Nanyang Environment and Water Research Institute

Perfluorinated compounds (PFCs) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been detected in the environment, in biota and in humans. The exposure pathways of these chemicals to humans are unclear. Tap water and bottled water are two possible pathways of PFCs occurrence in human blood. The major objectives of the study were to identify the occurrences of PFCs in tap and bottled water and to evaluate conventional water treatment processes performance on removal of PFCs. Solid phase extraction coupled with HPLC-ESI-MS/MS were used for the analysis of ten PFCs. PFCs were detected in all tap water samples and bottled water samples. The average PFOS and PFOA concentrations in tap water were 0.17 and 3.58 ng l 21 , respectively. PFOS and PFOA were not similarly distributed in all areas in the city. PFCs concentrations were higher in bottled water than in tap water. Moreover, the current treatment processes were not effective in removing PFCs in aqueous phase. Nevertheless, PFCs in particulate phase were effectively removed by primary sedimentation and rapid sand filtration. Based on the guideline from the New Jersey Department of Environmental Protection, PFOA concentrations in tap water and bottled water found in Bangkok were not expected to cause any health risks.

There is increasing concern about occurrences of perfluorinated compounds (PFCs) in the environment due to their persistent, bioaccumulation, and potentially toxic effects. We investigated contamination of 11 PFCs (C4-C12) in the Yodo River system, which is a major source of drinking water for more than 11 million people of Kansai region in Japan. PFCs were detected in higher concentration even exceeding more than 1000 ng/L in some cases. Composition profile of total PFCs concentration showed that PFOS, PFHxA, PFOA, and PFNA were occurring dominantly in the river system. PFOS and PFOA concentration were nearly proportional to a previous study in the same river system, indicating continuous

Extracellular polymers (ECP) Extracellular polymeric substances (EPS) Soluble microbial products (SMP) a b s t r a c t Effluents from biological processes contain a wide range of complex organic compounds, including soluble microbial products (SMP) and extracellular polymers (ECP), released during bacteria metabolism in mixed culture in bioreactors. It is important to clearly identify the primary components of SMPs and ECPs in order to understand the fundamental mechanisms of biological activity that create these compounds, and how to reduce these compounds in the effluent. In addition, these compounds constitute the main foulants in membrane bioreactors which are being used more widely around the world. A review on the extraction of ECP, characterization, and identification of SMPs and ECPs is presented, and we summarize up-to-date pretreatments and analytical methods for SMPs.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are two perfluorinated compounds (PFCs) used to produce everyday goods, including clothing, carpets, textiles, upholstery, paper, packaging and cleaning products. PFOS and PFOA belong to the class of chemical contaminants known as persistent organic pollutants (POPs). They are particularly difficult to deal with once released into the environment because they do not break down easily, they can travel long distances in the air or water supply and they can accumulate in human and animal tissue. Scientists have linked these chemicals, which can be toxic for both humans and wildlife, with serious environmental and health risks. Researchers have reported PFC contamination in river, tap and bottled water in Japan, the US, Europe and in developing countries such as Thailand, Malaysia and Vietnam. Conventional treatment technologies do not remove PFCs effectively from our water supplies, compounding the problem. Some advanced methods have been found to be effective in treating PFOS and PFOA in the water environment. However, these technologies have yet to be applied on a large scale due to regulative and economical constraints on their development.

Extracellular polymers (ECP) Extracellular polymeric substances (EPS) Soluble microbial products (SMP) a b s t r a c t Effluents from biological processes contain a wide range of complex organic compounds, including soluble microbial products (SMP) and extracellular polymers (ECP), released during bacteria metabolism in mixed culture in bioreactors. It is important to clearly identify the primary components of SMPs and ECPs in order to understand the fundamental mechanisms of biological activity that create these compounds, and how to reduce these compounds in the effluent. In addition, these compounds constitute the main foulants in membrane bioreactors which are being used more widely around the world. A review on the extraction of ECP, characterization, and identification of SMPs and ECPs is presented, and we summarize up-to-date pretreatments and analytical methods for SMPs.

