiometry in nitrogen removal in the presence of organic carbon. However, the presence of NO2(-) affected best in total nitrogen removal compared to other electron acceptors and maximum ammonia removal rate was 100 mg NH4(+)/g MLVSS/d. Based on the results, it is possible to suggest that rate of anoxic ammonia oxidation depends up on the respiration activities of mixed culture involving organic carbon, NO2(-), NO3(-) and SO4(2-). The process shows possibilities of new pathways of ammonia oxidation in organic contaminated sediments and/or wastewater in anoxic conditions.
Department of Civil Engineering, Environmental & Water Resources Engineering Division, IIT Madras, Chennai, 600 036, India. firstname.lastname@example.org
The present paper describes the development of Sulphidogenesis Cum Ammonia Removal Process (SCARP) with a simple sulphide inhibition control. The process was developed using synthetic effluent and its application for treatment of primary treated tannery effluent was demonstrated. This paper also discusses the effects of HRT and loading rates. The developed SCARP could treat efficiently the primary treated tannery effluent with influent concentrations of COD, SO4(2-) and NH4+ equal to 3,900 mg/L, 3,000 mg/L and 300 mg/L, respectively. An HRT of 10.5 hours was found to be adequate for COD, NH4-N and SO4(2-) loading rates of 8.9 kg COD/m3/d, 0.68 kg NH4+/m3/d, 6.84 kg SO4(2-)/m3/d, respectively. The overall removal efficiencies of COD, NH4-N and SO4(2-) for the above loading rates were in the ranges of 90.8-91.8%, 84-88.3% and 64.2-70.2%, respectively. The system performance was satisfactory for different loading rates and low COD/SO4(2-) ratios. The developed SCARP has good potential as a cost effective alternative treatment process to existing extended aeration process with nitrification-denitrification for the secondary treatment of tannery effluent.
Water Sci Technol. 2008 ;58 (1):7-12 18653930
School of Mechanical & Building Sciences, VIT University, Vellore, Tamilnadu, India.
The present study aimed mainly for the development of a wastewater treatment system incorporating enhanced primary treatment, anaerobic digestion of coagulated organics, biofilm aerobic process for the removal of soluble organics and disinfection of treated water. An attempt was also made to study the reuse potential of treated water for irrigation and use of digested sludge as soil conditioner by growing marigold plants. Ferric chloride dose of 30 mg/l was found to be the optimum dose for enhanced primary treatment with removals of COD and BOD to the extent of 60% and 77%, respectively. Efficient anaerobic digestion of ferric coagulated sludge was performed at 7 days hydraulic retention time (HRT). Upflow aerobic fixed film reactor (UAFFR) was very efficient in removals of COD/BOD in the organic loading rate (OLR) range of 0.25 to 3 kg COD/m(3)/day with COD and BOD removals in the range 65-90 and 82-96, respectively. Photo-oxidation followed by disinfection saved 50% of chlorine dose required for disinfection of treated effluent and treated water was found to be suitable for irrigation. The result also indicated that anaerobically digested sludge may be an excellent soil conditioner. From the results of this study, it is possible to conclude that the developed wastewater treatment system is an attractive ecologically sustainable alternative for sewage treatment from institutional/industrial/residential campuses.
Development of enhanced sulphidogenesis process for the treatment of wastewater having low COD/SO(4)(2-) ratio.
Environmental & Water Resources Engineering Division, Department of Civil Engineering, IIT Madras, Chennai 600036, India. email@example.com
An upflow hybrid sulphidogenesis reactor of 1.75 L volume was developed (at oxidation-reduction potential (ORP)=-225+/-25 mV) using flocculent extended aeration process sludge (selected based on screening study at COD/SO(4)(2-) ratio=1) for enhanced sulphidogenesis and COD removal. The reactor was subjected to various loading rate studies at a hydraulic retention time (HRT) of 1 day with COD/SO(4)(2-) ratio of 1.3. At loading rate of 2.5 kg COD/(m(3)day), excellent performance with more than 97% removal of sulphate was achieved within bottom 40% volume of the reactor. At a higher loading rate of 3.75 kg COD/(m(3)day), there was a decrease in both sulphate (70-75%) and COD (50%) removal efficiencies. A controlled and continuous air injection (0.19 L/(L min)) given at 40% volume of the reactor affected sulphide oxidation inside the reactor and enhanced the sulphate reduction in the reactor. The specific sulphate reduction capacity of mixed culture drawn from the bottom part of the reactor was 0.35 kg SO(4)(2-)/(kg VSS day). The results of this study showed that enhanced sulphidogenesis with sulphide inhibition control can maintain sulphate-reducing bacteria (SRB) in anaerobic reactor at low COD/SO(4)(2-) ratios between 1 and 2, with efficient simultaneous removal of COD and SO(4)(2-). The sulphide generated in the system can be recovered as elemental sulphur and/or oxidized back to sulphate.
