bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaerobic bioventing of unsaturated zone contaminated with DDT and DNT
Authors: Shah J. K. , Sayles G. D. , Suidan M. T. , Mihopoulos P. , Kaskassian S.
Published: May 2018

Initial degradation of highly chlorinated compounds and nitroaromatic compounds found in munition waste streams is accelerated under anaerobic conditions followed by aerobic treatment of the degradation products. The establishment of anaerobic environment in a vadose zone can be accomplished by feeding appropriate anaerobic gas mixture, i.e., “anaerobic bioventing”. The gas mixture contains an electron donor for the reduction of these compounds. Lab scale study was conducted to evaluate potential of anaerobic bioventing for the treatment of an unsaturated zone contaminated with 1,1,1-trichloro -2,2-bis(p-chlorophenyl)ethane (DDT) and 2,4-dinitrotoluene (DNT). Hydrogen was used as the electron donor. Using the soil columns innoculate with anaerobic microorganisms, it was observed that by feeding a gas mixture of 1% hydrogen, 1% carbon dioxide and nitrogen, methanogenic conditions were established and DDT was reductively dechlorinated. 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) accumulated as the intermediate product. The half life of DDT was calculated to be 8.5 months. DNT completely disappeared after six months of operation and no intermediates could be detected.
Biomarker studies on gold-lined sea bream (Rhabdosargus sarba) exposed to benzo[a]pyrene
Authors: Xu L. , Chen J. , Zhang Y. , Cheung C. C. , Lam P. K.
Published: May 2018

Gold-lined sea bream (Rhabdosargus sarba) were intraperitoneally injected with 35 mg/kg benzo[a]pyrene (in DMSO), with fish administered DMSO as the solvent control. Fish were sacrificed 3 days post injection and their livers dissected for the analysis of adenosine triphosphates (ATPase), glutathione-S-transferase (GST), DNA adducts and ethyoxyresorufin-O-deethylase (EROD). Exposure to B[a]P resulted in reduced ATPase activity, elevated GST activity and DNA adduct level, but no apparent change in EROD activity.
Effects of spilled oil on the tidal flat ecosystem - evaluation of wave and tidal actions using a tidal flat simulator
Authors: Cheong C. J. , Okada M.
Published: May 2018

The purpose of this study is to clarify the effects of wave and tidal actions on the penetration of spilled oil stranded on tidal flats and to evaluate the influence of the penetrated oil on seawater infiltration using tidal flat simulator. A simulator used was composed of tidal flat, wave maker, tide controlling device, temperature controlling system and computer controlling system. The infiltrations of seawater and fuel oil C into tidal flats were visualized using transparent glass beads as tidal flat sediments. Penetration behaviour of the spilled oil into the sediments was significantly different from that of seawater. Seawater infiltrated into the sediments both by wave action and tidal fluctuation, while fuel oil C penetrated by tidal movement only. The infiltration of seawater was reduced by penetrated oil. This result indicates that the penetrated oil diminishes infiltration of seawater into the sediments and thus results in the reduction in the supply of oxygen, nutrients, and organic matterto the benthic organisms in tidal flat.
Investigation of radical reactions for efficiency improvement in ozone-hydrogen peroxide treatment
Authors: Yasunaga N. , Furukawa S. , Kawaai Y. , Hirotsuji J.
Published: May 2018

It was verified by laboratory-scale experiments that the two-port ozone injection method was more advantageous for reaction efficiency in the ozone-hydrogen peroxide treatment than the conventional one-port ozone injection method under the condition of same ozone dose. The reason for this effectiveness was also investigated in detail by computer simulations in the wide range of the rate constant of OH radical reacting with TOC (kTOC). The laboratory-scale experiments revealed that the amount of TOC decomposed (δTOC) increased by up to 41% by the two-port injection method, indicating a 27% improvement in δO3/δTOC. A detailed investigation of these experimental results by computer simulations showed that by injecting ozone in two ports the amount of ozone consumed for the OH radical formation was increased more remarkably than that of ozone consumed for the radical chain reactions, and that the amount of OH radical reacting with TOC was increased more strikingly than that with ozone. Furthermore, it was found that the smaller the kTOC value within 105–109 M–1s–1 was, the more advantageous for the reaction efficiency the two-port injection method was.
Ion exchange selectivities of calcium alginate gels for heavy metals
Authors: Jodra Y. , Mijangos F.
Published: May 2018

An equilibrium model has been proposed and verified, based on the conditions in the gel phase and Donnan equilibrium theory, for the analysis of the experimental data on the recovery of lead, copper, cadmium, cobalt, nickel and zinc from synthetic, nonmetallic aqueous solutions on calcium alginate gels. This equilibrium model considers that the system behaves as an ion-exchange process between the calcium in the gels and the divalent metals in solution, and that the metallic portion enclosed in gel fluid is supposed an important quantitative contribution to the total amount of metal uptake by gels. According to the equilibrium constants calculated, it is deduced that the selectivity order is: Pb>Cu>Cd>Ni>Zn>Co.
The potential application of activated carbon from sewage sludge to organic dyes removal
Authors: Graham N. , Chen X. G. , Jayaseelan S.
Published: May 2018