The study concerned surface water contamination of two perfluorinated compounds: perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). Surveys were repeatedly conducted in the Yodo River basin in order to find out the contamination profiles and the sources of these compounds. Collected samples were analyzed for aqueous PFOS and PFOA concentrations, by solid phase extraction (SPE) coupled with LC/MS measurement, and other fundamental water quality parameters. PFOS and PFOA concentrations were measured from 0.4 to 123 ng/L and from 4.2 to 2600 ng/L, respectively. The concentrations were reproducible and the highest levels were found in effluents of some sewage treatment plants (STPs) and tributary streams. PFOA concentration was often higher than that of PFOS, but their profiles in the basin were somewhat similar. Both profiles were different from those of chloride, and DOC suggesting that there could be little relation between contamination of PFOS and PFOA in the basin with population and nature. Loads estimation revealed that main sources of the contaminants in Katsura River were three STP effluents while the sources in Uji River could be from Lake Biwa. It is suggested that other wastewaters than domestic wastewater contributed significant loads of PFOS and PFOA in highly contaminated STP effluents.

This manuscript presents a comparison of the A-stage and B-stage sludges in terms of anaerobic biodegradability and low molecular weight compounds present in the supernatant using Gas Chromatography-Mass Spectrometry (GC-MS). The GC-MS analysis of A-stage and B-stage supernatants identified respectively 43 and 19 organic compounds consisting mainly of aromatics (27.9% and 21%), alcohols (25.6% and 15%) and acids (30.2% and 15%). The methane potential was found to be 349±1 mL CH4/g VS and 238±12 mL CH4/g VS, respectively. After anaerobic digestion of these sludges, a greater proportion of aromatics (42% and 58%) and a lower proportion of acids (10% and 10%) and alcohols (16% and 10%) was observed.

Five commercially available assay kits were tested on the same protein sample with the addition of 17 different types of interfering substances typically found in the biological wastewater treatment, and a comparison of the use of these assays with 22 different protein and peptide samples is also presented. It was shown that a wide variety of substances can interfere dramatically with these assays; the metachromatic response was also clearly influenced by different proteinaceous material. Measurement of the "protein" content in the effluent of an anaerobic membrane bioreactor was then carried out using these assay methods. Quantitative results of the "protein" concentration in the different effluent samples, with or without spiked additions of Bovine Serum Albumin (BSA), showed considerable disagreement. We concluded that the "protein" measured in wastewater samples using standard colorimetric assays often shows false positive results and has little cor...

In light of global warming mitigation efforts, increasing sludge disposal costs, and need for reduction in the carbon footprint of wastewater treatment plants, innovation in treatment technology has been tailored towards energy self-sufficiency. The AB process is a promising technology for achieving maximal energy recovery from wastewaters with minimum energy expenditure and therefore inherently reducing excess sludge production. Characterization of this novel sludge and its comparison with the more conventional B-stage sludge are necessary for a deeper understanding of AB treatment process design. This paper presents a case study of a pilot-scale AB system treating municipal wastewaters as well as a bio- (biochemical methane potential and adenosine tri-phosphate analysis) and physico-chemical properties (chemical oxygen demand, sludge volume index, dewaterability, calorific value, zeta potential and particle size distribution) comparison of the organic-rich A-stage against the B-st...

