Reduction of dissolved organic matter in terms of DOC, UV-254, SUVA and THMFP in industrial estate wastewater treated by stabilization ponds

The aim of this research was to monitor the influent and effluent water quality of the aeration, facultative and oxidation water treatment ponds of an industrial estate. This industrial estate, the largest in northern Thailand, has proposed to utilization of reclaimed treated wastewater in their raw water supply so as to cope with the yearly water shortage during the dry season. Water samples were collected four times from four sampling points and evaluated for their dissolved organic matter (DOM) content in terms of dissolved organic carbon (DOC), ultraviolet light absorbance at 254 nm (UV-254), specific ultraviolet absorption (SUVA), trihalomethane formation potential (THMFP) and trihalomethane (THM) species. Average values of DOC, UV-254, SUVA and THMFP in the influent wastewater of 12.9 mg L⁻¹, 0.165 cm⁻¹, 1.29 L mg⁻¹m⁻¹ and 1.24 mg L⁻¹, respectively, were observed. The aeration ponds produced the best results: a 54% reduction of DOC, a 33% reduction of UV-254, and a 57% reduction of THMFP. However, SUVA in the aeration pond effluent showed a moderate increase. The facultative ponds and oxidation ponds did not take part in the reduction of DOC, UV-254, SUVA and THMFP. Average DOC, UV-254, SUVA and THMFP value of the treated wastewater were 5.8 mg L⁻¹, 0.107 cm⁻¹, 1.85 L mg⁻¹m⁻¹ and 468 μg L⁻¹, respectively. Chloroform, at 72.6% of total THMFP, was found to be the predominant THM species.     

Reduction of DOM fractions and their trihalomethane formation potential in surface river water by in-line coagulation with ceramic membrane filtration

This research was aimed at investigating the reduction of DOM fractions and their trihalomethane formation potential （THMFP） by in-line coagulation with 0.1 μm ceramic membrane filtration. The combination of ceramic membrane filtration with a coagulation process is an alternative technology which can be applied to enhance conventional coagulation processes in the field of water treatment and drinking water production. The Ping River water （high turbidity water） was selected as the raw surface water because it is currently the main raw water source for water supply production in the urban and rural areas of Chiang Mai Province. From the investigation, the results showed that the highest percent reductions of DOC, UV-254, and THMFP （47.6%, 71.0%, and 67.4%, respectively） were achieved from in-line coagulation with ceramic membrane filtration at polyaluminum chloride dosage 40 mg/L. Resin adsorption techniques were employed to characterize the DOM in raw surface water and filtered water. The results showed that the use of a ceramic membrane with in-line coagulation was able to most efficiently reduce the hydrophobic fraction （HPOA） （68.5%）, which was then followed by the hydrophilic fraction （HPIA） （49.3%）. The greater mass DOC reduction of these two fractions provided the highest THMFP reductions （55.1% and 37.2%, respectively）. Furthermore, the in-line coagulation with ceramic membrane filtration was able to reduce the hydrophobic （HPOB） fraction which is characterized by high reactivity toward THM formation. The percent reduction of mass DOC and THMFP of HPOB by in-line coagulation with ceramic membrane filtration was 45.9% and 48.0%, respectively.     

Characterization of brewery wastewater with spectrofluorometry analysis

The wastewater treatment systems from the three local breweries consist of upflow anaerobic sludge blanket (UASB) and activated sludge (AS) connected in series for which the influent and effluent from each treatment step were collected and determined for their dissolved organic matter (DOM) surrogate parameters including dissolved organic carbon (DOC), UV(254) and SUVA(254). The analyses suggested that the influent wastewater contained a high level of aromatic organic content classified as humic substances with high average molecular weight. Organic removal mostly occurred in the UASBs where DOC and UV(254) were reduced by 24-58% and 38-50%, respectively. Spectrofluorometry analysis (fluorescent excitation-emission matrix: FEEM) was reasonably accurate in evaluating DOM reduction during the treatment course. A total of eight fluorescent peaks were detected by the FEEM technique comprising (A) 230 nm(Ex)/315 nm(Em), (B) 275 nm(Ex)/315 nm(Em), (C) 230 nm(Ex)/365 nm(Em), (D) 285 nm(Ex)/365 nm(Em), (E) 290 nm(Ex)/400 nm(Em), (F) 335-355 nm(Ex)/405-465 nm(Em), (G) 255 nm(Ex)/455 nm(Em), and (H) 500 nm(Ex)/525 nm(Em). Peaks 'A and B' and 'C and D' were associated with tyrosine-like, tryptophan-like substances, respectively, whilst each individual peak E, F and G was associated with humic and fulvic acid-like substances. Peaks C, D, F and H were always found in the influent wastewater from all the breweries, whereas the effluents only exhibited Peak F. The origin of Peak H had not been recognized elsewhere and was not identified in this work. This suggested that FEEM could not only be used to monitor the reduction in DOM, but it could also provide details on the organic composition of the wastewater.     

Profiling and monitoring of DOM in brewery wastewater and treated wastewater

Dissolved organic matter (DOM) in raw and treated wastewater from two breweries in Thailand was profiled and monitored for the purpose of water reclamation. The wastewater and the effluent from the use of an upflow anaerobic sludge blanket (UASB) and activated sludge (AS) were collected and analyzed through a resin fractionation method using the fluorescent excitation?Cemission matrix (FEEM) technique. The results revealed that the major organic fractions in the brewery wastewater were hydrophobic acid (HPOA) and hydrophilic base (HPIB), accounting for 65% of total dissolved organic carbon (DOC) mass for brewery A and 56% of total DOC mass for brewery B. The FEEM results indicated that the organic matter in the wastewaters of both breweries were mainly composed of tryptophan-like substances, represented by peaks C (230 nm_Ex/340?C365 nm_Em) and D (265?C295 nm_Ex/315?C390 nm_Em), and humic-like substances, represented by peaks E (290 nm_Ex/400 nm_Em), F (330?C335 nm_Ex/395?C410 nm_Em), and G (255?C265 nm_Ex/435?C455 nm_Em). The analysis revealed that the reduction of DOM occurred mostly during the UASB treatment where most of the DOM reduction resulted from the removal of the HPOA and HPIB fractions. The HPOA fraction, a group of humic-like substances, is of particular concern when reclaiming treated brewery wastewater, and although it was reduced by more than 80% of its initial amount, it was still a dominant DOM fraction in the effluents.