bluuebunny/crossref_metadata_2025 huggingface dataset:
Springs at risk in Wadi Al Arroub near Hebron, Palestine
Authors: Qannam Z.S.
Published: May 2018

Al Arroub (pop. 9,000) is situated on the flanks of the Wadi Al Arroub, midway between Bethlehem and Hebron. Agricultural and domestic water needs are dependent on the springs which discharge to the wadi. This water is contaminated with raw sewage and presents a serious health hazard. The spring water and wadi flow were field tested and subjected to detailed chemical and biological analyses through 1997 and 1998. The results of these analysis demonstrate the extent to which springs could have been contaminated by the sewage conduit and from other sources. BOD and COD increases downstream as do concentrations of sodium and chloride, due to evaporation. Concentrations of sulfate and nitrates decrease as ammonia and hydrogen sulfide are lost, while nitrates and sulfates are absorbedby the flora within the conduit. The water from Haj Hamid and Ein Arroub should not be used for drinking unless treated. Ein Sowan's water can also become dangerous during the wettest parts of the rainy season. The main cause is the irresponsible disposal of sewage and of solid domestic wastes. Therefore, it is essential that enforceable legislation be enacted to protect this environment and the health of the inhabitants of Al Arroub.
Impact of solution variables on the removal of heavy metals from wastewaters by a recycled iron sorbent
Authors: Smith E.H. , Chatterjee S.
Published: May 2018

Waste shot-blast fines from surface finishing processes have been demonstrated to be effective for removing heavy metals from solution by adsorption.The technology offers the potential for inexpensive recovery and reuse of a material normally discarded as a solid waste. While metal removals compare favorably with those achieved by commercial sorbents, applications issues such as the impact of background metal-complexing agents require investigation. The presence of oxalic acid, a complexing organic compound, impacted cadmium and lead adsorption in accordance with predictions from metal speciation equilibria; i.e., a small but measurable reduction in lead removal was observed, but cadmium adsorption was relatively unaffected. The effects were repeated in dynamic column experiments, with lead removals reduced by 15 to 20% in the presence of the ligand. Efforts to model adsorption equilibria in the presence of oxalic acid did not fully capture the reduced lead removal, presumably because the model does not consider the complete formation of metal-oxalic acid complexes prior to contact with the sorbent.
Hydrogen-dependent denitrification: preliminary assessment of two bio-electrochemical systems
Authors: Kiss I. , Szekeres S. , Bejerano T.T. , Soares M.I.
Published: May 2018

An autotrophic biological process for the treatment of nitrate-contaminated drinking water was studied in the laboratory, with the objective of developing a continuous system which would be simple, stable and amenable to upscaling. Hydrogen generated by electrolysis of the water to be treated was the source of energy for denitrifying microorganisms. Two main process configurations were compared: (1) a single reactor where both the generation of hydrogen and denitrification took place, and (2) a two-reactor system where water was first enriched with hydrogen in an electrolysis cell prior to entering a packed-bed bioreactor. The reactors were operated in a continuous mode and granulated activated carbon served as physical support for the biomass. Although the highest rates of denitrification (0.45 kg N m−3 d−1) and the shortest residence times (removal of 18 mg N l−1 in 17 min) were obtained in the single-reactor system, the two-reactor system was more stable and more suitable for upscaling.
Hydrogen as a quick indicator of organic shock loading in UASB
Authors: Huang Y.-H. , Huang G.-H. , Chou S. , Cheng S.-S.
Published: May 2018

This study investigates the influence of organic shock loading on H2 production in an upflow anaerobic sludge bed (UASB) reactor. An esterification wastewater produced from a polyethylene terephthalate (PET) manufacturing plant was applied; the major organic pollutants are ethylene glycol and acetaldehyde. Experiments of two influent modes were performed here: a continuous-flow mode with a step input of shock loading and a batch mode with a pulse input of shock loading. Results of the continuous-flow experiments indicate that biogas production parameters such as H2 concentration and biogas production rate are more sensitive than water quality parameters such as pH, ORP, COD and TOC. In particular, H2, increasing by 140% within 1 hour, is a very important index upon the organic shock loading. It changes from 120 ppm to over 600 ppm as the organic loading rate increases from 4.4 to 13.2 kgCOD/m3·day through 4 hours of shock loading. Experiments of the batch shock loading with different pulse dosagesof ethylene glycol, acetaldehyde and the raw wastewater were also investigated. The amount of H2 production increased in proportion to an increase of organic load. Furthermore, the sequence of H2 production among the three types of shock loading is acetaldehyde> ethylene glycol> raw wastewater. To sum up, H2 shows a faster response rate than the other parameters. Therefore, H2 can be adopted as an important parameter for organic shock loading in UASB.
Fate and toxic effects of cyanide on aerobic treatment systems
Authors: Haghighi-Podeh M.R. , Siyahati-Ardakani G.
Published: May 2018

Many industries discharge significant quantities of cyanide into the environment. Removal of cyanide is a vital task of increasing importance. Currently, the chemical methods of treating cyanide wastewater are used worldwide. The high cost, disposal problems and toxic by-products formation of chemical methods for treating cyanide wastewater has opened the door for more investigation of new methods. This paper evaluates the fate and toxic effects of cyanide on aerobic treatment systems. Both batch and continuous flow experiments were performed. The results indicate that the aerobic biological treatment of cyanide wastewater is an effective technology, which offers many advantages over chemical treatment methods. The microbiological experimental results show that among the microorganisms present in the culture, oscillatoria, philodina, carchesium, pseudomonas and bacillus bacteria were resistant to cyanide and capable of biodegrading it. The results of this study indicate that biodegradation and sorption of cyanide are the most important and least important removal mechanisms, respectively.
Study on wet air oxidation of aqueous ferrous cyanide solution catalyzed by three metal salts
Authors: Lee B.-N. , Lou J.-C.
Published: May 2018

