Biocatalytic polymeric membranes to decrease biofilm fouling and remove organic contaminants in wastewater: a review

The presence of recalcitrant contaminants in wastewater is major challenge to decrease pollution and associated health issues. As a consequence, membrane technologies have recently attracted industrial attention, yet a major setback of membrane employment is membrane fouling which leads to frequent discarding of membrane modules. More than 45% of all membrane fouling cases are caused by biofilms that are resistant to antimicrobial agents. Here we review polymeric membranes with antifouling properties, with focus on surface properties, fabrication, characterization, biocatalysis using enzymes and application towards the removal of dyes, phenol, pesticides and fertilizers. Nano-engineered fabrication of polymeric membranes allow to decrease fouling by 80–90%. Immobilized oxidoreductases in polymeric membranes allow 65–98% removal contaminants in wastewater.

     

Factors influencing NOx emission of a stationary diesel engine fuelled with crude rice bran oil methyl ester blend – Taguchi approach

The main objective of this work is to control the NO_x emission of a stationary diesel engine fuelled with crude rice bran oil methyl ester blend with less sacrifice on smoke density and brake thermal efficiency (BTE) and also to investigate the factors influencing the objective. Fuel injection timing, percentage of exhaust gas recirculation and fuel injection pressure are chosen as the promising factors for the objective and NO_x emission, smoke density and BTE are considered as response variables. Tests were conducted as per Taguchi’s L₉ orthogonal array and the most influencing factor for each response variable and also the significance of each factor on the same was found out through analysis of variance (ANOVA). Response graph was drawn for each response variable and from the results of response graph and ANOVA the optimum combination of the factor levels in achieving the objective was obtained and the same was confirmed experimentally.     

Polylactic Acid (PLA) Biocomposites Filled with Waste Leather Buff (WLB)

A large amount of leather waste is generated from tanning industries and most of which are disposed of landfill or discharged into the natural water bodies without any treatment, causing environmental problems. The aim of this study is to develop eco-biocomposites using waste leather buff (WLB) as filler in Polylactic acid (PLA) matrix to reduce the environmental issues and provide sustainable solution. WLB/PLA composites were prepared by twins-screw micro extruder varying the WLB content from 2% to 30 wt%. These composite were extensively characterise by several techniques. Tensile properties of the composites showed addition of WLB resulted in improvement of tensile property of composite and reduction in percentage crystallinity of PLA matrix observed with increase in WLB content. The effect of WLB on properties of interfacial adhesion and dispersion in WLB/PLA composites were studied by SEM. Wettability of composites was tested by contact angle and water absorption studies. WLB/PLA composite showed increase in water absorption with WLB loading. These WLB/PLA composite could be used to develop low cost eco-friendly product material.     

A catchment scale assessment of water balance components: a case study of Chittar catchment in South India

Environmental Science and Pollution Research - The detailed analyses of the water balance components (WBCs) of the catchment help assess the available water resources, especially in the arid...     

Hydrogeochemical investigations to assess groundwater and saline water interaction in coastal aquifers of the southeast coast,Tamil Nadu,India

Environmental Science and Pollution Research - Groundwater and saline water interaction is the most common processes in the coastal aquifers that alters the quality of aquifer waters. The...     

Diesel reformulation using bio-derived propanol to control toxic emissions from a light-duty agricultural diesel engine

In the Indian agricultural sector, millions of diesel-driven pump-sets were used for irrigation purposes. These engines produce carcinogenic diesel particulates, toxic nitrogen oxides (NOx), and carbon monoxide (CO) emissions which threaten the livelihood of large population of farmers in India. The present study investigates the use of n-propanol, a less-explored high carbon bio-alcohol that can be produced by sustainable pathways from industrial and crop wastes that has an attractive opportunity for powering stationary diesel engines meant for irrigation and rural electrification. This study evaluates the use of n-propanol addition in fossil diesel by up to 30% by vol. and concurrently reports the effects of exhaust gas recirculation (EGR) on emissions of an agricultural DI diesel engine. Three blends PR10, PR20, and PR30 were prepared by mixing 10, 20, and 30% by vol. of n-propanol with fossil diesel. Results when compared to baseline diesel case indicated that smoke density reduced with increasing n-propanol fraction in the blends. PR10, PR20, and PR30 reduced smoke density by 13.33, 33.33, and 60%, respectively. NOx emissions increased with increasing n-propanol fraction in the blends. Later, three EGR rates (10, 20, and 30%) were employed. At any particular EGR rate, smoke density remained lower with increasing n-propanol content in the blends under increasing EGR rates. NOx reduced gradually with EGR. At 30% EGR, the blends PR10, PR20, and PR30 reduced NOx emissions by 43.04, 37.98, and 34.86%, respectively when compared to baseline diesel. CO emissions remained low but hydrocarbon (HC) emissions were high for n-propanol/diesel blends under EGR. Study confirmed that n-propanol could be used by up to 30% by vol. with diesel and the blends delivered lower soot density, NOx, and CO emissions under EGR.     

