The impact of hydroxyl radical (*OH) on the molecular weight distribution of natural organic matter (NOM) was investigated. *OH was generated via the photolysis of hydrogen peroxide (H2O2) by ultraviolet (UV) radiation of 254 nm, also known as UV/ H2O2 advanced oxidation (AO). Additionally, the impact of combined membrane and UV/H2O2 treatment on the molecular weight distribution of NOM was studied. High performance size exclusion chromatography (HPSEC) was used to determine the apparent molecular weight (AMW) distribution of chromophoric NOM (CNOM). Prior to AO, 33% of the CNOM in the water had AMW greater than 1400 Da. Meanwhile, lower AMW CNOM made up smaller amounts of the CNOM, with CNOM of AMW less than 450 Da making up 5% of the total. Under the AO conditions typically applied in drinking water treatment applications, NOM was not mineralized but was partially oxidized resulting in significant reduction in aromaticity. *OH preferentially reacted with higher AMW CNOM and the fragmentation of high AMW CNOM led to the formation of smaller AMW CNOM. Ultrafiltration removed all CNOM greater than 1400 Da AMW and a large portion of other high AMW fractions. In the absence of high AMW CNOM, *OH reacted more readily with all AMW fractions leading to a reduction in concentration of most AMW fractions. Whereas *OH reacted nonspecifically with all AMW fractions, the reaction rate between *OH and CNOM was observed to be dependent on molecular size.

, Ray, M.B., Low-temperature thermal pre-treatment of municipal wastewater sludge: Process optimization and effects on solubilization and anaerobic degradation, Water Research (2017Research ( ), doi: 10.1016Research ( /j.watres.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The present study examines the relationship between the degree of solubilization and biodegradability of 11 wastewater sludge as a result of low-temperature thermal pre-treatment. The main effect of thermal pre-12 treatment is the disintegration of cell membranes and thus solubilization of organic compounds. There is 13 an established correlation between chemical oxygen demand (COD) solubilization and temperature of 14 thermal pre-treatment, but results of thermal pre-treatment in terms of biodegradability are not well 15 understood. Aiming to determine the impact of low temperature treatments on biogas production, the 16 thermal pre-treatment process was first optimized based on an experimental design study on waste 17 activated sludge in batch mode. The optimum temperature, reaction time and pH of the process were 18 determined to be 80 o C, 5 hr and pH 10, respectively. All three factors had a strong individual effect (p < 19 0.001), with a significant interaction effect for temp.pH 2 (p = 0.002). Thermal pre-treatments, carried out 20 on seven different municipal wastewater sludges at the above optimum operating conditions, produced 21 increased COD solubilization of 18.3 ± 7.5 % and VSS reduction of 27.7± 12.3 % compared to the 22 untreated sludges. The solubilization of proteins was significantly higher than carbohydrates. Methane 23 produced in biochemical methane potential (BMP) tests, indicated initial higher rates (p = 0.0013) for the 24 thermally treated samples (k hyd up to 5 times higher), although the ultimate methane yields were not 25 significantly affected by the treatment. 26 Process Optimization and Effects on Solubilization and Anaerobic

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Ferrate­(VI) (FeVIO4 2, Fe­(VI)) is an emerging oxidant/disinfectant to treat a wide range of contaminants and microbial pollutants in wastewater. This study describes the inactivation of murine norovirus (MNV) by Fe­(VI) in phosphate buffer (PB) and secondary effluent wastewater (SEW). The decay of Fe­(VI) had second-order kinetics in PB while Fe­(VI) underwent an initial demand followed by first-order decay kinetics in SEW. The Chick–Watson inactivation kinetic model, based on integral CT (ICT) dose, well fitted the inactivation of MNV in both PB and SEW. In PB, the values of the inactivation rate constant (k d) decreased with an increase in pH, which was related to the reaction of protonated Fe­(VI) species (HFeO4 –) with MNV. Higher k d was observed in SEW than in PB. The inactivation of indigenous fecal coliforms (FC) in SEW was also measured. A two-population double-exponential model that accounted for both dispersed and particle-associated FC well fitted the inactivation data with determined k d and particle-associated inactivation rate constant (k p). Results show that Fe­(VI) was more effective in inactivating dispersed FC than MNV. The MNV inactivation results obtained herein, coupled with the detailed modeling, provide important information in designing an Fe­(VI) wastewater disinfection process.

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The effects of the advanced oxidation process (AOP) of ultraviolet radiation in combination with hydrogen peroxide (UV/H2O2) on the structure and biodegradability of dissolved natural organic matter (NOM) and on the formation of disinfection by-products (DBPs) through the post-UV/H2O2 chlorination were investigated using UV reactors equipped with either low-pressure amalgam lamps or medium-pressure mercury vapour lamps. With electrical energy doses and H2O2 concentrations typically applied in full-scale UV systems for water remediation, the UV/H2O2 AOP partially oxidized NOM, reducing its degree of aromaticity and leading to an increase in the level of biodegradable species. Also, when combined with a downstream biological activated carbon (BAC) filter, UV/H2O2 AOP reduced the formation of DBPs by up to 60% for trihalomethanes and 75% for haloacetic acids. Biological activated carbon was also shown to effectively remove biodegradable by-products and residual H2O2.

Performic acid (PFA) is an emerging disinfectant to inactivate bacterial and viral microorganisms in wastewater. In this study, the inactivation kinetics of murine norovirus (MNV) by PFA, in phosphate buffer and municipal secondary effluent wastewater, are reported for the first time. PFA decay followed first-order kinetics and the inactivation of MNV was governed by the exposure of microorganisms to PFA, i.e., the integral of the PFA concentration over time (integral CT or ICT). The extension of the Chick-Watson model, in the ICT domain, described well the reduction of MNV by PFA, with determined ICT-based inactivation rate constants, k d , of 1.024 ± 0.038 L/(mg•min) and 0.482 ± 0.022 L/(mg•min) in phosphate buffer and wastewater, respectively, at pH 7.2. Furthermore, the simultaneous PFA inactivation of MNV and fecal indicators indigenously present in wastewater such as fecal coliforms and enterococci showed that 1-log reduction could be achieved with ICT of 2, 1.5, and 3.5 mg•min/L, respectively. When compared with the most commonly used peracid disinfectant of municipal wastewater, peracetic acid (PAA), the ICT requirements determined using the fitted ICT-based kinetic models were ∼20 times higher for PAA than PFA, indicating a much stronger inactivation power of the PFA molecule.