bluuebunny/crossref_metadata_2025 huggingface dataset:
Cultural implications of wastewater reuse in fish farming in the Middle East
Authors: Mancy K. H. , Fattal B. , Kelada S.
Published: May 2018

The reuse of wastewater in fish farming is widely practiced to varying degrees in different regions of the world. Recently, the University of Michigan, in collaboration with the National Institute of Oceanography and Fisheries in Egypt, and the Hebrew University of Jerusalem, Israel, conducted a full-scale demonstration study in Egypt where raw sewage was treated and used in fish farming and the irrigation of crops and trees. The whole operation was carefully monitored for microbial pathogens, parasites, and toxic chemicals in the water and the fish. In spite of the fact that the produced fish were quite suitable for human consumption, consumers in Egypt did not accept them. While public health and safety concerns have traditionally been the main reason for resisting wastewater reuse, cultural and consumer behavior seem to be the overriding factors. International guidelines for hazard control in fish farming are not sufficient to change consumer behavior in certain regions of the world.
Municipal wastewater characteristics at Irtah pumping station in the Tulkarem city
Authors: Shaheen H.Q.
Published: May 2018

Wastewater flow samples were collected at 2-hour intervals for one week during the month of October 1998 at the Irtah wastewater pumping station in the Tulkarem city. The station collects about 32% of the wastewater of the Tulkarem city and 25% of the Tulkarem camp. The samples were mixed on 24-hour basis and tested for the pollution parameters BOD5, COD, total suspended solids, orthophosphate, total Kjeldahl nitrogen, ammonia nitrogen, nitrate, calcium, sodium and potassium. At the 2-hour intervals the wastewater flow was tested for conductivity, temperature, pH, and dissolved oxygen. The variation of the strength of these parameters and its relation to the flow values are observed and evaluated. The produced organic strength versus the flow and the 24-hour mixed samples are presented and commented upon.
Defluoridation in drinking waters
Authors: Azbar N. , Türkman A.
Published: May 2018

Although water supplies containing excessive amount of fluoride are generally very rare worldwide, there are locations in Turkey where drinking water contains very high fluoride concentrations. Especially in the middle and eastern part of Turkey, some mineral and drinking waters contain very high fluoride concentrations. It is a well known fact that drinking water exceeding the critical fluoride concentration (1 mg F−/L) may cause serious dental and skeletal damages.

In this study, various techniques were evaluated to find the most suitable solution for defluoridation for these regions, which have high concentrations of fluoride in their water supplies. For this purpose, various chemical agents including locally produced alumina were investigated. Locally produced alumina gave promising and economically sound results in terms of defluoridation capacity and availability.
The nonionic surfactant pollution profile of Israels Mediterranean Sea coastal water
Authors: Zoller U. , Hushan M.
Published: May 2018

Anionic and nonionic surfactants, as core components of detergent formulations, contribute significantly to the pollution profile of sewage and wastewaters of all kinds. In Israel about 15% of the total amount of ca. 4×108 m3/year of sewage is discharged, directly, or via receiving streams/rivers, into the Mediterranean Sea. Based on our previous findings that about 85% of the nonionic surfactants in the country sewage are nonbiodegradable alkylphenol-based ethoxylates, we have undertaken this study, aimed at mapping the receiving eastern Mediterranean seawater with respect to its nonionic surfactant pollution profile. The total concentrations of nonionic surfactants were found – via reverse phase HPLC determinations – to be within the range of 4.2–25.0 ppb in seawater samples taken 2–3 m off thecoastline at those locations where sewage-containing streams flow into the sea. Thus, neither the existing sewage treatment facilities nor natural biodegradation processes in receiving surface water systems are capable of avoiding this coastal water pollution. The potential estrogenic health risk of such concentrations of the anthropogenic EPEOs is dependent, among other factors, on their specific homological distribution, biodegradation rate (slower for those having >10 EO units) and survival.
Kinetics and physiological characteristics of autotrophic dentrification by denitrifying sulfur bacteria
Authors: Oh S.-E. , Kim K.-S. , Choi H.-C. , Cho J. , Kim I.S.
Published: May 2018

To study the kinetics and physiology of autotrophic denitrifying sulfur bacteria, a steady-state anaerobic master culture reactor (MCR) was operated for over six months under a semi-continuous mode and nitrate limiting conditions using nutrient/mineral/buffer (NMB) medium containing thiosulfate and nitrate. Characteristics of the autotropic denitrifier were investigated through the cumulative gas production volume and rate, measured using an anaerobic respirometer, and through the nitrate, nitrite, and sulfate concentrations within the media. The bio-kinetic parameters were obtained based upon the Monod equation using mixed cultures in the MCR. Nonlinear regression analysis was employed using nitrate depletion and biomass production curves. Although this analysis did not yield exact biokinetic parameter estimates, the following ranges for the parameter values were obtained: μmax =0.12-0.2 hr-1; k=0.3-0.4 hr-1; Ks=3-10mg/L; YNO3=0.4-0.5mg Biomass/mg NO3--N. Inhibition of denitrification occurred when the concentrations of NO3--N, and SO42- reached about 660mg/L and 2,000mg/L, respectively. The autotrophic denitrifying sulfur bacteria were observed to be very sensitive to nitrite but relatively tolerant of nitrate, sulfate, and thiosulfate. Under mixotrophic conditions, denitrification by these bacteria occurred autotrophically; even with as high as 2 g COD, autotrophic denitrification was not significantly affected. The optimal pH and temperature for autotrophic denitrification was about 6.5–7.5 and 33–35 °C, respectively.
Combination of a UASB reactor and a curtain type DHS (downflow hanging sponge) reactor as a cost-effective sewage treatment system for developing countries
Authors: Machdar I. , Sekiguchi Y. , Sumino H. , Ohashi A. , Harada H.
Published: May 2018

