Microalgae are biological sources with an extensive range of biotechnological applications, e.g., for bioremediation of industrial and municipal wastes. Microalgae are used to monitor environmental toxicants like pesticides, heavy metals, and pharmaceuticals and in the final stage of wastewater treatment when organic pollution should be removed. CO 2 capturing is also important due to the environmental issues. Macro/microalgae cultures, depending on their growth stages and life cycles, have great poten-tial for CO 2 fixation. They are a dominant group of microorganisms for biological treatments with regards to their substantial biosorption ability to deactivate toxic heavy metals. Actual carbon biofixation can be employed in the direction of environmental sustainability and economic facility. Besides, algae are sustainable feedstock to produce a wide range of biofuels by applying thermochemical or biological conversion methods.

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Microalgae Chlorella Vulgaris is enriched in vitamin B12 and cobalt ion which is positioned in the center of the vitamin molecule. This study aimed to investigate how different concentrations of cobalt chloride salt affected the vitamin B12 production by utilizing CO2 gas, to assess C. vulgaris biomass. Therefore, Bold's basal medium used as the medium and 0.5, 1.5, 2 and 2.5 μM cobalt chloride salt was added to C. vulgaris culture. Under four cobalt chloride salt treatments, the best growth rate was obtained at the 2 μM of cobalt chloride salt (0.186 + 0.07 g /L.d). CO2 gas was supplied by 5% CO2 gas cylinder and fermented milk as a novel biological CO2 gas generator (CO2,10%). Use of fermented milk is a practical approach for elimination of waste gas emission and converting CO2 into biomass. The results revealed that, in the presence of 5% CO2 gas, C. vulgaris vitamin B12 content at 2 and 2.5 μM cobalt chloride, were 166.23 ± 1.78 and 173.32 ± 4.23 μg /100 g of dry biomass (7 and 12% higher than control), respectively. However, under controlled condition (ambient air and 2 μM cobalt chloride) vitamin B12 content was 154.9 ± 1.14 μg / 100 g of dry biomass.

Nanofiltration processes for the removal of emerging contaminants such as nitrate are a focus of attention of research works as an efficient technique for providing drinking water for people. Polysulfone (PSF) nanofiltration membranes containing graphene oxide (GO)/Pt (0, 0.25, 0.5, 0.75, 1 wt%) nanoparticles were generated with the phase inversion pathway. The as-synthesized samples were characterized by FTIR, SEM, AFM, and contact angle tests to study the effect of GO/Pt on hydrophilicity and antibacterial characteristics. The results conveyed that insertion of GO/Pt dramatically improved the biofouling resistance of the membranes. Permeation experiments indicated that PSF membrane embracing 0.75 wt% GO/Pt nanoparticles had the highest nitrate flux and rejection ability. The membrane’s configuration was simulated using OPEN-MX simulating software indicating membranes maintaining 0.75 wt% of GO/Pt nanoparticles revealed the highest stability, which is well in accordance with experimental outcomes.

In the current work, novel dynamic membranes (DM) were tested and introduced for cheese whey wastewater treatment based on resistant and inexpensive materials, polyesters, and chitosan. For the investigation of dynamic membrane (pre-coated and self-forming) characterizations, polyester as a low-cost and natural material with chitosan were chosen to provide the support of the target membrane. The inherent antifouling character of chitosan accompanied by its high hydrophilicity have made this polymer known as an attractive agent for membrane-based wastewater treatment operations. Zinc oxide (ZnO) and powdered activated carbon (PAC) were employed as the dynamic layer. Neat polyester had a chemical oxygen demand (COD) rejection ratio of about 57.61%, but the flux declined sharply. The higher removal efficiency was for the self-forming type: total phosphate (94%) and citrate (95.5%). Fouled dynamic membranes were backwashed by sodium dodecyl-sulphate (SDS), warm water, and distilled water. Results demonstrated that the pre-coated was reduced and fouling increased the flux recovery rate (FRR) (9.1%) while use of the self-forming DM exhibited an aggravation of fouling by decreasing of support FRR (11.1%). It was found that by substitution of deionized water and hot water with SDS, FRR was enhanced. In the following, the photocatalytic ability of the product was investigated. The UV light source increased the removal ratio and FRR. For example, self-forming COD rejection was enhanced (6.63%).