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The non-aromatic, heterocyclic hexamine is one of the most refractory pollutants in some industrial effluents and food-grade plastics. This compound and its derivatives harm human health with limited options for eco-friendly biological treatment. This study reports the characterization of two rapid hexamine-removing bacterial isolates, Micromonospora citrea SRCHD01 and Micrococcus luteus SRCHD02, from wastewater of Hexamine producing plant at Vishakapatnam, India. The former is a structured biofilm former while the latter is a weak biofilm former with both isolates dividing faster under immobilized conditions. Isolate SRCHD01 could reduce 200 mg/L hexamine to 84.91 mg/L in 24 h with associated Chemical Oxygen Demand (COD) reduction of 99% from an initial concentration of 8028.93 mg/L within 120 h, making it the fastest hexamine-removing bacteria reported till date. The investigation opens a new avenue for studying the bioremediation of hexamine in biofilm reactors ensuring environmental protection. [ABSTRACT FROM AUTHOR]

Dairy industries are highly polluting, energy and fresh water consuming installations. The present study aims to make dairy effluent treatment plant operation less time consuming with minimal energy consumption while generating a value added product. Analysis of the temporal and spatial variation in performance of a biofilm based plug flow reactor involved in the biotransformation of Dairy Waste Water (DWW) revealed ammonia (57.68 mg L–1) rich liquid biofertilizer production within 4 h, with associated reduction of nitrate (70.77%), phosphate (36.44%), protein (62.87%), Biological Oxygen Demand (BOD) (26.38%) and Chemical Oxygen Demand (COD) (39.59%). The process was 4 times faster than the fastest existing process reported till date. The consortium showed a striking reduction in its doubling time from 78 min 56 sec (in suspension culture) to 17 min 10 sec (as biofilm) upon immobilization. It could produce 734.60 mg ammonia per kg of immobilization matrix from DWW. Metagenomic analysis revealed the robustness of the biofilm based biotreatment system. The novelty of this study is the innovative approach of rapid conversion of the waste from dairy industry into a value added product using microbes from geosphere in an energy efficient manner which would make dairy effluent treatment plant operation self-sustainable and eco-protective. [ABSTRACT FROM AUTHOR]

Modified medium DSMZ 641 used for the growth of SRB consortium developed in the laboratory through enrichment of soil slurry from wastewater fed aquaculture pond at Kolkata India, contained various components that added to the Chemical Oxygen Demand of the solution, making large scale operations using this consortium non-viable. The minimal medium optimization study was carried out using a "one at a time" approach analyzing sulfate reducing ability of the consortium. The consortium reduced soluble sulfate concentration by 70 and 78% (starting from an initial concentration of 2000–3000 mg/L) under suspended and immobilized states, respectively, in 50 mL working volume. The process upon scaling up to 9 L in a vertical biofilm reactor under batch mode could reduce sulfate from the optimized medium by 76% in 4 h, while the same in modified DSMZ 641 was 74%. Response Surface Methodology revealed the optimum concentration of Carbon (Lactic Acid), Nitrogen (Yeast Extract, Ammonium Chloride), and Phosphorus (Potassium Phosphate) in the medium to be 6 mL/L, 500 mg/L each and 750 mg/L respectively. [ABSTRACT FROM AUTHOR]

The present study attempts to integrate phyco-remediation and enhanced lipid productivity using microalgae-bacterial consortium enriched from wastewater fed aquaculture pond. Metagenomic analyses and microscopic images of the consortium revealed the presence of Chlorella variabilis, Parachlorella kessleri, Thermosynechococcus elongatus, Chlamydomonas, Phaeodactylum tricornutum, Oscillatoriales, Synechocystis sp. , Microcystis aeruginosa, Nostocales, Naviculales, Stramenopiles, other members of Chlorophyceae, Trebouxiophyceae, and Chroococcales along with potential bacterial bioremediants. During a 30 days trial run (15 days stabilization and 14 days remediation studies) for phyco-remediation drastic reduction in the nutrient and COD content from the tested wastewater samples was seen. There was up to 93% and 87.2% reduction in chemical oxygen demand (COD) and ammonium concentration, respectively. Further, almost 100% removal of nitrates and phosphates from the dairy wastewater upon 48 h of treatment with polyculture under ambient temperature (25 ± 2 °C) with 6309 lux illumination and mild aeration, was observed for all the seven cycles. Interestingly, the nutrient and COD concentrations in the treated water were below the discharge standards as per Central Pollution Control Board (CPCB) norms. In additions, biomass (reported as dry cell weight) was enhanced by 67% upon treatment with ammonia-rich dairy wastewater exhibiting 42% lipid, 55% carbohydrate, and 18.6% protein content enhancement. The polyculture mainly grown as attached biofilm to the surface, offered an easy harvesting and separation of grown biomass from the treated wastewater. Overall, dairy wastewater was found to be a potential nutrient source for microalgae-bacteria cultivation thereby making the treatment process sustainable and eco-friendly. [Display omitted] • 42% lipid and 1.7-fold algal biomass enhancement during dairy wastewater treatment. • Wastewater treatment within 48 h incubation for discharge and reuse. • An integrated approach for algal biomass production and wastewater treatment. [ABSTRACT FROM AUTHOR]

Dairy industry generates copious amount of wastewater from its milk processing unit (1–10 m3 of wastewater per m3 of processed milk) which needs to be treated before getting discharged. The conventional treatment processes are tedious, energy intensive, and an additional burden for the dairy industry. This study attempts to develop an alternative strategy to convert the dairy wastewater into liquid biofertilizer. A tailor-made microbial consortium-based biofilm reactor with 8.64 m3 d−1 processing capacity, within 16 h of hydraulic retention time (HRT) at ambient temperature produced biofertilizer containing 96.01 mg L−1 ammonia from dairy wastewater at a flow rate of 360 L h−1 with associated 73.72% nitrate, 72.46% phosphate, 61.30% Biological Oxygen Demand (BOD) and 57.23% Chemical Oxygen Demand (COD) reduction. A similar system of 10.94 m3 d−1 processing capacity at 456 L h−1 flow rate produced 298.79 mg L−1 ammonia with nitrate, phosphate, BOD and COD reduction of 42.71%, 84.80%, 89.55% and 76.68% respectively. This liquid biofertilizer could enhance grain yield in maize (Zea mays var. Vijay) by 1.19-fold. It increased biomass yield in Sorghum Sudan grass (Sorghum sudanense) by 3.5-folds and Lemongrass (Cymbopogon citratus var. Dhanitri and var. Krishna) by 2.1 and 2.64 folds respectively. It enhanced gel content in Aloe vera (Aloe elongata var. Ghikuari) by 1.63-folds when compared to chemical fertilizer treatment. This single-step dairy wastewater treatment system requires ten times less energy with the development of a value-added product (biofertilizer). It could make the dairy wastewater management a revenue earning (USD 10.28 d−1 for 600 m3 d−1 processing capacity reactor), eco-friendly, zero discharge process preventing the use of freshwater and chemical fertilizer in agriculture, and saving 89.99% carbon dioxide equivalent (CO 2 eq.) gas emission leading to environmental protection. [Display omitted] • Single-step process compared to 7–8 steps necessary in conventional wastewater treatment. • Microbe based bioconversion of dairy wastewater to ammonia rich biofertilizer. • Liquid biofertilizer enhanced yield of economic crop compared to chemical fertilizer. • 2.5 times inexpensive, 10 times less energy intensive compared to conventional system. • Minimizes fresh water consumption, 89.99% savings on CO 2 equivalent gas emission. [ABSTRACT FROM AUTHOR]