Treating agricultural non-point source pollutants using periphyton biofilms and biomass volarization.

Untreated domestic wastewater and agricultural runoff are emerging as a potent cause of non-point source (NPS) pollutants which are a major threat to aquatic ecosystems. Periphyton biofilm-based technologies due to their high growth rate, energy efficiency and low input costs offer promising solutions for controlling nutrient pollution in agricultural systems. In this study we employed periphyton floway to treat NPS pollution from the agricultural watershed. The process performance of outdoor single pass algae floway (AFW) was evaluated. Steady state average biomass concentration of 11.73 g m-2 d-1 and removal rate of nitrogen: 0.60 g m-2 d-1, phosphorus: 0.27 g m-2d-1, arsenic: 9.26 mg m-2 d-1, chromium: 255.3 mg m-2 d-1 and lead: 238.6 mg m-2 d-1 was achieved. In addition, the microalgae and their associated bacterial diversity and dynamics were analyzed. The results revealed a high diversity and rapid variations in the microbiome structure with diatom and cyanobacteria dominance combined with high N fixing and P solubilizing bacteria during most of the operational period. Elemental analysis of periphyton biomass was done for its safe use as slow-release fertilizer. Biofuel feedstock potential and nanoparticle generation potential of the biomass were analyzed. This work highlights the potential use of periphyton biofilms in remediation and recycling of NPS pollutants with simultaneous resource recovery.

Constructed wetland for improved wastewater management and increased water use efficiency in resource scarce SAT villages: a case study from Kothapally village, in India.

Evaluation a field-scale of constructed wetland (CW) for the treatment of rural wastewater (WW), in resource-scarce semi-arid tropic (SAT) villages, to provide improved wastewater management and increased water use efficiency, was the main objective of this study. A CW was commissioned in Kothapally village of Telangana to treat the wastewater generated from 100 households. The CW was vegetated with Typha latifolia and Canna indica. Average COD, sulfate and inorganic nitrogen removal efficiencies observed were 65%, 60% and 67% respectively, for the study period (one year). Removal efficiency for total coliform was consistently above 80%. The treated wastewater was stored in a farm pond and was utilized for irrigation in the nearby agricultural fields (0.6 ha). This perennial source of water, helped the nearby farmers to cultivate two additional crops, chickpea during rabi and sweetcorn during summer. The assured availability of water reduced their vulnerability to dry spells during the kharif by providing means for lifesaving irrigation. The biomass harvested from the constructed wetland was used as fodder for the livestock. A net additional income of Rs.70,000 (∼US$1,000) was realized by the farmers using the treated wastewater for cultivation. Similar constructed wetland-based wastewater management system can be scaled up across water scarce semi-arid tropics. Novelty statementField-scale performance evaluation of constructed wetland based wastewater treatment in a semi-arid tropic village is scarce in the literature. The work presented gives a feasibility assessment for this technology critical for its wide-scale application to augment rural wastewater management in resource poor villages.

Biodiesel production through algal cultivation in urban wastewater using algal floway.

The aim of this work was to study algal floway (AFW) to treat urban wastewater and to evaluate biomass productivity, lipid contents and biodiesel production. The results indicated the seasonal average algae productivity of 34.83 g dry weight m2 d-1 with a nutrient removal rate of 2.52 g m2 d-1N and 1.25 g m2 d-1P while the lipid content ranged between 14 and 22% of dry cell weight with the highest lipid productivity of 9.29 g m-2 d-1 during summer. Biodiesel quality was superior during summer with high centane number and cold filter plugging point values. High eicosapentaenoic acid content was found during winter growth cycles. AFW algae community was dominated by pennate diatoms during all growing seasons. This study is one of its kinds in Indian wastewaters and it provides fundamental information for further optimization and use of AFW to treat domestic wastewater and to produce algae biofuel feedstock.

Biodegradation of volatile organic compounds from paint industries.

Methyl ethyl ketone (MEK) and methyl iso-butyl ketone (MIBK) constitute significant proportion of the total VOC emissions from manufacturing and application processes of surface coatings. Biodegradation of MEK and MIBK using an acclimatized mixed culture was evaluated, under aerobic condition. Biodegradation studies were carried out using MEK and MIBK as single substrates and in combination. Mixed-pollutant studies were conducted in MEK-dominated system, MIBK-dominated system, and MEK-MIBK equi-concentration systems to understand the concentration-dependent interaction of these compounds in a biosystem. Experimental data obtained from single-pollutant system was used to estimate the biokinetic parameters, viz. µ(max), K(s), K(i), and Y(T), for these compounds. Among the several bio-kinetic models tested, Monod inhibition model was best suited for predicting the biodegradation of these two VOCs. Four multiple-substrate models, viz. no-interaction, competitive, un-competitive, and non-competitive were used to study the nature of inhibition for different combinations of these compounds. The biodegradation of MEK and MIBK mixtures was found to be best described by competitive inhibition model. However, the predictions were not very good for systems where MEK concentration was higher than MIBK concentration.