Bioaugmentation of polyethylene succinate-contaminated soil with Pseudomonas sp. AKS2 results in increased microbial activity and better polymer degradation

Pseudomonas sp. AKS2 isolated from soil degrades polyethylene succinate (PES) efficiently in the laboratory. However, this organism may not be able to degrade PES with similar efficiency in a natural habitat. Since in situ remediation is preferred for the effective removal of recalcitrant materials like plastic, in the current study, bioaugmentation potential of this organism was investigated. To investigate the potential of the AKS2 strain to bioaugment the PES-contaminated soil, a microcosm-based study was carried out wherein naturally attenuated, biostimulated, and AKS2-inoculated (bioaugmented) soil samples were examined for their ability to degrade PES. The results showed better degradation of PES by bioaugmented soil than other microcosms. Consistent with it, a higher number of PES-degrading organisms were found in the bioaugmented microcosm. The bioaugmented microcosm also exhibited a higher level of average well color development in BiOLOG ECO plate assay than the other two. The corresponding Shannon–Weaver index and Gini coefficient revealed a higher soil microbial diversity of bioaugmented microcosm than the others. This was further supported by community-level physiological profile of three different microcosms wherein we have observed better utilization of different carbon sources by bioaugmented microcosms. Collectively, these results demonstrate that bioaugmentation of PES-contaminated soil with AKS2 not only enhances polymer degradation but also increases microbial diversity. Bioaugmentation of soil with AKS2 enhances PES degradation without causing damage to soil ecology. Thus, Pseudomonas sp. AKS2 has the potential to be implemented as a useful tool for in situ bioremediation of PES.     

Adsorptive removal of toxic azo dye Amido Black 10B by hen feather

Purpose and aim

Amido Black 10B is an azo dye with very high toxicity. It is now established that the dye damages the reparatory system of humans and also causes skin and eye irritations. It is therefore considered worthwhile to develop a systematic procedure to eradicate Amido Black 10B from its aqueous solution using a waste material as adsorbent. Therefore, adsorption of the dye is achieved using hen feathers as adsorbent.

Materials and methods

Before using hen feather as adsorbent material, it is washed, cut into small pieces and activated using hydrogen peroxide. Detailed chemical and physical analysis of hen feather was also carried out by known analytical techniques. The adsorptive removal of the dye was made through batch experiments in 100 mL airtight flasks. The experiment is divided in three major categories, the preliminary investigations, adsorption isotherm measurements, and kinetic studies.

Results

Under preliminary investigations, the effect of pH, temperature, concentration of dye, and amount of adsorbent were carried out. It was found that with increase in pH, the adsorption of Amido Black 10B decreases; while with increasing the amount of hen feather, it increases. The isothermal studies indicate that the ongoing adsorption process is endothermic in nature and obeys Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevitch (D–R) adsorption isotherm models. The Gibb’s free energy and entropy of the adsorption were also calculated. The D–R isotherm model verified the involvement of chemisorption during the adsorption. The kinetic measurements indicate operation of pseudo second order process during the adsorption and dominance of film diffusion mechanism at all the temperatures.

Conclusions

The developed method is highly efficient and ecofriendly. It also ascertains a necessitous utilization of waste material hen feather for the benefit of the society.     

Low-density polyethylene degradation by Pseudomonas sp. AKS2 biofilm

Polyethylene materials are a serious environmental concern as their nondegradable nature allows them to persist in the environment. Recent studies have shown that polyethylene can be degraded by microbes at a very slow rate, whereby detectable changes are evident after several years. In the present study, we report the degradation of low-density polyethylene by Pseudomonas sp. AKS2. Unlike the previous reports, degradation by Pseudomonas sp. AKS2 is relatively fast as it can degrade 5?±?1 % of the starting material in 45 days without prior oxidation. This degradation can be altered by agents that modulate hydrophobic interaction between polythene and the microbe. As mineral oil promotes hydrophobic interactions, it enhances bacterial attachment to the polymer surface. This enhanced attachment results in increased biofilm formation and enhanced polymer degradation. In contrast, Tween 80 reduces bacterial attachment to the polymer surface by lowering hydrophobic interactions and thereby reduces polymer degradation. Thus, this study establishes a correlation between hydrophobic interaction and polymer degradation and also relates the biofilm formation ability of bacteria to polymer degrading potential.     

