International Journal of Environmental Science and Technology

Specific methanogenic activity of halophilic and mixed cultures in saline wastewater

*1R. Riffat and 2K. Krongthamchat

Wastewater containing high concentrations of salt, are difficult to treat using biological treatment processes, especially anaerobic processes. Limited information is available on methanogenic activity in saline environments. The objective of this research was to investigate the activity of halophilic methanogens, digester sludge and a mixed culture of halophilic and methanogenic bacteria, at various levels of salinity, in terms of lag period and specific methanogenic activity (SMA) at two temperatures. For the halophilic bacteria at 35 ^oC, the initial SMA ranged from 0.46 to 0.90 g acetate/g VSS.d, but decreased at higher salt concentrations. The maximum SMA varied from 1.2 to 2.08 g acetate/g VSS.d. High sodium chloride concentrations had a significant adverse effect on digester sludge. At 25 ^oC, at salt concentrations of 30 g/l and above, the digester sludge could not acclimate even in 50 days. Little difference was observed in the maximum SMA of mixed culture and halophilic bacteria at high salt concentrations of 40 -50 g/l.

Destroying hills in the northeastern part of Bangladesh:
A qualitative assessment of extent of the problem and its probable impac

1Md. Sirajul Islam, 2G. M. Jahid Hasan and 3Md. Aktarul Islam Chowdhury

Indiscriminate cutting of hills in the Sylhet region has become a major environmental issue. The nature and life style of Sylhet intimately related with the hills are thus under the threat of a drastic imbalance in its ecosystem. Due to such hill cutting the mostly affected sectors of this region will be its weather and climate, geomorphology and hydrology, and the indigenous flora and fauna. As a result the frequency of natural calamities like earthquake, flash flooding etc may increase considerably. Deforestation and resulting increased soil erosion, decreased ground water recharge and deteriorated water quality might also be as consequences of such hill cutting. This paper investigates the cause and extent of the problem along with its probable impact and finally suggests actions for conservation of hills for ecological balance of the region.

Coupled solution of oil slick and depth averaged tidal currents on three-dimensional geometry of Persian Gulf

*S. R. Sabbagh Yazdi

In this paper, simulation of oil spill due to tidal currents in Persian Gulf is performed by coupled solution of the hydrodynamics equations and an equation for convection and diffusion of the oil. The hydrodynamic equations utilized in this work consist of depth average equations of continuity and motion in two dimensional horizontal planes. The effect of evaporation is considered in the continuity equation and the effects of bed slope and friction, as well as the Coriolis effects are considered in two equations of motion. The overlapping cell vertex finite volume method is applied for solving the governing equations on triangular unstructured meshes. Using unstructured meshes provides great flexibility for modeling the flow in arbitrary and complex geometries, such as Persian Gulf flow domain. The results of the hydrodynamic model for tidal currents in Persian Gulf domain is examined by imposing tidal fluctuations to the main flow boundary during a limited period of time. Finally, the developed model is used to simulate an accidental oil spill from a point in Persian Gulf.

Evaluation of twenty four new Gossypium hirsutum strains for growth, yield, fibre quality and ClCuV resistance under environment of Punjab, Pakistan

*M. Hassan, M. A. Haq, M. Aslam, M. Saleem, K. P. Akhtar and S. Sarwar Alam

Twenty four new strains were tested for their yield, quality and Leaf Curl Virus (ClCuV) resistance. NIAB-111/S, NIAB-98 and NIAB-999 were significantly high fruit bearing varieties at 90 days completing 59.54, 48.26 and 46.00% fruiting respectively. Seed cotton yield of VH-142 was highest with 5417 kgha-1 and 52 per plant boll bearing, DNH-57 and NIAB-999 remained second and third with 5234 and 5095 kg ha-1 seed cotton yield, respectively. BH-160 and CRIS-467 were found to be second and third highest boll bearing varieties with 50.97 and 40.20 per plant average bolls respectively. Plant height in CRIS-467, MNH-642 and SLH-224 was significantly higher in comparison to other varieties.NIAB-98, CIM-499 and CIM-506 were found short stature varieties in comparison with other but out of these NIAB-98 and CIM-506 were in high yielding position and CIM-499 was found medium yielder variety. GOT% of MNH-642 remained highest having value of 45.00%. While GOT%. of NIBGE-1, CRIS-168 and CRIS-467 was at lowest position with 35.73, 35.89 and 36.62% respectively. NIAB-111, CIM-499 and BH-160 were at first position in terms of fibre fineness with micronaire values 3.98, 4.00 and 4.07 μg/inch having fibre length 28.53, 31.38 and 30.23 mm respectively. Out of 26 varieties, 16 varieties resulted maturity index in the range of 85.03% and 90.30% with highest maturity index in case of NIBGE-1 (i.e. 90.30%) followed by NIAB-999 and MNH-642 with 89.55 and 85.5% respectively.CRIS-168, CRIS-468 and CRIS-467 were found viral susceptible.

