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Biochar (BC) is a viable wastewater treatment agent. Water lettuce (Pistia spp.) an invasive aquatic plant in Sri Lanka has been used in this study to produce BC by pyrolysis. Industrial water was filtered through activated and non-activated BC samples having 65-125 mm and 125-250 mm particle sizes. Filter with sand and gravel served as standard for comparison. The filter unit containing activated BC showed higher treatment efficiency. pH was reduced from 8.72 ± 0.01 to 6.87 ± 0.01; biological oxygen demand (BOD5) from 57 ± 1.73 to 15.67 ± 1.15 ppm; chemical oxygen demand (COD) from 512 to 128 ppm, total Kjeldahl nitrogen (TKN) from 158.67 ± 2.89 ppm to 33 ppm, ammoniacal nitrogen from 22.63 to 3.13 ± 0.01 ppm; chromium from 0.0625 to 0.0245 ppm, and zinc from 0.9886 to 0.2105 ppm. Optimization study revealed that the BC integrated filter units could be used to treat wastewater in three cycles. Thereafter their efficiency is reduced. The BCs with small particle size (65-125 mm) recorded the highest treatment efficiency. This particle size showed 99.72% turbidity reduction. Reduction of total phosphate, ammoniacal nitrogen, total suspended solids, COD, nitrate, BOD5 and TKN was recorded as 97.82%, 91.49%, 88.38%, 88.18%, 87.44%, 84.38% and 84.38% respectively. BC derived from Pistia spp. has proven to be promising adsorbent for wastewater treatment. Findings of the study show a long-term green wastewater treatment method that makes effective use of an invasive aquatic plant. [ABSTRACT FROM AUTHOR]

Urbanization and rapid industrialization have led to the escalation of municipal solid waste generation and accumulation. Composting is widely recognized as a sustainable solution for solid waste management. However, its long-term investment is considered a disadvantage. The present research study discusses the rapid biotransformation of solid waste into valorized compost. Bacteria were isolated from soil, solid waste, and leachate samples from open dump sites. From the 18 different bacterial consortia created using potential isolates, the five most promising consortia were selected based on concurrent different enzyme production. These selected consortia were incorporated into typical compost bins with Municipal Solid Waste (MSW). Daily monitoring of enzymatic activity, pH, conductivity, bulk density, moisture, and temperature, along with other composting parameters, was conducted. The study’s results demonstrated that consortium No. 5, comprising Bacillus haynesii, Bacillus amyloliquefaciens, and Bacillus safensis, exhibited significant (p<0.05) enzyme activity of cellulase, amylase, lipase and proteinase enzymes during composting compared to the control and other treatment setups. Consortium No. 5 also facilitated rapid and successful composting, as evidenced by significant alterations of composting parameters by exhibiting a shorter average composting time, reducing it from 110±10 days to 20±3 days, showcasing the potential applicability of formulated bacterial consortium as a sustainable and greener approach to the global solid waste problem. The novelty of this study lies in the isolation of local bacterial strains from open dump sites soil, MSW, and MSW leachate samples, which were then utilized in the composting organic fraction of MSW, enhancing the potential for effective waste management. [ABSTRACT FROM AUTHOR]