The second generation of our originally proposed sewage treatment system, which consists of a UASB reactor as an anaerobic pre-treatment unit and curtain-type DHS (downflow hanging sponge) reactor as an aerobic post-treatment unit, was installed at a municipal sewage treatment site. A 550-day continuous experiment demonstrated that the whole combined system successfully achieved 94–97% of unfiltered-BOD removal, 81–84% of unfiltered-COD removal, and 63–79% of SS removal, at an overall HRT of 8 h (6 h for UASB and 2 h for DHS units). The combined system performed an excellent organic removal as well as a fairly efficient nitrification, i.e. 52–61% of ammonia-nitrogen removal. Our proposed combined system possesses prominent advantages: requiring neither external aeration input nor excess sludge withdrawal.
Modeling of arsenic rejection considering affinity and steric hindrance effect in nanofiltration membranes
Authors: Oh J.I. , Urase T. , Kitawaki H. , Rahman M.M. , Rhahman M.H. , Yamamoto K.
Published: May 2018

Rejection characteristics of arsenic compounds such as arsenite, dimethyl arsinic acid, and arsenate were examined regarding the effect of pH change in nanofiltration. Rejection mechanism of arsenic compounds was explained by comparing experimental rejection with calculation of the Extended Nernst-Planck model coupled with steric hindrance model. Nanofiltration membranes of the same material show similar rejection characteristics of arsenic compounds in different species. Steric hindrance and electrostatic effect in the nanofiltration membranes was well described by the model because the rejection of chloride, sulfate and arsenate ions, which exist in ionized forms at a wide pH range showed quite good agreement between model calculation and experimental result. The rejection of dimethyl arsenic acid and arsenite required the consideration of mutual interaction between membrane material and solutes as well as steric hindrance and electrostatic effect. A system with ultra low-pressure nanofiltration membrane coupled with pre-oxidation device was suggested for the treatment of arsenic in groundwater in Bangladesh.
Enhanced bioremediation of trichloroethene contaminated by a biobarrier system
Authors: K C.M. , Yang L.
Published: May 2018

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this study was to develop a barrier system, which includes a peat (used as the primary substrates) layer to enhance the aerobic cometabolism of TCE in situ. A laboratory-scale column experiment was conducted to evaluate the feasibility of using this peat biobarrier to remediate aquifers contaminated by TCE. This system was performed using a series of continuous-flow glass columns including a soil column, a peat column, followed by two consecutive soil columns. Activated sludges were inoculated in all three soil columns to provide microbial consortia for TCE cometabolism. Simulated TCE contaminated groundwater with a flow rate of 0.25 L/day was pumped into the system. Effluent samples from each column were analyzed for TCE and its degradation byproducts [cis-dichloroethylene (cis-DCE) and vinyl chloride (VC)]. Average removal efficiency was 96% for TCE over a 60-day operating period. Accumulation of VC was observed due to the depletion of oxygen in the system. Results from this laboratory study reveal that the developed biobarrier treatment scheme would be expected to provide a more cost-effective alternative to remediate chlorinated-solvent contaminated aquifers.
pH effect on the surface and bulk characteristics of metallic cations/SiO2 suspensions
Authors: Kuan W.H. , Lo S.L. , Wang M.K.
Published: May 2018

The surface and bulk properties of Al(III)/SiO2 and Fe(III)/SiO2 suspensions were determined as a function of prepared pH. The TEM results showed that Al(III) tends to form Al(OH)3 coatings on the surface of SiO2 while Fe(III) tends to form the discrete Fe(OH)2 phase in bulk solution with system pH increase. The charge reversals (CR) observed in the Al(III)/SiO2 system represent, in order of increasing pH, the point-of-zero charge (PZC) on the SiO2 substrate (CR1), the pH of surface nucleation of Al(OH)3 (CR2), and, at high pH, the PZC of the Al(OH)3 coating (CR3). The observed electrophoresis mobility of Fe(III)/SiO2 is the overall result contributed by negatively charged SiO2 and positively charged Fe(OH)3.
Suspended carrier technology allows upgrading high-rate activated sludge plants for nitrogen removal via process intensification
Authors: Münch E.v. , Barr K. , Watts S. , Keller J.
Published: May 2018

The Oxley Creek wastewater treatment plant is a conventional 185,000 EP BOD removal activated sludge plant that is to be upgraded for nitrogen removal to protect its receiving water bodies, the Brisbane River and Moreton Bay. Suspended carrier technology is one possible way of upgrading this activated sludge wastewater treatment plant for nitrogen removal. Freely moving plastic media is added to the aeration zone, providing a growth platform for nitrifying bacteria and increasing the effective solids residence time (SRT).

