Pretreatment optimisation and kinetics of batch anaerobic digestion of liquidised OFMSW treated with NaOH: Models verification with experimental data.

The enormous generation of municipal solid waste (MSW) due to increased urbanization is causing threat to the environment. MSW is a mixed waste and it comprises of organic fraction as the key fraction called organic fraction of municipal solid waste (OFMSW) along with other fractions. The pretreatment of OFMSW is necessary step to increase the biogas yield. In the present work, NaOH hydrolysis of mechanically liquidised OFMSW was carried out to reduce its complexity and improve the biogas production. Furthermore, hydrolysis parameters were optimised by RSM model for NaOH pretreatment. Optimised conditions achieved from RSM analysis were 0.46 N NaOH loading, 72 h reaction time and 36.05 °C operating temperature. The RSM predicted values of response sCOD and VFA at optimum condition were in good agreement with experimental data signifying the model adequacy. The kinetic of batch anaerobic digestion of OFMSW treated with NaOH at different concentrations and optimised condition had been studied to see the suitability of first order model and modified Gompartz model. The experimental results obtained were best fitted using normalized root mean square error analysis. Biogas production after pretreatment at 0.1, 0.5, 0.9 N NaOH concentration and RSM optimised condition was 369.24, 435.24, 327.84 and 465.67 NL/kg VS, respectively.

Characterization of organophosphate pesticide sorption of potato peel biochar as low cost adsorbent for chlorpyrifos removal.

There has been a growing interest in the scientific world in the production of biochar from natural organic wastes as potential sustainable precursors for bioremediation. Potato peel biochar was produced by slow pyrolysis method under oxygen-limited conditions and used as bio adsorbent in bioremediation of commercial pesticide having Chlorpyrifos as an active component. Chlorpyrifos is an organophosphate pesticide, highly neurotoxic, and primarily targets the central nervous system of pests and insects. The excess residues of chlorpyrifos are hazardous to environmental flora and fauna. Chlorpyrifos was treated against biochar at varying physical parameters and further optimized by using response surface methodology through Box-Behnken design (BBD). 72.06% of pesticide removal was observed post 24 h of treatment against a pesticide concentration of 1346.85 µg/ml with a biochar concentration of 1.04 mg/ml under room temperature at pH 5.04. Biochar was characterized by proximate and ultimate analysis, FTIR, and SEM-EDX. Characterization by SEM-EDX showed the surface morphology and minerals on the peel and biochar. Microgram of potato peel shows pores of larger size than biochar having many cavities with different dimensions. In the plant system, growth morphology, nutritional status, polyphenols, total antioxidant content, and free radical scavenging activity were assessed. Enhancement in presence of biochar was recorded in growth morphology and plant biomolecules including photosynthetic pigments. Better translocation of the nutrient is recorded in biochar treated plants, as evidenced by the low amount of carbohydrate and protein in treated leaves. Biocompatibility assessment of chlorpyriphos in fish erythrocytes showed 43.26% hemolysis by pesticide-treated biochar. The practical use of this approach can also be best utilized if applied to those geographical regions where the soil pH is acidic. Biochar is a marketable bio-product, which can have a positive impact in agriculture, industries, and the energy sector creating a bio-based economy with reduced environmental pollution.

Experimental process parameters optimization and in-depth product characterizations for teak sawdust pyrolysis.

Pyrolysis is an efficient thermochemical route to obtain biofuels in the form of bio-oil, biochar and pyrolytic gas from the processing of biomass. Pyrolysis experiments were performed with teak sawdust to determine the yield and main characteristics of solid, liquid and gaseous products. Experiments were carried out in the temperature range of 400-700 °C in 100 °C intervals, nitrogen flow rate of 150-250 mL/min, packed bed height in between 2 and 8 cm and particle size in between 0.18 and 0.60 mm. The maximum bio-oil and biochar yield were observed at 600 °C (48.8%) and 400 °C (37.42%), respectively. Physical properties (viscosity, density, carbon residue, pH and HHV) of bio-oil were determined and the chemical properties were investigated using FTIR and GC-MS. Further, biochar was characterized with proximate, ultimate, HHV, FTIR, SEM-EDX, BET surface area and XRD analysis. Non-condensable gases coming out during pyrolysis were analyzed using gas chromatography and amount of H2, CH4, CO and CO2 were determined. According to characterization results, bio-oil can be used as biofuel after up gradation or as source of valuable chemicals, biochar can be utilized as solid fuel or seems to be suitable in waste stream purification as it has very high BET surface area. In addition, pyrolytic gases have significant amount of methane and hydrogen that provides good combustion properties.