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

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.     

Three dimensional fluorescent spectroscopy analysis for the evaluation of organic matter removal from industrial estate wastewater by stabilization ponds.

The fluorescent excitation emission matrix (FEEM) was utilized to evaluate the removal of organic matter by stabilization ponds, which consist of aeration, facultative, and oxidation ponds of a central wastewater treatment plant of an industrial estate in northern Thailand. The result shows that six fluorescent peaks of influent wastewater and effluent water after aeration, facultative, and oxidation ponds were detected from the FEEMs at 230 nmEx/295 nmEm (A), 275 nmEx/300 nmEm (B), 240 nmEx/355 nmEm (C), 280 nmEx/355 nmEm (D), 275 nmEx/410 nmEm (E) and 330 nmEx/410 nmEm (F). The putative origins of peaks A and B, C and D, and E and F were tyrosine-like, tryptophan-like, and humic and fulvic acid-like substances, respectively. The aeration pond was the main course of action used to reduce the tyrosine-like substances at peaks A and B by 88 and 52%, respectively, and tryptophan-like substances at peaks C and D by 43 and 39%, respectively. There was only a 20 per cent decrease of humic and fulvic acid-like substances at peak E and an 18 per cent decrease at peak F through the use of aeration ponds. Total per cent reductions of total fluorescent organic matter after aeration ponds; facultative ponds; and oxidation ponds were 46, 51 and 54%, respectively. These values were notably similar to the total percent reduction of DOC by the same respective processes at 54, 53, and 55%.     

Removal of organic impurities in waste glycerol from biodiesel production process through the acidification and coagulation processes

Treatment of waste glycerol, a by-product of the biodiesel production process, can reduce water pollution and bring significant economic benefits for biodiesel facilities. In the present study, hydrochloric acid (HCl) was used as acidification to convert soaps into salts and free fatty acids which were recovered after treatment. The pH value, dosages of polyaluminum chloride (PACl) and dosage of polyacrylamide (PAM) were considered to be the factors that can influence coagulation efficiency. The pH value of waste glycerol was adjusted to a pH range of 3-9. The PACl and PAM added were in the range of 1-6 g/L and 0.005-0.07 g/L. The results showed best coagulation efficiency occurs at pH 4 when dosage of PACl and PAM were 2 and 0.01 g/L. The removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), total suspended solids (TSS) and soaps were 80, 68, 97 and 100%, respectively. The compositions of organic matters in the treated waste glycerol were glycerol (288 g/L), methanol (3.8 g/L), and other impurities (0.3 g/L).