This paper presents the results from operating a pilot plant for 7 months at the Oxley Creek WWTP in Brisbane, Australia. Natrix Major 12/12 plastic media, developed by ANOX (Lund, Sweden), was trialed in the pilot plant. The pilot plant was operated with a mixed liquor suspended solids concentration of 1220 mg/L and a total hydraulic residence time of 5.4 hours, similar to the operating conditions in the full-scale Stage 1&2 works at the Oxley Creek WWTP. The plastic carriers were suspended in the last third of the bioreactor volume, which was aerated to a DO setpoint of 4.0 mg/L. The first third of the bioreactor volume was made anoxic and the second third served for carbon removal, being aerated to a DO setpoint of 0.5 mg/L.

The results from the pilot plant indicate that an average effluent total inorganic nitrogen concentration (ammonia-N plus NOx−N) of less than 12 mg/L is possible. However, the effluent ammonia concentrations from the pilot plant showed large weekly fluctuations due to the intermittent operation of the sludge dewatering centrifuge returning significant ammonia loads to the plant on three days of the week. Optimising denitrification was carried out by lowering the DO concentration in the influent and in the carbon removal reactor. The results from the pilot plant study show that the Oxley Creek WWTP could be upgraded for nitrogen removal without additional tankage, using suspended carrier technology.
The effect of clay particles on the efficacy of a biocide
Authors: Pereira M.O. , Vieira M.J. , Melo L.F.
Published: May 2018

The effect of kaolin particles on the bacterial activity as well as on the efficacy of a biocide was investigated. The results show that the presence of the clay particles enhance the Pseudomonas fluorescens activity for all buffered pH values tested, this increase being more relevant for the more adverse pH for this bacteria growth. The results also demonstrated that kaolin reduces the ability of desinfection of a carbamate-based biocide against P. fluorescens suspensions.
Total nitrogen removal in two-step biofiltration
Authors: Pujol R. , Tarallo S.
Published: May 2018

A one-year study was carried out on two semi-industrial submerged up-flow biofilters - a pre-denitrification (pre-DN) step followed by a nitrifying (N) step, designed to treat the primary settled municipal wastewater of a full scale plant for both carbon and nitrogen removal. Performances of the pre-DN step have been investigated showing high removal denitrifying capacities – 1 to 1.2 kg NO3−–N removed per m3 of reactor per day–, obtained with high TSS and carbon loading rates, at a water velocity up to 21.5 m3/ m2.h. The complete treatment plant – primary settlement + pre-DN/N loop – has demonstrated a nitrogen removal efficiency ranging from 70% without any additional carbon, up to 85% with methanol. COD and TSS removal rates were 91% and 97% respectively.

The above results show that two submerged biofilters in series form a treatment line suitable for nitrogen removal. This technical choice leads to very compact full scale plants such as Ahlen WWTP (Germany, 85 000 PE).
Integration of nitrification and denitrification in biofilm airlift suspension reactors
Authors: van Loosdrecht M.C.M. , van Benthum W.A.J. , Heijnen J.J.
Published: May 2018

This paper describes several aspects that are relevant when nitrification and denitrification are integrated in one high rate, compact, biofilm reactor. These features included reactor design, oxygen availability for nitrification, possibilities for forcing the N-removal process over nitrite, and possible emission of nitrogen intermediates. It is concluded that it is possible with a proper process and oxygen control to force the N-removal in a stable manner over nitrite, thereby saving COD need. A possible complication is the risk of emission of NO and N2O which needs further attention in future research.
Description of biofilm formation by determination of developmental axis
Authors: Xavier J.B. , Mahló R. , Reis A.M. , Almeida J.S.
Published: May 2018

The formation of a multispecies denitrifying biofilm was monitored by confocal scanning laser microscopy (CSLM). The time series of tri-dimensional reconstitutions was used to develop a methodology for biofilm structural characterization based on the identification of axis of development. The algorithm is an adaptation of the standard medial axis transform technique (MAT) and was applied to both 2D sections and to the 3D stack. The use of development axis as the primary structural feature is a well-established practice to the study of morphogenesis of superior organisms. The extension of the concept to microbial aggregates is justified by the experimental realization of its highly structured nature. The determination of development axis (DA) is scalable and can be applied to structures with time resolution (effectively corresponding to four dimension structures) in order to define unifying measures of biofilm morphogenesis. Practical applications of DA characterization include the determination of how density of specific biofilms will be reflected in pore turtuosity, which in turn will condition the internal mass transfer limitations.
Biofilm characteristics in biological denitrification biofilm reactors
Authors: Chen C-Y. , Chen S-D.
Published: May 2018

The biological denitrification method applied to treat municipal sewage containing low levels of nitrogen compounds and contaminated groundwater is very popular. There are few studies in the literature on the treatment of industrial wastewater containing high levels of nitrogen compounds. To assess the feasibility of biofilm and immobilized cells for treating wastewater which contains high-strength nitrogen compounds, the biofilm characteristics of the biological denitrification process in attached-growth reactors were studied.

