Effect of peracetic acid, ultraviolet radiation, nanofiltration-chlorine in the disinfection of a non conventional source of water (Tula Valley).

Water supply for human consumption requires certain quality that reduces health risks to consumers. In this sense, the process of disinfection plays an important role in the elimination of pathogenic microorganisms. Even though chlorination is the most applied process based on its effectiveness and cost, its application is being questioned considering the formation of disinfection by-products (DBPs). Therefore, alternative disinfectants are being evaluated and some treatment processes have been proposed to remove DBPs precursors (organic matter. This paper reports the results of disinfection of a non conventional source of water (aquifer recharged unintentionally with raw wastewater) with peracetic acid (PAA) and ultraviolet radiation (UV) as well as nanofiltration (NF) followed by chlorination to produce safe drinking water. The results showed that a dose of 2 mg/L PAA was needed to eliminate total and faecal coliforms. For UV light, a dose of 12.40 mWs/cm(2) reduced total and faecal coliforms below the detection limit. On the other hand, chlorine demand of water before NF was 1.1-1.3 mg/L with a trihalomethane formation potential (THMFP) of 118.62 mug/L, in contrast with chlorination after NF where the demand was 0.5 mg/L and THMFP of 17.64 mug/L. The recommended scheme is nanofiltration + chlorination.

Trujillo J, Barrios JA, Jimenez B.

Instituto de Ingeniería, UNAM, Ciudad Universitaria, Apartado Postal 70-472, 04510, Coyoacán, México, D.F. México Tel.: +52 (55) 5623 3600 E-mail: jtrujillom@iingen.unam.mx; jbarriosp@iingen.unam.mx; bjimenezc@iingen.unam.mx.

Evaluation of innovative operation concept for flat sheet MBR filtration system.

One of the most limiting factors for the extension and acceptance of MBR filtration systems for municipal and industrial wastewater is the impact of membrane fouling on maintenance, operation and cleaning efforts. One field of action in the European Research Project \”AMEDEUS\” is the development and testing of MBR module concepts with innovative fouling-prevention technology from three European module manufacturers.This article deals with the performances of the flat-sheet modules by A3 Water Solutions GmbH in double-deck configuration evaluated over 10 months in Anjou Recherche under typical biological operation conditions for MBR systems (MLSS = 10 g/l; SRT = 25 days). By using a double-deck configuration, it is possible to operate with a net flux of 25.5 l/m(2).h at 20 degrees C, a membrane air flow rate of 0.21 Nm(3)/h.m(2) (of membrane) to achieve a stable permeability of around 500-600 l/m(2).h.bar. Additionally, it was observed that it is possible to recover the membrane performance after biofouling during operation without intensive cleaning and to maintain stable permeability during peak flows.The evaluated concepts for equipping and operating MBR systems will be applied to several full-scale plants constructed by A3 Water Solutions GmbH.

Weinrich L, Grélot A.

A3 Water Solutions, Magdeburger Str. 16a, 45881, Gelsenkirschen, Germany lutz-weinrich@a3-gmbh.com.

Role of dissolved humic substances surrogates on phthalate esters migration from sewage sludge.

The facilitated transport of dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP), the priority endocrine disrupting chemicals in sludge, by dissolved humic substances (HS) was evaluated by batch extraction. The DBP, much less hydrophobic than DEHP, was inclined to migrate from sludge matrix into humic substances solutions, while the DEHP could not migrate facilitated by most humic and fulvic acids solutions, except the humic acid surrogate of high humification. This result revealed that the affinity of DEHP in sludge matrix exceeded DBP and was not susceptible by weak HS. The hydrophobic property controlled the association of phthalic acid esters on sludge residual phases. Migration rate of DBP was positively correlated to the weight-average molecular weight of HS surrogates and the aromatic extents of HA. Some functional groups in HS molecules benefited to the facilitated transport of DBP.

Zheng Z, He PJ, Zhang H, Shao LM.

State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, PR China solidwaste@mail.tongji.edu.cn.

Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation.

Recently, the membrane bioreactor (MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub-critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub-critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules (e.g. polysaccharides) may play an important role in membrane fouling under sub-critical flux operation.

Su YC, Huang CP, Lee HC, Pan JR.

Institute of Environmental Engineering, National Chiao Tung University, 75 Po-Ai Street, Hsinchu, Chinese Taiwan E-mail: harrysu.ev92g@nctu.edu.tw; cphuang@mail.nctu.edu.tw; jayamerican.ev93g@nctu.edu.tw cphuang@mail.nctu.edu.tw jayamerican.ev93g@nctu.edu.tw.

Microbial characteristics of biogas.

The microbial diversity of biogas was analyzed in order to examine the aerosolization behavior of microorganisms. Six biogas samples were analyzed: five from mesophilic and thermophilic anaerobic digestors treating different wastes, and one from landfill. Epifluorescent microscopic counts revealed 10(6) prokarya m(-3). To assess the difference occuring in aerosolization, 498 biogas-borne 16S ribosomal DNA were analyzed and compared to published anaerobic digestor microbial diversity. Results show a large microbial diversity and strong discrepancy with digestor microbial diversity. Three different aerosolisation behaviour patterns can be identified: (i) that of non-aerosolized microorganisms, Deltaproteobacteria, Spirochaetes, Thermotogae, Chloroflexi phyla and sulfate-reducing groups, (ii) that of passively aerosolized microorganisms, including Actinobacteria, Firmicutes and Bacteroidetes phyla and (iii) that of preferentially aerosolized microorganisms, including Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, as well as strictly aerobic and occasionally pathogenic species, presented high levels of aerosolization.

Moletta M, Wery N, Delgenes JP, Godon JJ.

INRA, UR050, Laboratoire de Biotechnologie de l\’Environnement, Narbonne, F-11100, France E-mail: godon@supagro.inra.fr; delgenes@supagro.inra.fr; weryn@supagro.inra.fr; marina.moletta@cstb.fr.

Odor control during post-digestion processing of biosolids through bioaugmentation of anaerobic digestion.

The effects of bioaugmenting anaerobic biosolids digestion with a commercial product that contained selected strains of bacteria from genera Bacillus, Pseudomonas, and Actinomycetes, along with ancillary organic compounds containing various micronutrients were evaluated. The main objective of the study was to investigate the effects of bioaugmentation specifically on the performance of methanogenesis during anaerobic digestion, as well as on the generation and fate of odor-causing compounds during the storage of the digested biosolids. The bench-scale digester with 5 g/L bioaugment generated 29% more net CH(4) than a control during the eight weeks of operation. In addition, the average residual propionic acid concentration in the bioaugmented digester was 46% lower than that in the control. The biosolids digested in the bioaugmented digester generated a negligible amount of methyl mercaptan (CH(3)SH) during 10 days of post-digestion storage, while CH(3)SH concentration in the control reached nearly 300 ppmv during the same period. Similarly peak dimethyl sulfide (CH(3)SCH(3)) generated by stored biosolids from the bioaugmented digester was only 37% of that from the control. Similar results were obtained in a subsequent short term study designed to confirm the repeatability of the findings.

Tepe N, Yurtsever D, Duran M, Mehta RJ, Bruno C, Punzi VL.

Spotts, Stevens and McCoy, Inc., 1047 N. Park Road, Reading, PA, 19610, USA.