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Introduction: It is a well-known fact that the demand of water increases with population increase. W.H.O. reported that by 2025, half of the population will be not able to have a clean source of water (1). Thus, water has to be used judiciously and should not be wasted. Estimates vary, but a typical household use about 80-100 gallons of water per day. The largest use of water in every house is for washing clothes, bathing, toilet flush, washing dishes. Urban waste water which includes water from bath, shower, hand basins, washing machine, dishwashers and kitchen sinks, but excludes streams from toilets is called grey water (2). Grey water which is also primarily discharged from washed laundry contains high in surfactants and is also very high in suspended solids, turbidity and oxygen demand. When the grey water is released without treatment it can cause environmental pollution and serious threat to living being. Currently treatment of laundry water is a challenge because of rapid population growth and also it is not accompanied by infrastructure improvements, especially in the field of sanitation. It is important that wastewater should be treated in order to save water as a future source and protect the environment from pollution. Previously grey water treatment was done physically where pollutants from grey water were removed by coarse sand and soil filtration (3). Now with the advancement of membrane-based water treatment technologies, such treatment methods have come into focus (4). The main object of this study to recover the valuable surfactant solution and generate potable water both of which could be reused again thereby leading to a cost effective, sustainable and environment friendly process. Methods: An experimental setup has been developed which uses a spiral wound UF membrane that essentially removes the suspended matter from the grey water that was taken as the feed solution. The reject from this membrane is recycled back to the feed tank whereas the permeate enters a spiral wound RO membrane where the surfactant is removed from the solution thereby allowing potable water pass as a permeate. Both the membrane modules were optimized for its operating pressure and flowrates. Results & Discussions: The collected grey water used for the experiment was found to have TDS of 749 ppm, Turbidity of 106 NTU and BOD of 290 mg/l. On treating it using the UF membranes, the recovered surfactant was found to have a TDS of 830 ppm, turbidity of 12.6 NTU and BOD of 110 mg/l indicating the collection of concentrated surfactant solution. The potable water which was collected later as RO permeate tested to have a TDS of 25 ppm, turbidity of 0.41 NTU and BOD of just 20mg/l indicating that the RO permeate is now potable. Conclusions: The process leads to an effective separation process where the grey water obtained from washing machine was first cleaned of dirt materials using UF membranes and further separating the surfactant solution from the mixture and yielding potable water. The recovered concentrated surfactant solution as well as potable water could be reused again for future washes. The process thus leads to conservation of water too in addition to being cost effective and environment friendly. Keywords: Grey water treatment; surfactant recovery; potable water recovery; UF and RO membranes. Acknowledgment: The authors would like to thank the Vice Chancellor, Tripura University for providing necessary research facility. References 1. WHO. No Title [Internet]. W.H.O. 2019 [cited 2021 Sep 11]. Available from: https://www.who.int/news-room/fact-sheets/detail/drinking-water. 2. Reang S, Nath H. Grey water treatment with spiral wound UF and RO membranes. Mater Today Proc. 2021 Jan 1;46:6253–9. 3. A. Carmalin Sophia Harjeet Nath and N. V. S. Praneeth. Synthesis of nano-porous carbon from cellulosic waste and its application in water disinfection. Curr Sci (Research Commun. 2016;111(No. 8):1377. 4. Venkatesh T, Senthilmurugan S. Grey water treatment and simultaneous surfactant recovery using UF and RO process. Sep Sci Technol. 2017. &nbsp

In the current study red mud is used as a medium to adsorb the hazardous exhaust gas containing gaseous fluorides coming out of aluminum industries as a measure to control environmental pollution. A high temperature fluidized bed reactor is used in this case which can be operated at around 300°C using a ceramic heater connected to the fluidized bed column. Optimally sized red mud powder having good fluidization quality is used to check the adsorbing properties of the gaseous fluorides on the metallic components present in red mud. Various characterization techniques like PSA, TGA-DTA, FT-IR, ICP-MS, FESEM, EDX and XRD are used. These characterization techniques proves the reaction between the metallic components present in red mud with the gaseous fluorides due to the presence of AlF 3 , FeF 2 , FeF 3 and NaF observed in the products. This report thus proves the applicability of fluidized bed reactor in treating the gaseous exhaust containing fluorides using red mud which otherwise is considered as a waste in the aluminum industry itself.

Red Mud (RM) is a solid waste product obtained from aluminum industries via Bayer’s process. India is one of the largest producers of RM producing around 4 million tons annually. Its disposal is one of the major concerns as it is highly alkaline in nature and is a potential threat to air, water and land. Currently RM is being dumped on land or in RM ponds near the alumina refineries and with the cost of the land going high it is becoming a big problem for the industries. Due to the differences in the ore type in its production process, there is a variation in the mineralogical composition between the residues from India and other countries. Its properties such as iron content in the form of ferric oxide (Fe2O3), high surface area etc. makes it attractive potential reactants for many reactions. In this paper the structural and phase compositions of RM is being studied with the help of PSA, XRD, FESEM, EDX, BET and FT-IR techniques.

The present study deals with the preparation of new cellulosic catalyst materials, viz. paper and textile industry waste. Activated nano-carbons were prepared from these waste materials using thermo-chemical method. Nano-silver particles (AgNP) were embedded into the synthesized carbons to incorporate antimicrobial properties. The catalyst materials were characterized using FESEM-EDX, XRD, FTIR, etc. The characterization results showed that the materials were nanoporous and silver was uniformly distributed throughout the catalyst. The suitability of the catalyst as an antimicrobial agent was studied using pour plate technique. The main advantages of the disinfecting materials over conventional materials were: (i) only small quantities (mg) of catalysts are required to deactivate microorganism for up to 1 litre of water; (ii) time required for more than 99% disinfection is less (60 min); (iii) carbon has been synthesized from cellulosic wastes which otherwise would pollute the environment, hence it is a waste recycling process. The carbons exhibited more than 99% E. coli removal within 60 min.