The present study has been conducted to assess the surface water quality of Halda River from September 2015 to March 2016. DO, BOD5, COD, pH, EC, Chloride, Alkalinity, and Hardness concentrations in water samples have been found to range within 0.93-5.15 mg/L, 30-545 mg/L, 43-983 mg/L, 6.3-7.3, 110-524 uS/cm, 12-56 mg/L, 35-67 mg/L, and 38-121 mg/L, respectively. Multivariate statistical analyses, such as Principal Component Analysis (PCA) as well as Correlation Matrix (CM) have revealed significant anthropogenic pollutant intrusions in water. Cluster Analysis (CA) has indicated decent results of rendering three different groups of resemblance between the two sampling sites, reflecting the different water quality indicators of the river system. A very strong positive linear relation has been found between COD and BOD (1.000), hardness and EC (0.993), pH and DO (0.979), hardness and COD (0.929), hardness and BOD (0.924), EC and COD (0.922), and EC and BOD (0.916) at a significance level of 0.01, proving their common origin entirely from industrial effluents, municipal wastes, and agricultural activities. River Pollution Index (RPI) has indicated that the water from rivers at Kalurghat and Modhunaghat varied from low to high pollution, which is due to the former area's being mostly industrial zone with some domestic sewage, while the latter underwent less industrial activities. On the contrary, lots of agricultural activities have been found in Modhunaghat. Use of river water can pose serious problems to human health and aquatic ecosystem via biological food chain. The present research suggests special preference for proper management of the river with eco-friendly automation along with development of the country's sustainable economic.

The present study is aimed at characterizing the landfill leachate as well as its impact on the surrounding groundwater in Kolkata, India. Landfill leachate has been seasonally characterized from 2012-2014, indicating the landfill site in methanogenic phase with high contamination of organics, nutrients, salts, and heavy metals. Sixty groundwater samples have been analyzed for twenty two physico-chemical parameters in pre-monsoon, monsoon, and post-monsoon season of 2014. Seasonal alterations of groundwater quality have been evaluated with a statistical tool, Kruskal-Wallis test, to assess the influence of leachate, showing significant changes in almost all its physico-chemical parameters with sampling time. Majority of groundwater samples were contaminated with Hg, Pb, Cd, Cr, Fe, and Mn, indicating very little effect of redox control on the occurrence and transport of heavy metals. Comparison of physico-chemical parameters with World Health Organization (WHO) and Bureau of Indian Standards (BIS) indicate that majority of groundwater samples have been inadequate to use as potable water. Therefore, this study would help in developing policies for landfill leachate treatment programs and controlling groundwater pollution at the concerned landfill site.

Certain species of Hermetia illucens, also known as the Black Soldier Fly(BSF), were found in a compost plant in Roorkee located in Northern India. Its larvae arevoracious eaters of organic waste, hence can play an ecologically-important role in solidwaste management. Morphological analysis of various stages of BSF life cycle by SEMshowed that its body along with its wings is densely covered with hair. The identifiedspecies of BSF were black in color and oviposited into the composted material. The larvaegrew up to 30 mm long in 12 days from an initial length of only 6mm, gaining almost 200%of its initial weight after voraciously feeding on organic waste. The mouth of the H. illucensshowed a well-developed mandibular-maxillary complex that had similar characteristics ofscavengers, making the insect a suitable candidate for organic waste consumption.

In Nigeria irrigated agriculture is an important tool for economic growth, food security, and poverty reduction during dry periods of rain-fed agriculture. The concentration and composition of dissolved constituents in water determines its quality for irrigation use. Water quality studies strongly suggest that agriculture is a leading source of water quality problems, due to pesticides and other agro-inputs, widely used by farmers to improve agricultural productivity. Poor quality irrigation water would therefore obviously affect soil quality and crop productivity. This study was carried out in 2015 to assess the presence of metals and physical properties of water, used for irrigation in Kwara state, Nigeria. Samples were randomly collected from thirty irrigation sources in three senatorial zones of Kwara State. The samples were analyzed for the presence of metals and water quality parameters, using standard procedures. Results showed that the highest concentration of Sulphate (7.0mg/L), Nitrate (8.9mg/L), Sodium (31.6mg/L), Calcium (3.1mg/L), and Magnesium (0.7) ions were within acceptable limits. The Sodium Adsorption Ratio, an indicator for water suitability in agricultural irrigation as well as a standard diagnostic parameter for the sodicity hazard of a soil, was significantly the highest (22.7) in Kwara North. Results of the study point to the need for an effective irrigation water quality assessment to curb nonpoint source pollution that could be caused by improper use of chemicals and pesticides by farmers.

For the first time, the present study removes ions of mercury, in the form of Hg (I) and Hg (II) ions, from aqueous solutions by adsorbing them onto titanium dioxide nanoparticles. The effects of various parameters, such as solution's initial pH, temperature, sorbent dosage, initial mercury concentration, and contact time have been examined on the adsorption process. The experimental results have been compared with Langmuir, Freundlich, and Temkin adsorption isotherms. The maximum adsorption, obtained for Hg (I) and Hg (II) ions, have been 97.5% and 98.6%, respectively. Also, it has been shown that the Langmuir isotherm has better fitting with the equilibrium data than the Freundlich and Temkin isotherms. Thermodynamic parameters of the adsorption, such as and  have been calculated, the negative values of which show that the mercury ions adsorption is an exothermic process and that randomness is decreased, respectively. The study of adsorption kinetics shows that the adsorption of Hg (I) and (II) ions with TiO2 nanoparticles is pseudo-second order.

