• Energy Research
• engineering and technology close
• 6. Clean water close
• IN close
• SA close
• BE close
• CM close

In this study, levulinic acid (LA) was produced from rice straw biomass in co-solvent biphasic reactor system consisting of hydrochloric acid and dichloromethane organic solvent. The modified protocol achieved a 15% wt LA yield through the synergistic effect of acid and acidic products (auto-catalysis) and the designed system allowed facile recovery of LA to the organic phase. Further purification of the resulting extractant was achieved through traditional column chromatography, which yielded a high purity LA product while recovering ∼85% wt. Upon charcoal treatment of the resultant fraction generated an industrial grade target molecule of ∼99% purity with ∼95% wt recovery. The system allows the solvent to be easily recovered, in excess of 90%, which was shown to be able to be recycled up to 5 runs without significant loss of final product concentrations. Overall, this system points to a method to significantly reduce manufacturing cost during large-scale LA preparation.

Considerable interest is being shown in using biochar production from waste biomass with a variety of disciplines to address the most pressing environmental challenges. Biochar produced by the thermal decomposition of biomass under oxygen-limited conditions is gaining popularity as a low-cost amendment for agro-ecosystems. The efficiency of biochar formation is affected by temperature, heating rate, feedstock type, particle size and reactor conditions. Properties such as pH, surface area and ash content of produced biochar increases with increasing temperatures. Biochar produced at lower heating rates may have high porosity and be beneficial for morphological changes in the soil. Biochar can help to enhance soil health and fertility as well as improve agricultural yield. As a result, biochar can assist in increasing food security by promoting sustainable agricultural systems and preserving an eco-friendly environment. Biochar is also widely being used as a sorbent for organic and inorganic pollutants, owing to its large surface area, allowing it to be immobilized from soil with ease. The functional groups and charges present on the surface of biochar play an important role in pollutants removal. This review focuses on the mechanisms of biochar production using different waste materials as a feed stock, factors that influence biochar quality as well as application of biochar in agricultural soil and their reclamation as well. This article also discusses knowledge gaps and future perspectives in the field of biochar-based toxic-pollution remediation.

The growing population and increasing urbanization have led to a surge in domestic wastewater generation, posing significant challenges for effective and sustainable treatment. The present study demonstrates a novel and sustainable approach for the onsite treatment of domestic wastewater using an integrated settler-based biofilm reactor (ISBR) with efficient biogas generation. The ISBR provides an optimized environment for the growth of biofilm, facilitating the removal of organic pollutants and pathogens. Moreover, the ISBR enables the recovery of a valuable resource in the form of biogas, thus enhancing the overall utility of the treatment process. The performance of the ISBR was comprehensively evaluated at laboratory scale through treating the actual domestic wastewater generated from the hostel of Manipal University Jaipur. The ISBR system was operated under an ambient environment at a hydraulic retention time (HRT) of 24 h. The results demonstrated remarkable efficiency in terms of chemical oxygen demand (COD), total suspended solids (TSS), and coliforms removal, with average removal efficiency being more than 90%. According to the COD mass balance analysis, 48.2% of the influent COD was recovered as bioenergy. The chromatogram revealed a high percentage of methane gas in the collected biogas sample. The field emission scanning electron microscope (FESEM) analysis of the accumulated sludge in the ISBR system depicted the morphology of methanogenic bacteria. Both the experimental and theoretical results confirmed the feasibility and sustainability of the ISBR system at the onsite level.

In a study of the electrochemical behavior of low-cyanide silver plating baths and of the properties of the deposits obtained, it was found that the current-potential curve obtained with a solid electrode showed a two-step reduction wave, the height of the first being 1/5 that of the second. Analysis of the results of polarographic and rotating disk electrode measurmenents sugests that the rate-controlling steps wereAgCN+e-_??_Ag+CN-……(1)Ag(CN)2-+e-_??_Ag+2CN-……(2)for the first and second waves respectively. The Tafel plots of the two waves showed linear relationships at their rising portions, and the reactions are accordingly concluded to be slow chargetransfer controlled.In baths to which selenocyanate ion was added, the increase in current was markedly greater for the second wave than for the first, and the wave was shifted to the positive side. Potential decay curves for the baths containing selenocyanate ion obtained by the current interrupter method showed lower differential capacities than those for baths that were free of selenocyanate ion. This indicates that the selenocyanate ions were adsorbed preferentially at the electrode, suppress the adsorption of cyanide ions and enhancing the silver deposition reaction.Deposits obtained by jet plating were matt at current densities lower than 50A/dm2, and their appearance was not affected by the addition of selenocyanate ion. At above 50A/dm2, deposits obtained from selenocyanate-free baths were burnt, but deposits obtained from baths with selenocyanate ion added were mirror-bright with a strong (200) orientation up to around 150A/dm2.