Alteration of macroinvertebrate community in tropical aquatic systems in relation to sediment redox potential and overlaying water quality

*1D. Chakrabarty and 2S. K. Das

Limnological studies in two tropical Indian aquatic habitats showed that macroinvertebrate communities have greater diversity than other biotic communities present there. Sediment redox potential is found to be an important factor for alteration of macroinvertebrate communities in aquatic bodies. Anthropogenic activities have influenced the changing of sediment redox potential values of the studied sites and there by affected the macroinvertebrate communities.

Control of disinfection by products formation potential by enhanced coagulation

Jar-test experiments were conducted to study enhanced coagulation effectiveness in removal of disinfection by products (DBPs) from Zayandehrud River at Isfahan Province-the center part of Iran- in 2004. In this study, the removal of suspended and colloidal particles and natural organic matter (NOM) at various coagulant doses and coagulation pHs was assessed through raw and treated water measurements of turbidity, UV254 absorbance, TOC, and dissolved organic carbon (DOC). The trihalomethane formation potential (THMFP) was also determined by a mathematical relationship with TOC. Results indicated that NOM removal was a function of coagulant type, coagulant dose, and pH of coagulation. In general, TOC, DOC, and UV254 absorbance removal enhanced with increasing coagulant dose. However, further increases in coagulant dosage had little effect on disinfection by-products precursors removal. Ferric chloride was consistently more effective than alum in removing NOM. Coagulation pH was appeared to be a determining factor for maximum NOM removal and the removal of DBPs precursors by enhanced coagulation was significantly enhanced at pH 5.5 in comparison with initial pH of water. Furthermore, it is specified that preadjustment of pH with sulfuric acid reduced the coagulant dosage and thus, production of sludge. The reduction in THMFP was consistent with the trends observed for DBPs precursors removal data (i.e. UV254 and TOC data).

Polycyclic aromatic hydrocarbons in Niger Delta soil: contamination sources and profiles

*1A. Olajire Abbas and 2W. Brack

The distribution and sources of PAHs in soil as well as PAHs profiles have been investigated in areas with anthropogenic pollution in the Niger Delta (Nigeria) such as Warri and Ughelli. PAHs were identified in 21 soil samples (0- 10cm upper layer) collected in May, 2003. The typical total PAHs level in Niger Delta soil ranged from 182 ± 112 - to - 433 ±256 ìg/kg dw. PAH concentrations in soil samples from Warri Refinery, Tanker Loading point and Ugboko via Rapele oil field were quite high ( the mean ÓPAH concentrations were 433, 402 and 384 ìg/kg dry weight respectively). The dominant PAHs in soil samples were pyrene, naphthalene and benzo[k]fluoranthene. The soil total PAHs (PAH_tot.) concentration, normalized to organic carbon content (OC), ranged from 11.4 to 47.2 mg PAHtot./kg OC; and showed that organic matter of the soil samples from Quality Control Centre, Ugelli West is highly contaminated with PAHs and had a value of 47.2 ± 31.2 mg PAH_tot./kg OC. Two and three ring aromatic hydrocarbons predominated in soil samples from Ughelli West , Tanker Loading point and Delta Steel Company, which is indicative of petrogenic origin.

