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The treatment of waste gas (WG) containing dichloromethane (DCM) using advanced oxidation processes (AOPs) [UV and UV-TiO2], biological treatment (BT), and their combination (AOPs-BT) was tested. AOP tests were performed in an annular photo-reactor (APHR), while BT was conducted in a continuous stirred tank bioreactor (CSTBR). The effects of gas flow rate (Qgas), inlet DCM concentration ([DCM]i), residence time (τ), photocatalyst loading (PH-CL) and % relative humidity (% RH) on the AOPs performance and the removal of DCM (%DCMr) were studied and optimized. The UV process exhibited %DCMr ≤ 12.5 % for tests conducted at a [DCM]i ≤ 0.45 g/m3, Qgas of 0.12 m3/h and τ of 27.6 s, respectively, and < 4 % when the [DCM]i ≥ 4.2 g/m3. The UV-TiO2 achieved a %DCMr ≥ 71 ± 1.5 % at Qgas of 0.06 m3/h, [DCM]i of 0.45 g/m3, τ of 55.2 s, PH-CL of 10 g/m2, and %RH of 50, respectively. The BT process removed ∼97.6 % of DCM with an elimination capacity (EC) of 234.0 g/m3·h. Besides, the high %DCMr of ∼98.5 % in the UV-BT and 99.7 % in the UV-TiO2-BT processes confirms AOPs-BT as a promising technology for the treatment of recalcitrant compounds present in WG.

Interleaving of converters is a concept in the power electronics domain, which has been used extensively for dc-dc converters to improve the performance. Interleaving ensures reduction in the peak-to-peak ripple for both input and output currents. This concept also guarantees a reduction in the current stress levels for all the switching components involved in the converter circuit. In this paper, a switchedcapacitor (SC) based single-stage single-phase inverter operating in interleaved configuration has been proposed which is interfaced with a photovoltaic (PV) module and powers a stand-alone load. This inverter uses SC blocks to step-up the PV voltage and then delivers high quality ac voltage to load. A modified version of SC blocks has been used in this work, by ensuring that an equal number of controlled and uncontrolled switches are connected in each SC block, fewer controlled switches are put to use and economy is achieved. To consume maximum power from the PV panel and to operate it at its maximum power point, the Perturb and Observe technique has been employed. Feasibility of the proposed work has been evaluated by simulation studies in MATLAB/Simulink.

The increase in atmospheric CO2concentration and the release of nutrients from wastewater treatment plants(WWTPs) are environmental issues linked to several impacts on ecosystems. Numerous technologies havebeen employed to resolves these issues, nonetheless, the cost and sustainability are still a concern. Recently,the use of microalgae appears as a cost-effective and sustainable solution because they can effectively uptakeCO2and nutrients resulting in biomass production that can be processed into valuable products. In this study sin-gle (Spirulina platensis(SP.PL)andmixed indigenous microalgae(MIMA) strains were employed, over a 20-monthperiod, for simultaneousremoval of CO2fromflue gases and nutrientfrom wastewater under ambient conditionsof solar irradiation and temperature. The study was performed at a pilot scale photo-bioreactor and the effect offeed CO2gas concentration in the range (2.5–20%) on microalgae growth and biomass production, carbon diox-ide bio-fixation rate, and the removal of nutrients and organic matters from wastewater was assessed. TheMIMAculture performed significantly better than the monoculture, especially with respect to growth and CO2bio-fixation, during the mild season; against this, the performance was comparable during the hot season. Optimumperformance was observed at 10% CO2feed gas concentration, thoughMIMAwas more temperature and CO2concentration sensitive.MIMAalso provided greater removal of COD and nutrients (~83% andN99%) thanSP.PLunder all conditions studied. The high biomass productivities and carbon bio-fixation rates(0.796–0.950 gdw·L-1·d-1and 0.542–1.075 gC·L-1·d-1contribute to the economic sustainability of microalgae as CO2removal process. Consideration of operational energy revealed that there is a significant energy benefitfrom cooling to sustain the highest productivities on the basis of operating energy alone, particularly if the indig-enous culture is used.