Environmental and Water Resources Engineering Division, Department of Civil Engineering, IIT Madras, Chennai 600036, India. firstname.lastname@example.org
This study describes the feasibility of anaerobic ammonia removal process in presence of organic matter. Different sources of biomass collected from diverse eco-systems containing ammonia and organic matter (OM) were screened for potential anaerobic ammonia removal. Sequential batch studies confirmed the possibility of anaerobic ammonia removal in presence of OM, but ammonia was oxidized anoxically to nitrate (at oxidation reduction potential; ORP=-248+/-25 mV) by an unknown mechanism unlike in the reported anammox process. The oxygen required for oxidation of ammonia might have been generated through catalase enzymatic activity of facultative anaerobes in mixed culture. The oxygen generation possibility by catalase enzyme route was demonstrated. Among the inorganic electron acceptors (NO(2)(-), NO(3)(-) and SO(4)(2-)) studied, NO(2)(-) was found to be most effective in total nitrogen removal. Denitrification by the developed culture was much effective and faster compared to ammonia oxidation. The results of this study show that anaerobic ammonia removal is feasible in presence of OM. The novel nitrogen removal route is hypothesized as enzymatic anoxic oxidation of NH(4)(+) to NO(3)(-), followed by denitrification via autotrophic and/or heterotrophic routes. The results of batch study were confirmed in continuous reactor operation.
Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India.
Hospital effluents are loaded with pathogenic microorganisms, partially metabolized pharmaceutical substances, radioactive elements, and other toxic substances. Such effluents if not treated properly can damage the natural environment and create a biological imbalance. This paper points out the areas of concern for hospital wastewater disposal and reports the findings of a limited physico-chemical study of treatment options for hospital effluents conducted at Christian Medical College and Hospital, Vellore, Tamil Nadu. The effluent collected was checked for conventional parameters and subjected to coagulation experiments. The raw and settled effluents were coagulated with FeCl(3), filtered and disinfected. Physico-chemical treatment seems to be an attractive option for the cost-effective disposal of hospital effluents. The results of this study call for further detailed study in this area.
Department of Civil Engineering, Vellore Institute of Technology (Deemed University), Vellore 632014, Tamilnadu, India. email@example.com
This study examines the potential reuse of textile effluent treatment plant (ETP) sludge in building materials. The physico-chemical and engineering properties of a composite textile sludge sample from the southern part of India have been studied. The tests were conducted as per Bureau of Indian Standards (BIS) specification codes to evaluate the suitability of the sludge for structural and non-structural application by partial replacement of up to 30% of cement. The cement-sludge samples failed to meet the required strength for structural applications. The strength and other properties met the Bureau of Indian Standards for non-structural materials such as flooring tiles, solid and pavement blocks, and bricks. Results generally meet most ASTM standards for non-structural materials, except that the sludge-amended bricks do not meet the Grade NW brick standard. It is concluded that the substitution of textile ETP sludge for cement, up to a maximum of 30%, may be possible in the manufacturing of non-structural building materials. Detailed leachability and economic feasibility studies need to be carried out as the next step of research.
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Lab scale study on electrocoagulation defluoridation process optimization along with aluminium leaching in the process and comparison with full scale plant operation.
Poonam Gwala, Subhash Andey, Vasant Mhaisalkar, Pawan Labhasetwar, Sarika Pimpalkar, Chetan Kshirsagar
Water Technology and Management Division, National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India.