The Richardson-Zaki relationship can adequately describe the bioparticle fluidization phenomenon developed in biological denitrification reactors. The terminal settling velocity of bioparticles was 1.88—5.14 cm/s for activated carbon and 2.98 cm/s for immobilized cells, respectively. The dry density of biofilm grown on activated carbon decreased as the biofilm thickness increased and ranged between 63 and 93 mg/cm3. The biomass concentration in the reactor varied with the changes in both superficial velocity and biofilm thickness. The maximum biomass concentration occurred at the biofilm thickness of 400–700μm. Furthermore, a large amount of biofilm was grown on the surface of immobilized cells and there was only a small amount of microorganisms grown inside the cell beads.
Full scale parallel operation of a biological aerated filter (BAF) and activated sludge (AS) for nitrogen removal
Authors: Thøgersen T. , Hansen R.
Published: May 2018

In connection with the reconstruction and capacity extension of the Frederikshavn Central Wastewater Treatment Plant in the period between 1989 and 1995 the existing activated sludge plant (AS) was supplemented with a biological aerated filter (BAF). The parallel operation with two wastewater flows has made a comparison of the two plants possible in relation to operating data, operating costs and experience. For the purpose of optimizing the operation, tests were conducted to increase the hydraulic capacity of the plant during rain and control strategies for the plants were considered for dry weather as well as wet weather situations. This paper discusses the experience gained from the plant operation as well as the considerations made in relation to future control strategies and possibilities of increasing the total hydraulic capacity during rain.
Mathematical modeling of autotrophic denitrification in a nitrifying biofilm of a rotating biological contactor
Authors: Koch G. , Egli K. , Van der Meer J.R. , Siegrist H.
Published: May 2018

The mechanism of significant nitrogen loss in an aerobic rotating biological contactor (RBC) treating ammonium-rich waste water could be identified with the aid of batch experiments, mathematical modeling and microbial analysis. It turned out that the aerobic ammonium and nitrite-oxidizing organisms (nitrosomonas and nitrobacter clusters) are dominant in the upper aerobic 100–200 μm of the biofilm. It is assumed that nitrite, appearing as an intermediate product close to the surface of the aerobic biofilm layer, diffuses into deeper anoxic layers of the biofilm. It is reduced anaerobically there in parallel with ammonium oxidized as described in the Anammox (anaerobic ammonium oxidation) process. This was confirmed in an anoxic batch test with suspended biofilm removed from the RBC. Unknown micro-organisms were detected, some of them similar to the Anammox organisms. A mathematical model which describes the kinetics of the aerobic ammonium-oxidizing, aerobic nitrite-oxidizing and anoxic ammonium-oxidizing micro-organisms was formulated and fitted into the AQUASIM biofilm compartment. The distribution of the populations within the biofilm as well as the ammonium, nitrite and nitrate degradation along the RBC in a steady state and during short-term experiments were modeled and compared with the experimental data.
Dynamic modeling of ammonia removal at low temperatures in drinking water rapid filters
Authors: Uhl W. , Gimbel R.
Published: May 2018

In drinking water production from surface water raw water quality is subject to major changes. In the case studied here, ammonia concentration varies between 0.05 and 4.2 mg/l. While at high temperatures effective ammonia removal is no problem at low temperatures ammonia breakthrough at the rapid filters can be observed. It was hypothesised that ammonia breakthrough mainly is a dynamic problem. A model was developed which takes into account the dynamic changes of attached nitrifiers due to growth, death and deposition of bacteria from the liquid phase. Backwashing was taken into account. The dynamic simulation showed that the model well describes the dynamic behaviour of the rapid filters with respect to ammonia removal over a period of one year.
Rapid quantification and in situ detection of nitrifying bacteria in biofilms by monoclonal antibody method
Authors: Noda N. , Ikuta H. , Ebie Y. , Hirata A. , Tsuneda S. , Matsumura M. , Sumino T. , Inamori Y.
Published: May 2018

Fluorescent antibody technique by the monoclonal antibody method is very useful and helpful for the rapid quantification and in situ detection of the specific bacteria like nitrifiers in a mixed baxterial habitat such as a biofilm. In this study, twelve monoclonal antibodies against Nitrosomonas europaea (IFO14298) and sixteen against Nitrobacter winogradskyi (IFO14297) were raised from splenocytes of mice (BALB/c). It was found that these antibodies exhibited little cross reactivity against various kinds of heterotrophic bacteria. The direct cell count method using monoclonal antibodies could exactly detect and rapidly quantify N. europaea and N. winogradskyi. Moreover, the distribution of N. europaea and N. winogradskyi in a biofilm could be examined by in situ fluorescent antibody technique. It was shown that most of N. winogradskyi existed near the surface part and most of N. europaea existed at the inner part of the polyethylene glycol (PEG) gel pellet, which had entrapped activated sludge and used in a landfill leachate treatment reactor. It was suggested that this monoclonal antibody method was utilized for estimating and controlling the population of nitrifying bacteria as a quick and favorable tool.
Significance of substrate C/N ratio on structure and activity of nitrifying biofilms determined by in situ hybridization and the use of microelectrodes
Authors: Satoh H. , Okabe S. , Norimatsu N. , Watanabe Y.
Published: May 2018