The objective of this research work was to study the potential application of activated carbon from sewage sludge to organic dye removal. Methylene blue and crystal violet were the two dyes investigated in the present study. Three activated carbons were produced from the exclusive sewage sludge (referred to as DS), the sludge with the additive of coconut husk (DC) and sludge with the additive of peanut shell (DP) respectively. They were characterized by their surface area and porosity and their surface chemistry structure. Adsorption studies were performed by the batch technique to obtain kinetic and equilibrium data. The results show that the three sludge-derived activated carbons had a developed porosity and marked content of surface functional groups. They exhibited a rapid three-stage adsorption process for both methylene blue and crystal violet. Their adsorption capacities for the two dyes were high, the carbon DP performed best in the adsorption whereas the carbon DC performed worst. It is therefore concluded that the activated carbons made from sewage sludge and its mixtures are promising for dye removal from aqueous streams.
Aerobic biodegradation of gasoline oxygenates MTBE and TBA
Authors: Wilson G. J. , Richter A. P. , Suidan M. T. , Venosa A. D.
Published: May 2018

MTBE degradation was investigated using a continuously stirred tank reactor (CSTR) with biomass retention (porous pot reactor) operated under aerobic conditions. MTBE was fed to the reactor at an influent concentration of 150 mg/l (1.70 mmol/l). A second identical reactor was operated as a control under the same conditions with the addition of 2.66 g/l of sodium azide, to kill any biological activity. Results from these experiments suggest that biomass retention is critical to the degradation of MTBE. The rate of MTBE removal was shown to be related to the VSS concentration. MTBE removal exceeded 99.99% when the VSS concentration in the reactor was over 600 mg/l. Results obtained from batch experiments conducted on mixed liquor samples from the porous pot reactor indicate that the individual rates of biodegradation of MTBE and TBA were higher for initial concentrations of 15 mg/l than for concentrations of 5 mg/l. The presence of TBA at lower concentrations did not effect the rate of MTBE degradation, however higher concentrations of TBA did reduce the rate of biodegradation of MTBE. Denaturing Gradient Gel Electrophoresis (DGGE) analysis reveals that the culture consisted of a community of bacterial organisms of about 6 species.
Effect of compost in phytoremediation of diesel-contaminated soils
Authors: Vouillamoz J. , Milke M. W.
Published: May 2018

The effect of compost on phytoremediation of diesel-contaminated soils was investigated using 130 small (200 g) containers in two screening tests. The experiments were conducted in a controlled environment using ryegrass from seed. Containers were destructively sampled at various times and analyzed for plant mass and total petroleum hydrocarbons. The results indicate that the presence of diesel reduces grass growth, and that compost helps reduced the impact of diesel on grass growth. The addition of compost helps increase diesel loss from the soils both with and without grass, though the addition of grass leads to lower diesel levels compared with controls. A second set of experiments indicates that the compost helps in phytoremediation of diesel-contaminated soil independent of the dilution effect that compost addition has. The results indicate that the compost addition allowed diesel loss down to 200 mg TPH/kg even though the compost would be expected to hold the diesel more tightly in the soil/compost mixture. The simplicity of the screening tests led to difficulties in controlling moisture content and germination rates. The conclusion of the research is that the tilling of compost into soils combined with grass seeding appears to be a valuable option for treating petroleum-contaminated soils.
Decolorization of a reactive copper-phthalocyanine dye under methanogenic conditions
Authors: Beyhill M. I. , Matthews R. D. , Pavlostathis S. G.
Published: May 2018

The objective of this research was to assess the biological decolorization of the copper-phthalocyanine dye Reactive Blue 7 (RB7) under methanogenic conditions using a mixed, methanogenic culture in a repetitive dye addition batch assay. The initial rate of decolorization was 13.2 mg/L-d and 5.7 mg/L-d for the first and second dye addition, respectively. For an initial RB7 concentration of ca. 300 mg/L, the extent of decolorization remained constant (about 62%) for each repetitive RB7 addition and resulted in a residual color build up. Declining absorbance ratio values (A664/A620) with increasing incubation time confirmed that the observed color removal was due to transformation as opposed to adsorption on the biomass. Chemical decolorization assays using sodium dithionite as the reducing agent resulted in similar absorbance spectra to that obtained after biological decolorization. In addition, in both the chemical and biological decolorization assays, partial oxidation of the reduced dye solution upon exposure to air resulted in higher residual color, indicating that the reduction and decolorization of RB7 are partially reversible. These results also suggest that RB7 reduction and decolorization both chemically and biologically most likely followed a similar reduction mechanism.
Comparison of dye wastewater treatment by normal and anoxic+anaerobic/aerobic SBR activated sludge processes
Authors: Panswad T. , Techovanich A. , Anotai J.
Published: May 2018