The catalytic wet oxidation (CWO) process with Cu2+, Mn2+, and Ce2+ as catalysts, respectively, was applied to investigate the degradation of ferrocyanide (Fe(CN)64-) solution. For the conversions of Fe(CN)-64- during the noncatalytic wet oxidation (WO) process up to 99.9% was attained after a reaction time of 70 min. The COD removal efficiency was observed as only 38% in a noncatalytic oxidation; however, it could be enhanced to 75%, 61%, and 50% in the presence of Cu2+, Mn2+, and Ce2+, respectively. Both noncatalytic and catalytic wet oxidation processes of Fe(CN)-64- solution were considered to be a two-step reaction at pH 9.0 and temperatures of 433-473 K. The oxidation rate was initially fast, followed by a slow step, which did obey first-order kinetics with respect to chemical oxygen demand (COD). Both the 2+ and Ce2+ catalyzed oxidation showed a significant effect on the reduction of activation energy during the first reaction of the WO runs.
Competitive adsorption of copper and lead ions on an iron-coated sand from water
Authors: Lai C.H. , Chen C.Y. , Shih P.H. , Hsia T.H.
Published: May 2018

Iron oxides are good adsorbents for some metal ions. However, the adsorbent properties of these oxides are not fully exploited in water or wastewater operations because of difficulties associated with their separation from the aqueous phase. An oven process with agitators for applying an iron oxide coating onto the sand surface to utilize the adsorbent properties of the coating and filtration properties of the sand media was developed. The competitive adsorption of iron-coated sand for copper and lead ions from water was investigated by batch and column experiments. Among the two metal ions studied, the coated sand has greater affinity for the removal of lead ions compared to copper ions at a concentration of 5×0-5M, 1×10-4M and an interval of pH=2.5∼6.5. Adsorption behaviors of copper and lead ions at the iron oxide/water interface could be proved to form chemisorption through the SEM/EDAX analysis. From the column experiment results, both copper and lead ions could be removed simultaneously by the iron-coated sand in a continuous treatment unit.
Ozone treatment of distillery slop waste
Authors: Alfafara C.G. , Migo V.P. , Amarante J.A. , Dallo R.F. , Matsumura M.
Published: May 2018

Ozonation of distillery slop waste was done to evaluate the process in terms of organic matter removal and decolorization efficiencies. The chemical properties of melanoidins, which are known to harbor the chromophoric groups in the waste were also investigated. Ozone had primary effects on the decolorization of the slops and improvement in its biodegradability, compared to organic matter removal (as COD). A decolorization efficiency of 80% and a biodegradability improvement of 40% was obtained in 40 hours. Only 16% of the COD was removed. The melanoidins had a 10% decrease in molecular weight indicating slight depolymerization. UV spectral studies of melanoidins showed that olefinic linkages (which are said to be important in the structure of the chromophores) decreased.
Activation mechanism and effectiveness in reusing sludge from water purification
Authors: Ebie K. , Lee J.-H. , Yoon T.-H.
Published: May 2018

The sludge extracted from chemical sedimentation basins shows a high concentration of aluminium which was added in the rapid mix tank. Therefore, the sludge volume after activation treatment with hydrochloric acid can be reused in order to coagulate turbid matter and humic substances in influent water. This study has focussed on examining the effectiveness of this sludge recycling process. HPLC with a RI detector was used to determine the molecular weight (M. W.) of PAC in the pH range of 3.0∼5.0. Results indicated that PAC was composed of two kinds of aluminium complexes at pH 3, having a M. W. of about 11,200 and 6,400. The M. W. of PAC in the pH variation and after the repetition of the activation treatment was also determined. Moreover, the abilities of PAC activated under the variable pH values to coagulate simulated natural surface water containing kaolin or humic acid were evaluated though jar-tests. When the pH in activated PAC was set at under 4, the coagulability of PAC did not deteriorate even if the activation treatment was repeated three times. In conclusion, the effectiveness of this process in practical use has been made clear from three points of view: the ph, the M. W., and the coagulability of PAC.
Biological sulphate removal from acid mine effluent using ethanol as carbon and energy source
Authors: Greben H.A. , Maree J.P. , Singmin Y. , Mnqanqeni S.
Published: May 2018

Mining effluents are major contributors to mineralization of receiving waters and can be toxic to man, animals and plants due to unacceptably high concentrations of heavy metals. A biological sulphate removal process has been developed for the treatment of sulphate-rich industrial effluents, where sulphate is converted via sulphide to sulphur in an anaerobic single-stage reactor. Ethanol is used as carbon and energy source. Sulphate was removed from acid mine water over a period of 95 days from 3000 mg/l down to less than 200 mg/l and the formed sulphides to less than 200 mg/l. The VSS value in the reactor varied between 3 and 4 g/l, resulting in a specific sulphate removal rate from 0.47 to 2.47 g SO4/(g VSS.d), while the volumetric rate was 2.5 and 8.4g SO4/(2.d) at HRT of 18 to 4.3 h. The experimental COD/sulphate ratio was between 0.55 and 0.84, which is in accordance with the theoretical value of 0.67. The experimental sulphide/sulphate ratio was less than the theoretical value of 0.33 due to the conversion of sulphate to sulphur and due to metal sulphide precipitation. Iron and copper were removed completely and aluminium, manganese and zinc to less than 4 mg/l.
Recovery of biodegradable plastics from activated sludge process
Authors: Takabatake H. , Satoh H. , Mino T. , Matsuo T.
Published: May 2018