The effect of substrate C/N ratio on the spatial distributions of ammonia-oxidizing bacteria and their activity was investigated by using microelectrodes with high spatial resolution and fluorescent in situ hybridization (FISH) technique. In this study, an interspecies competition for O2 between ammonia-oxidizing bacteria and heterotrophic bacteria was experimentally evaluated. An autotrophic nitrifying biofilm originally cultured at C/N=0 was used as a model biofilm to study changes in specific NH4+ oxidation rate profiles in the biofilm when the substrate C/N ratio was varied. As C/N ratio increased, specific NH4+ oxidation rates decreased in the outer part of the biofilm due to interspecies competition, while they were unchanged in the inner part. The increase in substrate C/N ratio (i.e., addition of acetate) immediately induced the interspecies competition for O2 between ammonia-oxidizing bacteria and heterotrophic bacteria at the outer part of the biofilm. As a result of the interspecies competition, NH4plus; oxidation was restrained, resulting in a decrease in the ammonia-oxidizing bacterial populations. This experimental result clearly explains the stratified spatial distributions of ammonia-oxidizing bacteria within the biofilms at higher substrate C/N ratios. The combined application of microelectrodes and FISH techniques provides new insights into microbial ecology and population dynamics of nitrifying bacteria within multi-species biofilms.
Enhanced removal of ammonium by combined nitrification/adsorption in expanded clay aggregate filters
Authors: Gisvold B. , Ødegaard H. , Füllesdal M.
Published: May 2018

Long-term experiments were carried out on a nitrifying biofilter with a zeolite-containing expanded clay aggregate filter media (Filtralite ZL) receiving daily peak loads of ammonia. The filter removed ammonium from domestic wastewater by a combination of nitrification and sorption of ammonium. The filter was biologically regenerated continuously and there was no deterioration in performance after 10 months of continuous experiments. Isotherm experiments confirmed that the Filtralite ZL granules that had been used for more than 8 months had about the same capacity as the unused material. Desorption experiments that were carried out indicated that desorption of ammonium from the filter material was mainly caused by an exchange of cations from the wastewater even at low cation concentrations.
Biodegradation of thiophene by cometabolism in a biofilm system
Authors: Rivas I.M. , Arvin E.
Published: May 2018

An investigation of the cometabolic degradation of thiophene in the presence of benzene has been performed in a continuous biofilm system in order to study the kinetics of this conversion. The study showed result that thiophene interferes with the metabolism of benzene: benzene is not completely mineralised in the presence of thiophene. The micro-organisms are inactivated by thiophene, its metabolites or the metabolites of benzene. For low ratios of thiophene to benzene in the inlet of the reactor, the bacteria seem to adapt to thiophene and regain part of their activity that was lost when thiophene was introduced in the system. A hypothesis for this phenomena is that toxic metabolites of thiophene are converted biologically or abiotically into compounds, which are less harmful and inhibiting to the micro-organisms. Resting cells, which have been activated previously with benzene, are able to degrade thiophene, and this conversion leads to the inactivation or the death of the cells.
Toward a standardization of the microbial inoculum for ready biodegradability testing of chemicals
Authors: Vazquez-Rodriguez G. , Goma G. , Rols J.L.
Published: May 2018

Activated sludge constitutes a widely used inoculum source in biodegradability tests, due principally to its microbial diversity and ubiquity. In ready biodegradability tests, the composition and the quantity of this type of inoculum are the major factors which affect the reproducibility of results. Experiments with dodecylbenzene sulfonate were carried out to evaluate the impact of the non-controlled inoculum on test response. At low inoculation levels, cellular growth and soluble residual carbon accumulation were favoured and low mineralization levels were obtained. A procedure for inoculum preparation was proposed: it consists in a pre-treatment of activated sludge, collected in different municipal wastewater treatment plants, by centrifugation (500 g for 4 minutes) which enabled the supernatant cellular density (CFU concentration) to be more uniform than with the conventional decantation procedure (30 min).
Treatment of high organic-loaded industrial effluents
Authors: Castillo Rivera L.A. , Sillet S. , Roussy J. , Degorce Dumas J.-R. , Thomas O.
Published: May 2018

There are many treatment schemes for industrial wastewater in existence. Generally, the choice of bioprocess is determined with respect to efficiency and ease of operation. This choice is obviously dependent on the possibility for the wastewater to be readily biodegradable. This consideration leads to the use of more adapted process based on chemical operations or even incineration. Starting from the need of non transferring techniques (without production of sludge), UV/H2O2 photooxidation has been studied for the treatment of several chemical process- and waste-water containing dissolved organic carbon concentrations in the range of 5 to 30 g.L-1 were studied. More precisely, the effect of simple steps such as pH adjustment or coagulation have been studied before application of Advanced Oxidation Process schemes. Depending on the initial organic matter concentration (e.g. DOC) conversions higher than 80% can be achieved.
Nitrogen and organics removal from industrial wastewater using natural zeolite media
Authors: Chung Y.-C. , Son D.-H. , Ahn D.-H.
Published: May 2018

Biological removal of nitrogen from industrial wastewater was investigated by a novel O/A (oxic/anoxic) type process with natural zeolite circulation. This process consists of ammonium ion removal by zeolites and subsequent biological regeneration of zeolites. Two types of raw wastewater with high strength ammonia nitrogen (300–400 mg/L) from a fertilizer industry and a tannery industry, separately, were prepared for laboratory scale experiments. After ammonia ion removal from the influent wastewater by zeolite in the anoxic reactor, nitrifying bacteria, either attached to the zeolite or suspended in solution, participated in the conversion of ammonia to nitrite and nitrate in the following oxic reactor. Zeolites saturated with ammonia nitrogen were continuously regenerated and circulated in the proposed process without the use of chemical regenerants such as NaCl. Experimental results showed an 88–92% removal of ammonia nitrogen and high settleability in the final clarifier for both examples of wastewater. The results support that the proposed biological reactors with zeolite powder circulation are very effective in treating high strength nitrogen bearing wastewater.
The role of (auto)catalysis in the mechanism of an anaerobic azo reduction
Authors: van der Zee F.P. , Lettinga G. , Field J.A.
Published: May 2018