The impact of farming on river banks on water quality of the rivers

B. Chimwanza, *P. P. Mumba, B. H. Z. Moyo and W. Kadewa

A study was carried out in a strip of a river in the dry and rainy seasons to assess the effect of farming along river banks on the quality of water in rivers. The results showed that there was an increase in the concentration of nitrate in the water downstream in both the rainy and dry seasons. In both rainy and dry seasons, the total nitrogen in the soil was highest (p<0.01) in the middle section. Significant seasonal differences (p<0.01) were observed for phosphate in water, being higher in the dry season. In the soil, the concentration of phosphate showed significant sectional differences (p<0.01) in the rainy season with the highest concentration observed in the lower section (1.74±0.01mg/l) and the least in the upper section (1.02±0.01g/l). However, in the dry season, the highest concentration was obtained in the middle section (1.69±0.01mg/l) and the least in the upper section (1.15±0.02 mg/l). The results suggest that the farms along the riverbanks have an impact on the water quality of the water in the river. It is therefore recommended that there should be close monitoring of the activities of the farms on riverbanks to minimise their impacts on the natural ecosystems that they interact with. Frequent monitoring of the water quality in the rivers relative to the farming estates should be done.

Comparative study of body composition of four fish species in relation to pond depth

1M. Ali, 1F. Iqbal, 1A. Salam, 1F. Sial and 2M. Athar

Fish specimen of Labeo rohita, Cirrhinus mrigala, Hypophthalmicthys molitrix and Catla catla were sampled from three ponds of different depths (152 cm, 122 cm and 76 cm) to compare the body composition of these species in relation to pond depth. There was significant (P < 0.001) effect of pond depth on water, ash, organic, fat and protein contents (all % wet and dry body weight). It was observed that pond depth has significant effect (P < 0.01) on condition factor in pond B (122 cm depth) and no effect in pond A and C. Maximum mean values of body composition were observed in Labeo rohita in all the three ponds. Present study demonstrates that fish cultured in ponds of different depths have different values of protein which can help guide the farmers to select best pond depths to produce protein rich fish.

Treatment of dye solution containing colored index acid yellow 36 by electrocoagulation using iron electrodes

1*M. Kashefialasl, 2M. Khosravi, 1R. Marandi and 2,3 K. Seyyedi

The removal of pollutants from effluents by electrocoagulation has become an attractive method in recent years. This paper deals with the batch removal of the reactive textile dye Colored Index (C. I.). Acid yellow 36 from an aqueous medium by the electrocoagulation method using iron electrodes. The effects of electrolyte concentration, initial pH, current density, electrode area, interelectrode distance, dye concentration, and treatment time on the decolorization efficiency have been investigated. Iron hydroxypolymeric species formed during an earlier stage of the operation efficiently remove dye molecules by adsorption and precipitation, and in a subsequent stage, Fe(OH)₃ flocs trap colloidal precipitates and make solid liquid separation easier during the flotation stage. These stages of electrocoagulation must be optimized to design an economically feasible electrocoagulation process. The increase of current density up to 127.8 A/m2 enhanced the color removal efficiency. Our results showed that the optimum electrolysis time was 6 min. The optimum pH was determined 8. It was also found that the color removal percent (R.P.%) with increasing of dye concentration, decrease. The optimum amount of electrolyte (NaCl) was found to be 8 g/l when the dye concentration was 50 mg/l.

Chemical analysis of drinking water of villages of Sanganer Tehsil, Jaipur District