In this research, the effects of different color intensities, anoxic+anaerobic times and types of substrate on color removal effectiveness were studied using 16-litre bench scale sequencing batch reactor (SBR) anoxic+anaerobic/aerobic models. The systems were fed with a synthetic wastewater containing 500 mg/l of COD, 50 mg/l of N, 15 mg/l of P along with 10, 40 and 80 mg/l of reactive diazo Remazol Black B dye. The anoxic+anaerobic/aerobic periods were 0/11 (normal aerobic SBR), 2/9, 4/7 and 8/3 hours, respectively. The color removal occurred mainly under the anaerobic environment, while a slight attenuation was noticed under the aerobic condition. A better decolorization could be achieved with a longer anoxic+anaerobic period. The sodium acetate was a slightly better co-substrate for the color removal than glucose. The decolorization efficiency dwindled as the fed dye concentration increased, but the overall color removal leaned in the opposite direction. The phosphorus removal of the anoxic+anaerobic/aerobic systems was outstanding, whereas only 50% removal was achieved for the aerobic process. A dye concentration of up to 80 mg/l did not have any significant impact on the performance of the polyphosphate accumulating organisms (PAOs). The removal of organic carbon and TKN was comparable among all experiments regardless of system configurations, color intensities and types of substrate.
Use of image analysis and rheological studies for the control of settleability of filamentous bacteria: application in SBR reactor
Authors: Dagot C. , Pons M. N. , Casellas M. , Guibaud G. , Dollet P. , Baudu M.
Published: May 2018

To monitor the ability of flocs to settle in Sequencing Batch Reactor sludge, two methods were tested during two operation cycles. Firstly, an automated image analysis procedure has been tested to quantify the floc size and the length and number of filaments. Secondly, rheological measurements (Bingham viscosity and shear stress) have been used to characterise the dispersion of the sludge which can reflect the cohesive strength of aggregates and so the influence of filamentous bacteria on rheological properties. These results were compared with settling parameters such as Sludge Volume Index or settling velocity. Correlations between the measured parameters with image analysis and parameters such as Sludge Volume Index have been obtained. If it is more difficult to analyze rheological results, it seems however that the thixotropy and the Bingham viscosity distinguish poor settlement owing to some filamentous bulking. The first results are promising, although they require confirmation in the long term.
Enhanced biological phosphorus removal in a semifull-scale SBBR
Authors: Arnz P. , Arnold E. , Wilderer P. A.
Published: May 2018

A 17 m3 Sequencing Batch Biofilm Reactor (SBBR) was operated for enhanced biological phosphorus removal and nitrification for a period of 384 days. Enhanced biological phosphorus removal (EBPR) activity was instantly induced after start-up of EBPR operation mode and low phosphate effluent values were reached from the first batch onward. Process stability with regard to nitrification and EBPR were very good although high nitrate loads from backwashing disturbed the P removal performance. Due to anoxic conditions in the beginning of the cycle, readily degradable COD was depleted by denitrification. Consequently, particulate matter was the main carbon source for phosphorus accumulating organisms. Anaerobic hydrolysis or fermentation was found to be the rate limiting process in the SBBR cycle. Simultaneous denitrification occurred in the first 30 minutes of aeration and - to a lesser extent - during the remaining aeration time, enhancing nitrogen removal and indirectly also phosphorus removal.
Full-scale demonstration of biological nutrient removal in a single tank SBR process
Authors: Keller J. , Watts S. , Battye-Smith W. , Chong R.
Published: May 2018

Complete biological nutrient removal (BNR) in a single tank, sequencing batch reactor (SBR) process, is demonstrated here at full-scale on a typical domestic wastewater. The unique feature of the UniFed process is the introduction of the influent into the settled sludge blanket during the settling and decant periods of the SBR operation. This achieves suitable conditions for denitrification and anaerobic phosphate release which is critical to successful biological phosphorus removal. It also achieves a “selector” effect, which helps in generating a compact, well settling biomass in the reactor.

The results of this demonstration show that it is possible to achieve well over 90% removal of COD, nitrogen and phosphorus in such a process. Effluent quality achieved over a six-month operating period directly after commissioning was: 29 mg/l COD, 0.5 mg/l NH4-N, 1.5 mg/l NOx-N and 1.5 mg/l PO4-P (50%-iles of daily samples). During an 8-day, intensive sampling period, the effluent BOD5 was <2 mg/l in all samples and the total phosphorus averaged 0.17 mg/l in the effluent. Detailed sampling and analysis during one cycle and at various depths clearly showed the deliberate stratification achieved in the tank during the settling and decant period, allowing biochemical reactions to occur during this normally “non-productive” period.

The simplicity and flexibility of the UniFed system allows it to be used in numerous applications, particularly for industrial situations where a high degree of uncertainty of the wastewater composition during the design stage or where changing requirements based on changes on the production side are present. The single tank operation without any recycle also reduces the capital costs for a full BNR system compared to the comparatively complex continuous flow processes.
Biological nutrient removal in a full-scale SBR treating piggery wastewater: results and modelling
Authors: Tilche A. , Bortone G. , Malaspina F. , Piccinni S. , Stante L.
Published: May 2018

Research activities carried out at ENEA during the last few years allowed development of a Sequencing Batch Reactor (SBR) that is able to remove biologically organic waste, nitrogen and phosphorus and that showed to be particularly suited to obtain low effluent nutrient concentrations even starting from concentrated wastes. This plant, in more than one year of operation, is quite steadily obtaining more than 98% removal of nitrogen, phosphorus and COD. On the basis of the experimental results, a simulation model has been built and calibrated. The model showed the potential to be used for forecasting the behaviour of the process, being able to reproduce a process imbalance that followed the tentative reduction of aeration time.
Anaerobic treatment of domestic sewage at low temperature
Authors: Elmitwalli T. , Zeeman Gr. , Lettinga G.
Published: May 2018