An excess or lack of fluoride in drinking water is harmful to human health. Desirable and permissible standards of fluoride in drinking water are 1.0 and 1.5 mg/L, respectively, as per Indian drinking water quality standards i.e., BIS 10500, 1991. In this paper, the performance of an electro-coagulation defluoridation batch process with aluminium electrodes was investigated. Different operational conditions such as fluoride concentration in water, pH and current density were varied and performance of the process was examined. Influence of operational conditions on (i) electrode polarization phenomena,(ii) pH evolution during electrolysis and (iii) the amount of aluminium released (coagulant) was investigated. Removal by electrodes is primarily responsible for the high defluoridation efficiency and the adsorption by hydroxide aluminium floc provides secondary effect. Experimental data obtained at optimum conditions that favored simultaneous mixing and flotation confirmed that concentrations lower than 1 mg/L could be achieved when initial concentrations were between 2 and 20 mg/L. pH value was found to be an important parameter that affected fluoride removal significantly. The optimal initial pH range is between 6 and 7 at which effective defluoridation and removal efficiencies over 98% were achieved. Furthermore, experimental results prominently displayed that an increase in current density substantially reduces the treatment duration, but with increased residual aluminium level. The paper focuses on pilot scale defluoridation process optimization along with aluminium leaching and experimental results were compared with a full-scale plant having capacity of 600 liter per batch.
User perception study for performance evaluation of domestic defluoridation techniques for its application in rural areas.
National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India.
Fluoride concentrations in ground water have been monitored in rural areas of Dhar and Jhabua districts in Madhya Pradesh, India. A correlation of fluoride concentration with pH, TDS and conductivity has been estimated to identify surrogate monitoring parameter. Further, fluoride removal from drinking water has been achieved by using adsorbents specially developed for domestic applications. These adsorbents have been evaluated using three different methods namely; loose adsorbent, pre-packed sachet and packed bamboo column. Comparative evaluation of these methods has been demonstrated in the laboratory and field. The stringent limit of 1mg/L for fluoride concentration in drinking water has been achieved by use of specially designed adsorbents. A feedback from end-users in Tarapur and Ukala villages of Dhar districts Madhya Pradesh regarding the adsorbents and its acceptability has been collected. User's perception regarding these household treatments reveals encouraging response for defluoridation methods. According to user's perception loose adsorbent approach emerged out as most simple, clean and safe household defluoridation method.
National Geophysical Research Institute (Council of Scientific & Industrial Research), Uppal Road, Hyderabad, 500 606, India. firstname.lastname@example.org
This article deals with a systematic hydrochemical study carried out in coastal aquifers, Tuticorin, Tamil Nadu, to assess groundwater quality. A total of 29 groundwater samples were collected and analyzed. Results showed that total dissolved solids (TDS), sodium (Na+), magnesium (Mg2+), chloride (Cl-), and sulfate (SO₄²⁻) significantly damaged groundwater systems. The degree of salinization due to seawater mixing in a well or a given area could be indicated by an increase in nearly all major cations and anions. Toxic elements (i.e., Pb and As) were higher than the maximum permissible limits of drinking water. Cross plot of HCO₃⁻/Cl-(molar ratios) versus TDS indicated that about 62% of the analyzed samples were saline. Factor analysis showed that groundwaters, affected by seawater intrusion/industrial activity, were separated from the clusters. An attempt was made to identify the hydrochemical processes that accompany current intrusion of seawater using ionic changes. It was estimated that the mixing rate of seawater intrusion was about 5.81% during April 2007. An index, called 'Seawater Mixing Index'(SMI), was also adopted and its value was SMI>1.18 with EC>3,000 μS/cm about 62% of the sampled waters, were saline. Further, a few trace elements (i.e., Sr, B, and Li) were used as indicators for responding to the change in fresh to saline groundwater environments in coastal aquifers.
Environ Monit Assess. 2010 Mar 30;: 20364310
Department of Industries and Earth Sciences, The Tamil University, Thanjavur, Tamil Nadu, India, email@example.com.
Fluoride in high concentration in groundwater has been reported from many parts of India. However, a systematic study is required to understand the behavior of fluoride in natural water in terms of local hydrogeological setting, climatic conditions, and agricultural practices. The present study is an attempt to assess hydrogeochemistry of groundwater in parts of Palar river basin pertaining to Kancheepuram district Tamil Nadu to understand the fluoride abundance in groundwater and to deduce the chemical parameters responsible for the dissolution activity of fluoride. The study area is geologically occupied by partly sedimentary and partly crystalline formations. A total of 50 dug cum borewell-water samples, representing an area of 2,628.92 km(2). The results of the chemical analyses in September 2009 show fluoride abundance in the range of 1 to 3.24 mg/l with 86% of the samples in excess of the permissible limit of 1.5 mg/l. Presence of fluoride-bearing minerals in the host rock, chemical properties like decomposition, dissociation, and dissolution, and their interaction with water are considered to be the main causes for fluoride in groundwater. Chemical weathering with relatively high alkalinity favors high concentration of fluoride in groundwater. Villagers who consume nonpotable high fluoride water may suffer from yellow, cracked teeth; joint pains; and crippled limbs and also age rapidly.