P. Jain, *J. D. Sharma, D. Sohu and P. Sharma

Due to pressure of human activity, urbanization and industrialization, the groundwater sources are degraded gradually; therefore pure, safe, healthy and odorless drinking water is a matter of deep concern. There are many pollutants in groundwater due to seepage viz. organic and inorganic pollutants, heavy metals, pesticides, fluorides etc. In Rajasthan state, all 32 districts are affected with high fluoride concentration in groundwater and among these Jaipur ranks second. The drinking water samples were collected in clean polyethylene plastic containers from villages (Code No. 51-100) of Sanganer Tehsil of Jaipur District. The water samples were analysed for pH, Fluoride (F^-), Electrical Conductivity (EC), Total Dissolved Solid (TDS), Calcium (Ca), Magnesium (Mg), Total Hardness (TH), Chloride (Cl^-), Carbonate (CO3^-2), Bicarbonate (HCO₃^-), Alkalinity, Sodium (Na⁺), Potassium (K⁺) and Nitrate (NO₃^-using standard techniques in laboratory (APHA, 1985). The results revealed that most of the water samples were below or out of limited; according to the WHO standards (1996). The fluoride concentration ranged from 0.4 to 5.4 ppm, where 42% samples showed fluoride less than permissible limit and 48% water samples were within optimum limit i.e. 1-1.5 ppm while 10% samples contained Fluoride higher than permissible limit. pH of all the samples were within limit (6 to 9.2), while EC of all the water samples were out of limit i.e. 300 µmhos/cm. The alkalinity was greater than permissible limit (200 mg/l) in 98% villages and only 2% villages had below than optimum limit. The NO₃^- concentration was less than permissible limit (45 mg/l) in 64% villages whereas 26% samples showed higher concentration of NO₃^-. However only 10% samples contain optimum level of nitrate. Moreover Na concentration was greater than permissible (50 to 60 mg/l) limit in 98% water samples whereas K⁺ concentration was below the optimum (20 mg/l) level in all the samples studied. The results revealed that the quality of drinking water of Sanganer is very poor, which can be used for drinking and cooking only after prior treatment.

Slope stabilization with Gleditshia caspica and Parrotia persica

1*G. H. Bibalani, 2B. Majnonian, 3E. Adeli and 4H. Sanii

The stabilization roles of two species, Gleditshia caspica and Parrotia persica, were studied on slopes in northern part of Iran. Landslides developed in this area because of incorrect land use and clear cutting of forest to change to agriculture land. Spread planting of Gleditshia caspica and Parrotia persica can help to control instability of soil in this area. Bishop's method was used to calculate the safety factor of slopes. This calculation was studied for the following conditions with vegetation cover of Gleditshia caspica, with Parrotia persica and without vegetation cover. Parrotia persica helped to stabilize slopes with 45-60% grades and Gleditshia caspica helped for slopes with 25-40% grades.

Investigating the relationship between wind erosion and value of animal habitats in desert areas

*1S. M. Azarkar, 2H. Ahmadi, 2N. Khorasani and 2M. Karami

Animal species in desert habitats are taken into consideration because of their uniqueness and inherent value. However the added pressures from climate and human have made living conditions difficult and acute for them. Wind erosion is one of the common phenomena in desert areas; this phenomenon can affect biotic value of those areas. Climatic constraints along with human development in such areas result in enhancing the effect of wind erosion, and as a result, affect the value of animal habitats. Therefore, by estimating the rate of wind erosion in such areas, the capability of environment for providing appropriate conditions for animal species' subsistence can also be estimated. The objective of this research is to find the relation between the rate of wind erosion and value of animal habitat in Sarakhs as a representative of Razavi Khorasan Province. This research has been carried out in four steps: a) Approximate identification of each animal habitat in the area. b) Estimating the wind erosion based on IRIFR model. c) Estimating the approximate value of each of the animal habitats in the area. d) Determining the correlation between the value of each animal habitat with the average rate of wind erosion in that habitat. Investigating the relation between the average rate of wind erosion and the value of animal habitats which indicates that there is a significant correlation between them, that is to say, effective factors in increasing the rate of wind erosion have affected the quality of animal habitats, and proportional to their intensity, decreased the value of habitat.

Synthetic vegetation: An ecosystem prosthesis

*M. A. Woodley

In this paper, an entirely novel, theoretical restoration/conservation tool will be described. This tool will take the form of self-sustaining ‘synthetic vegetation' designed, through the use of solar energy, to generate Oxygen through the electrolysis of water and sequester CO2 in a disposable form through the formation of Carbonic acid amongst other things; in short simulate many of the major functions of living vegetation. The environmental role of synthetic vegetation as a terrestrial ecosystem ‘prosthesis' is evaluated with a Carbon acquisition calculation and a cost benefit analysis reviewing the benefits of utilization in the context of material costs. It is proposed that synthetic vegetation could greatly aid in conservation by regenerating degraded environments and speeding up the process of restoration.