The study aims to comprehensively assess the energy and water consumption pattern in the seafood industries and suggest measures for the sustainable development of the sector. The unscrupulous usage of water and higher consumption of energy resulted in an uncontrolled generation of wastewater and enormous usage of fossil fuels. In the seafood industry, energy is primarily used for machinery and equipment handling processes such as freezing, refrigeration, heating, cooling, and drying. Similarly, a huge amount of clean water is used for cleaning machinery and plant, and for operations like washing of raw material, de-icing, defrosting, and salt splashing. As a consequence, in the energy-water nexus, additional energy is required for drawing fresh water and further processing of wastewater demands energy that results in air pollution and greenhouse gas emissions and incurring additional costs to the plant. Hence, this review mainly focuses on the significance of energy and water use optimization in the seafood industry, the existing trend of energy and water use pattern and management practices, optimization strategies, and the seafood-energy-water nexus and its environmental implications.

Abstract Enhancing microalgae biomass productivity through different abiotic and environmental factors optimization is crucial. Design of experimental (DOE) methodology using Taguchi orthogonal array (OA) was studied to evaluate the specific influence of eight important factors (light, pH, temperature, carbon concentration, nitrates, phosphates, magnesium ion concentration and carbon source) on the biomass production using three levels of factor (2 1 × 3 7 ) variation with experimental matrix [L 18 -18 experimental trails]. All the factors were assigned with three levels except light illumination (2 1 ). Substantial influence on biomass productivity is observed with carbon concentration contributing 16.8%, followed by nitrates 12.8% and light 9.3%. Experimental setup eight (Light, pH-8.5, Temperature 25°C, Carbon concentration 10 g/l, nitrates 1.5 g/l, phosphates 0 g/l, magnesium 150 mg/l, Carbon source (glucose)) showed maximum biomass growth (5.26 g/l) and good substrate degradation (63%, COD removal efficiency) contributing to carbohydrate production (257 mg/g biomass) which is further converted to lipids (20% Total lipid and 10% Neutral lipids). Chlorophyll ( a , b ), carbohydrates composition, FAME analysis for lipid percentage were monitored during process operation. Elemental analysis reveals that the carbon to hydrogen and oxygen ratio present in dried algal biomass can be hydrothermally liquefied (HTL) to produce biocrude.

Abstract A process engineering strategy was developed for cultivation of high density biomass of Chlorella sp. FC2 with improved productivity under photoautotrophic condition. The process engineering strategy involved a combinatorial approach of: (i) optimization of CO2 concentration in the inlet gas stream & aeration rate; (ii) growth kinetic driven feeding recipe for limiting nutrients; and (iii) dynamic increase in light intensity. The strategy was tested by growing the cells on laboratory grade BG11 medium. With an attempt to reduce the cultivation cost, the growth performance of the organism was then evaluated on commercial grade BG11 medium. Finally, hydrothermal liquefaction was carried out for direct conversion of microalgal slurry into bio-crude oil. Cultivation on laboratory grade BG11 medium resulted in biomass titer and overall productivity of 8.41 g L−1 and 575.9 mg L−1 day−1 respectively. Significant improvement in biomass titer (13.23 g L−1) and overall productivity (731.6 mg L−1 day−1) was observed when grown on commercial grade BG11 medium. Higher fraction of hydrocarbon in the bio-crude oil depicted better oil quality. Thermal gravimetric analysis revealed that maximum distillate fraction lies within the boiling point range of 200–300 °C which is suitable for conversion into diesel oil, jet fuel, and fuel for stoves.

Abstract Small hydropower projects (SHPs), though generally considered more environmentally benign and socially acceptable as compared to large projects, yet their overall sustainability is under suspicion in the Himalayan regions. Almost all SHPs in this region are being developed as run of the river mode which generally causes less/no submergence and quite less displacement of people as compared to large reservoir based hydropower production mode. However, in the absence of proper planning and monitoring mechanism, these projects are causing implacable tunnelling of hills, choking of streams, conversion of streams into dry ditches and long term socio-environmental impacts. This paper presents a SHP development study from hydro rich Beas river basin of Himachal Pradesh, a state nestled in western Himalayan region of India. In depth field studies, focus group discussions with the project affected people and interaction with project proponents of five SHPs in this region suggest that sustainability issues with respect to SHPs are not small vis-a-vis size of their installed capacity. There is an urgent need to take steps to include SHPs having an installed capacity of above 10 MW into the ambit of environment clearance process which is absent in many countries of the world at present.

Abstract It is usual to extract hot water from a storage tank, using displacement by cold water from the mains; this causes the temperature of the outgoing hot water to decrease with time. In order to alleviate this undesirable feature a number of tanks in series may be employed. In this communication the effect of number of tanks on the outlet temperature of hot water, has been analytically investigated; it has been assumed that the only heat exchange, taking place in the tanks is on account of flow of water. The considerations in this analysis are similar to those made by Rabinovich and Fert [1] and Rabinovich [2], for a system of tanks in a solar collector loop without any outflow of water. Thus the analysis is best applicable when hot water is extracted at a fast rate, so that the gain or loss of heat by other mechanisms is negligible, compared to that due to the flow of water. The analysis should also be applicable to shallow solar ponds, Sodha et al. [3], and built in storage water heaters, Sodha et al. [4].