Evaluation of groundwater quality and its suitability for drinking and agricultural use in Thanjavur city, Tamil Nadu, India.
Department of Science and Mathematics, School of Engineering and Science, Curtin University of Technology, CDT 250, 98009, Miri, Sarawak, Malaysia. firstname.lastname@example.org
As groundwater is a vital source of water for domestic and agricultural activities in Thanjavur city due to lack of surface water resources, groundwater quality and its suitability for drinking and agricultural usage were evaluated. In this study, 102 groundwater samples were collected from dug wells and bore wells during March 2008 and analyzed for pH, electrical conductivity, temperature, major ions, and nitrate. Results suggest that, in 90% of groundwater samples, sodium and chloride are predominant cation and anion, respectively, and NaCl and CaMgCl are major water types in the study area. The groundwater quality in the study site is impaired by surface contamination sources, mineral dissolution, ion exchange, and evaporation. Nitrate, chloride, and sulfate concentrations strongly express the impact of surface contamination sources such as agricultural and domestic activities, on groundwater quality, and 13% of samples have elevated nitrate content (>45 mg/l as NO(3)). PHREEQC code and Gibbs plots were employed to evaluate the contribution of mineral dissolution and suggest that mineral dissolution, especially carbonate minerals, regulates water chemistry. Groundwater suitability for drinking usage was evaluated by the World Health Organization and Indian standards and suggests that 34% of samples are not suitable for drinking. Integrated groundwater suitability map for drinking purposes was created using drinking water standards based on a concept that if the groundwater sample exceeds any one of the standards, it is not suitable for drinking. This map illustrates that wells in zones 1, 2, 3, and 4 are not fit for drinking purpose. Likewise, irrigational suitability of groundwater in the study region was evaluated, and results suggest that 20% samples are not fit for irrigation. Groundwater suitability map for irrigation was also produced based on salinity and sodium hazards and denotes that wells mostly situated in zones 2 and 3 are not suitable for irrigation. Both integrated suitability maps for drinking and irrigation usage provide overall scenario about the groundwater quality in the study area. Finally, the study concluded that groundwater quality is impaired by man-made activities, and proper management plan is necessary to protect valuable groundwater resources in Thanjavur city.
Department of Civil Engineering, V L B Janakiammal College of Engineering & Technology, Coimbatore - 641042. email@example.com
The ground water quality in Coimbatore city along the Noyyal river during pre-monsoon and post-monsoon seasons in 2005 is discussed in this paper. Water samples were collected from 12 wells on either side of the river. The physico-chemical analysis of the collected samples was carried out for the parameters, such as pH, total dissolved solids (TDS), electrical conductivity (EC), total hardness (TH), alkalinity, calcium (Ca2+), magnesium (Mg2+), chloride, sulphates (SO4(2-)) and sodium (Na+). From the study, it is revealed that EC, Ca2+, Mg2+ have high concentrations in pre- and post-monsoon seasons. In most of the places, the quality of water was not found suitable for irrigational and industrial activities because of high concentrations of electrical conductivity and total hardness. In general, the values of all the studied parameters were high and above the standards during the post-monsoon season, compared to the pre-monsoon season in 2005.
Groundwater geochemistry and identification of hydrogeochemical processes in a hard rock region, Southern India.
Department of Civil Engineering, Government College of Engineering, Salem, 636 011, Tamil Nadu, India. firstname.lastname@example.org
Hydrogeochemical investigations were carried out in Chithar River basin, Tamil Nadu, India to identify the major geochemical processes that regulate groundwater chemistry. For this study, long-term (1991-1997) and recent water quality data (2001-2002) for 30 groundwater wells spread over the study area were used to understand the groundwater geochemistry and hydrogeochemical process regulating groundwater quality. Groundwater quality data obtained from more than 400 water samples were employed. Results of electrical conductivity and chloride express large variation between minimum and maximum values and high standard deviation, which suggests that the water chemistry in the study region is not homogeneous and influenced by complex contamination sources and geochemical process. Nitrate and depth to water table expose the influences of surface contamination sources, whereas dissolved silica, fluoride and alkalinity strongly suggest the effect of rock-water interaction. In the study region, weathering of carbonate and silicate minerals and ion exchange reactions predominantly regulate major ion chemistry. Besides, the concentrations of sulphate, chloride and nitrate firmly suggest the impact of agricultural activities such as irrigation return flow, fertiliser application, etc on water chemistry in the study region.