In this research, PHA (polyhydroxyalkanoate) production system by activated sludge was studied. PHA behaves as carbon and energy storage material in bacteria. And PHA is a biodegradable plastic when extracted from bacteria. In this paper, the investigations from 3 aspects were reported; control of PHA composition, PHA production under coexistence of nitrogenous compounds, and influence of enrichment condition on PHA productivity. As results, it was possible to regulate PHA composition by utilizing acetate and propionate as carbon source and by regulating its composition. Nitrogenous compounds did not depress PHA productivities in the case of activated sludge, while nitrogenous compounds usually depress in general. PHA contents of MLSS were achieved up to 57% by using anaerobic-aerobic activated sludge. But microaerophilic-aerobic process could supply stably the activated sludge which accumulated PHA with high efficiency.
A study of water-land environment carrying capacity for a river basin
Authors: Chen C.H. , Wu R.S. , Liaw S.L. , Sue W.R. , Chiou I.J.
Published: May 2018

The concept of driving force-state-response (DSR) framework was used to identify and develop the assessment model of water-land environment carrying capacity (WLECC) for a river basin. The river basin water-land management (RBWLM) decision support system was developed, based on the assessment model of WLECC, as a decision making tool. The Chung-Kang river basin, located in northern Taiwan, was used as a case study to generate a sustainable water-land management strategy. This strategy simultaneously derives the optimal solutions for land use management, water demand allocation, and water quality management. Furthermore, the sustainable WLECC can also be obtained. The WLECC can be used as the area-based indicator of sustainability to accurately measure the progress towards sustainable development for a river basin.
Application of artificial neural network to control the coagulant dosing in water treatment plant
Authors: Yu R.-F. , Kang S.-F. , Liaw S.-L. , Chen M.-c.
Published: May 2018

Coagulant dosing is one of the major operation costs in water treatment plant, and conventional control of this process for most plants is generally determined by the jar test. However, this method can only provide periodic information and is difficult to apply to automatic control. This paper presents the feasibility of applying artificial neural network (ANN) to automatically control the coagulant dosing in water treatment plant. Five on-line monitoring variables including turbidity (NTUin), pH (pHin) and conductivity (Conin) in raw water, effluent turbidity (NTUout) of settling tank, and alum dosage (Dos) were used to build the coagulant dosing prediction model. Three methods including regression model, time series model and ANN models were used to predict alum dosage. According to the result of this study, the regression model performed a poor prediction on coagulant dosage. Both time-series and ANN models performed precise prediction results of dosage. The ANN model with ahead coagulant dosage performed the best prediction of alum dosage with a R2 of 0.97 (RMS=0.016), very low average predicted error of 0.75 mg/L of alum were also found in the ANN model. Consequently, the application of ANN model to control the coagulant dosing is feasible in water treatment.
Identifying useful real-time control parameters in ozonation process
Authors: Yu C.-P. , Yu Y.-H.
Published: May 2018

Industrial wastewaters that contain phenolic compounds are resistant to biodegradation and need preoxidation to improve their biodegradabilities. Preoxidation of these wastewaters by using ozone as the chemical oxidant has been found previously to be quite effective in promoting their biodegradability. In combined ozonation and biological processes, if we want to stop ozonation at the optimum condition (i.e. the maximum biodegradability), a biodegradation test is required. Since biodegradation tests such as BOD/TOC and oxygen uptake would take a long time, we could not know the time to stop ozonation immediately. This study was undertaken to identify process parameters (pH, ORP, ozone concentration in water, ozone gas concentration at the reactor outlet) that could be useful for monitoring and real-time control purposes in ozonation processes. We want to correlate these parameters with biodegradability and intermediates formed in ozonation processes. Results showed that the rapid increase of dissolved ozone and the first plateau termination of off-gas ozone concentrations are good indicators for the depletion of p-nitrophenol, the maximum of biodegradability and the elimination of toxicity. From the mean oxidation state curve, ozonation of p-nitrophenol could be divided into three stages, and a similar pattern could also be observed in ORP profiles. From the results of this research, the application of ozone concentration and ORP profiles as real-time control parameters seems promising.
Novel Nitrospira-like bacteria as dominant nitrite-oxidizers in biofilms from wastewater treatment plants: diversity and in situ physiology
Authors: Daims H. , Nielsen P.H. , Nielsen J.L. , Juretschko S. , Wagner M.
Published: May 2018