Sorption of the veterinary antimicrobials sulfadimethoxine and ormetoprim in soil

Currently, limited research on the fate of antimicrobials in the environment exists, once they are discharged in human and animal wastes. Sorption of two antimicrobials, sulfadimethoxine (SDM) and ormetoprim (OMP), was investigated in two soils and sand using a series of batch experiments. Because OMP and SDM are often administered in combination, their sorption was also investigated in combination as co-solutes. The rate of SDM and OMP sorption was rapid over the first few hours of the experiments, which then slowed considerably after 16 to 68 h. OMP sorption was enhanced at high concentrations when in combination with SDM, with linear sorption coefficients ranging from 1.3 to 58.3 L.kg(-1) in the single solute experiments and 4.96 to 89.7 L.kg(-1) in the co-solute experiments. Sorption of OMP as a single solute seems to provide a better fit with the Freundlich equation, which became more linear (n approached 1) when SDM was present. Overall, SDM sorbed less than OMP in the two soils and sand. SDM linear sorption coefficients ranged from 0.4 to 25.8 L.kg(-1) as a single solute and 2.5 to 22.1 L.kg(-1) as a co-solute. Sorption of SDM becomes more nonlinear (n < 1) when SDM is present in combination with OMP. Overall, sorption of both antimicrobials increased in the selected soils and sand as the organic matter, clay content, and cation exchange capacity increased. These experiments indicate relatively low sorption of SDM and OMP in natural soils, making them a potential threat to surface and ground water.     

Role of blue green algae biofertilizer in ameliorating the nitrogen demand and fly-ash stress to the growth and yield of rice (Oryza sativa L.) plants

Rice is a major food crop throughout the world; however, accumulation of toxic metals and metalloids in grains in contaminated environments is a matter of growing concern. Field experiments were conducted to analyze the growth performance, elemental composition (Fe, Si, Zn, Mn, Cu, Ni, Cd and As) and yield of the rice plants (Oryza sativa L. cv. Saryu-52) grown under different doses of fly-ash (FA; applied @ 10 and 100 tha(-1) denoted as FA(10) and FA(100), respectively) mixed with garden soil (GS) in combination with nitrogen fertilizer (NF; applied @ 90 and 120 kg ha(-1) denoted as NF(90) and NF(120), respectively) and blue green algae biofertilizer (BGA; applied @ 12.5 kg ha(-1) denoted as BGA(12.5)). Significant enhancement of growth was observed in the plants growing on amended soils as compared to GS and best response was obtained in amendment of FA(10)+NF(90)+BGA(12.5). Accumulation of Si, Fe, Zn and Mn was higher than Cu, Cd, Ni and As. Arsenic accumulation was detected only in FA(100) and its amendments. Inoculation of BGA(12.5) caused slight reduction in Cd, Ni and As content of plants as compared to NF(120) amendment. The high levels of stress inducible non-protein thiols (NP-SH) and cysteine in FA(100) were decreased by application of NF and BGA indicating stress amelioration. Study suggests integrated use of FA, BGA and NF for improved growth, yield and mineral composition of the rice plants besides reducing the high demand of nitrogen fertilizers.     

Emission inventory of evaporative emissions of VOCs in four metro cities in India

High concentrations of volatile organic compounds (VOCs) in ambient air of urban areas stress the need for the control of VOC emissions due to the toxic and carcinogenic nature of many VOCs commonly encountered in urban air. Emission inventories are an essential tool in the management of local air quality, which provide a listing of sources of air pollutant emissions within a specific area over a specified period of time. This study intended to provide a level IV emission inventory as par the United States Environmental Protection Agency (USEPA) definition for evaporative VOC emissions in the metro cities of India namely Delhi, Mumbai, Chennai, and Kolkata. The vehicular evaporative emissions are found to be the largest contributor to the total evaporative emissions of hydrocarbons followed by evaporative losses related to petrol loading and unloading activities. Besides vehicle-related activities, other major sources contributing to evaporative emissions of hydrocarbons are surface coating, dry cleaning, graphical art applications, printing (newspaper and computer), and the use of consumer products. Various specific preventive measures are also recommended for reducing the emissions.     

