Coagulation of waste water from the point of view of physic-chemical interactions

Abstract

The widespread use of reagent coagulation in the technology of purification of natural and waste waters is due to the complexity of the chemical composition and phase-dispersed state of the aqua systems of these waters, on the one hand, and the multifactorial action of coagulants on them, on the other. The mechanisms of interaction between coagulants and pollutants of wastewater which are in different phase-dispersed states include the physicochemical phenomena of coagulation, heterocoagulation, adagulation and sorption. The physicochemical concept “coagulation” reflects only one mechanism of coagulants’ action on pollutants. This leads to the appearing of the problem in terminological description of the physicochemical processes’ combined action when adding coagulants to the water being cleaned. The purpose of the study is to justify the use of universal indicators characterizing the multifactorial nature of the coagulation process, its formalization and quantitative assessment. The solution of the problem is to use the concept of “coasorption”, which determines the multifactorial nature of the interaction between coagulants and pollutants, and to use the technological indicator “specific coasorption”, which establishes a quantitative relationship between the pollutants’ indicators and the dose of coagulant. The test coagulation’s results of two different types of synthetic dyes’ solutions using aluminum salts reflect the difference in the mechanisms of their interaction with the coagulant. The formula for coasorption isotherm can be used to determine the required doses of reagents for coagulation of water basing on the initial and residual content of pollutants in the purified waters.

An Overview of Wastewater Treatment and Reuse in The Gulf Cooperation Council Countries

“…Additionally, coagulation and flocculation can also be applied to the wastewater treatment process to enhance the quality to meet the required standards. Coagulation is a process used in the neutralization of charges and formation of a gelatinous mass that traps particles, hence, creating a mass that is big enough to be trapped or settle in the filter [71]- [73] . Flocculation involves the moderate stirring or agitation of the solution to reduce turbidity in the water [67],…”