Azo dyes are non-specifically reduced under anaerobic conditions, but the slow rates at which many dyes react may present a serious problem for the application of anaerobic technology as a first stage in the complete biodegradation of these compounds. Therefore, it is significant to explore the mechanism of anaerobic azo reduction, especially with respect to its kinetics. With that purpose, decolouration of the monoazo dye C.I. Acid Orange 7 (AO7) was studied in batch experiments. Experiments indicated that chemical reduction by sulphide is partially responsible for the anaerobic conversions of AO7. Mathematical evaluation of the experimental results pointed out that autocatalysis played an important role in the chemical reduction of AO7. Further tests made clear that 1-amino-2-naphthol was the dye's constituent aromatic amines that accelerated the reduction process, possibly by mediating the transfer of reducing equivalents. The impact of redox mediation by quinones was further evaluated by testingthe catalysing effects of anthraquinone-2,6-disulphonic acid (AQDS) and of autoclaved sludge. AQDS appeared to be an extremely powerful catalyst, capable of increasing the first-order chemical reduction rate constants by a factor 10 to 100. Also autoclaved sludge, possibly because of mediation by sludge organic matter, accomplished accelerated azo reduction rates. Azo reduction in living sulphidogenic anaerobic sludge environments is 3 times more rapid than the chemically catalysed reaction with sulphide. The exact role of the biological activity remains to be clarified.
Use of a sequencing batch biofilter for degradation of azo dyes (acids and bases)
Authors: Quezada M. , Linares I. , Buitrón G.
Published: May 2018

The degradation of azo dyes in an aerobic biofilter operated in an SBR system was studied. The azo dyes studied were Acid Red 151 and a textile effluent containing basic dyes (Basic Blue 41, Basic Red 46 and 16 and Basic Yellow 28 and 19). In the case of Acid Red 151 a maximal substrate degradation rate of 288 mg AR 151/lliquid·d was obtained and degradation efficiencies were between 60 and 99%. Mineralization studies showed that 73% (as carbon) of the initial azo dye was transformed to CO2 by the consortia. The textile effluent was efficiently biodegraded by the reactor. A maximal removal rate of 2.3 kg COD/lliquid·d was obtained with removal efficiencies (as COD) varying from 76 to 97%. In all the cycles the system presented 80% of colour removal.
Diagnostic and resulting approaches to restore petroleum-contaminated soil in a Mexican tropical swamp
Authors: Gallegos Martínez M. , Gómez Santos A. , González Cruz L. , Montes de Oca García M.A. , Yáñez Trujillo L. , Zermeño Eguía Lis J.A. , Gutiérrez-Rojas M.
Published: May 2018

A multidisciplinary three-step methodology is being developed to diagnose the extent and type of petroleum pollutants and resulting technological approaches to restore a contaminated site. At first, the site was delimitated and its zones identified by using remote sensors. An area of 307 ha considered of major importance to the national Mexican oil company, Petróleos Mexicanos (PEMEX), was identified. 75% of total analyzed soil samples ranged between 10-50,000 ppm of total petroleum hydrocarbons (TPH) and 25% between 50,000 and 434,000 ppm. Aliphatic and asphaltene groups were predominant and technological alternatives were proposed. In a second phase the identification of native botanical and microbial capabilities to biodegrade pollutants was achieved. Three native botanical species were selected for greenhouse studies: Cyperus laxus showed low sensitivity to TPH resulting in higher seed germination efficiency and growth rate. Since microbial consortia isolated from C. laxus rhizosphere were able todegrade up to 70% of TPH in 30 days laboratory cultures, a phytoremediation-reforest alternative was finally proposed to PEMEX. In a third step, the construction of a pilot plant in situ is now in course wherein both treatability studies and reforest strategies are being developed.
Enzymatic degradation of alkylphenols, bisphenol A, synthetic estrogen and phthalic ester
Authors: Tanaka T. , Yamada K. , Tonosaki T. , Konishi T. , Goto H. , Taniguchi M.
Published: May 2018

Five endocrine disrupting chemicals were degraded enzymatically in model bottom sediments. Since alkylphenols, bisphenol A, synthetic estrogen and phthalic esters are hydrophobic and found to be in bottom sediments in the water environment, we used a model polluted sediment in which those chemicals were adsorbed on sea sand. The concentration of alkylphenols (nonylphenol and octylphenol) and synthetic estrogen (ethynylestradiol) were decreased by fungal laccases which oxidize phenols with the aid of molecular oxygen. Bisphenol A was degraded by laccase from basidiomycetes with the aid of extracellular polymers. Dibutyl phthalate was hydrolyzed by lipase from Candida cylindracea. These results will be useful in the remediation of the bottom sediments polluted by endocrine disrupting chemicals.
Sources, trends, implications and remediation of mercury contamination of lakes in remote areas of Canada
Authors: Trip L. , Allan R. J.
Published: May 2018

