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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.
Water Conservation
Published in Mary K. Theodore, Louis Theodore, Introduction to Environmental Management, 2021
Mary K. Theodore, Louis Theodore
A significant concept related to modern wastewater reuse practices is that of treatment “fit for purpose.” This concept suggests that the appropriate level of treatment should be dictated by the end application of the reclaimed water for achieving economic efficiency and environmental sustainability. This concept suggests that for many nonpotable uses of reclaimed water (i.e., urban landscape and garden use), secondary treatment will be adequate to protect public health and the environment. Other applications, such as cooling or industrial process water needs, may require additional tertiary treatment to reach required water quality levels. Direct potable water reuse would require advanced treatment to ensure near complete removal of microbial and trace metals plus synthetic organic compounds with minimal risk to the public. Table 21.1 provides a summary of the defined categories of water reuse applications as per the EPA [5].
Biological Treatment Systems
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
The activated-sludge process of wastewater purification is a common process for the secondary treatment of wastes. The activated sludge consists of a gelatinous matrix in which filamentous and unicellular bacteria are imbedded and on which protozoa attach and feed. The bacterial genera which predominate depends on the characteristics of organic matter in the waste water, such as Pseudomonas for hydrocarbon and carbohydrate wastes and Alcaligenes, Bacillus, and Flavobacterium for proteinaceous wastes. The process consists of mixing activated sludge, recirculated from a final settling tank, with incoming raw or primary sewage to form a mixed liquor, which is subsequently aerated and from which activated sludge is later settled. When a plant is first started, it can be seeded with an activated sludge from a currently operating plant. If no seed sludge is available, then one can be built up over a short period of time (4–6 weeks) by simply continually aerating, settling, and returning the residue of the sewage.
Oil extraction from scum and ex situ transesterification to biodiesel
Published in Biofuels, 2021
Sravan Kumar Yellapu, Rajwinder Kaur, Rajeshwar D. Tyagi
In the wastewater treatment plant process, primary sludge is a result of the capture of suspended solids and organics in the primary treatment process through gravitational sedimentation, typically by a primary clarifier. The secondary treatment process uses microorganisms to consume the organic matter in the wastewater. The microorganisms feed on the biodegradable materials present in the wastewater in the aeration tank and then flow into a secondary clarifier where the biomass settles out and is removed as secondary sludge. Scum is a floatable material skimmed from the surface of primary and secondary settler tanks, especially from the surface of grit chambers in wastewater treatment plants. It is mainly composed of fats, oil, and grease (FOG) which are rich in free fatty acids (Marufuzzaman et al., 2014) and have a high lipid content (Bi et al., 2015; Sangaletti-Gerhard et al., 2015). The possibility of using municipal sludge as a feedstock for biodiesel production is a critical approach to decrease the sludge management cost. Moreover, there is a significant availability of sludge with high oil content in the developed countries (Wang et al., 2016). The amount of oil present in sludge varies and is strongly dependent upon the population and urbanization of the city (Wang et al., 2015).
The design for wastewater treatment plant (WWTP) with GPS X modelling
Published in Cogent Engineering, 2020
Conventional wastewater treatment consists of a combination of physical and biological processes to remove solids, organic matter and nutrients from wastewater. General terms used to describe different degrees of treatment, in order of increasing treatment level, are preliminary, primary, secondary and tertiary or advanced wastewater treatment (Janssen, Meinema, & van der Roest, 2002). However, the key treatment process in the conventional sewage treatment is the secondary treatment process, which consists of biological treatment by utilizing mixed types of microorganisms in a controlled environment. Several aerobic and anaerobic biological processes are used for secondary treatment, including activated sludge process, total oxidation process, contact stabilization, aerated lagoons, waste stabilization ponds, trickling filters and anaerobic treatment. Activated sludge process is the most widely applied process comparable to other biological process for its facility design is well known as well as having characterized operation parameters (Culp, 1978).
Decentralized wastewater treatment using passively aerated biological filter
Published in Environmental Technology, 2019
Sohair I. Abou-Elela, Mohamed S. Hellal, Olfat H. Aly, Salah A. Abo-Elenin
The selection of the most appropriate wastewater treatment technology is usually uncertain and complex since many alternatives are available and many criteria, such as investment costs, energy consumption and odors, are involved in the decision-making processes [6]. In most rural areas, there is a tremendous demand to develop reliable domestic wastewater treatment technologies which must fulfill many requirements, such as simple design, use of non-sophisticated equipment, high treatment efficiency, low operating and capital costs. Wastewater treatment processes that can achieve an effluent standard at minimal cost are generally preferred especially in countries that have a shortage in water and energy crisis. Energy cost becomes year by year a hard and difficult issue for the municipalities putting major economic barriers to their sustainability and to supply quality services to their citizens. It has been estimated that over 20% of the total energy spent by the municipalities is for the operation of the wastewater treatment plants [7]. Aerobic treatment of wastewater is considered a secondary treatment. The effluent from this treatment should meet the standard limits of 30 mg/l biological oxygen demand (BOD5), 60 mg/l chemical oxygen demand (COD) and 25 mg/l total suspended solids (TSS) [8].