The results of research concerning the feasibility of anaerobic treatment of domestic sewage at low temperature are summarized in this article. The batch tests demonstrated a high biodegradability of domestic sewage at 20°C (74%). Both batch and continuous experiments for the treatment of domestic sewage showed that the removal of SS prior to anaerobic treatment of domestic sewage not only provides a stable reactor performance but also improves the removal of both colloidal (CODcol) and dissolved COD (CODdis). The results of the pre-treatment of domestic sewage in an anaerobic filter (AF) and an anaerobic hybrid (AH) reactor showed that the AF reactor is an efficient process for the removal of suspended COD (CODss), viz. 82%, at an HRT of 4 h and 13°C. The novel AF reactor consists of vertical sheets of reticulated polyurethane foam with knobs, where the biomass was only in attached form. For the treatment of pre-settled sewage at 13°C, the AH reactor, with granular sludge, showed a higher total COD (CODt) removal than the UASB reactor as a result of higher CODcol removal. Therefore, the performance of a two-step system, AF+AH (with granular sludge) reactor, was investigated with different HRTs at 13°C. For optimization of CODss and CODdis an HRT of 4+4 h is needed, while for optimization of CODcol removal an HRT of 4+8 h is required. A CODt removal of 71% was achieved with 60% conversion to methane from the removed CODt when the AF+AH system was operated at an HRT of 4+8 h at 13°C.
Ecology and equity: key determinants of sustainable water security
Authors: Swaminathan M. S.
Published: May 2018

Trends in water consumption indicate that demand for water for household and industrial uses in developing countries could double as a proportion of total water demand in the next 25 years. Scope for expansion of water supply will, at the same time, be limited because development of irrigation and urban water supplies is becoming increasingly expensive, and often involves high costs in terms of environmental degradation and human resettlement. Without fundamental reform of water management, the rapid growth in urban water demand will require large transfers of water from irrigated agriculture, thereby threatening food security. Hence, water supply and demand should be managed in an integrated fashion, simultaneously considering all uses and sources. This will call for the establishment of community centred food and water security systems and national water trusts.

Once such systems and Trusts are established there could be a legally binding Global Water Convention on the model of the Global Convention on Climate and Biodiversity. The details of such a Global Water Conventions can be finalized at one of the future Stockholm Water Symposia. There are uncommon opportunities today for a water-secure world through synergy between technology, public policy and peoples‘ participation.
The value and price of water (The women of Lutsheko)
Authors: Kasrils Ronnie
Published: May 2018

The recommendations in the World Water Vision for full cost pricing fail to comprehend the reality of deep poverty. For the very poor, particularly in rural areas, systems that provide subsidies simply to be paid back in water charges are neither appropriate nor workable. Nor does charging for water that supplies people's basic needs have a significant impact (when compared to large users in agriculture, industry etc) on resources management. The related issue of private sector involvement is also shown to need care and caution to achieve successful results.
Production and oxidation of methane at low temperature by the microbial population of municipal sludge checks situated in north-east Europe
Authors: Nozhevnikova A. N. , Nekrasova V. K. , Kevbrina M. V. , Kotsyurbenko O. R.
Published: May 2018

Methanogenic and methane-oxidizing activities of the microbial population of sewage sludge checks (Moscow and Syktyvkar regions) were studied at temperatures ranging from 5 to 25°C. The number of methanogens in silt samples reached 1010 cells/ml. A temperature decrease from 25 to 5°C led to a sharp decrease of methanogenesis in the silt samples. Nevertheless, methanogenesis was still significant even at 5°C. Different organic substrates, including polymeric and aromatic compounds, were degraded with methane production at 6°C. At depths of 20-40 cm the number of methanotrophic bacteria reached 1011 cells/ml. Methane oxidative activity of the microbial populations in the silt was less sensitive to the 25° to 5°C temperature decrease. Ten methanotrophic species, able to grow at 6°C, were enriched from the Syktyvkar sludge lagoon and identified by indirect immunofluorescence. Enrichments obtained from the Syktuvkar region (62 N) contained more species of methane oxidizing bacteria able to grow at low temperature then methanogenic enrichments obtained from Moscow region (56 N).
Study of thermal hydrolysis as a pretreatment to mesophilic anaerobic digestion of pig slurry
Authors: Bonmatí A. , Flotats X. , Mateu L. , Campos E.
Published: May 2018

Feasibility of anaerobic digestion of pig slurry is dependent, among other factors, on the biogas production rate, which is low compared with other organic wastes, and on the profitable uses of surplus thermal energy produced, a limiting factor in warm geographical areas. The objectives of this work are determining whether low temperature thermal pretreatment (<90°C) improves pig slurry anaerobic digestion, and determining whether organic matter degradation during the thermal pretreatment is due to thermal phenomena (80°C) or to enzymatic ones (60°C). The thermal degradation tests showed that hydrolysis occurring during the thermal pretreatment is due to thermal phenomena. The increase in soluble substances were significantly larger at 80°C than at 60°C (both during 3 h). Two types of slurry were used in the batch anaerobic digestion tests. The effect of thermal pretreatment differed with the type of slurry: it was positive with almost non-degraded slurries containing low NH4+-N concentration, and negative (inhibition of the anaerobic digestion process) when using degraded slurries with high NH4+-N content.
Biodegradation of 1,1,1,2-tetrachloroethane under methanogenic conditions
Authors: Culubret E. N. , Luz M. , Amils R. , Sanz J. L.
Published: May 2018

