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Two phase bioreactor was constructed, designed and developed to evaluate the chlorpyrifos remediation. Six biotic and abiotic factors (substrate-loading rate, slurry phase pH, slurry phase dissolved oxygen (DO), soil water ratio, temperature and soil micro flora load) were evaluated by design of experimental (DOE) methodology employing Taguchi's orthogonal array (OA). The selected six factors were considered at two levels L-8 array (2^7, 15 experiments) in the experimental design. The optimum operating conditions obtained from the methodology showed enhanced chlorpyrifos degradation from 283.86 µg/g to 955.364 µg/g by overall 70.34% of enhancement. In the present study, with the help of few well defined experimental parameters a mathematical model was constructed to understand the complex bioremediation process and optimize the approximate parameters upto great accuracy.

In the present study, the effect of chlorpyrifos (CP), its degradation product TCP and N-substituted aromatic compounds (nitrophenol and amino phenol) on methane production from organic solid waste...

In this study, a novel immobilizing carrier with α-Fe2O3 magnetic nanoparticles was developed and used for immobilization of atrazine-degrading bacterial isolates of Bacillus spp. Since the free cells of microorganisms generally not succeed to degrade pollutants; thus, extra treatments are alluring to make strides biodegradation. Scanning electron microscope (SEM) images appeared that after immobilization the bacterial cells were totally retained and entirely distributed on the surface of α-Fe2O3 magnetic nanoparticles. The performance of α-Fe2O3 immobilized cells in atrazine (ATZ) degradation was compared with the free cells, which was about 90.56% in 20 days. Experimental results exhibited that ATZ could be degraded at a broad range of physicochemical parameters viz. pH (4.0 to 9.0), temperature (20 to 45 °C), ATZ concentration (50 to 300 mg L−1) and agitation speed (50 to 300 rpm), which underlines that α-Fe2O3 immobilized cells could tolerate a higher range of ATZ concentration as compared to free cells. This research demonstrated that α-Fe2O3 could be applied as a potential carrier in cell immobilization and biodegradation of ATZ herbicide with greater efficiency.

The effect of biosurfactants (surfactin and rhamnolipid) on the methane production from organic solid waste (OSW) investigated using co-culture of facultative anaerobes Methanosarcina mazei and Pseudomonas aeruginosa+Bacillus subtilus. The biosurfactants were applied in the concentration ranges 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 5.g/l respectively. Cumulative methane production (P), maximum methane production rate (Rmax) and lag phases (e) were analyzed using the modified Gompertz model. Results revealed that both the biosurfactants were effective in methane production enhancement. The maximum cumulative methane production of 2.10 L-CH4/L-substrate and 1.91 L-CH4/L-substrate recorded at 3.5% surfactin and 3.0% rhamnolipid, respectively. Corresponding highest methane yields were 77.7 mL CH4/g Carboinitial and 70.7 mL CH4/g Carboinitial, respectively. The lag phase decreased from 13.9±0.2 hours at control to a minimum of 9.93±0.04 and 10.02±0.02 surfactin and 3.0% rhamnolipid, respectively. Volatile fatty acid generation subsequently increased with biosurfactants additive.

The massive growth of urbanization, agriculture, and other anthropogenic activities has created serious environmental pollution with the use of numerous recalcitrant chemicals. Various polycyclic aromatic hydrocarbons, aromatic hydrocarbons, nitroaromatic compounds, polychlorinated biphenyls, dioxins, and their derivatives are greatly toxic, mutagenic, and carcinogenic to natural microflora as well as to humans. In the biodegradation of toxic organic compounds, xenobiotics, and heavy metals, hyperaccumulating plants and plant-associated bacteria (including endophytic bacteria and rhizospheric bacteria) have enormous potential to improve phytoremediation. In particular, endophytic and rhizospheric bacteria may break down recalcitrant chemicals in polluted soil. Approaches from toxicology, stress physiology, and ecotoxicology will be helpful for the characterization of plant responses to recalcitrant chemicals. Therefore, it is necessary to understand plants’ adaptation strategies against various harmful recalcitrant chemicals.

The impact of prevailing disturbances in montane habitats of Nanda Devi Biosphere Reserve (NDBR) was studied on soil microbial population, biomass, soil respiration and enzyme activities during wet and dry seasons. The physico-chemical characteristics of soils exhibited conspicuous variation in total carbon and nitrogen content; being maximum in grazed meadow soil in wet season and minimum in intact forest soil in dry season. The rate of N-mineralization and nitrification was maximum (31.5 μg g − 1 day − 1 and 10.3 μg g − 1 day − 1 ) in grazed meadow soil during wet season and minimum (9.7 μg g − 1 day − 1 and 4.8 μg g − 1 day − 1 ) in intact forest soil during dry season. The bacterial and fungal populations were also highest in grazed meadow soil followed by disturbed forest, residential area and lowest in intact forest soil, especially in wet season. The soil respiration and enzyme activities (dehydrogenase and alkaline phosphatase) were found maximum in grazed meadow soil during wet season and minimum in intact forest soil during dry season. Correlation analysis among variables at different sites revealed significant and positive correlation among soil organic matter, microbial biomass and activities, emphasizing ‘successional effect’ on health and fertility status of soil.

A pot experiment was carried out to evaluate the effect of Pseudomonas fluorescens and Trichoderma harzianum inoculation on the uptake of zinc (Zn) and cadmium (Cd) by Indian mustard (Brassica juncea) from the soil having three different concentrations of Zn (300, 600, 900 mg/kg) and Cd (5, 10, 15 mg/kg) separately. Microbial inoculation resulted in significantly better plant growth, available metal content and their uptake than control (without microbes). Available Zn was enhanced, ca.1.6- and 1.4-fold and Cd ca. 2.5- and 1.8-fold, by P. fluorescens and T. harzianum, respectively. P. fluorescens resulted in an increase in Zn uptake by 113.9, 51.9 and 58.4% and T. harzianum by 42.6, 32.1 and 33.9% over control from soils having 300, 600 and 900 mg Zn, respectively, while of the corresponding results for Cd were 110.2, 48.9 and 58.1% with P. fluorescens and 42.6, 30.9 and 33.4% with T. harzianum from soil having 5, 10 and 15 mg Cd, respectively, after 90 days of treatment. In general the rate of m...

The effect of plant-eating by the slug, Mariaella dussimieri Gray, and by certain lepidopteran insects and their larvae was studied under field conditions, on the growth of two sympatric annual weeds, Galinsoga ciliata (Raf.) Blake and G. parviflora Cav., in pure and mixed stands. Under the influence of herbivory, both weeds generally produced a greater number of leaves, but the leaf area per plant was drastically reduced. Plant survival and seed output decreased in both weeds due to herbivory, but the effect was more severe in G. parviflora, especially in the mixed stands. Herbivory also reduced the dry matter yield and delayed flowering in G. parviflora. Relatively poor growth of G. parviflora in the mixed stand exposed to herbivory could be attributed to its preferential feeding by the slug and insects which reduced the competitive ability of this weed against G. ciliata.