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Sustainable Wastewater Treatment Using Microalgae Technology
Published in Akinola Rasheed Popoola, Emeka Godfrey Nwoba, James Chukwuma Ogbonna, Charles Oluwaseun Adetunji, Nwadiuto (Diuto) Esiobu, Abdulrazak B. Ibrahim, Benjamin Ewa Ubi, Bioenergy and Environmental Biotechnology for Sustainable Development, 2022
Emeka G. Nwoba, John N. Idenyi, Christiana N. Ogbonna, James C. Ogbonna, Mathias A. Chia
The effluent from primary treatment is subjected to secondary treatment. The aim of secondary treatment is to use physical phase to remove settleable materials and biological process to remove suspended and dissolved organic compounds. After the secondary treatment, the water has some degree of effluent quality and is called secondary treated water. During secondary treatment, dissolved and colloidal compounds whose concentrations are determined by a measure of their biochemical oxygen demand are removed by the activities of microorganisms such as bacteria and protozoa that degrade biodegradable and soluble organic pollutants like sugars, fats and short-chain carbon compounds from various sources. Waste stabilization pond is the most widely used facility for secondary treatment of wastewaters.
Integrated treatment strategy
Published in Xiaoling Lei, Bo Lu, Integrated Water Environment Treatment, 2021
The biological stabilization pond is a semi-artificial ecosystem, with its principle of sewage purification similar to the self-purification mechanism of natural waters, in which the biophases include bacteria, algae, protozoa, metazoa, aquatic plants and higher aquatic animals; and abiotic factors mainly include light, temperature, wind, organic loading, dissolved oxygen, pH, nitrogen and phosphorus nutrients. The main ecological characteristic is the symbiotic relationship between bacteria and algae. Under suitable light and temperature conditions, algae use carbon dioxide, inorganic nutrients and water to synthesize algal cells and release oxygen through photosynthesis. Heterotrophic bacteria use the oxygen dissolved in water to degrade organic matters, generate carbon dioxide, NH3-N and water, which become raw materials for algae to synthesize cells. In the series of reactions, dissolved organic matters in wastewater gradually reduce, algae cells and inert biological residues gradually increase and are discharged along with water. Finally, pollutants are not only removed but also recycled as resources in the forms of aquatic crops and aquatic products, and purified sewage is also reused as reclaimed water resource. The sewage treatment is combined with sewage utilization, realizing the sewage resource utilization in sewage treatment. However, the stabilization pond is greatly affected by temperature during operation, so it may cause unpleasant odor or breeding of mosquitoes and flies, affecting the environment.
Physicochemical and Biological Treatability Study of Textile Dye Wastewater
Published in Gregory D. Boardman, Hazardous and Industrial Wastes, 2022
Christine A. Phillips, Gregory D. Boardman
The Plant’s wastewater enters an aerated stabilization pond where some biological treatment occurs. After leaving the pond, polymers are added to remove the color. The wastewater is then filtered and sent to the receiving stream. About 85% of the dyes used by the Plant are acid dyes. The remainder of dyes used are premetallized (about 10%) and cationic (about 5%). When cationic dyes are used, they are mixed with acid dyes and are referred to as cat-acid dye by Plant personnel. The Plant’s treatment system is not effective on cat-acid dyes. When these dyes are in use, the color of the treated wastewater increases. Treatment is also inhibited in the wintertime when biological treatment effectiveness is low.
Removals of estrone and 17β-estradiol by microalgae cultivation: kinetics and removal mechanisms
Published in Environmental Technology, 2019
Chantima Ruksrithong, Songkeart Phattarapattamawong
Each microalgae strain (S. obliquus and C. vulgaris) was individually cultivated in a 5 L algae reactor. All reactors were daily fed with the synthetic wastewater separately spiked with E1 and E2. The depth of the wastewater was 0.3 m. The initial concentration of microalgae was 100 mg L−1 as dry weight (mgDW L−1). The pH of the solution was controlled in the range of 6.8–7.0. Both E1 and E2 influent concentrations were 5.0 µg L−1, the maximum concentration found in Thailand piggery wastewater [28]. All reactors were illuminated by fluorescence light at a light intensity of 2000 lx. Fluorescence light was installed at 1.0 m of height from the water surface. Since contamination by other microorganism was unavoidable, the control reactor without algae addition was also operated to compare the differences. The reactors were mixed by a pneumatic system. The air was filtrated with a 0.25 µm cellulose filter. The operation was kept in a semi-continuous mode, with controlled temperature range of 32 ± 3°C. The hydraulic retention time was designed for 5 days, typical operating criteria for a stabilization pond. The sample was daily collected until the system reached steady state.