Applied Water Science (v.2, #4)

Prevalence of fluorosis is mainly due to the consumption of more fluoride through drinking water. It is necessary to identify the fluoride endemic areas to adopt remedial measures for the people under the risk of fluorosis. The objectives of this study were to identify the exact location of fluoride endemic areas in Manur block of Tirunelveli District and to estimate fluoride exposure level through drinking water for different age groups. Identification of fluoride endemic areas was performed through Isopleth and Google earth mapping techniques. Fluoride level in drinking water samples was estimated by fluoride ion selective electrode method. A systematic clinical survey conducted in 19 villages of Manur block revealed the rate of prevalence of fluorosis. From this study, it has been found that Alavanthankulam, Melapilliyarkulam, Keezhapilliyarkulam, Nadupilliyarkulam, Keezhathenkalam and Papankulam are the fluoride endemic villages, where the fluoride level in drinking water is above 1 mg/l. Consumption of maximum fluoride exposure levels of 0.30 mg/kg/day for infants, 0.27 mg/kg/day for children and 0.15 mg/kg/day for adults were found among the respective age group people residing in high fluoride endemic area. As compared with adequate intake level of fluoride of 0.01 mg/kg/day for infants and 0.05 mg/kg/day for other age groups, the health risk due to excess fluoride intake to the people of Alavanthankulam and nearby areas has become evident. Hence the people of these areas are advised to consume drinking water with optimal fluoride to avoid further fluorosis risks.
Keywords: Dental fluorosis; Fluoride exposure; Fluoride endemic area; Isopleths technique; Google earth map

Bioremediation of hexavalent chromium by a cyanobacterial mat by Dhara Shukla; Padma S. Vankar; Sarvesh Kumar Srivastava (245-251).
The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2–10, 15–30 and 300 ppm at pH 5.5–6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform–infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5–6.2.
Keywords: Tannery effluent; Cyanobacteria; FT-IR; Energy dispersive X-ray analysis; Freundlich isotherm; Scanning electron microscopy

A study on groundwater geochemistry and water quality in layered aquifers system of Pondicherry region, southeast India by R. Thilagavathi; S. Chidambaram; M. V. Prasanna; C. Thivya; C. Singaraja (253-269).
Geochemical signatures of groundwater in the Pondicherry region, south India, were determined. The coastal aquifers are fragile and this situation becomes more intense in layered aquifer systems like that of the Pondicherry region. In this region, groundwater occurs in alluvium, Lower Cuddalore, Upper Cuddalore, Tertiary, Cretaceous and mixed aquifers. The geochemical signature of groundwater in these formations was studied by collecting 93 groundwater samples. The collected samples from specific formations were analysed for physical parameters, such as electrical conductivity (EC), pH and major ion concentrations, such as Ca, Mg, Na, K, Cl, HCO3, PO4 and SO4. The results of the analysis were interpreted with geology; the ionic concentrations in the groundwater vary spatially and temporally. The abundance of these ions are in the following order: Na > Ca > Mg > K = Cl > HCO3 > SO4. Interpretation of analytical data shows that Ca–Na and Cl–SO4–HCO3 is the dominant facies in all the formations. Groundwater in the area is generally hard and fresh-brackish in most of the formations and brackish in nature in alluvium formation. The sodium absorption ratio shows that most of the samples are grouped under excellent category to good category in all the formations. The residual sodium carbonate also are in good category in all the formations. Chloro-alkaline indices reveal that the majority of samples show negative values in all the litho units indicating the exchange of Na and K in groundwater with Mg or Ca in rock. Scholler classification of water indicates that longer residence time of water with more prominent base exchange. High EC and TDS values in certain locations of alluvial, Upper Cuddalore and Cretaceous formations prove to be unsuitable for drinking and irrigation purposes.
Keywords: Groundwater; Aquifers; Geochemistry; Water quality; Pondicherry

The spatial variability of the δ18O and δD compositions of rain is attributed to variations in amount of precipitation (PPT), altitude effect, and air masses originating from different sources. Air masses that enter the area passing the Mediterranean Sea result in higher d-excess. The cold and dry continental air masses originating from the European continent come in contact with the warm Mediterranean Sea water, resulting in rapid evaporation and large scale convergence. The low d-excess value is less than 16 ‰ and associated with air masses that cross over the North African continent and controlled by a local orographic effect. The change in isotopic composition of δ18O in PPT with altitude is −0.15 ‰ per 100 m. A statistical model confirms that a slight decrease in annual average precipitation has occurred since 1988 and attributed to a minor change in climate. The current level of tritium in rain corresponds to the average level of tritium in the atmosphere. Rabba station recorded a twofold higher tritium concentration in 1995 than the other stations, which may be from leakage from a nuclear station in Israel. The chemistry of rainwater demonstrates a wide range of salinity (100–600 mg/l). The lowest solute concentrations are found at high elevations, and the highest solute concentrations are found in the eastern desert and the Jordan Rift valley. The salinity of rain is affected by desert dust, aerosols, amounts of PPT, and the direction of rain fronts. The aerosols and windblown soil are the most prevailing as the country is confined between three seas and the outcrop surficial geology is mainly sedimentary rocks.
Keywords: Environmental isotope; Precipitation; Hydrochemistry; Climate change

