Effects of the chlorination on organic matter removal and microbial communities during soil aquifer treatment for wastewater reclamation.

Soil aquifer treatment (SAT) has been widely applied for wastewater reclamation, which cooperates secondary treatment (i.e. A2O process) and disinfection treatment (chlorination) in wastewater treatment plants (WWTPs), to remove organic matter. This study compared dissolved organic carbon (DOC) characteristics, substrate utilisation patterns, and microbial communities between pre-chlorination SAT and SAT columns, and effective removals of DOC were observed in the pre-chlorination SAT and SAT columns. However, the composition of HiA in SAT columns without chlorination was less than in pre-chlorination SAT columns for DOC fraction. In comparison to A2O effluent, different metabolic patterns and the composition of the microbial community were demonstrated by the top layer of SAT column and pre-chlorination SAT column. Furthermore, deeper layers showed similarities in the metabolic pattern and composition of the microbial community. Overall, pre-chlorination minimised the change of the microbial communities from A2O effluent in the top layer of SAT except for deeper layers, and DOC concentrations decreased in pre-chlorination SAT column. Thus, the cooperation of SAT and wastewater treatments could be suitable for wastewater reclamation.

Detection of Escherichia coli, rotavirus, and Cryptosporidium spp. from drinking water, kitchenware, and flies in a periurban community of Lusaka, Zambia.

Fecal contamination with a poor water, sanitation and hygiene environment in urban informal settlements poses diarrhea risks. Little information is available on the contamination of environmental media with enteric pathogens in such settlements. We investigated the contamination of Escherichia coli, rotavirus, and Cryptosporidium spp. in water, on kitchenware, and on flies in urban informal settlements of Chawama and Kanyama, Lusaka, Zambia. These environmental media were examined by XM-G agar cultivation for E. coli and specific real-time RT-PCR assays to detect rotavirus and Cryptosporidium spp. E. coli; rotavirus, and Cryptosporidium spp. were detected in samples of household stored drinking water (6 of 10 samples, 3 of 10 samples, and 2 of 10 samples, respectively), cups (10 of 20 samples, 2 of 13 samples, 1 of 13 samples, respectively), and flies (35 of 55 samples, 5 of 17 samples, 1 of 17 samples, respectively). The ranges of rotavirus concentrations in household stored drinking water, on cups, and flies were 2.9 × 102-2.2 × 105 copies/L, 1.2 × 102-4.3 × 102 copies/cup, and 5.0 × 101-2.0 × 102 copies/fly, respectively. These results indicate the contribution of drinking water and kitchenware to enteric pathogen exposure and potential role of flies in microbial transmission.

Temperature affects growth, geosmin/2-methylisoborneol production, and gene expression in two cyanobacterial species.

Cyanobacterial blooms accompanied by taste and odor (T&O) compounds affect the recreational function and safe use of drinking water. Geosmin and 2-methylisoborneol (2-MIB) are the most common T&O compounds. In this study, we investigated the effect of temperature on geosmin and 2-MIB production in Dolichospermum smithii and Pseudanabaena foetida var. intermedia. More specifically, transcription of one geosmin synthase gene (geoA) and two 2-MIB synthase genes (mtf and mtc) was explored. Of the three temperatures (15, 25, and 35 °C) tested, the maximum Chl-a content was determined at 25 °C in both D. smithii and P. foetida var. intermedia. The maximum total geosmin concentration (19.82 µg/L) produced by D. smithii was detected at 25 °C. The total 2-MIB concentration (82.5 µg/L) produced by P. foetida var. intermedia was the highest at 35 °C. Besides, the lowest Chl-a content and minimum geosmin/2-MIB concentration were observed at 15 °C. There was a good positive correlation between geosmin/2-MIB concentration and Chl-a content. The expression levels of the geoA, mtf, and mtc genes at 15 °C were significantly higher than those at 25 and 35 °C. The transcription of the mtf and mtc genes in P. foetida var. intermedia was higher at 35 °C than at 25 °C. The results highlight unfavorable temperature can increase the potential of geosmin/2-MIB synthesis from the gene expression level in cyanobacteria. This study could provide basic knowledge of geosmin/2-MIB production by cyanobacteria for better understanding and management of T&O problems in drinking water.

Effects of elevated nitrogen on the growth and geosmin productivity of Dolichospermum smithii.

Geosmin is one of the most common earthy-musty odor compounds, which is mainly produced by cyanobacteria in surface water. Nitrogen (N) is an important factor affecting the growth of cyanobacteria and its secondary metabolites production due to the eutrophication. In this study, we compared the effects of elevated N on the growth and geosmin productivity of Dolichospermum smithii NIES-824 (synonym Anabaena smithii NIES-824), aiming to better understand the mechanisms involved and give an important and fundamental knowledge to solve off-flavor problem. Results show that elevated N concentration promoted more chlorophyll a (Chl-a) production, whereas the geosmin synthesis decreased, revealing a possible competitive correlation between the Chl-a concentration and geosmin production of D. smithii NIES-824. The majority of geosmin (> 90%) was retained intracellularly during the 28 days of cultivation. The qRT-PCR analysis demonstrates that the expression level of the geosmin synthase gene (geoA) was constitutive and decreased at the higher N concentration during the exponential growth phase of cyanobacterial cells. Furthermore, the decrease of geoA expression during the decline phase suggested that geoA transcription was closely related to cell activity and isoprenoid productivity.

