Reduction of organic matter and trihalomethane formation potential in reclaimed water from treated industrial estate wastewater by coagulation

Abstract

Raw water from treated industrial estate wastewater in northern Thailand was used in jar-test coagulation experiments with variations of separate alum and ferric chloride dosages from 10 to 80 mg/L at pH conditions ranging from 5 to 6.5. Natural organic matter (NOM) surrogates and trihalomethane formation potential (THMFP) were determined to study their reduction. The obtained results showed that total organic carbon (TOC) were gradually reduced from the average value of about 6.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Moreover, dissolved organic carbon (DOC) were reduced from an average value of 5.1 mg/L to a level of about 4.0 mg/L by alum and ferric chloride dosages of approximately 40 mg/L. Specific ultraviolet absorption (SUVA) were decreased from an average value of approximately 4.7 L/mgm to a level of about 2 L/mgm by alum and ferric chloride dosages of approximately 20 mg/L. In addition, chlorine demands at 1 day reaction were the same as those of 7-day demands with a correlation coefficient of 0.98 (n = 10, correlation significant at the 0.01 level). Interestingly, chloroform of approximately 65 and 60% of total THMFP was found as the predominant THMFP species in treated industrial estate wastewater and reclaimed water, respectively, in comparison with other THM species. Maximum THMFP percentage removal of 25 and 28 by using alum and ferric chloride dosages of about 80 mg/L at pH 5.5 and 5 were obtained, respectively, at the examined conditions.

Reduction of dissolved organic matter in secondary municipal effluents by enhanced coagulation

“…The removal trends are consistent with those seen in drinking water treatment [25]. In addition, the optimum pH for DOC removal in ferric chloride coagulation has also been observed to be 5 for wastewater [19]. As mentioned in literature [25], iron hydroxide flocs are more positively charged at acidic pH values.…”

“…El Samrani et al [18] investigated the nature of coagulant species formed during the clarification of municipal sewage with a commercial ferric chloride. Musikavong et al [19] studied the reduction of organic matter and trihalomethane formation potential in reclaimed water from treated industrial estate wastewater by coagulation. Amuda and Alade [20] examined the removal of chemical oxygen demand (COD), total suspended solids (TSS), and total phosphorus (TP) in abattoir wastewater by coagulation.…”

Modeling the Formation of Chlorination By-Products During Enhanced Coagulation

“…The UV 254 generally decreases with increasing ferric dose, indicating preferential removal of the humic fraction. As a comparison with Musikavong et al, study, they found that the removal of aromatic substances by alum and ferric chloride coagulation is more effective than the removal of DOC, and it can be concluded from these results that bigger aromatic molecules are removed more effectively than both smaller aromatic molecules (Musikavong et al, 2005). This result supports the conclusion that TLW's NOM was as amenable to chemical coagulation because of its moderate humic fraction.…”

Variables affecting melanoidins removal from molasses wastewater by coagulation/flocculation

“…Iron salts achieving better organic removal than alum salts have been reported in a number of literatures [20][21][22]. In addition, chloride-based metal salts removed more COD by almost 10% than sulfate-based ones, which implies that counter-ions introduced as anions can have a significant effect on the coagulation process.…”