Chlorinated aliphatic hydrocarbons are widely used as solvents and as intermediates in chemical synthesis, so they can be found in industrial wastewaters and released to the environment where they became a serious health risk due to their toxic properties and high chemical stability. Most of these compounds are xenobiotic and recalcitrant to biodegradation. In this article we report the effect of different co-substrates in the 1,1,1,2-tetrachloroethane (1,1,1,2-TeCA) degradation by anaerobic granular sludge, and its degradative pathway. Our results show that this compound is easy and rapidly biodegradable under methanogenic conditions, even in the absence of external electron donors. 1,1,1,2-TeCA is equimolecularly degraded to 1,1-dichloroethene (1,1-DCE) by reductive dichloroelimination. 1,1-DCE is only completely biodegraded in the presence of lactic acid as co-substrate. Although 1,1,1,2-TeCA can be apparently removed by autoclaved granular sludge, the compound is not transformed but retained inside the granules. The primary biodegradation of 1,1,1,2-TeCE to 1,1-DCE is a biotic process mediated by anaerobic bacteria.
Degradation of p-nitrophenol in a batch biofilter under sequential anaerobic/aerobic environments
Authors: Melgoza R. M. , Buitrón G.
Published: May 2018

A combined process anaerobic/aerobic in a single reactor was studied. P-nitrophenol (PNP) was used as the model compound. During the anaerobic stage the target compound is modified in such a way that the intermediate product is more readily biodegradable by the aerobic phase. A pilot biofilter was used for the experiment. The biofilter was packed with a volcanic stone (puzolane) to serve as support to the microorganisms and it was inoculated with activated sludge. The microorganisms were acclimated with an initial concentration of 25 mg PNP/l during 75 days (25 cycles). After 230 days of operation, the reaction time of the cycles was reduced to 11.5 h (8 h for the anaerobic phase and 3.5 h for the aerobic one). The PNP was transformed to p-aminophenol (PAP) in the anaerobic phase, with efficiencies near to 100%. A mineralization of 100% of the PAP was found in the oxidative stage. Global efficiencies of PNP mineralization of 98% were obtained. The reaction rates were 16 mg PNP/l-h (PNP uptake), 14 mg PAP/l-h (PAP formation) and 20 mg/l-h (PAP mineralization).
Workshop 8 (synthesis): simple, small-scale and appropriate technology for potable water
Authors: Narayanan Ravi , Hultmann Bengt
Published: May 2018

The low quality and quantity of water supply in much of the world is best tackled by a multi-disciplinary, small-scale, appropriate-technologies approach.
Photobiological effects of polychromatic medium pressure UV lamps
Authors: Kalisvaart Ben F.
Published: May 2018

Ultraviolet (UV) light has become widely accepted for the disinfection of potable water, process water and wastewater as an alternative to chlorination. To avoid the failure of a UV disinfection system due to the recovery of micro-organisms, certain additional wavelengths in the UV area are emitted by newly developed UV lamps. To reduce the chance of microbial recovery after ultraviolet irradiation, damage must be inflicted in as many areas of the micro-organism as possible. The effective killing of micro-organisms by improved polychromatic medium pressure UV lamps is due to their exceptionally high UV energy output at specific wavelengths across a broad section of the UV spectrum. The combination of these properties results in several different lethal effects in small and large micro-organisms. Important biological molecules other than DNA are likely to be damaged, which helps to prevent the recovery of irradiated micro-organisms. Absorption line spectra of absorbing nucleotide bases, DNA and other biological molecules, including proteins and enzymes, show how effective UV light can be. Recent findings on the biological effects of short wavelengths on Bacillus subtilis, Cryptosporidium parvum and Escherichia coli confirm the effect of short wavelengths. Practical comparisons with conventional low pressure UV lamps at equal UV dosages show better killing rates from polychromatic medium pressure lamps, without formation of disinfection byproducts (DBPs).
Removal of organic carbon, nitrogen and phosphorus in sequential batch reactors integrating the aerobic/anaerobic processes
Authors: Callado N. H. , Foresti E.
Published: May 2018