A wide range of chemicals and dyes are being used in textile industry, and are often found in the wastewater produced. This study attempts to investigate the reduction of COD, TSS, and dye in effluents from the dyeing and washing unit of textile industry, using electrocoagulation process. The reactor is equipped with 10 iron electrodes, connected to a direct current (DC) source in a monopolar electrode configuration. In each stage of the experiment, 2.5 l of the effluent enters the reactor and the effects of a number of important operational parameters such as voltage, pH, and reaction time is studied on the removal of COD, TSS, and dye parameters. Results show that the optimum operational conditions are reaction time of 120 min, voltage of 30 V, and pH of 7, which reduces COD, TSS, and dye by 87%, 91%, and 98%, respectively. Therefore, it has been concluded that the efficiency of pollutants removal from the wastewater improves as voltage and reaction time are increased.

Petroleum refining industries produce large amounts of toxic effluents, causing environmental pollution. Iran is an oil-rich country that encounters oil pollution in its soil and water. Bioremediation of these pollutants is an appropriate solution to tackle them, compared to physical and chemical remediation methods. There are some factors that increase the rate of biodegradation; therefore, this study aims to determine the rate of gasoil bioremediation by two indigenous bacterial isolates (from oil-contaminated soils of an oil refinery south of Tehran) in two different media, namely soil and soil-sawdust mixture. The two superior indigenous bacteria has been isolated through three steps with results indicating that in an optimal environmental condition (temperature= 27±2 °C, humidity of 60%, water holding capacity, and daily manual aeration), bacterial isolates are able to degrade about 78.87% and 93.53% of gasoil during 45 days in soil and soil-sawdust mixture media, respectively. These results imply the role of sawdust in improving aeration, water holding capacity, and-consequently- increasing bioavailability of gasoil to bacteria.

The present study investigates the transesterification of corn oil with methanol over two oxides of MgO and ZnO at 65 ͦC and 1 atm. These two catalysts have been prepared via a conventional co-precipitation process. As for MgO, the corresponding mixed metal nitrate solution has been mixed and heated at the presence of urea. ZnO has also been synthesized by co-precipitation of metal acetate at the presence of oxalic acid and ethanol. The catalysts then have been characterized by means of X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD results indicate high purity for both catalysts. Also, catalytic activity has been evaluated in methanol reflux temperature through corn oil transesterification, with the impacts of reaction variables, like catalyst amount, methanol/oil molar ratio, and reaction time on biodiesel yield, investigated by means of HNMR spectrum. Under appropriate transesterification conditions at 65 °C (catalyst amount= 5%, methanol/ oil ratio= 20, and reaction time= 10 hr), an ME content of 62.61% can be achieved, using MgO catalyst. Similarly, the experiments have been repeated to achieve the best yield, using ZnO catalyst, with the highest rate, equal to 53.1%, obtained in 9% of catalyst and methanol/oil ratio of 30 over 10 hr. Furthermore, reusability of ZnO and MgO has been evaluated in transesterification reaction.

Conserving water resources and protecting them from pollution are of high account in the natural cycle of our life. This study has tried to determine the refining potential and capacity of water hyacinth (Eichhornia crassipes) in order to remove the cadmium from water, studying the influence of factors such as initial concentration of cadmium, contact time, absorbent mass, and pH. Results have shown that the best efficiency of cadmium, more than 99%, was obtained in the optimum conditions (i.e. retention time of 30 hours, adsorbent dose of three plants (12 stems), and pH=6.6). By increasing the initial concentration of cadmium from 0.28 to 8.28 mg/L, the elimination efficiency did not change; moreover, by increasing the absorbent mass, the elimination efficiency increased from 98.4 to 99.8 and the lowest retention time was obtained for the balance. All experiments have been repeated three times, showing in the end that water hyacinth is able to absorb cadmium up to 8.28 mg/L. This process follows Freundlich isotherm (R2=0.98). Results of this study indicate that this plant can grow well at high levels of cadmium and the growth of water hyacinth is better in the presence of cadmium than control conditions (city water). Finally, it can be concluded that it is necessary to provide a reliable, cheap, and fast method to eliminate pollution. Eichhornia crassipes, a promising plant with great functionality, can be used as a refiner in order to eliminate the heavy metals in wastewater (sewage) effluents, particularly industrial sewage.

This study presents the natural dye recovery from various biodegradable temple and household wastes. The raw material for colour extraction consisted residual flowers and garlands from various temples as well as onion and vegetables peels from vegetable markets, university hostels, and households, which were washed, dried, crushed, and sieved. The extracted natural colours were produced by means of ultra-sonication, and were dried in the spray drier, being characterized by FT-IR and UV-Vis Spectrophotometers. They were used to dye various fabrics such as cotton, silk, and wool, not to mention different mordents. It was found out that the remaining residue, left after dye extraction, was rich in nutrients, hence, it could be further used as the resource material, itself. As a result, we explored these residual wastes for vermicomposting and biochar production, which can be further employed as an organic fertilizer for agriculture. Overall, the present waste management approach will lead to a closed-loop environmental management through waste reduction and reutilization. It will also provide value-added materials for economic gains from waste. Thus, it can be promoted as a potential mechanism to maintain the environmental sustainability at wider scales.