The long-range atmospheric transport and deposition of mercury (Hg) into lakes has become a subject of increasing interest. In Canada today, the main sources of anthropogenic, atmospheric Hg are considered to be power stations and waste incinerators in the United States and Europe. Increases in deposition of Hg have been recorded in lake sediment cores from many parts of Canada. Where Hg input to lakes from local sources in Canada has been reduced, concentrations in lake sediments and lake biota have declined. However, in many remote lake, fish consumption advisories are still in effect for Hg. Debate continues over the sources of this mercury, whether long-range anthropogenic, atmospheric or natural. Many remedial actions have been taken in the past, and continue to be taken, to reduce Hg releases to the environment in Canada.
Recent contamination of persistent chlorinated endocrine disrupters in cetaceans from the North Pacific and Asian coastal waters
Authors: Minh T. B. , Prudente M. S. , Watanabe M. , Tanabe S. , Nakata H. , Miyazaki N. , Jefferson T. A. , Subramanian A.
Published: May 2018

To elucidate the global distribution and toxicological impacts of persistent organochlorines (OCs) on cetaceans, the present study determined the concentrations of organochlorine pesticides such as DDT and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), chlordane compounds (CHLs) and PCBs including toxic coplanar congeners in the blubber of 10 species of adult male odontoceti cetaceans collected from several locations in the North Pacific Ocean and coastal waters of Japan, Hong Kong, Philippines and India during 1985–1997. Concentrations of tris(4-chlorophenyl)methane (TCPMe) and tris(4-chlorophenyl)methanol (TCPMOH), which are among the newly identified contaminants, were also determined. Residue pattern was in the order of DDTs≥PCBs>CHLs>HCHs>HCB>TCPMOH>TCPMe. Greater DDT concentrations were found in cetaceans from the Japan Sea, coastal waters of Hong Kong and India, indicating serious marine pollution in industrialized Asian nations and current usage of DDTs in tropical regions. In general, cetaceans inhabiting cold and temperate waters contained relatively higher concentrations of PCBs, HCHs, CHLs and HCB as compared with those from tropical regions, reflecting atmospheric transport from the tropical sources to the northern sinks. Latitudinal distribution of TCPMe and TCPMOH in cetaceans from the North Pacific Ocean and Asian coastal waters was similar to that of DDTs, suggesting the less transportable nature of TCPMe and TCPMOH in the marine environment. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphin from Philippines) to 510 pg/g wet wt (in hump-backed dolphin from Hong Kong). Toxic evaluation of coplanar PCBs using TEQ concept indicates an increasing impact on cetaceans from mid-latitudes. Mono-ortho congener IUPAC 118 or non-ortho congener IUPAC 126 was estimated to have the greatest toxicity contribution. The estimated TEQ concentrations in the blubber of some cetacean species exceeded the level associated with immunosuppresion in harbour seals.
Bioasay for chemical toxicity using yeast Saccharomyces cerevisiae
Authors: Iwahashi H. , Fujita K. , Takahashi Y.
Published: May 2018

Multi-endpoint bioassay is a system for gathering information relative to the effects of newly synthesized chemicals and pollutants in the environment. To develop the multi-endpoint bioassay system, we estimated the effects of chemicals on growth ability (IC50), viability (LD50), stress protein induction, prion mutation, mitochondrial mutation, and chromosomal mutation using the yeast Saccharomyces cerevisiae as a model organism. These endpoints showed characteristic values to 32 kinds of reference chemicals, and we classified the chemicals into seven groups according to the endpoints. We concluded that the yeast system has the potential to be a multi-endpoint bioassay relative to human health and the ecosystem in general.
Optimization of sol-gel based fibre-optic cholinesterase biosensor for the determination of organophosphorus pesticides
Authors: Tsai H.-C. , Doong R.-A.
Published: May 2018

A sol-gel based fiber-optic biosensor with acetylcholinesterase as the biorecognition element has been developed for the rapid determination of organophosphorus pesticides. Nine fluorescent indicators, acridine, acridine orange, neutral red, DAPI, rhodamine B, fluorescein, umbelliferone, FITC on celite and FITC-dextran, have been examined to optimize the fiber-optic system. Results showed that acridine and FITCs were sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. However, the sensitivity of acridine was 260 times lower than that of FITCs. Higher toxicity of acridine to acetylcholinesterase than FITC was also observed. Moreover, the high-molecular-weight FITC-dextran showed low leakage rate when immobilizing using sol-gel technology, showing that the FITC-dextran was a suitable pH sensitive fluorescent indicator for the OPPs biosensor. The response of the fiber-optic biosensor to the substrate, acetylcholine, was highly reproducible (RSD=3.5%). A good linearity of acetylcholine in the range from 0.5 to 20 mM was also obtained (R2=0.98). Furthermore, a 30% inhibition can be achieved in 30min when 152 ppb paraoxon was added into the system. The results show the possibility for real-time determination of organophosphorus pesticides by using the biosensor developed in this study.
The effects of the co-existing compounds on the decomposition of micropollutants using the ozone/hydrogen peroxide process
Authors: Kosaka K. , Yamada H. , Matsui S. , Shishida K.
Published: May 2018