The frequency and distribution of putatively nitrite-oxidizing, Nitrospira- like bacteria in nitrifying biofilms from two reactors receiving wastewater with different ammonia and salt concentrations were observed by fluorescent in situ hybridization. For this purpose, new 16S rRNA-directed oligonucleotide probes targeting the bacterial phylum Nitrospira and the three main lineages within this phylum were developed and evaluated. The diversity of Nitrospira-like bacteria in the reactors was additionally investigated by retrieval and comparative analysis of full 16S rRNA sequences from the biofilms. We found that, despite of the differences in the influent composition, Nitrospira-like bacteria form dominant populations in both reactors. In addition, first insights into the physiology of these still unculturable bacteria were obtained by the incubation of active biofilm samples with radioactively labeled substrates followed by the combined application of fluorescent in situ hybridization and microautoradiography. The results are discussed in consideration of the frequently observed dominance of Nitrospira-like bacteria in nitrifying bioreactors. Consequently, high priority should be assigned to future studies on the ecology and physiology of these organisms in order to increase our fundamental understanding of nitrogen cycling and to enable knowledge-driven future improvements of nitrifying wastewater treatment plants.
Simulation of tertiary denitrification with methanol in an upflow biofilter
Authors: Horn H. , Telgmann U.
Published: May 2018

A biofilm model for the simulation of denitrification with methanol in a 3 m high upflow biofilter is presented. This model considers mass transfer at the bulk/biofilm interface, mass transport in the liquid phase of the biofilter and mass transport and substrate utilization in the biofilm. The biofilter was run with different filtration rates between 11 and 29 m/h. The methanol dosage ranged between 2.6 and 3.8 g CH3OH/g NO3−N. The denitrification rate ranged between 1 and 4.8 kg/m3d and depended mainly on the filtration rate and the methanol dosage. To carry out a simulation, the biofilter was divided into five segments. Each segment was simulated as a totally mixed reactor tank. The experimental results were used to fit the maximum growth rate of the denitrifying bacteria and the yield coefficient for the process growth in the simulation. The simulation of nitrate and COD concentration in the effluent matches very well the experimental results even when the filtration rate changed. It was also possible to simulate the measured concentration profiles in the biofilter with the presented model.
Tertiary nitrification in pure oxygen moving bed biofilm reactors
Authors: Bonomo L. , Pastorelli G. , Quinto E. , Rinaldi G.
Published: May 2018

Two bench-scale reactors, fed with the secondary effluent of a municipal wastewater treatment plant (WWTP), were used in order to study tertiary nitrification in pure oxygen moving bed biofilm reactors (PO-MBBRs) with patented KMT® media as biofilm carriers. The process allowed to measure very high nitrification rates, both in ammonia limiting conditions (up to 7 gN m−2 d−1; oxygen-to-ammonia nitrogen ratio higher than 3–4 mgO2 (mgN)−1) and in oxygen limiting conditions (up to 8 gN m−2 d−1; oxygen-to-ammonia nitrogen ratio lower than 1–2 mgO2 (mgN)−1). Since the process proved flexible and reliable, it is suitable for full-scale application to municipal WWTPs. Typical application could regard, but is not limited to, tertiary nitrification of secondary effluent from existing high-purity oxygen activated sludge systems designed to achieve only organic carbon removal.
Aeration control on a nitrifying biofilter system by using on-line analyzers
Authors: Puznava N. , Thornberg D. , Magnin P. , Reddet E.
Published: May 2018

Two new ways of controlling the aeration in nitrifying biofilters, by measuring on-line dissolved oxygen and ammonia concentration in the effluent of the filter, are compared to the standard control using time tables with constant air flow. Both on pilot and large scale, the new process control concepts proved to be very efficient in optimizing operation costs for aeration (up to 70% during rainy days) and to guarantee a demanded effluent quality.
Observations during start-up of biological phosphorus removal in biofilm reactors
Authors: Castillo P.A. , González-Martínez S. , Tejero I.
Published: May 2018

This research describes the start-up phase of Biological Phosphorus Removal (BPR) processes in two reactors. A Submerged Fix Bed Reactor (SFBR) working with a mixture of synthetic wastewater and domestic sewage and seeded with activated sludge coming from a BPR facility. A second reactor, a Biofilm Membrane Reactor (BMR), was fed with synthetic wastewater and seeded with a mixture of a pure culture of Acinetobacter lwoffi and fresh domestic sewage. It was found that Organic Loading Rates (OLR) above 5 gCOD/m2·d do not guarantee the adequate Mean Cellular Retention Time (MCRT) for the development of Poly-P organisms. Anaerobic periods should not be short during start-up phase or facultative bacteria will efficiently compete for food and, eventually, facing long aerobic periods, the Poly-P organisms may not need the phosphate mechanism to survive short anaerobic periods. Even if COD removal is observed during the anaerobic phase, further P accumulation during the aerobic phase will not be significant, unless the COD removal results in PHB formation. A loss in the BPR capacity of the Poly-P microorganisms was observed after seeding a reactor with active Poly-P organisms. The drop of BPR activity after seeding a reactor with active Poly-P organisms can be caused by the loss of genetic material due to the new environmental conditions and the new influent substrate.
Biofilm models for the practitioner
Authors: Morgenroth E. , van Loosdrecht M.C.M. , Wanner O.
Published: May 2018

Even though mathematical biofilm models are extensively used in biofilm research, there has been very little application of these models in the engineering practice so far. However, practitioners would be interested in models that can be used as tools to control plant operation under dynamic conditions or to help them handle complex interactions between particle removal, carbon oxidation, nitrification, denitrification and biological phosphorus removal. But even though there is a whole range of biofilm models available, it is difficult for the practitioner to select the appropriate modeling approach. Practitioners, experimenters and modelers should work together to identify the important processes that shoud be included in models. Guidance for model selection, calibration and application should be provided.
Methyl tertiary-butyl ether (MTBE) biodegradation in batch and continuous upflow fixed-biofilm reactors
Authors: Acuna-Askar K. , Englande A.J. , Hu C. , Jin G.
Published: May 2018