Changes in water volume of the Aral Sea after 1960 by Behzod Gaybullaev; Su-Chin Chen; Dilmurod Gaybullaev (285-291).
The Aral Sea is the biggest saline lake in Central Asia. This brackish water body was the world’s fourth largest lake before it started to shrink in the 1960’s due to water withdrawal for land irrigation. The runoff decreased from 20.6 km3 in 2003 to 4.5 km3 in 2010 and precipitation reduced from 9.4 km3 in 1960 to 3 km3 in 2010. Based on comparative hydrological data between 1960 and 2005, water volume of the Aral Sea reduced significantly. The observed values of runoff, evaporation, precipitation, and water volume were used to estimate water volume from 1957 to 2010, and the coefficient of determination for predicted water volume is 0.7647. We have obtained regression parameters using previously observed data to further estimate corresponding magnitudes of precipitation, runoff, and evaporation from 2011 to 2031, and as a result are then applied in the estimation of the water volume. Our prediction proposes that water volume of the Aral Sea will be decrease approximately to 75.4 km3 in 2031.
Keywords: Aral Sea; Water balance; Evaporation; Irrigation

Hibiscus rosa-sinensis leaf extract as coagulant aid in leachate treatment by Nik Azimatolakma Awang; Hamidi Abdul Aziz (293-298).
Hibiscus rosa-sinensis is a biodegradable material that has remained untested for flocculating properties. The objective of this study is to examine the efficiency of coagulation–flocculation processes for the removal of color, iron (Fe3+), suspended solids, turbidity and ammonia nitrogen(NH3–N), from landfill leachate using 4,000 mg/L alum in conjunction with H. rosa-sinensis leaf extract (HBaqs). Hydroxyl (O–H) and (carboxyl) C=O functional groups along the HBaqs chain help to indulge flocculating efficiency of HBaqs via bridging. The experiments confirm the positive coagulation properties of HBaqs. The Fe3+ removal rate using 4,000 mg/L alum as sole coagulant was approximately 60 %, and increased to 100 % when 4,000 mg/L alum was mixed with 500 mg/L HBaqs. By mixing, 4,000 mg/L alum with 100–500 mg/L HBaqs, 72 % of SS was removed as compared with only 45 % reduction using 4,000 mg/L alum as sole coagulant.
Keywords: Alum; Coagulant aid; Hibiscus rosa-sinensis ; Leachate

Dalbergia sissoo pods, a lignocellulosic nitrogenous waste biomass, was evaluated for sequestering of Cr(VI) from synthetic wastewater. Dalbergia sissoo pods (DSP) were used in three different forms, viz. natural (DSPN), impregnated in the form of hydrated beads (DSPB), and in carbonized form (DSPC) for comparative studies. Batch experiments were performed for the removal of hexavalent chromium. Effects of pH adsorbent dose, initial metal-ion concentration, stirring speed, and contact time were investigated. The removal of metal ions was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration, and other studied process parameters. Maximum metal removal for Cr(VI) was observed at pH 2.0. The experimental data were analyzed based on Freundlich and Langmuir adsorption isotherms. Kinetic studies indicated that the adsorption of metal ions followed a pseudo-second-order equation.
Keywords: Waste water; Biosorption; Kinetics; Dalbergia sissoo ; Cr(VI)

Hydrochemical investigations were carried out in Bukan area, Northwestern Iran, to assess chemical composition of groundwater. A total of 35 groundwater samples were collected and analyzed for major cations and anions. The domination of cations and anions was in the order of Na+ > Ca2+ > Mg2+ > K+ for cations and HCO3 > SO42− > Cl in anions. The similarity between rock and groundwater chemistries in the recharge area indicates a significant rock-water interaction. The hydrochemical types Na + HCO3 + CL + Mg and Na + Cl are the predominate forms in the groundwater, followed by water Ca + Mg + SO4 + Cl and Ca + Mg + HCO3. Assessment of water samples according to exceeding the permissible limits prescribed by WHO for drinking purposes indicated that groundwater in study area is chemically suitable for drinking uses. The most dominant classes C2–S2, C2–S1 and C3–S2 were found in the studied area. The salinity hazard for water wells is classified as medium and high salinity.
Keywords: Hydrochemical; Groundwater; Bukan

In the present paper, the phenol removal from wastewater was investigated using agri-based adsorbent: Terminalia chebula-activated carbon (TCAC) produced by carbonization of Terminalia chebula (TC) in air-controlled atmosphere at 600 °C for 4 h. The surface area of TCAC was measured as 364 m2/g using BET method. The surface characteristic of TCAC was analyzed based on the value of point of zero charge. The effect of parameters such as TCAC dosage, pH, initial concentration of phenol, time of contact and temperature on the sorption of phenol by TCAC was investigated using conventional method and Taguchi experimental design. The total adsorption capacity of phenol was obtained as 36.77 mg/g using Langmuir model at the temperature of 30 °C at pH = 5.5. The maximum removal of phenol (294.86 mg/g) was obtained using Taguchi’s method. The equilibrium study of phenol on TCAC showed that experimental data fitted well to R–P model. The results also showed that kinetic data were followed more closely the pseudo-first-order model. The results of thermodynamic study showed that the adsorption of phenol on TCAC was spontaneous and an exothermic in nature.
Keywords: Phenol; Adsorption; Point of zero charge; Pseudo first-order; Redlich and Peterson isotherm; Taguchi design; Orthogonal arraysS/N ratio