The performance of a bench-scale apparatus composed of two sequential batch reactors (SBR), forming an anaerobic/aerobic treatment system, was evaluated as to its potential use for biological removal of organic matter and nutrients. Both the reactors with 12.5 L of useful volume each were operated for the batch cycles of 12 hours receiving 8.0 L of substrate in each cycle. The first reactor (SBRAn) fed with synthetic substrate simulating domestic sewage was meant to remove the largest fraction of carbonic matter and to promote the substrate ammonification. The second reactor (SBRAe) was operated under alternating aerobic and anoxic conditions to establish conditions for achieving nitrification; denitrification and biological phosphate removal in the same batch cycle. Sodium acetate was used as an external carbon source for phosphate removal. Processes monitoring included the analyses of: COD, NTK-N, NH4+-N, NO2−-N, NO3−-N, PO43--P, alkalinity, volatile acids, pH, redox potential, total, fixed and volatile solids. Under the operating conditions imposed, the system exhibited high performance in removing organic matter (COD), nitrogen and phosphorus, producing effluent with COD, NTK-N and PO43--P concentrations lower than 50.0 mg/L, 4.0 mg/L and 1.0 mg/L, respectively.
Influence of agitation rate on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass
Authors: Ratusznei S. M. , Rodrigues J. A.D. , Camargo E. F.M. , Zaiat M. , Borzani W.
Published: May 2018

The present work reports on the influence of the mechanical agitation rates on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass on polyurethane foam, as inert support, treating synthetic domestic wastewater. The reactor was operated at 30°C and an 8-hour cycle was used to treat approximately 0.5 L of the synthetic substrate with a COD concentration of nearly 500 mg/L. The studied agitation rates ranged from no agitation to 750 rpm. The system attained non-filtered substrate removal efficiency greater than 83% when agitation was employed. A very short start-up period and good solid retention could be observed. The use of agitation increased the efficiency of the reactor and enabled reduction of the total cycle time. An empirical equation and a first-order kinetic model are proposed to analyze the influence of agitation rates on the reactor's performance.
Investigation of the reaction pathway of OH radicals produced by Fenton oxidation in the conditions of wastewater treatment
Authors: Yoon J. , Lee Y. , Kim S.
Published: May 2018

Fenton reaction has been often used to treat industrial wastewater or landfill leachate. However, most mechanistic research into the Fenton reaction has been confined to low concentration conditions (usually the concentration of iron is less than 1 mM). These conditions are removed from the circumstances of real application. This is especially true in the treatment of landfill leachate in Korea. Therefore, we investigated the characteristics of the Fenton system using high concentrations of iron (mostly [Fe2+] = 1∼10 mM, [H2O2] = 5 mM, [Organic (t-BuOH or methanol)] = 0 or 30 mM) and interpreted the results from the known reaction mechanisms of the Fenton system. As a result, the use of high ferrous ion [≥1 mM) is believed to be appropriate for producing large quantities of OH• within a short period of time, causing fast consumption of hydrogen peroxide. However, OH• scavenging by the ferrous ion, the changes of oxidation products due to the oxygen depleted conditions, and the precipitation effect of ferric ion must be considered for the successful application of Fenton reaction. On the other hand, in low ferrous ion (<1 mM), it is important to utilize the redox cycles of iron in an effective manner.
River Water Quality Model no. 1 (RWQM1): III. Biochemical submodel selection
Authors: Vanrolleghem P. , Borchardt D. , Henze M. , Rauch W. , Reichert P. , Shanahan P. , Somlyódy L.
Published: May 2018

The new River Water Quality Model no.1 introduced in the two accompanying papers by Shanahan et al. and Reichert et al. is comprehensive. Shanahan et al. introduced a six-step decision procedure to select the necessary model features for a certain application. This paper specifically addresses one of these steps, i.e. the selection of submodels of the comprehensive biochemical conversion model introduced in Reichert et al. Specific conditions for inclusion of one or the other conversion process or model component are introduced, as are some general rules that can support the selection. Examples of simplified models are presented.
River Water Quality Model no. 1 (RWQM1): Case study I. Compartmentalisation approach applied to oxygen balances in the River Lahn (Germany)
Authors: Borchardt D. , Reichert P.
Published: May 2018

A case study on the application of the River Water Quality Model No. 1 (RWQM1) is presented in order to illustrate the importance of modelling a sediment compartment for an ecologically meaningful assessment of the impact of wastewater effluents and combined sewer overflows. The focus of this case study is on the compartmentalisation approach of the RWQM1 that makes such a description possible. In contrast to this, a strongly simplified biochemical submodel is used that considers only oxygen and dissolved substrate. The object of the case study is the River Lahn, a moderately polluted 5th order stream in Germany, for which the connectivity of surface/subsurface flows and mass fluxes within river sediments have been intensively investigated. The hyporheic flow between a downwelling and upwelling zone of a riffle-pool sequence has been studied with the aid of tracer experiments and continuous records of water constituents. High diurnal fluctuations of oxygen travelled to considerable depth of the sediment and oxygen in the interstitial water decreased considerably while travelling through the riffle. Starting with the implementation of a strongly simplified version of the biochemical part of the RWQM1, but with the consideration of a sediment pore water compartment in addition to the water column compartment, a calibration procedure is performed using tracer data from the water column and the sediment. The calibrated model is then used to study the system response to wastewater treatment plant effluent and combined sewer overflow emissions. The modelling approach makes it possible to quantify the sediment oxygen demand and the spatial and temporal extent of sediment zones with oxygen depletion. However, the spatially averaged approach does not account for inhomogeneities in the sediment. It is shown that for this river with its alluvial coarse sediments even moderate emissions from sewerage systems may be high enough to drop sediment oxygen concentrations to low levels while those in the surface flow remain close to saturation. Similarly, it is demonstrated that combined sewer overflows may cause anoxic sediment oxygen conditions for extended time periods. The implications for ecologically sound river water quality modelling and for specific quality objectives are discussed.
River Water Quality Model no. 1 (RWQM1): Case study II. Oxygen and nitrogen conversion processes in the River Glatt (Switzerland)
Authors: Reichert P.
Published: May 2018