Coliform MPN counts of municipal raw sewage and sewage treatment plant in relation to the water of Buckingham Canal at Kalpakkam (Tamil Nadu, India).
Department of Ecology and Environmental Sciences, Pondicherry University, Pondicherry - 605 014.
Most Probable Number (MPN) of Total Coliforms (TC) and Faecal Coliforms (FC), and the physicochemical variables - temperature, Dissolved Oxygen (D.O.), Biochemical Oxygen Demand (B.O.D.), Chemical Oxygen Demand (C.O.D.), nitrates, phosphates and chlorides of municipal raw sewage and that of aeration tank and secondary clarifier of the Sewage Treatment Plant (STP), in relation to water at the treated sewage out-fall point, down-stream and up-stream of the Buckingham Canal at Kalpakkam were analyzed. Total Coliform and Faecal Coliform MPN counts were higher, 170 and 70/100 mL respectively in the raw sewage. However, the counts of the former in the aeration tank though remained similar, that of FC decreased to 50/100 mL; both of the counts further decreased to 30 and 44/100 mL respectively, in the secondary clarifier and were 110 and 23/100 mL, respectively at the treated sewage out-fall point in the canal. Total coliforms MPN was more than 18 times less in the water at the up-stream than that of the treated sewage out-fall point in the canal. Interestingly MPN of the FC in the up-stream water was nil while it was 8/100 mL in the canal's down-stream point. It is concluded that the FC, B.O.D., C.O.D., nitrates, phosphates and chlorides decreased and the D.O. increased in the treated-sewage due to the treatment of raw sewage through the STP.
Assessment of groundwater quality and hydrogeochemistry of Manimuktha River basin, Tamil Nadu, India.
Centre for GeoTechnology, Manonmaniam Sundaranar University, Tirunelveli, 627 012, India. email@example.com
Groundwater quality assessment study was carried out around Manimuktha river basin, Tamil Nadu, India. Twenty six bore well samples were analyzed for geochemical variations and quality of groundwater. Four major hydrochemical facies (Ca-HCO(3), Na-Cl, Mixed CaNaHCO(3), and mixed CaMgCl) were identified using a Piper trilinear diagram. Comparison of geochemical results with World Health Organization, United States Environmental Protection Agency, and Indian Standard Institution drinking water standards shows that all groundwater samples except few are suitable for drinking and irrigation purposes. The major groundwater pollutions are nitrate and phosphate ions due to sewage effluents and fertilizer applications. The study reveals that the groundwater quality changed due to anthropogenic and natural influence such as agricultural, natural weathering process.
Srikrupa Institute of Pharmaceutical Sciences, Velkatta, Kondapak (mdl), Siddiped (Rd), Medak-502277, Andhra Pradesh, India. firstname.lastname@example.org
The prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to find out the fluoride endemic areas to adopt remedial measures to the people on the risk of fluorosis. The objectives of this study are to estimate the fluoride exposure through drinking water from people of different age group and to elucidate the fluoride endemic areas through mapping. Assessment of fluoride exposure was achieved through the estimation fluoride level in drinking water using fluoride ion selective electrode method. Google earth and isopleth technique were used for mapping of fluoride endemic areas. From the study it was observed that Nilakottai block of Dindigul district in Tamil Nadu is highly fluoride endemic. About 88% of the villages in this block have fluoride level more than the prescribed permissible limit in drinking water. Exposure of fluoride among different age groups was calculated in this block, which comprises 32 villages. The maximum estimated exposure doses were 0.19 mg/kg/day for infants, 0.17 mg/kg/day for children and 0.10 mg/kg/day for adults. When compared with adequate intake of minimal safe level exposure dose of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, a health risk due to fluorosis to the people in Nilakottai block has become evident. From the results, the people in Nilakottai block are advised to consume drinking water with fluoride level less than 1 mg/l. It has been recommended to the government authorities to take serious steps to supply drinking water with low fluoride concern for the fluorosis affected villages.