MTBE was effectively biodegraded under oxidizing environmental conditions in the presence of an acclimated mixed culture isolated from a petrochemical biotreater. MC-1 (Gram-positive coccus), MC-2 (Acinetobacter lwoffii) and MC-3 (Bacillus sp.) were present in the culture medium, with MC-1 being the predominant organism. The presence of other easily assimilated carbon sources in the culture medium influenced MTBE biodegradation. In batch studies, 62–73% MTBE was biodegraded in 144–192 hours at an initial concentration of 100 ppm as the sole carbon source, with the ORP ranging from 191–274 mv, and at a temperature of 29°C. The overall K rate constants and the specific k rate constants were evaluated using a first order rate equation. Mean values determined were 1.79×10-1 day-1 and 1.66×10-2 day-1/(mg/L cell mass), respectively. Continuous upflow fixed biofilm reactor studies were performed at retention times of 0.25, 0.5, and 1 day at an initial MTBE concentration of 150 ppm. Results indicated that approximately 53% MTBE was biodegraded for the 0.25 day retention time and 70% for both the 0.5 and 1.0 day retention times. Three kinetic models were evaluated for all experimental retention times. These included: Model I (Eckenfelder); Model II (Arvin) and Model III (first-order biphasic). Results indicated that model III yielded the highest and most consistent correlation coefficients for all retention times evaluated.
Degradation of phenol and p-cresol in reactors
Authors: Fang Herbert H.P. , Zhou Gong-Ming
Published: May 2018

The effects of hydraulic retention time (HRT) and phenol concentration on the degradation of phenol and p-cresol in wastewater were investigated in two respective UASB (upflow anaerobic sludge blanket) reactors with effluent recirculation at 37 °C for over 440 days. After acclimation, nearly all the phenol and p-cresol at moderate concentrations could be degraded without carbohydrate as a co-substrate. Treating a wastewater containing 800 mg/l of phenol and 300 mg/l of p-cresol at HRT ranging 2–12 hours, the first reactor consistently removed 95% of phenol, 65% of p-cresol and 85% of COD at 8–12 hours of HRT; the efficiency, however, decreased at lower HRT. Treating wastewater containing a constant p-cresol concentration of 400 mg/l at 24 hours of HRT, the second reactor was able to remove 75–80% of COD when the phenol was 1200 and 1500 mg/l; the removal efficiency decreased as phenol concentration further increased. High levels of residual phenol and p-cresol in the effluent suppressed the activity of biogranules. The suppression of bioactivity was not permanent. Biomass was able to regain its activity fully after lowering the phenolic concentrations in the wastewater.
Reactive textile dye colour removal in a sequencing batch reactor
Authors: Lourenço N.D. , Novais J.M. , Pinheiro H.M.
Published: May 2018

Two sequencing batch reactors (SBRs) with sequenced anaerobic/aerobic phases were used to study biological colour removal from a simulated cotton textile effluent containing an azo reactive dye. One of the reactors was daily fed with Remazol Brilliant Violet 5R dye and the other was used as control. When operating with a sludge retention time (SRT) of 15 days the total COD removal was around 80%, with 30% being removed anaerobically. After 40–50 days of acclimatization the colour removal efficiency reached a maximum, stable value of 90% from a feed dye concentration of 90 mg/l, almost all being removed during the anaerobic phase. This colour removal was attributed to microbial degradation rather than adsorption and colour removal capacity was not lost even after a seven-day absence of dye in the fed substrate. The dye-fed reactor experienced a reduction in the ORP values attained during the non-aerated phase, after acclimatization, an effect not observed in the dye-free control. Under denitrifying conditions it was observed that the decolouration levels achieved in the anaerobic phase decreased from 90% to 70% after only two cycles with a feed containing 45–60 mg NO3/l. Reduction of the SRT value from 15 to 10 days reduced the biomass concentration from 2.0 to 1.2 g VSS/l and lowered colour removal levels from 90% to 30–50%. When the SRT value was increased back to 15 days the colour removal capacity of the system was completely recovered, suggesting that with a SRT of 10 days the adequate microbial population could not be installed in the reactors.
Comparison of three advanced oxidation processes for degradation of textile dyes
Authors: Aplin R. , Waite T.D.
Published: May 2018

This paper examines the use of three advanced oxidation processes in degrading the textile dye, Reactive Red 235. The dye was oxidised using ozonation, standard Fenton's reagent (Fe2+/H2O2) and a modified photo-Fenton's process (UV/Fe oxalate/H2O2) under a variety of conditions. The effects of initial dye concentration, initial pH and NaCl concentration were studied for each process. Each process was found to have different optimum conditions as determined by the underlying reaction mechanisms.
Trichloroethylene elimination assay by naural consortia of heterotrophic and methanotrophic bacteria
Authors: Hourbron E. , Escoffier S. , Capdeville B.
Published: May 2018

