Mechanisms during suspended solids and phosphate concentration variations in wastewater coagulation process

Abstract

Coagulation-flocculation process is one of the most commonly used treatment process in water and wastewater treatment. Particles (PA) and phosphates (P) removal are the main objectives in wastewater coagulation. There is a general agreement on the dominant mechanism of PA and P removal during coagulation. While it is agreed that the PA and P removal reactions are competitive and takes place simultaneously, there is no clear understanding on the ratio of distribution of coagulants among the PA and P removal. The ratio can be significantly influenced by the content of PA and P, in addition to other water and coagulant quality factors. This paper attempts to provide a qualitative ratio of coagulant distribution based on PA:P proportion in raw water and OH:Al ratio in coagulants.

Effects of coagulant morphology and chemical properties on soluble reactive phosphate removal in corn ethanol wastewater

“…Compared to biological treatment, chemical precipitation continues to be a widespread method for P removal due to its economic feasibility, robustness, and high efficiency (Sun et al, 2017). Salts of iron (Fe) and aluminum (Al) have been used for P precipitation for decades; however, the removal mechanisms are complex and still not completely understood (Jiang & Graham, 1998;Manamperuma et al, 2016). The Al and Fe, typically added in the forms of aluminum sulfate (alum) and ferric chloride, can directly react with phosphate to produce insoluble AlPO 4 and FePO 4 .…”

Estimating Phosphorus and COD Concentrations Using a Hybrid Soft Sensor: A Case Study in a Norwegian Municipal Wastewater Treatment Plant

“…Step 4-Generate TP and COD Removal Models Dosage of coagulant (x PAX ) and dosage of polymer (x POL ) are important control variables, used to adjust the removal efficiencies of solids and phosphates in WWTPs [13]. A positive correlation between the dosage of coagulant/flocculant and the removal percentages, substantiated with systematically designed jar tests, can be found in the literature [22]. The results of these jar tests are often used as a basis to determine the optimal dosage of coagulants and polymer.…”

Newly developed membrane contactor-based N and P recovery process: Pilot-scale field experiments and cost analysis

“…Phosphorus removal with coagulation takes place in three main possible scenarios: metal-PO 4 formation, metal-hydroxy-PO 4 complexes formation, and adsorption onto metal hydroxides (Manamperuma et al, 2016). However, the formation of metal-PO 4 is unlikely to occur in the typical wastewater treatment environment (Smith et al, 2007) because the alkalinity of wastewater neutralizes the acidity of the coagulants, producing hydrous metal oxides.…”