bluuebunny/crossref_metadata_2025 huggingface dataset:
Solubilization of organic sludge by thermophilic aerobic bacteria as a pretreatment for anaerobic digestion
Authors: Hasegawa S. , Shiota N. , Katsura K. , Akashi A.
Published: May 2018

Solubilization of organic sludge by thermophilic aerobic bacteria as a pretreatment for anaerobic digestion was investigated. The thermophilic bacteria which solubilized organic sludge were isolated from the thermophilic aerobic digestion reactor. The bacterium type SPT2-1 could grow at pH ranging from 5.0 to 8.5 with optimal temperature at 60–70°C. In batch experiments, 25–30% of volatile suspended solids (VSS) in the pre-heated sludge were solubilized on inoculating with the isolated bacteria although little was solubilized without inoculation. The isolated bacteria appeared to secret the extracellular enzymes including proteases and amylases. In continuous flow experiments, sludge solubilization rate (VSS removal) was around 40% under aerobic as well as microaerobic conditions. No accumulation of volatile fatty acids in the treated sludge was observed under aerobic conditions while significant amounts of them were accumulated under microaerobic conditions. Production of biogas on anaerobic digestion of the microaerobically-pretreated sludge was increased by 1.5 when compared with the sludge without pretreatment.
Methods for increasing the biogas potential from the recalcitrant organic matter contained in manure
Authors: Angelidaki I. , Ahring B.K.
Published: May 2018

The biogas potential of manure could be significantly increased by treatment of the recalcitrant organic matter (biofibers) contained in the manure. Several treatment methods were tested. Mechanical maceration resulted in an average increase of the biogas potential of approximately 17% as shown by the continuous stirred reactor experiment. In general the smaller the fibers the higher the biogas potential was. The best results showed an approximately 20% increase of the biogas potential with fibers smaller than 0.35 mm as measured by batch experiments. The increase was approximately 16% with fibers of size 2 mm. Chemical treatment of the fibers with bases such as NaOH, NH4OH or a combination of bases also resulted in an increased methane potential. However, combination of maceration and chemical treatment did not result in a further increase of the methane potential. There was not any significant difference of the biogas potential from fibers in the range 5–20 mm. Treatment of the fibers with hemicellulolytic or cellulolytic enzymes did not result in any significant increase of the methane potential. However, biological treatment of the fibers of the manure with the hemicellulose degrading bacterium B4 resulted in a significant increase of the biogas potential of manure. An increase of approximately 30% in methane potential was achieved compared to controls.
Characterization and anaerobic treatment of the sanitary landfill leachate in Istanbul
Authors: Inanc B. , Calli B. , Saatci A.
Published: May 2018

In this study, characterization and anaerobic treatability of leachate from Komurcuoda Sanitary Landfill located on the Asian part of Istanbul were investigated. Time based fluctuations in characteristics of leachate were monitored for an 8 month period. Samples were taken from a 200 m3 holding tank located at the lowest elevation of the landfill. COD concentrations have ranged between 18800 and 47800 mg/l while BOD5 between 6820 and 38500 mg/L. COD and BOD5 values were higher in summer and lower in winter due to dilution by precipitation. On the other hand, it was quite interesting that such a dilution effect was not observed for ammonia. The highest ammonia concentration, 2690 mg/L was in November 1998.

BOD5/COD ratio was larger than 0.7 for most samples indicating high biodegradability, and acidic phase of decomposition in the landfill.

For anaerobic treatability, three different reactors, namely an upflow anaerobic sludge bed reactor, an anaerobic upflow filter and a hybrid bed reactor, were used. The anaerobic reactors were operated for more than 230 days and were continuing operation when this paper was prepared. Organic loading was increased gradually from 1.3 kgCOD/m3.day to 8.2 kg COD/m3.day while hydraulic retention time was reduced from 2.4 days to 2.0 days. All the reactors showed similar performances against organic loadings with efficiencies between 80% and 90%. However the reactors have experienced high ammonia concentrations several times throughout the experimental period, and showed different inhibition levels. Anaerobic filter was the least affected reactor while UASB was the most. Hybrid bed reactor has exhibited a similar performance to anaerobic filter although not to the same degree.
Anaerobic treatment of landfill leachate by sulfate reduction
Authors: Henry J.G. , Prasad D.
Published: May 2018

The present study was conducted to investigate the effectiveness of the sulphate-reduction pathway in the anaerobic treatment of landfill leachate. The effects of several COD/SO4 ratios (keeping COD constant) and loadings on anaerobic filter performance were studied and compared with the results from anaerobic filters which followed the methanogenic pathway.

Results indicated that the treatability of leachate by sulphate reducing bacteria (SRB) was dependent upon the leachate strength. With high strength leachate (COD=15000 mg/L) from the Keele Valley Landfill, it was found that at lower COD/SO4 ratios (≤1.6) toxic conditions developed in the system that were more inhibitory to the SRB than to the methane producing bacteria (MPB). As the COD/SO4 ratio increased, methanogenesis predominated. No predominance of SRB occurred at any COD/SO4 ratio with high strength leachate. The highest COD removal achieved was about 70% of which 20% was accomplished by the SRB at a COD/SO4 ratio of 1.6 and an organic loading rate (OLR) of 4 kg COD/m3.d.

With low strength leachate (COD=1500-3300 mg/L) from the Brock West Landfill, and a COD/SO4 ratio <1, SRB became predominant. In these anaerobic filters in which SRB were predominant, the SRB reduced the COD as well as the MPB could. Sulphide inhibition did not take place at any loading in units treating low strength leachate. Consequently, both SRB and MPB should function at COD/SO4 ratios between 1 and 3. About 60% COD removal was achieved at a loading of 2.8 kg COD/m3.d and a COD/SO4 ratio of 1.0. However at a loading of 6 kg COD/m3.d only 27% COD removal was achieved, all of it through the sulphate-reduction pathway. These OLR values are comparable to those applied in systems where methanogenesis was dominant.