Xenobiotic compounds generated from the various industrial activities are toxic and could affect the natural ecosystem. So far biological processes have been used for treatment of those compounds. It has been reported that xenobiotic compounds can be degraded in pure cultures of methanotrophic bacteria. Therefore, the aim of this study is to demonstrate the capacity of several natural consortia of heterotrophic and methanotrophic bacteria in degradation of trichloroethylene (TCE). Treatability of TCE was studied using 3 different consortia of heterotrophic and methanotrophic bacteria. After a first culture with methane and contact with TCE, all the consortia tested showed a biological TCE degradation efficiency between 29 and 43%. Using acetylene as MMO inhibitor, the implication of this enzyme on the three inocula was demonstrated very well. It was found that the toxicity threshold of TCE to the tested bacteria fell into a range of 30 to 40 mg/l. At not toxic TCE concentration of 5 and 10 mg/l, the maximal TCE specific activity was observed after an incubation of 15 minutes. This initial degradation rate could be used as indicator of the efficiency of a natural inoculum for TCE degradation. The impact of the initial TCE and biomass concentration on the TCE degradation kinetics was also evaluated. In the experiments, the TCE degradation was subject to first order kinetics. The maximum specific degradation rate of TCE was estimated at 48.9 mg TCE/mg SST.h.

These experiments clearly demonstrate that methanotrophic bacteria are ubiquitous in the environment, and a lot of them can degrade TCE. This shows good perspectives for in situ treatment of TCE-contaminated sites by enrichment of the methanotrophic natural populations.
Biodegradation potential assessment of microbial consortia isolated from a diesel-contaminated soil
Authors: Milcic-Terzic J. , Lopez-Vidal Y. , Vrvic M.M. , Saval S.
Published: May 2018

Diesel, toluene and naphthalene-degrading microbial consortia were isolated from a diesel-contaminated soil. The presence of catabolic genes, xylE and ndoB responsible for toluene/xylene and naphthalene biodegradation, respectively, were screened by PCR techniques in all microbial consortia. The diesel-consortium possessed both catabolic genes, the toluene-consortium only the xylE gene, while the naphthalene-consortium possessed only the ndoB gene. On the basis of these results, it was concluded that contaminated soil has indigenous microbes with a high natural potential for biodegradation.
Treatment of methanol in a dry biofilm reactor using tubular carrier
Authors: Thalasso F. , Omil F. , Otero J.O. , Lema J.M.
Published: May 2018

A 13.4 l Dry Tubular Biofilm reactor (DTB), with 19 PVC tubes as carrier, was used to treat polluted air using methanol as a model pollutant. The design of this reactor was based on the creation of a mist by contacting the waste gas and a discontinuous liquid nutrient supply into an atomising nozzle. Air was fed into the reactor at specific gas flow rates from 60 to 230 m3/m3 · h, containing from 0.25 to 2.84×10-3 kg/m3 of methanol (volumetric loading rates from 1.4 to 4.7 kg/m3 · d). Biofilm growth was observed from the very beginning of the experiment although preferentially on the reactor's wall and not on the tubular carrier. Methanol degradation was observed to increase along the experiment and reached 1.24 kg/m3 · d. The efficiency of this system was limited by the clogging of the tubes used as carrier. The biofilm developed directly on the wall of the reactor had a specific methanol degradation rate of 1.08 kg/kgVSS · h, while only 0.6 kg/kgVSS · h of methanol were degraded after a long lag phase by the biomass developed inside the tubular carrier. Another experiment was carried out with the empty reactor without PVC tubing. In that case, a specific degradation rate of 4.15 kg/m3 · d was observed, which confirm that PVC tubular carrier was clearly not favourable to the process.
Organochlorine contamination in fish and mussels from Cambodia and other Asian countries
Authors: Monirith I. , Nakata H. , Watanabe M. , Takahashi S. , Tanabe S. , Tana T. S.
Published: May 2018

Contamination by organochlorine compounds (OCs) was examined in fish and mussels collected from Cambodia and other Asian developing countries in 1997 and 1998. DDT and its metabolites were the predominantly detected compound in both fish and mussel samples. PCBs were second highest, followed by HCHs, CHLs, and HCB. Freshwater fish contained higher concentrations of DDTs than marine fish and mussels, implying that the source of DDTs originated from inland watersheds such as the Mekong River, Basac River, Tonlesap River, and Tonlesap Great Lake. Comparison of the OC residue levels in fish and mussels from Cambodia with those in other Asian and Oceanic regions suggested that Cambodia is one of the countries least contaminated by OCs. In other words, it can be concluded that among Asian and Oceanic countries Cambodia has kept a “Clean Environment”.
Cloning and expression of DL-2-haloacid dehalogenase gene from Burkholderia cepacia
Authors: Ohkouchi Y. , Koshikawa H. , Terashima Y.
Published: May 2018

Burkholderia cepacia strain KY, which can utilize a herbicide 2,4-D as a sole carbon and energy source, catalyzes the hydrolytic dehalogenation of both D- and L-2-haloalkanoic acids. We have cloned the gene encoding DL-2-haloacid dehalogenase, and obtained a recombinant plasmid (pUCDEXL) containing approximately 4.5 kbp insert. In both of B. cepacia strain KY and this clone E. coli JM109/pUCDEXL, DL-2-haloacid dehalogenase was induced significantly with monohalogenated acetic acids, such as chloroacetate, bromoacetate and iodoacetate. This dehalogenase was also overexpressed in E. coli using three different promoters. In pET vector systems with T7 lac promoter, a large amount of dehalogenase was selectively expressed, but some parts of the protein were accumulated in the form of inclusion bodies. This problem was overcome to carry on growth and induction at 22°C, and at the same time, the maximum specific activity of dehalogenase was reached at 12.6 U/mg, 500-fold higher activity than in wild strain, B. cepacia strain KY grown with 2,4-D.
Organic compounds in municipal landfill leachates
Authors: Paxéus N.
Published: May 2018

