The present investigation characterizes tannery effluents by determining water quality parameters and some selected trace metallic constituents in order to measure the magnitude of environmental pollution. Effluents and sediments have also been used to isolate chromium-resistant bacteria, collected from Hazaribagh area, Dhaka, claimed to be increasing Cr (VI)-enriched environments, and utilized to reduce Cr (VI). The pH, TDS, DO, and EC values of all investigated samples have been within the range of 4.35 to 9.74, 290 to 9,200 mg/L, 1.5 to 4.90 mg/L, and 587 to 19,000 µs/cm, respectively. The concentrations of trace metallic constituents have been determined by means of Atomic Absorption Spectrophotometer (AAS), giving the following ranges: Cr: 14.282 to 6,769.554 mg/L; Cd: 1.546 to 2.214 mg/L; Pb: 18.808 to 32.026 mg/L; Cu: 1.522 to 2.578 mg/L; Zn: 0.682 to 8.688 mg/L; Fe: 1.37 to 108.556 mg/L; and Mn: 3.494 to 17.17 mg/L. The order of trace metallic constituents in the effluent samples was Cr > Fe > Pb > Mn > Zn > Cd > Cu. The water quality parameters and metallic constituents’ concentration were higher than that of standard permissible limits in all the examined samples. The average number of Cr (VI)-resistant bacteria in the sediment samples with glucose (0.5%, w/v) supplementation was 2.35× 103 CFU/gm at 24h. One of the representative isolate was able to tolerate up to 400 mg/L of K2Cr2O7 as Cr (VI). The bacteria, isolated in the present study, can be used as eco-friendly biological agents for the remediation and/or detoxification of chromium (Cr) pollution from the chromium contaminated environments.

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.

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.

Land leveling is one of the most important steps in soil preparation and cultivation. Although land leveling with machines requires considerable amount of energy, it delivers a suitable surface slope with minimal soil deterioration as well as damage to plants and other organisms in the soil. Notwithstanding, in recent years researchers have tried to reduce fossil fuel consumption and its deleterious side effects, using new techniques such as Artificial Neural Networks (ANNs) and Adaptive Neuron-Fuzzy Inference System (Fuzzy shell-clustering algorithm) models that will lead to a noticeable improvement in the environment. The present research investigates the effects of various soil properties such as Embankment Volume, Soil Compressibility Factor, Specific Gravity, Moisture Content, Slope, Sand Percent, and Soil Swelling Index in energy consumption. The study consists of 90 samples, collected from three different regions. The grid size has been set on 20 m * 20 m from a farmland in Karaj Province, Iran. The aim is to determine the best linear model, using ANNs and ANFIS model to predict environmental indicatorsand find the best model for land leveling in terms of its output (i.e. Labor Energy, Fuel energy, Total Machinery Cost, and Total Machinery Energy). Results show that ANFIS can successfully predict labor energy, fuel energy, total machinery cost, and total machinery energy. All ANFIS-based models have R2 values above 0.995 and MSE values below 0.002 with higher accuracy in prediction, given their higher R2 value and lower RMSE value.

One of the major factors, contributing to the emission of greenhouse gases in the environment is generation of pollutant gases in municipal landfills. As for the design and building of a gas collecting system, it is necessary to properly estimate the amount and type of the landfill emissions. By means of LandGEM model, this study predicts the amount and type of the landfill gases, produced for 30 years (from 2016 to 2045) in Jiroft. Results show that in 2045, 3, 324, 274 tons of waste will be disposed in municipal landfills of Jiroft and the total amount of produced gas, methane, carbon dioxide, and non-methane organic compounds will be 32, 994, 8813, 24,181, and 378.8 tons/year, respectively. Furthermore, the rate of landfill gas emissions from 2016 to 2045 has been achieved. Maximum concentrations of methane, carbon dioxide and non-methane organic compounds in 2045, in 700 meters from landfill, will be 40, 590, 112, 700, and 1765 tons/m3 respectively. Based on the results, obtained from this article, landfill pollutants such as CH4, CO2, and NMOC's can reach up to 15 kilometers from landfill, thus social places should be located farther than 15 kilometers from the landfill site of Jiroft. The results, obtained in this paper, can be used to identify the effect of Jiroft landfill in global emission of greenhouse gases and proper management of the landfill gas not only reduces greenhouse gas emissions, diminishing their effects on public health, but can be also used as a sustainable energy source.

Fertilizers usually enhance potassium (K) content and other naturally occurring radioactive materials in agricultural fields that eventually enter the human food chain through plants. In this study, pot-grown rice plants planted in soil that is relatively high in natural radioactive content was used to estimate the individual influence of fertilizer applications on the uptake of 226Ra, 232Th, and 40K using gamma-ray spectrometry. Three types of common fertilizers used in rice cultivation (with percentages) 17.5N:15.5P:10K, 17N:3P:25K+2MgO, and 46N (i.e., urea) were separately added to the potted-rice plants which were in three different growth stages: emergence stage (10 days), maximum tillering stage (40 days), and initiation stage (70 days). Fertilizers at various concentrations (0, 100, 200, 300, and 400 mg kg–1) were applied in the first stage of plant growth, whereas only 200 mg kg–1 fertilizer was applied in the second and third stages. Results showed that the uptake of 226Ra, 232Th, and 40K by rice grains was affected by different concentrations of fertilizer and its application time. However, these findings suggested insignificant health risk related to the ingestion dose of grains treated with selected fertilizers.