Biodegradation of pharmaceuticals and personal care products in the sequential combination of activated sludge treatment and soil aquifer treatment.

Soil aquifer treatment (SAT), applied after activated sludge treatment (AST), has been widely used for wastewater reclamation. AST and SAT show potential for removing micropollutants, including pharmaceuticals and personal care products (PPCPs). However, the role of sequential combination of AST and SAT on the biodegradation of PPCPs was not clear in previous studies. In this study, the removal characteristics of PPCPs in AST and SAT were evaluated to assess the legitimacy of sequential combination of AST and SAT. SAT showed effective removals of antibiotics (> 80%), including fluoroquinolones and macrolides by sorption, but poor removals of amide pharmaceuticals (i.e. carbamazepine and crotamiton) were observed in both AST and SAT. Additionally, biodegradation contributed to the effective removal of carboxylic PPCPs (i.e. ketoprofen and gemfibrozil) in both ASTs and SAT, but effective biodegradation of halogenated acid and polycyclic aromatic compounds (i.e. clofibric acid and naproxen) was observed only in SAT (82.1% and 81.8%, respectively). Furthermore, the microbial substrate metabolic patterns showed that amino acids, amines, and polymers were biodegradable in SAT, which was fit for the biodegradation characteristics of PPCPs in SAT. For microbial communities, Proteobacteria were dominant in AST and SAT, but Acidobacteria and Actinobacteria were more abundant in SAT than AST, which could contribute to the effective removals of halogenated acid in SAT. Considering PPCP biodegradation and substrate metabolism, SAT displays a wider range on the biodegradation than AST. Therefore, we conclude that these two processes can complement each other when used for controlling PPCPs.

Formation of N-nitrosodimethylamine by chloramination of anthropogenic nitrogenous compounds with dimethylamine monitored by Japanese water authorities.

Pollutant release and transfer registers (PRTRs) compounds accidentally released to source waters can be important precursors of the carcinogenic N-nitrosodimethylamine (NDMA) during drinking water treatment. The NDMA formation potentials (NDMAFPs) of 31 anthropogenic nitrogenous compounds with dimethylamine (DMA) moiety on the Japanese PRTR and the registered precursors listed by the Ministry of Health, Labour and Welfare of Japan are investigated as well as influencing factors (i.e., NH2Cl dose and water matrices) on the NDMAFPs of precursors. Tertiary amines with aryl groups ß-positioned to the nitrogen atom of the DMA moiety formed high concentrations of NDMA (35-51%) during chloramination. Moreover, dimethylcarbamoyl chloride (DMCCl) was considered a new NDMA precursor with NDMAFP of 1.1%, higher than DMA, a traditional NDMA precursor. Excessive NH2Cl dose enhanced the NDMA formation, and the NDMAFP of DMCCl significantly decreased in river water; the effect of the matrix in river water varied and was compound-specific. Among the selected nitrogenous compounds, NDMAFPs of 15 excessed the current guideline concentration for NDMA in Japan (100 ng/L) assuming an accidental release of 0.144 mg C/L (the concentration in previous Japanese water quality accident in May 2012), and 2-(dimethylaminomethyl) thiophene (DMAMT) showed the highest NDMAFP at 58 µg/L.

Determination of Caffeine and Its Metabolites in Wastewater Treatment Plants Using Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

For caffeine and its seven major metabolites (i.e., theobromine, theophylline, paraxanthine, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, and xanthine), an optimized analytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for their detection in wastewater samples was developed in this study. Extraction of these compounds (recoveries ranged from 60.3 to 83.2%) was made possible by combining universal polymeric reversed-phase cartridge and polymeric strong cation exchange cartridge. This method was applied to the determination of caffeine and its metabolites in the influent and effluent of an anaerobic-anoxic-oxic (A2O) process. In the A2O influent, caffeine and its metabolites (except xanthine) ranged from 1.39 to 5.45 µg/L, and their concentrations in the A2O effluent ranged from 10.2 to 171.3 ng/L. The mass load of caffeine was 14.9 g/day/1000 inhabitants, considering the population served by the target wastewater treatment plant (WWTP). The concentration of caffeine derivatives in wastewater influent is a tool for estimating the population size in the area served by WWTPs.

Formation of chlorinated haloacetic acids by chlorination of low molecular weight compounds listed on pollutant release and transfer registers (PRTRs).

Anthropogenic compounds accidentally released to the environment could be important precursors of disinfection byproducts (DBPs) in drinking water treatment processes. In this study, the haloacetic acid formation potentials (HAAFPs) of 155 anthropogenic compounds listed on the Japanese pollutant release and transfer register (PRTR) system were evaluated. The results showed that phenolic and aromatic amine compounds were important HAA precursors, and chlorinated phenols showed high HAAFPs (>400 µg/mgC). Moreover, trichlorfon and ethyl chloroacetate (HAAFP of 104.9 and 602.3 µg/mgC, respectively) were also important HAA precursors because of their ability to undergo hydrolysis. Although most anthropogenic compounds with high HAAFPs showed high chlorine consumptions, no clear correlation between HAAFPs and chlorine consumptions was found in this study. In addition, the quantitative structure-activity relationship (QSAR) approach was a useful tool for predicting the chlorine consumption of organic compounds but was not effective for predicting HAAFPs based on the information currently available. A scenario study assuming a hypothetical accidental release predicted that the release of 3,4-dichloroaniline (HAAFP of 407.6 µg/mgC) would lead to a violation of the current drinking water quality standards for HAAs in Japan.