Short and long-term effects of clofibric acid and diclofenac on certain biochemical and ionoregulatory responses in an Indian major carp, Cirrhinus mrigala

Extensive use of pharmaceuticals in human and veterinary medicine and aquaculture practices pose a serious threat to aquatic organisms. In the present investigation, Cirrhinus mrigala an Indian major carp was exposed to different concentrations of clofibric acid (CA) and diclofenac (DCF) and certain biochemical and ionoregulatory responses were assessed under short and long term exposures. During short-term (96 h) exposure period, plasma glucose and sodium (Na⁺) levels were increased at all concentrations (1, 10 and 100 μg L⁻¹) of CA and DCF treated fish. Plasma protein and chloride (Cl⁻) levels were found to be decreased at all concentrations of CA and DCF exposed fish comparatively to control groups. Meanwhile an increase in plasma potassium (K⁺) level was noted in fish exposed to CA treatments alone and in DCF treatments it was decreased. In long-term exposure (35 d), plasma Na⁺ and Cl⁻ levels were found to be significantly increased at all concentration of CA and DCF. However, a biphasic trend was observed in plasma glucose, protein and K⁺ levels. In both the treatments, a significant (P < 0.01 and P < 0.05) changes were observed in all parameters measured in fish exposed to different concentrations of CA and DCF. The results of the present investigation indicate that both the drugs caused significant changes in biochemical and ionoregulatory responses of fish at all concentrations. The alterations of these parameters can be useful in monitoring of pharmaceutical residues present in aquatic environment.     

A mathematical model for a hybrid anaerobic reactor

A mathematical model for a hybrid anaerobic reactor (HAR), which uses self-immobilized anaerobic bacterial granules under completely fluidized condition, has been developed. Stoichiometry of glucose fermentation into methane has been considered in this model. The model includes: (1) a biofilm model which describes substrate conversion kinetics within a single granule; (2) a bed fluidization model which describes the distribution of biogranules within the fluidized bed and (3) a reactor model which links the above two to predict the substrate and products concentration profile along the reactor height. Product and pH inhibition for each group of bacteria has been considered in the kinetic model. The spatial distribution of each group of anaerobic bacteria within granules has been found to play a vital role in bringing about the conversion. Experiments were conducted in the reactor using a synthetic effluent containing glucose as the carbon source to study the treatment efficiency. The model was simulated first assuming a 3-layered distribution [MacLeod, F.A., Guiot, S.R., Costerton, J.W., 1990. Layered structure of bacterial aggregates produced in an upflow anaerobic sludge bed and filter reactor. Applied and Environmental Microbiology 56, 1598-1607.] of anaerobic bacteria within granules and then homogeneous distribution [Grotenhuis, J.T.C., Smit, M., Plugge, C.M., Yuansheng, X., van Lammeren, A.A.M., Stams, A.J.M., Zehnder, A.J.B., 1991. Bacterial composition and structure of granular sludge adapted to different substrates. Applied and Environmental Microbiology 57, 1942-1949.] of anaerobic bacteria. The predictions of model simulation with the assumption of layered structure closely represented the experimental data.     

Studies on the influence of natural resource utilization by humans on foraging behavior of honey bees at rural ecosystems

Environmental Science and Pollution Research - Human utilization of natural resources acts as a main driver in altering the ecosystem service and functions. Apart from indirect influence, these...     

In situ conservation of endangered tree species (Elaeocarpus venustus Bedd.) habitated in Agasthiyamalai Biosphere Reserve,Southern Western Ghats,India

Environmental Science and Pollution Research - Elaeocarpus venustus is an endemic as well as endangered tree species habitated in the wet evergreen forests of Southern Western Ghats (SWG), India....