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Adsorption of nitrogen and phosphorus in wastewater by modified biochar
Published in Binoy K. Saikia, Advances in Applied Chemistry and Industrial Catalysis, 2022
The treatment of phosphorus compounds has always been an extremely complex and costly environmental problem. At present, some researchers have put forward relevant methods for the recovery and reuse of phosphorus. So far, the research methods of phosphorus removal can be divided into three categories: physical methods, chemical methods, and biological methods. In wastewater treatment plants, the activated sludge process is most commonly used as the main biological treatment technology (Huang et al. 2021). To be more specific, phosphorus accumulating bacteria release phosphorus under anaerobic conditions, and excessive phosphorus uptake under aerobic conditions to achieve the purpose of phosphorus removal. However, biological phosphorus removal has the defects of strict experimental parameters, long cycles, and unstable effects. Chemical phosphorus removal may lead to phosphorus precipitation and the formation of phosphate-rich sludge, which increases the cost and risk of sludge treatment and disposal. At present, physical adsorption is considered to be one of the most effective technologies to remove pollutants from water because of its low cost, high efficiency, and simple operation (Liu et al. 2013). Therefore, it has been widely studied by scholars. The core of its research and application is adsorbent (Shakoor et al. 2021). The performance of the adsorbent will directly affect the adsorption effect of pollutants.
Design and Operation of Chemical Phosphorus Removal Facilities
Published in Richard Sedlak, Phosphorus and Nitrogen Removal from Municipal Wastewater, 2018
Chemical phosphorus removal from municipal wastewater typically involves: addition of metal salts (aluminum or iron) or lime to wastewater to form insoluble phosphate precipitates, removal of the precipitate from the wastewater, and disposal of the precipitate with the settled sludge. Many process options are available, but the decisions which must be made by the designer to maximize phosphorus removal and minimize capital and operating costs can generally be classified as follows: Selection of the chemical to insolublize the phosphorusDefinition of the point (or points) of chemical addition to the wastewater flow stream
Comparison and strategy of nitrogen removal at different low temperatures in a pilot-scale A2/O system
Published in Environmental Technology, 2019
Xiaoying Liu, Ao Zeng, Yatao Wang, Peiju Liu, Yuan Chen, Yinghe Jiang
In China, the anaerobic/anoxic/oxic (A2/O) process is applied in nearly all wastewater treatment plants (WWTPs) for nitrogen and phosphorus removal. However, due to insufficient carbon source and deficiencies of the A2/O process, simultaneously achieving efficient removal of nitrogen and phosphorus is difficult [1–3]. To ensure the effluent total nitrogen (TN), NH3–N, and total phosphorus (TP) concentrations to achieve the National standard A of level I (CODcr ≤ 50 mg L−1, TN ≤ 15 mg L−1, NH3–N ≤ 5 (or ≤8 for water temperatures ≤ 12°C) mg L−1, TP ≤ 0.5 mg L−1), which is specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002), chemical phosphorus removal techniques are usually employed in many WWTPs [4,5]. It is reported that at least 90–95% of phosphorus is removed by chemical removal techniques, which is efficient to relieve the constraints of carbon sources and to ensure low effluent TP concentration [5,6]. Therefore, nitrogen removal has become one of the most vital problems for improving WWTPs.
Correlation between phosphorus removal technologies and phosphorus speciation in sewage sludge: focus on iron-based P removal technologies
Published in Environmental Technology, 2023
Mohamed Amine Saoudi, Patrick Dabert, Arnaud Ponthieux, Fabien Vedrenne, Marie-Line Daumer
In sewage treatment plants (STP), P is removed from wastewater mainly by two methods: i) Chemical Phosphorus Removal (CPR) using metal salts to precipitate the dissolved phosphorus (diss-P), or ii) Enhanced Biological Phosphorus Removal (EBPR), where specific microorganisms, called Phosphorus Accumulating Organisms (PAO), accumulate the dissolved phosphorus within their cell and use it as an energy source [7]. Some large STPs combine both methods to reduce operating costs [8]. In both modes, phosphorus is removed from the wastewater's liquid phase and transferred to the sewage sludge, whether as a chemical precipitate or within the settled biomass. Phosphorus is then concentrated in sewage sludge, making it a promising phosphorus recovery source [9,10].