Modelling forward osmosis-nanofiltration integrated process for treatment and recirculation of leather industry wastewater

Modelling of a forward osmosis-nanofiltration (FOsingle bondNF) integrated treatment system for treating hazardous wastewater has been done with model validation against experimental data of a semi-pilot unit using live wastewater from a leather industry. The flat sheet cross flow forward osmosis (FO) membrane module ensured near 100% rejection of chromium while total pollution load of the wastewater in terms of chemical oxygen demand (COD), chlorides and sulphates came down by 98%. A reasonably high water flux of about 48 L/m2 h (LMH) could be sustained in the FO module. The coupled downstream NF system recovered the draw solute NaCl by more than 98% for recycling in the FO loop. That the developed model is capable of predicting system performance quite accurately is reflected in low relative error ( 0.98) and high Wilmot d-index (>0.95). The model will help assess operating conditions, system design and hence industrial scale up

Photocatalytic conversion of CO2 to methanol using membrane-integrated Green approach: A review on capture, conversion and purification

In the modern world, due to the ever increasing demand of electricity, industrialization and auto-mobilization, the abundance of greenhouse gases has shoot up to a critical level. A critical review has been initiated which provides a comprehensive literatures survey in the last two decades on the novel approaches available on different technologies for the anthropogenic CO2 capturing and conversion to methanol. In addition to that, merits and demerits of existing conventional technologies for downstream separation, purification and concentration enrichment of methanol have been discussed and compared with membrane-based system to find out the best optimal conditions. Extensive literature review reveals that the development of graphene based, TiO2/CuSO4 coupled photocatalyst for conversion of CO2 to methanol (33–37 mg/g catalyst) and downstream separation and purification using microfiltration membranes (Flux 100-110  L/m2h) stand out to be the best possible options for catalyst recycle and product recovery. In the previous studies the conversion was found as low as in the range of 10–20  mg/g catalyst without any development of hydrogen exfoliation graphene based nanocomposite material as well as any integration of spent catalyst recycle or product purification technology based on membrane separation. Such innovation and integration of process design employing cutting-edge schemes not only reduces the concentration of CO2 in biosphere but also produces renewable energy. These efforts towards green manufacturing while confirming the potentials of sustainable business is undeniably essential and should be stimulated

An improved enzymatic pre-hydrolysis strategy for efficient bioconversion of industrial pulp and paper sludge waste to bioethanol using a semi-simultaneous saccharification and fermentation process

The current study investigated an integrated fermentation process for efficient conversion of pulp and paper sludge (PPS) material to bio-ethanol. To achieve maximum yield of reducing sugar from the pretreated PPS, most influencing parameters such as enzyme dosages, surfactant dosages on PPS loadings were optimized in a batch saccharification process using response surface methodology. The experimental validation studies under optimal conditions of 6% (w/w) solid loading condition, 0.16 % (w/w) of surfactant concentration and 158 FPU/gm of enzyme 2 loading resulted in a maximum reducing sugar yield of 45 ± 3.75 % (w/w). Separate batch saccharification studies were conducted with 4% to 7% (w/w) solid loading to formulate best operating conditions for fed-batch saccharification with 13% (w/w), 18% (w/w) and 22% (w/w) high solid loading. The PPS solid loading of 18% (w/w) in fed-batch saccharification resulted in maximal release of glucose and xylose of 79.56 g/L and 8.65 g/L respectively at 60 h. Further improvement in the conversion of PPS to bioethanol was established through adoption of fed batch semi-simultaneous saccharification and co-fermentation (S-SSCF) process. Fermentation using co-cultivation of two yeast species namely P. stipitis NCIM 3499 and Baker’s yeast resulted in maximum ethanol concentration of 42.34 g/L with 0.53 g/g yield from 18 % (w/w) solid loading. Thus, the current study demonstrated the potential application of PPS waste as a feedstock material for ethanol production, which can be adopted by industries as an environment-friendly alternative to common solid waste management

Catalytic conversion of CO2 to biofuel (methanol) and downstream separation in membrane-integrated photoreactor system under suitable conditions

A heterogeneous photocatalyst has been developed using sono-chemical assisted sol-gel method by maintaining aweight ratio of 1:2:3 for hydrogen exfoliation graphene, titanium oxide andcopper sulphateand exhaustively characterized. Rigorous experimentations have been done using newly developed heterogeneous photocatalyst for efficient capturing and maximum conversion of carbon di oxide to methanol by mutual effects of governing conditions, like as catalyst dose, pH, CO2 flow rate and temperature. Optimization study has been carried out employing a statistical approach of response surface methodology which reveals the maximum methanol productivity and yield. Approximately, 134 g/Lh of productivity and 40 mg/gcatof yield were found after 3 h of illumination under UV in an annular type Pyrex reactor at an optimum catalyst dosage of 10 g/L, CO2 flow rate of 3 L/m, pH of 3, and process temperature of 50 °C. By the judicial integration of flat-sheet cross flow microfiltration membrane module for catalyst separation and recycle, a steady state permeate flux 145 L/m2h was achieved at an applied pressure of 3 bar and cross-flow feed rate of 700 L/h

Green synthesis of MeOH derivatives through in situ catalytic transformations of captured CO2 in a membrane integrated photo-microreactor system: A state-of-art review for carbon capture and utilization

Globally, industrial production sectors have become increasingly concerned about reducing CO2 evolution, through planned carbonization with concurrent substitution of fossil fuels with renewable energy resources, since the release of the Paris climate accord regulations. CO2 is an inexpensive substrate used for the production of useful chemicals and fuels through various chemical and biological processes. As a result, reducing CO2 emissions while producing non-fossil fuels, such as methanol or its derivatives, could be an appealing solution to the global energy problems. The high cetane number, low autoignition temperature, and low extract pollutant value of dimethyl ether, one of the most valuable methanol derivatives, make it a clean and eco-friendly alternative to fossil fuels. Recent literature from the last five years is critically reviewed in the present study to assess the current best practices for CO2 capture and conversion into high value fuels. Particular emphasis has been placed on atmospheric CO2 capture, photoconversion, and the downstream purification of the final product using membrane-based technologies for a sustainable future. Currently, there is a compelling need for an impending transition away from fossil fuel-based technologies toward inventive new technologies using renewable energy sources through carbon management via CO2 conversion and utilization.Web of Science182art. no. 11341