Arsenic accumulation in native plants of West Bengal, India: prospects for phytoremediation but concerns with the use of medicinal plants

Arsenic (As) is a widespread environmental and food chain contaminant and class I, non-threshold carcinogen. Plants accumulate As due to ionic mimicry that is of importance as a measure of phytoremediation but of concern due to the use of plants in alternative medicine. The present study investigated As accumulation in native plants including some medicinal plants, from three districts [Chinsurah (Hoogly), Porbosthali (Bardhman), and Birnagar (Nadia)] of West Bengal, India, having a history of As pollution. A site-specific response was observed for Specific Arsenic Uptake (SAU; mg kg(-1) dw) in total number of 13 (8 aquatic and 5 terrestrial) collected plants. SAU was higher in aquatic plants (5-60 mg kg(-1) dw) than in terrestrial species (4-19 mg kg(-1) dw). The level of As was lower in medicinal plants (MPs) than in non-medicinal plants, however it was still beyond the WHO permissible limit (1 mg kg(-1) dw). The concentration of other elements (Cu, Zn, Se, and Pb) was found to be within prescribed limits in medicinal plants (MP). Among the aquatic plants, Marsilea showed the highest SAU (avg. 45 mg kg(-1) dw), however, transfer factor (TF) of As was the maximum in Centella asiatica (MP, avg. 1). Among the terrestrial plants, the maximum SAU and TF were demonstrated by Alternanthera ficoidea (avg. 15) and Phyllanthus amarus (MP, avg. 1.27), respectively. In conclusion, the direct use of MP or their by products for humans should not be practiced without proper regulation. In other way, one fern species (Marsilea) and some aquatic plants (Eichhornia crassipes and Cyperus difformis) might be suitable candidates for As phytoremediation of paddy fields.     

Environmental impact of coal washery and Damodar River water on the morphometry and biochemical changes of maize (Zea mays L.) and soil health

Enormous quantity of water is used for coal beneficiation and accordingly huge amount of effluents are being generated. In this study an attempt was made to evaluate the potential of this effluent water for irrigation. Water samples were collected from three different points (a) feeding point, (b) thickening point, and (c) outlet point of coal washery, and from Damodar River for monitoring the water quality. The samples were analyzed for various parameters and compared with prescribed standard, which revealed that the total suspended solids of thickening point and Damodar River were higher. A pot experiment with maize was conducted to study the suitability of this coal washery water for irrigation. Pots were irrigated with water from the three points of washery and Damodar River in two concentrations (100% and 50% dilution with distilled water); pure distilled water was used for control. There was 100% germination in all the treatments. The plant growth, chlorophyll content and soil quality parameters were significantly better in washery and Damodar River water treated pots. The Damodar River water and washery water from feeding and outlet point could be successfully used for irrigation. In general mixing with good quality water has shown better results.     

Particulate matter concentration in ambient air and its effects on lung functions among residents in the National Capital Region, India

The World Health Organization has estimated that air pollution is responsible for 1.4 % of all deaths and 0.8 % of disability-adjusted life years. NOIDA, located at the National Capital Region, India, was declared as one of the critically air-polluted areas by the Central Pollution Control Board of the Government of India. Studies on the relationship of reduction in lung functions of residents living in areas with higher concentrations of particulate matter (PM) in ambient air were inconclusive since the subjects of most of the studies are hospital admission cases. Very few studies, including one from India, have shown the relationship of PM concentration and its effects of lung functions in the same location. Hence, a cross-sectional study was undertaken to study the effect of particulate matter concentration in ambient air on the lung functions of residents living in a critically air-polluted area in India. PM concentrations in ambient air (PM_1, PM_2.5) were monitored at residential locations and identified locations with higher (NOIDA) and lower concentrations (Gurgaon). Lung function tests (FEV₁, PEFR) were conducted using a spirometer in 757 residents. Both air monitoring and lung function tests were conducted on the same day. Significant negative linear relationship exists between higher concentrations of PM₁ with reduced FEV₁ and increased concentrations of PM_2.5 with reduced PEFR and FEV₁. The study shows that reductions in lung functions (PEFR and FEV₁) can be attributed to higher particulate matter concentrations in ambient air. Decline in airflow obstruction in subjects exposed to high PM concentrations can be attributed to the fibrogenic response and associated airway wall remodeling. The study suggests the intervention of policy makers and stake holders to take necessary steps to reduce the emissions of PM concentrations, especially PM_1, PM_2.5, which can lead to serious respiratory health concerns in residents.