Optimising natural organic matter removal from low turbidity waters by controlled pH adjustment of aluminium coagulation

Variables affecting melanoidins removal from molasses wastewater by coagulation/flocculation

“…Since pH control is suggested as one of the most important factors governing NOM removal in the coagulation process [25], pH control, instead of initial pH adjustment test, was performed to avoid variable coagulation pH and consequently variable organic removal efficiency [26]. The tested pH levels were in the range of 4-8, and coagulant dosages were in the range of 4-9 g/L.…”

Influence of coagulation mechanisms on the residual aluminum – The roles of coagulant species and MW of organic matter

“…Based on previous studies [32,33], different mechanisms or their combination may be dominant under different conditions. For Al 2 (SO 4 ) 3 , the influence of the pH on coagulation mechanisms was correlated with the coagulant hydrolysed species [11].…”

Review of Coagulation’s Rapid Mixing for NOM Removal

“…For example, Al salts dissociate when added to water, and the charged Al hydrolysis products interact electrostatically with anionic NOM to form insoluble charge-neutral products. In operational regions, where insoluble Al hydroxide is formed, the NOM can be removed by entrapment (i.e., sweep coagulation) or surface adsorption (Gregor et al (1997), Nason and Lawler (2009)). The effectiveness of a coagulation process in removing NOM varies according to the nature of the NOM (i.e., its molecular weight, charge density, hydrophobicity and so forth), the physicochemical characteristics of the water and the operational conditions, such as the initial mixing intensity and duration (Letterman et al (1999)).…”

“…Therefore, PDM is suggested as being an effective coagulation process (Zouboulis and Tzoupanos (2009) (1999)). The work conducted by Gregor et al (1997) is a good example for the EC, and they reported that adjusting the pH downwards to between 4 and 5 prior to coagulant addition will encourage the formation of soluble NOM-Al complex from low-turbidity waters. In case of most waters, therefore, acid must be added to maintain the desired coagulation pH for EC, and excess coagulant is required to improve the removal of OM.…”