In this study, cold plasma was used to prepare plasma‐activated water (PAW) from a dielectric barrier discharge plasma source, with ambient air as the plasma‐forming gas. The PAW prepared was characterized for its physicochemical parameters, some of which followed a strong linear correlation with activation time (ta). The effects of PAW addition on the cell viability of human breast cancer cells (MDA‐MB‐231) and healthy murine muscle‐derived fibroblast cells were investigated using the MTT assay. The volume of PAW added and ta of PAW showed a significant impact. The PAW prepared was selective toward killing cancer cells at specific ta. PAW retains its potency against cancer cells after 14 days of refrigerated storage.

Successful application of plasma-activated water (PAW) as an alternate source of nitrogen for agricultural application requires low specific energy consumption. This work reports on a dielectric barrier discharge (DBD) plasma reactor for the generation of PAW having low specific energy (SE) consumption. The SE to produce N in PAW was 3.26 GJ/kg of N, which is 68% lower than the lowest value reported to date for DBD-PAW systems. The PAW generated was characterized for its physico-chemical parameters, most of which showed a linear increase with activation time (ta). The concentration of hydrogen ion and that of the nitrate, which is the desired product for agricultural application, remained stable for four weeks in the PAW. The results indicate that minimal reactive oxygen species was formed in the plasma zone and only reactive nitrogen species (RNS) was formed confirming selectivity toward RNS.

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Rural areas in developing countries face the twin challenges of water scarcity and risk of groundwater contamination due to lack of water treatment options. A decentralized greywater treatment system for reuse is an option that addresses both of these challenges. This study reports the performance of a decentralized greywater treatment and reuse system which was constructed and operated for over 12 months in a government-managed school in rural India. The handwash and kitchen wash wastewater streams were treated separately due to differences in the initial greywater characteristics. The treatment stages included pre-treatment using screens and grease traps, slow sand biofiltration combined with anaerobic sludge bioreactor, and aeration before the final ozone-based disinfection stage. The treated water at the end of all these stages was used for toilet-flushing in the school. The treatment system was operated for one year and sampling was performed to investigate the system performance. The overall treatment system showed removal efficiencies of 99 %, 98 %, 66 %, 73 %, 98 %, 96 % and >99.99 % for the parameters of turbidity, total suspended solids, nitrate, total phosphorus, biological oxygen demand (5 days), chemical oxygen demand and fecal coliform respectively. This study quantifies the performance of each subsystem and demonstrates for the first time that a decentralized greywater treatment can be operated effectively and economically in a rural Indian setting.

Arc velocity and erosion rate measurements were performed on nanostructured pure Cu cathodes in 10−5 Torr vacuum (1.3324 m Pa), in an external magnetic field of 0.04 T. Five different kinds of nanostructured cathodes were produced by spraying pure Cu powders of three different sizes, on Cu coupons by atmospheric pressure plasma spraying and high velocity oxygen fuel spraying techniques. The erosion rates of these electrodes were obtained by measuring the weight loss of the electrode after igniting as many as 135 arc pulses, each of which was 500 µs long at an arc current of 125 A. The arc erosion values measured on three kinds of nanostructured coatings were 50% lower than the conventional pure massive Cu cathodes. Microscopic analyses of the arc traces on these nanostructured coatings show that the craters formed on these coatings were smaller than those formed on conventional Cu (<1 µm in diameter compared with 7–12 µm diameter on conventional Cu). It was concluded that nanostructured cathodes had lower erosion rates than conventional pure Cu cathodes.