This study investigated the performance of a submerged anaerobic membrane bioreactor (SAMBR) fed with synthetic wastewater (544 ± 22 mgCOD/L) operating at different hydraulic retention times (HRTs -12 h, 8 h, 6 h, 4 h, 2 h, and 1 h) at both steady state, and under transient load conditions (2 and 1 h), and the SMPs produced under these conditions. COD removal at decreasing HRTs (12 h, 8 h, 6 h, 4 h, and 2 h) was high (>94%), but decreased to 80% when operating at 1 h HRT. VFAs accumulated when the HRT was decreased to 2 h and 1 h, accounting for 69% and 89% of the effluent COD, respectively. Effluent SMPs accounted for an average of 14±2 mgCOD/L at steady state, but this fluctuated more during transient conditions (12±6 mgCOD/L). The COD *Revised Manuscript (clean for typesetting) Click here to view linked References equivalent of dissolved methane in the effluent was 17% at 4 h HRT, exceeding the saturation value of methane. Low MW compounds were identified using gas chromatography-mass spectrometry (GC-MS), with solid phase extraction (SPE) as the pre-treatment. 120 compounds were identified in the effluent at steady state, and were alkanes (39), alkenes (3), esters (11), alcohols (7), nitrogenated compounds (11), phenols (11), and others (9). Increases in cyclooctasulfur, N-butyl-benzenesulfonamide, alkanes, 1-naphthalenol, camphor, 2-methylphenol, and (Z)-9-octadecenamide were also found during transient conditions, and these compounds were not found in the feed; hence it is possible that these compounds were produced by microorganism as byproducts from substrate utilization.

Identification of soluble microbial products (SMPs) released during bacterial metabolism in mixed cultures in bioreactors is essential to understanding fundamental mechanisms of their biological production. SMPs constitute one of the main foulants (together with colloids and bacterial flocs) in membrane bioreactors widely used to treat and ultimately recycle wastewater. More importantly, the composition and origin of potentially toxic, carcinogenic, or mutagenic SMPs in renewable/reused water supplies must be determined and controlled. Certain classes of SMPs have previously been studied by GC-MS, LC-MS, and MALDI-ToF MS; however, a more comprehensive LC-MS-based method for SMP identification is currently lacking. Here we develop a UPLC-MS approach to profile and identify metabolite SMPs in the supernatant of an anaerobic batch bioreactor. The small biomolecules were extracted into two fractions based on their polarity, and separate methods were then used for the polar and nonpolar ...

Effluents from wastewater treatment systems contain a variety of organic compounds, including end products from the degradation of influent substrates, nonbiodegradable feed compounds, and soluble microbial products (SMPs) produced by microbial metabolism. It is important to identify the major components of these SMPs to understand what is in wastewater effluents. In this study, physical pretreatments to extract and concentrate low molecular weight SMPs (MW< 580 Da) from effluents were optimized. Liquid-liquid extraction (LLE) of a 200 mL effluent sample showed the best performance using a mixture of n-hexane, chloroform, and dichloromethane (70 mL) for extraction. For solid phase extraction (SPE), two OasisHLB cartridges were connected in-line to optimize recovery, and the eluted samples from each cartridge were analyzed separately to avoid overlapping peaks. Four solvents varying from polar to nonpolar (methanol, acetone, dichloromethane, and n-hexane) were selected to maximize...

The production of soluble microbial products (SMPs) and colloids in a submerged anaerobic membrane bioreactor (SAMBR) under different feed pHs (pH 5 and pH 11) was evaluated, and they were found to have a significant effect on SAMBR performance. Fluctuations in pH inside the SAMBR affected cell metabolism and/or enhanced cell lysis in the reactor, but the system recovered within 24 h for the pH 5 shock, and 8 h for the pH 11 shock. Carbohydrates (30k -200kDa) were found at very high concentrations with the pH 5 shock, while higher concentrations of "protein-like" compounds (1,500kDa -0.2μm) were found with the pH 11 shock. The pH shocks affected membrane fouling primarily through increased colloids, which formed a charged concentration polarization layer on the membrane surface. Larger colloids (1-5μm) related to "protein-like" compounds caused more membrane fouling than smaller ones. Alkanes, alkenes, esters, alcohols, phenols, nitrogen-compounds and sulfur compounds were the major groups of compounds identified in the effluent and supernatant samples. The membrane-fouling layer ("dynamic membrane") is an important factor in the removal of low MW compounds in the SAMBR, and changes in pH inside the SAMBR had a significant effect on effluent quality.