The effect of co-existing compounds on the decompositions of three target compounds (i.e., 1,2,4-trichlorobenzene (TCB), 1,4-dioxane, and 17β-estradiol) using the ozone/hydrogen peroxide (O3/H2O2) process was investigated. Their reactivities toward HO• are assumed to be of the order of 109 /M · s. The decomposition rate of TCB was much higher during the O3/H2O2 process than during ozonation in the presence of bicarbonate ion, an inhibitor of radical chain reactions. 17β-Estradiol, a highly reactive target compound toward ozone, was decomposed at lower ozone dose than TCB and 1,4-dioxane, lowly reactive target compounds toward ozone, in the presence of humic acid. The reactivities of the co-existing compounds toward HO• were significantly related to the treatment efficiency of TCB when their concentrations as TOC were similar. The effect of humic acid, fulvic acid, and glucose, target compounds highly reactive toward HO•, on the decomposition of TCB was similar regardless of co-existing compounds. On the other hand, significantly lower effect of acetate and oxalate ions, target compounds lowly reactive toward HO•, on the decomposition of TCB was observed. Ozone dose required for the decomposition of TCB was inversely proportional to TCB concentration when HO• generated was greatly scavengedby co-existing compounds. On the other hand, ozone dose required for the decomposition of TCB was less affected by TCB concentration when HO• generated was used effectively for the decomposition of TCB.
Pilot plant evaluation of an ozone-microfiltration system for drinking water treatment
Authors: Hashino M. , Mori Y. , Fujii Y. , Motoyama N. , Kadokawa N. , Hoshikawa H. , Nishijima W. , Okada M.
Published: May 2018

We have developed a novel ozone resistant microfiltration (MF) module using an organic hollow fiber membrane made of polyvinylidenefluoride (PVDF). A new filtration system using this MF module together with ozone dose provided three to four times higher permeate flux compared with the filtration without ozone. The reaction of ozone with organic materials in feed water was necessary to occur on the surface of the membrane to have higher permeate flux.
Heavy metal removal in waste stabilisation ponds and high rate ponds
Authors: Toumi A. , Nejmeddine A. , El Hamouri B.
Published: May 2018

Heavy metals, zinc (Zn), copper (Cu) and lead (Pb) removal in two wastewater treatment units were compared. One of the systems consisted of a train of Waste Stabilisation Ponds (WSP) including one anaerobic, three facultative in series and two maturation ponds, also in series. The other system, called High Rate Ponds (HRP) consisted of one anaerobic, one High Rate Algal Pond (HRAP) and two maturation ponds in series. The two treatment systems were located on the same site and received the same wastewater. Data collected from the two treatment systems, for a period of three consecutive months (May, June and July, 1995) show that the content of the three elements in the crude wastewater of the city of Ouarzazate varied from 210 to 340 mg/l for Zn; 35 to 55 for Cu and 30 to 25 for Pb. The removal rate for the three elements reached 91, 92 and 71% respectively for Zn, Cu and Pb in the WSP train. The corresponding values in the HRP train were, respectively 89, 88 and 51%. However, since the two trainswere not receiving the same flow, the use of specific removal rate expressed as mg removed m-2 d-1 showed that the HRAP was 1.3, 10 and 2 times more efficient respectively for Zn, Cu and Pb removal than the three facultative ponds in series of the WSP. Also, the collected data showed that the content of the sediment of the anaerobic pond was high for all the three elements. However, the recorded concentrations 613, 99 and 78 mg/kg, respectively for Zn, Cu and Pb did not exceed the EEC recommended limits.
Pursuing the effect of aeration, pH increment, and H2O2 coupled with UV irradiation on the removal efficiency of manganese by microfilter membrane
Authors: Rahman Md. Abdur , Huang J.Y. , Iwakami Y. , Fujita K.
Published: May 2018

Aeration, a very common method used in conventional water treatment industries for oxidation and mixing purposes, was used along with pH increment for removal of manganese by microfilter membrane. However, experiments showed that aeration instead of accelerating the manganese oxidation process as normally expected rather declined the manganese removal percentage by a noticeable difference from that obtained by pH increment alone. As high as 97% manganese removal could be attained by microfilter membrane with an increased pH level of 9.7 of the raw water, whereas the removal percentage was reduced to 60% when the mechanical aeration was incorporated.

H2O2, being activated by UV light decomposes into very reactive OH-radical which is of very high oxidizing potential and can break down or change the physical properties of even very strongly-bonded compounds which then can be removed by any suitable physical means. From this principle, H2O2 coupled with UV irradiation was also included in the experiment of manganese removal by microfilter membrane to pursue it's manganese removal efficiency. However, experiments showed that a negative manganese removal occurred with amount of manganese in the filter water surpassing the amount of manganese in the raw water. Also a very high trend in the manganese and turbidity level was found in the membrane washed drain water, which helped conclude that H2O2 coupled with UV irradiation should not be used as a process for manganese removal by microfilter membrane, rather it can be used as a process for washing of the membrane module.
Practical experiences from membrane filtration plants for humic substance removal
Authors: Ødegaard H. , Thorsen T. , Melin E.
Published: May 2018

Humic substances are high molecular weight, organic molecules that give the water a yellow/brownish colour. They are normally removed from water by coagulation. During the last 10 years around 70 membrane filtration plants for drinking water supply have been built in Norway. The paper outlines the basic design of these plants and gives information on choice of membrane, treatment efficiency, membrane flux, membrane fouling, membrane cleaning and disposal of wastes as well as general operating experiences. It is concluded that the owners of the membrane filtration plants are quite satisfied and that the method will be used in increasingly larger plants.