Leachates from three municipal landfills in the Göteborg area of western Sweden were characterised in terms of their content of individual organic compounds. Two of the investigated landfills were still in use during the time of this study. The third landfill was closed down in the mid-seventies. More than 200 individual organic compounds and classes of compounds were identified in the leachate with concentrations ranging from less than one up to several hundred μg/L. Among the compounds common to all three landfills were plasticizers (phthalates, benzenesulfonamides), phosphate esters, substituted phenols, chlorinated phenols, phenolic antioxidants and siloxanes as well as the compounds formed during the degradation of organic wastes (dihydro-dioxin, pyrazines and several sulphur-containing odorous volatiles). Dioxanes and dioxolans found in the leachates have not been previously reported. Compounds originated from previously disposed oil contaminated wastes dominate the leachate from an old closed landfill. Its replacement, a new regional landfill has a leachate dominated by alcohols and ethers. This difference is attributed to regional measures in waste management.
Copper removal by polymer immobilised Rhizopus oryzae
Authors: Al-Hakawati M. S. , Banks C. J.
Published: May 2018

Rhizopus oryzae, strain IMI 057412, was immobilised by inclusion in six different polymers: polyvinlformal, polysulfone, polyurethane, alginate, polyacrylamide, k-carrageenan, polyethyleneimine(PEI). It was also grown on a seventh, polyurethane. The biomass/polymer matrices were formed into equal size units (4 mm spheres or cubes) and the resulting biomass/polymer matrices were used to uptake copper at 2 mg/l from a laboratory-formulated copper solution in shake flask experiments at room temperature and initially neutral pH. Results showed that the copper uptake capacity of immobilised biomass was either equal to or less than that of free biomass. Biomass immobilised in polyurethane gave a capacity equal to that of free biomass, while other matrices hindered the uptake to different degrees. The k-carrageenan matrix proved to be unstable in the copper solution and dissolved during the experiment releasing the biomass and leading to an erroneous result. The polymer matrices without biomass, with theexception of alginate and polysulfone, showed no measurable copper adsorption capacity. All the experiments were conducted in duplicate with a maximum variation between them of 7%.
Wastewater treatment by pond systems: experiences in Catalonia, Spain
Authors: García J. , Mujeriego R. , Bourrouet A. , Peñuelas G. , Freixes A.
Published: May 2018

An evaluation of the 24 existing pond systems for treatment of urban wastewater in Catalonia (north-eastern Spain) was conducted in 1997-1998. The evaluation covered 13 aerated ponds, 7 waste stabilization ponds (WSP), and 4 maturation ponds added to conventional biological wastewater treatment plants (WWTP). The technical characteristics of the pond systems were obtained through a survey completed during several visits to the plants. Performance data was supplied by the Catalonia Wastewater Agency and the monthly monitoring campaigns conducted during 12 months in five WWTP. The average ratio of water surface to population equivalent (p-e) is 1.3 m2/p-e for aerated ponds, 9.6 m2/p-e for WSP and 1.7 m2/p-e for maturation ponds added to conventional WWTP. Average electrical energy consumption is 0.5 kW.h/m3 for aerated ponds and 0.04 kW.h/m3 for WSP (when wastewater has to be pumped from the sewer). Most of the WSP show an inadequate level O & M, because the very limited operator attendance (0.6 h/dayon average) as compared to aerated ponds (3.2 h/day on average). Effluent quality of aerated ponds (31 mg SS/l and 22 mg BOD5/l, on average) is usually better that of WSP (100 mg SS/l and 67 mg BOD5/l, on average). Most of the WSP are overloaded, with only two of the pond systems receiving less than 50 kg BOD5/ha. Facultative WSP show a better performance than anaerobic WSP; anaerobic WSP have very high overloading conditions (with more than 250 kg BOD5/ha.d). Average effluent quality of all the pond systems studied comply with European Union standards.
A contour plot approach that uses data accumulated during routine monitoring to obtain insights into lagoon behaviour
Authors: Hurse T.J. , Connor M.A.
Published: May 2018

Regular monitoring of wastewater characteristics is undertaken on most wastewater treatment plants. The data acquired during this process are usually filed and forgotten. However, systematic analysis of these data can provide useful insights into plant behaviour. Conventional graphical techniques are inadequate to give a good overall picture of how wastewater characteristics vary, with time and along the lagoon system. An approach based on the use of contour plots was devised that largely overcomes this problem. Superimposition of contour plots for different parameters can be used to gain a qualitative understanding of the nature and strength of relationships between the parameters. This is illustrated in an analysis of monitoring data for lagoon 115 East at the Western Treatment Plant, near Melbourne, Australia. In this illustrative analysis, relationships between ammonia removal rates and parameters such as chlorophyll a level and temperature are explored using a contour plot superimposition approach. It is concluded that this approach can help improve our understanding, not only of lagoon systems, but of other wastewater treatment systems as well.
Harmful cyanobacterial toxic blooms in waste stabilisation ponds
Authors: Oudra B. , El Andaloussi M. , Franca S. , Barros P. , Martins R. , Oufdou K. , Sbiyyaa B. , Loudiki M. , Mezrioui N. , Vasconcelos V.
Published: May 2018