Various simplifications of the river water quality model no. 1 are applied to data sets from the river Glatt in Switzerland. In a first application, the biomass responsible for nitrogen and oxygen conversion processes is quantified based on known reaeration rates, measured concentrations of ammonia, nitrite and oxygen and assumed growth parameters of algae and bacteria. In a second application, the model is extended to calculate chemical equilibria of inorganic carbon compounds dissolved in the water and daily variations in pH. The influence of partially unknown inflow concentrations and of calcite precipitation on fluctuations in electrical conductivity and pH are discussed. In the last model, the processes of growth of sessile algae and bacteria, detachment of algae, and grazing by benthic organisms are introduced. Due to lack of data for quantifying these processes, this last model application is speculative. Nevertheless, it is interesting because it shows a direction to which river water quality modelling would have to proceed in order to increase its predictive capabilities.
Risk based urban watershed management under conflicting objectives
Authors: Novotny V. , Clark D. , Griffin R. J. , Booth D.
Published: May 2018

Ecological impairment and flooding caused by urbanization can be expressed numerically by calculating the risks throughout the watershed (floodplain) and along the main stems of the streams. The risks can be evaluated in terms of the present and/or future. This article describes the methodologies for ascertaining the risks in the Geographical Information Systems (GIS) environment. The objectives of urban flood controls and ecological preservation/restoration of urban waters are often conflicting and, in the past, the sole emphasis on flood control led to destruction of habitat and deterioration of water quality. An optimal solution to these two problems may be achieved by linking the risks to the concepts of risk communication, risk perception, and public willingness to pay for projects leading to ecological restoration and ecologically sustainable flood control. This method is appropriate because, in each case, public funds are used and the projects require approval and backing of policy makers and stakeholders. This article briefly describes a research project that attempts to resolve the conflict between the flood protection and stream ecological preservation and restoration and suggests alternative ways of expressing benefits of urban stream flood control and restoration projects.
Use of ozone and hydrogen peroxide in the post-treatment of UASB treated alkaline fruit cannery effluent
Authors: Sigge G.O. , Britz T.J. , Fourie P.C. , Barnardt C.A. , Strydom R.
Published: May 2018

UASB treatment of cannery effluents was shown to be feasible. However, the treated effluent still does not allow direct discharge to a water system and a further form of post-treatment is necessary to reduce the COD to lower than the legal limit of 75 mg/l. The use of ozone, hydrogen peroxide and granular activated carbon were used singly or in combination to assess the effectiveness as post-treatment options for the UASB treated alkaline fruit cannery effluent. Colour reduction in the effluent ranged from 15% to 92% and COD reductions of 26-91% were achieved. Combinations of ozone and hydrogen peroxide gave better results than either oxidant singly. The best results were achieved by combining ozone, hydrogen peroxide and granular activated carbon, and COD levels were reduced to levels sufficiently below the 75 mg/l limit.
Integration of chemical and biological treatments for textile industry wastewater: a possible zero-discharge system
Authors: Lee H.H.W. , Chen G. , Yue P.L.
Published: May 2018

Theoretical and experimental studies have established that integrated treatment systems (mostly chemical and biological) for various industrial wastewaters can achieve better quality of treatment and can be cost-effective. In the present study, the objective is to minimize the use of process water in the textile industry by an economical recycle and reuse scheme. The textile wastewater was first characterized in terms of COD, BOD5, salinity and color. In order to recycle such wastewater, the contaminants should be mineralized and/or removed according to the reusable textile water quality standards. Typical results show that this is achievable.

An economic analysis has been conducted on the proposed integrated system. The economic analysis shows that the integrated system is economically more attractive than any of the single treatment technologies for achieving the same target of treatment. The information presented in this paper provides a feasible option for the reduction of effluent discharges in the textile industry.
Small diameter gravity sewers: self-cleansing conditions and aspects of wastewater quality
Authors: Dias S. P. , Matos J. S.
Published: May 2018

The construction of conventional sewerage systems in small communities, with pipes laid on a uniform slope and manholes regularly spaced, is sometimes not economically feasible, because of the high costs of sewer installation. Under those circumstances, the small diameter gravity sewers (SDGS) have often proven to be substantially less costly than conventional sewers. Typically, in SDGS systems the wastewater from one or more households is discharged into an interceptor tank (or a single compartment septic tank). The settled effluent is discharged afterwards into small diameter sewers operating under gravity.

