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Integrated Omics Approaches to Understand and Improve Wastewater Remediation
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
In contrast, secondary water treatment, also known as biological treatment, involves the use of microbes to remove soluble and insoluble impurities. The biological treatment of wastewater includes aerobic and anaerobic digestion. A reactor circulates water while a high concentration of microorganisms is maintained. The organic matter is converted into water, carbon dioxide, and ammonia gas by microbes, most of which are bacterial and fungal strains (Kumar et al., 2020c; Suneja and Sharma, 2020). The organic matter is sometimes transformed into various compounds such as alcohol, glucose, and nitrate. In addition, the bacteria degrade inorganic stuff which is hazardous. At this stage, toxic organics and inorganics should be removed from the effluent. There are a variety of aerobic reactor designs in use today, ranging from the widely used activated sludge reactor to more contemporary systems with improved slurry retention, such as biofilm reactor design, membrane reactor design, and aerobic activated sludge reactor designs (Sponza and Gok, 2011). Anaerobic processes convert organic matter to carbon dioxide and methane through a reaction chain that comprises the phases of acidogenesis, lysis, methanogenesis, and acetogenesis (Rodríguez et al., 2015). The activated sludge system reactor is one of the most commonly utilized anaerobic digesters for wastewater treatment (Meena et al., 2021).
Polymers as Coagulants for Wastewater Treatment
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
Sai Harsha Bhamidipati, Dharani Prasad Vadlamudi, Sudheshna Moka
Pollution is one of the major causes of fresh water scarcity, apart from droughts and lack of rainfall. While on one hand the demand for fresh water is increasing due to increasing population and expansion of agriculture as well as industry, its availability is on a constant decline. Some of the major water pollutants include suspended organic matter, heavy metals, and organic compounds entering water bodies from various sources. Effective and safe methods of water treatment are thus indispensable to sustain life on Earth. In general, there are four steps in large-scale water treatment: coagulation and flocculation, sedimentation, filtration, and disinfection. Each of the steps employs various chemicals/materials such as coagulants, flocculants, sand, charcoal, etc. that bring about the desired effect. The coagulation and flocculation step is very crucial as it directly affects the efficiency of filtration process and hence the overall water purity achieved. This chapter describes different types of coagulants used for water treatment, with an emphasis on polymeric materials.
Application of Green Technology in Water and Wastewater Treatments
Published in Shrikaant Kulkarni, Ann Rose Abraham, A. K. Haghi, Renewable Materials and Green Technology Products, 2021
Remya Vijayan, Sijo Francis, Beena Mathew
Water treatment involves the removal of unwanted chemical, physical, and biological pollutants from raw or contaminated water to produce pure water for specific applications like human consumption, medical, industrial, chemical, and pharmacology requirements. It is not possible to recognize a water sample of fine quality by visual observation. The only method to attain the details required for deciding the suitable technique for water treatment is chemical analysis. The chemical analysis is somewhat expensive. The international standards like the World Health Organization (WHO) or governments are usually set the standards for drinking water quality.
Fabrication of spirulina based activated carbons for wastewater treatment
Published in Environmental Technology, 2022
Mustafa Rakib, Yeshaswini Baddam, Balakrishnan Subeshan, Ayse B. Sengul, Eylem Asmatulu
Water treatment is a process that provides high-quality water for human consumption purposes, used to remove different contaminants such as suspended solids, nitrogen, pesticides, toxic metals, bacteria, and viruses from raw water. Currently, various physical, chemical, or biological processes are used to remove such contaminants from water, including coagulation/flocculation, sedimentation, filtration, oxidation, adsorption, disinfection, and membrane filtration [2–4]. Traditional water treatment methods, including sedimentation, flocculation, coagulation, and filtration generally aim to eliminate suspended and colloidal particles. Other treatment processes such as adsorption, chlorination, oxidation, and membrane filtration aim to remove dissolved organic and inorganic compounds. Among all treatment processes, the adsorption process can effectively remove tastes, odours, synthetic organic compounds, disinfection by-products, and inorganic chemicals [5,6]. In adsorption processes, activated carbon is commonly applied as an adsorbent because of its extremely high porosity, high adsorptive capacity, and high surface area [7–16]. By using carbonaceous materials such as wood, coal, rice husks, coconut shells, and agricultural materials, it is possible to construct it by carbonisation and chemical or physical–chemical activation [17–24].
Fit-for-purpose urban wastewater reuse: Analysis of issues and available technologies for sustainable multiple barrier approaches
Published in Critical Reviews in Environmental Science and Technology, 2021
Disinfection is a key water treatment process to ensure microbiological quality and consumption safety of water supplies. Historically, chlorine was the most common disinfectant in water treatment in the forms of chlorine gas (Cl2), sodium hypochlorite (NaOCl), or solid calcium hypochlorite (Ca(ClO)2). Water chlorination may result in formation of DBP compounds, such as trihalomethanes (THMs), haloacetic acids (HAAs), and others, some known to be human carcinogens (Sadiq & Rodriguez, 2004). For this reason, other chemicals have been proposed to carry out water disinfection, such as ozone and peracetic acid (CH3CO3H): the first is a known, extremely reactive oxidizing agent, also used as a basis of some AOPs, the second is a highly reactive and corrosive organic compound, used as bactericide and fungicide that releases active oxygen and reactive hydroxyl radicals in solution. Both have higher disinfection efficiencies than chlorine, but peracetic acid is relatively expensive, and is difficult to store due to its high reactivity.
Scientometric study of drinking water treatments technologies: Present and future challenges
Published in Cogent Engineering, 2021
Lorgio G. Valdiviezo Gonzales, Fausto F. García Ávila, Rita J. Cabello Torres, Carlos A. Castañeda Olivera, Emigdio A. Alfaro Paredes
Coagulation-flocculation is the most commonly employed process in water treatment due to its simplicity and effectiveness (Teh et al., 2016). Mejía et al. (2020) demonstrated that the extraction of lipids from Moringa oleifera seeds used as a coagulant at a dose of 0.5 g/l improves the removal of turbidity (up to 97.8%) and chemical oxygen demand COD (51.4%), compared to the seed applied without pretreatment (turbidity: 87.3%; COD: 26.3%) in wastewater. However, the production and toxicity of sewage sludge and the ineffectiveness in the removal of metals and emerging pollutants (including the increase of chemical oxygen demand in the application of natural coagulants) are the reason for a rich scientific production seeking improvements in these processes (Teh et al., 2020). In addition, coagulation-flocculation is applied as pretreatment in the control of particulate matter, microorganisms, natural organic matter (NOM), synthetic organic carbon, disinfection by-product precursors (DBP), some inorganic ions, and metals (Kalaitzidou et al., 2020; Trinh & Kang, 2011).