A coccoid picocyanobacterium Synechocystis sp. (0.6-2 μm of cell diameter) was found to be dominant during summer period in the experimental wastewater stabilisation pond of Marrakesh. The taxonomy of this isolated strain was confirmed by electron microscope study. The general patterns of ultrastructure and the mode of cell division resemble Chroococcales. The cyanobacterium strain was axenic and cultured on both inorganic Z8 and BG13 media. Mammalian toxicity was confirmed by mice bioassay. The major sympton of poisoning was severe diarrhoea. Histopathological study shows a slight hepatotoxicosis associated with a pronounced change in the intestinal mucosa which shows swelling and destruction of villi epithelium and shedding of enterocytes into the lumen. Although slow, these kinds of poisoning are comparable to those induced by okadiac acid intraperitoneal mice injection (diarrhetic shellfish poisoning “DSP” toxins). By using the enzyme-linked immunosorbent assay (ELISA), the amount ofhepatotoxins “microcystins” was determined. The result shows that Synechocystis can produce a small amount of total microcystine [an average of 15 μg−1 dry weight corresponding to 20 ng(109cell)−1]. These findings lead us to consider Synechocystis as both a potent neurotoxin and hepatotoxin producer. Because of the confirmed cyanobacterium toxicity, an eventual ecological implication should be considered. However, a toxic chronic test experiment on Daphnia was simultaneously carried out. Juvenile D. magna (less than 24 hours old), were fed three concentrations (104, 106, 108 cells / ml) of Synechocystis. A group of organisms fed with Chlorella vulgaris (3. 105 cells/ml) and another group without food, were studied as control treatments. Only animals cultured with 104 cells/ml of cyanobacterium survived at 80% until the end of the test (21 days). Reproduction and normal growth occurred in control treatments fed with Chlorella vulgaris and the group fed with the lowest concentration of Synechocystis. One-way ANOVA statistical analyses show significant differences in Daphnia survival and growth, between treatments with and without Synechocystis and between treatments with and without food. In terms of this study, there is evidence that toxic picocyanobacteria blooms occurring in wastewater stabilization ponds of Marrakesh, could have harmful repercussions on zooplanktonic, bacteria and other algae communities. Consequently, this will constitute a possible hindrance for sewage self-purification process and system treatment performance. In addition, the reuse of such treated wastewater effluent for irrigation will constitute an additional, potent, health hazard for animals and human's.
Sulphur and phosphorus transformations in wastewater storage and treatment reservoirs in northeast Brazil
Authors: Araújo A. L. , de Oliveira R. , Mara D. D. , Pearson H. W. , Silva S. A.
Published: May 2018

Sulphur and phosphorous transformations were studied in two pilot-scale wastewater storage and treatment reservoirs on the basis of four experiments carried out at EXTRABES in northeast Brazil. The reservoirs were fed with the effluent from an anaerobic pond and after filling they were allowed to rest until faecal coliform numbers dropped below 100 cfu/100 ml (10 times below the WHO guideline for unrestricted irrigation). During the filling periods sulphate was reduced to sulphide which reached high values by the beginning of the rest period, decreasing thereafter due to its oxidation, mainly to sulphate. Based on these results a rest period of at least two months is required for sulphide to fall to safe levels from the point of view of biological toxicity. Total phosphorus removal in the reservoirs was low, 9–33%; soluble orthophosphate concentrations remained virtually unchanged, especially when the initial organic loading was high.
Some influences of sediments in aerated lagoons and waste stabilization ponds
Authors: Chabir D. , El Ouarghi H. , Brostaux Y. , Vasel J. L.
Published: May 2018

Respirometric tests have been undertaken on sediments in aerated lagoons and waste stabilization ponds to quantify their oxygen demand and to determine the main factors governing the process. Factors such as seasonal variations, temperature, substrate, sediment layer thickness, density of macro-invertebrates and suspended sediments were investigated. The results showed that temperature and substrate concentration are the main factors that influence sediment oxygen demand; followed by spatial heterogeneity and resuspension of sediments, whereas the density of macro-invertebrates could have an effect in summer (hot season). Sediment layer thickness had no effect. A model of sediment oxygen demand is developed for the two main factors (temperature and substrate) with an r2 of 0.98.
Sludge production in membrane bioreactors under different conditions
Authors: Wagner J. , Rosenwinkel K-H.
Published: May 2018

With membrane bioreactors, the production of surplus sludge is lower than with conventional activated sludge systems, a fact that has been confirmed in a large number of analyses. There is, however, no consensus about the dimension of the reactions and their respective causes. In order to examine these, at the University of Hanover a pilot plant with a capacity of 220 l was run for one year without any extraction of surplus sludge. The plant was started with 2 g MLSS/l; after one year, this value had risen to approximately 18 g MLSS/l. In order to be able to set the plant for different sludge loads (0.04 to 0.2 kg COD/(kg MLSS · d)), the wastewater was artificially stocked up. The emerging result was that in contrast to conventional systems the sludge growth was lower, but still continuously existing. Then, comparisons with theoretical approaches were run – among others with the ASM1-Model – which confirmed the findings. One possible reason could be the different biocoenoses, which was assumed to be the cause after several microscopic examinations had been run.