In this paper, special emphasis is given to the analysis of self-cleansing conditions and to the analysis of risks of sulphide generation and occurrence of septic conditions in SDGS systems. For the evaluation of the self-cleansing conditions, the critical velocity and the critical shear stress were computed according to the Shields equation. The forecasting of dissolved oxygen concentrations and sulphide build-up along the lines, for different flow conditions, was done running an established wastewater quality model.
The purification performance of infiltration basins fitted with pretreatment facilities: a case study
Authors: Bardin J. P. , Gautier A. , Barraud S. , Chocat B.
Published: May 2018

In the south-east of France, the evacuation of stormwater by infiltration into the ground is being developed for large aquifer systems such as the ground water in the Rhône valley and in the eastern part of Lyons. A study proposal has been presented to the water management department of the conurbation of Lyons, aimed at quantifying, within a reasonably short space of time, the effects, in terms of transport of pollutants, of the stormwater infiltration system in the underground water in eastern Lyons. To this end, a one year duration experiment was carried out on the Vénissieux infiltration basin which drains stormwater from a 380 hectares industrial catchment area. Its peculiar configuration also made it possible to acquire new knowledge on the qualitative operation of a few pretreatment facilities. After describing the operation of the basin and the experimental protocol, we shall present a body of data that we monitored and our conclusions about the behaviour of the pollution throughout the facilities. Then, we present methods used to assess the pollution removal performance of the infiltration basin and its pretreatment devices, the results obtained, and our conclusions about the impact of the infiltration basin on groundwater and soil.
Effects of aquatic macrophytes on physico-chemical conditions of three contrasting lowland streams: a consequence of diffuse pollution from agriculture?
Authors: Wilcock R. J. , Nagels J. W.
Published: May 2018

Three lowland streams in developed pasture catchments with different farming intensities exhibited contrasting summer diurnal variations in pH, DO and temperature. These are ascribed to differences in dominant aquatic vegetation and their respective effects on shade, and on photosynthetic production and respiration within each stream. The stream dominated by submerged macrophytes had the greatest amplitude swings in DO and pH, and DO levels of 86–128% saturation. Floating marginal macrophytes reduced photosynthetic inputs while providing additional organic loading for respiration, with consequent flat DO and pH curves and conditions not conducive to healthy stream ecosystems. The third stream was shaded by riparian plants, which inhibited photosynthetic effects on DO and pH so that diurnal variation was intermediate between the other two streams. The interaction between nutrients and increased insolation in agricultural catchments, in stimulating aquatic plants, needs to be better understood for managing the sustainability of stream habitats and ecosystems.
Photocatalytic thin film cascade reactor for treatment of organic compounds in wastewater
Authors: Chan A.H.C. , Porter J.F. , Barford J.P. , Chan C.K.
Published: May 2018

The photocatalytic oxidation of benzoic acid was investigated in a pilot scale-cascade photoreactor. The photoreactor consists of an array of UV lamps (40 W, 365 nm) illuminating a cascade of three inclined 316 stainless steel plates, on which titanium dioxide (TiO2) was immobilized by electrophoretic deposition. The percentage removal of total organic carbon (TOC) of liquid samples was determined. The photocatalytic process was affected by several operating parameters. Increasing the solution temperature was found to reduce the dissolved oxygen (DO) level and to decrease the rate of the degradation process. The Langmuir-Hinshelwood equation was found to be accurate for modeling the degradation of benzoic acid with initial concentrations of 50 ppm, 75 ppm and 100 ppm. The rate of removal of TOC was positively affected by UV light intensity, but appeared to be independent of solution flowrate in the range examined. Control experiments confirmed that the effects of adsorption of the solute onto the TiO2 catalysts and photolytic degradation were negligible.
Simulation of hyporheic self-purification in rivers: the assimilative capacity of proteins
Authors: Namour Ph , Le Pimpec P.
Published: May 2018

For the biochemical study of assimilation capacity (AC), two hypotheses were put forward (three levels of response, the hyporheon being the main site of self-purification). A physical model was designed, simulating the hyporheon and its response to increasing inputs of proteins was studied. The analyses evidence a low accumulation of proteins in the hyporheic biofilms for daily flows ranging from 0.1 to 20 mg/day. The percolation of proteins stimulates the proteolytic activity (increase in Vm) whereas the Km shows no significant change ; the assimilation capacities thus stimulated are vastly superior to the daily loads introduced into the system and explain the low accumulation of proteins. This stimulation concerns only a shallow active zone < 2 cm. For the future, a method of localising zones of hyporheic infiltrations (micro-piezometry, tracing, etc.) should be developed to monitor in situ the action of inputs of organic matter (OM) to estimate the AC of the river.
Dihydroxybenzenes: driven Fenton reactions
Authors: Rodríguez J. , Parra C. , Contreras D. , Freer J. , Baeza J.
Published: May 2018

Different compounds that reduce Fe(III) and that simultaneously increase the oxidation potential of the H2O2/Fe2+ system, have been evaluated. In this work, the improving of Fenton reactions by 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA) or 1,2-dihydroxybenzene (CAT) were studied. The three compounds are able to reduce Fe(III) to Fe(II), but the kinetic results depend on the method used to determine the Fe(II) ion. The dihydroxybenzenes (DHBs) degrades veratryl alcohol (VA), a lignin model compound, to a greater extent than observed in a typical Fenton reaction. The rate of VA degradation was associated with the duration of the chemiluminescence (CAT > 2,3-DHBA > 3,4-DHBA) and not with the sum of integrated counts. The treatment of a cellulose pulp bleaching effluent with DHBs/Fe(III)/H2O2 was evaluated by analyzing their depolymerization at pH 4 and 7 through molecular mass distribution determinations.