It was also observed that once the methanogens were established in the units, it was not possible to displace them completely. However, where methanogenesis had not been previously established, it was found that sulphate-reduction could be the sole pathway for COD removal.

From this study, it can be concluded that there is no advantage to the sulphate-reduction pathway in the anaerobic treatment of landfill leachate. The other options for increasing the loadings, i.e. the use of high surface/volume filter media (to achieve higher biomass concentrations) or high rate systems are likely to be more successful.
Determinant impact of waste collection and composition on anaerobic digestion performance: industrial results
Authors: Saint-Joly C. , Desbois S. , Lotti J-P.
Published: May 2018

The performance of the anaerobic digestion process depends deeply on the quality of the waste to be treated. This has been already demonstrated at the lab-scale. The objective of this study is to confirm this result at the industrial scale, with very long representative period and with the same process, the Valorga process. According to the waste quality and the collection type and even with the same conditions of fermentation, the biogas yield can vary by a factor of 1.5 when it is expressed (under normal conditions of pressure and temperature) in m3 biogas/t fresh waste, and by a factor of 2 when it is expressed in m3 CH4/t volatile solids. So, the biogas performance does not characterise a process since it is deeply governed by waste composition. This biogas productivity becomes a pertinent parameter only with consistent and relevant hypothesis and/or analytical results on the waste composition which depends on the collection procedure, the site characteristics and the season.
Full scale experience with the BIOCEL process
Authors: ten Brummeler E.
Published: May 2018

The BIOCEL process is a mesophilic dry anaerobic batch digestion system for solid organic wastes. In the BIOCEL process organic solid wastes, such as source separated organic fraction of MSW (biowaste) is converted into enriched compost and biogas. In the process net energy production is achieved by converting the biogas to heat and power with a heat-electric power production unit. In September 1997 the first full scale plant is started-up in Lelystad, The Netherlands. This plant is processing 50,000 tons of biowaste (organic fraction of MSW from source separation) per year. The plant has a net energy production and therefore contributes to prevention of CO2 emissions from fossil fuels. In the BIOCEL-system the several compost fractions are produced with a “wet” separation process. During the wet separation sand and contaminants are removed. An important aspect of compost quality is the absence of several types of pathogens. It appears that anaerobic digestion with the BIOCEL- process results in complete inactivation of several important groups of plant and animal pathogens. The mechanism that causes the inactivation is not yet fully understood, but the relatively high Volatile Fatty Acids concentration during the first two weeks of the digestion process might presumably be the key factor.
Odour nuisance and dispersion modelling: an objective approach to a very subjective problem
Authors: Simms K. L. , Wilkinson S. , Bethan S.
Published: May 2018

The three main components of a study into the behaviour of material emitted into the atmosphere, i.e. emissions, dispersion and impacts, are discussed in the context of predicting odour nuisance. In particular, the importance of the effects of buildings on dispersion, and the significance of short averaging times are considered. Finally, an approach is suggested for modelling odour nuisance that takes account of the current understanding of atmospheric processes.
Bioscrubbing, an effective and economic solution to odour control at wastewater treatment plants
Authors: Hansen N. G. , Rindel K.
Published: May 2018

Based on odour nuisances from the Damhusaaen Wastewater Treatment Plant in Copenhagen, it was decided that the critical sections of the inlet structure to the treatment plant should be covered and enclosed. The ventilation air, 6000m3/h, is cleaned in a bioscrubber process. These installations have reduced the odour in the surroundings of the treatment plant to the extent that it is no longer noticeable. A cleaning efficiency for hydrogen sulphide of >99% and low residual emissions, <0.1 mg/m3 of organic sulphur compounds, are obtained in the bioscrubber. The consumption of the sodium hydroxide for neutralising the sulphuric acid formed is stoichiometric in relation to the amount of sulphur compounds removed. This results in relatively low operating costs corresponding to half to one fourth of the operating costs of a chemical scrubber at normal influent concentrations. In addition, the bioscrubber has proven reliable with only little maintenance and low space requirements. Abioscrubber can thus be considered an environment-friendly and competitive alternative to chemical scrubbers and biofilters.
Biological prevention and removal of hydrogen sulphide in sludge at Lillehammer Wastewater Treatment Plant
Authors: Einarsen A. M. , Æsøy A. , Rasmussen A-I. , Bungum S. , Sveberg M.
Published: May 2018

Formation of H2S and other odorous compounds in sludge can be prevented efficiently by controlled dosage of nitrate. Lillehammer WWTP (N) had problems with malodour that originated mainly from the sludge treatment. Highlevels of H2S caused poor working conditions, and resulted in an overloaded hypochlorite scrubber. In addition, neighbours were complaining. Controlled dosing was necessary to avoid increased loads on the nitrogen removal process and floating sludge in the thickener, and to keep the H2S concentration and chemical costs low. This resulted in considerably better working environment and eliminated complaints from neighbours. A cost-benefit for Nutriox® Septicity Control has been performed.
Source and occurrence of Giardia and Cryptosporidium in Paris rivers
Authors: Rouquet V. , Homer F. , Brignon J. M. , Bonne P. , Cavard J.
Published: May 2018

This paper presents an investigation of the variability of concentrations of Giardia cyst and Cryptosporidium oocyst in two main rivers of Ile-de-France: the Seine (upstream from Paris) and its largest tributary: the Marne. The first goal of this study was to examine risk of presence of Cryptosporidium and Giardia at the drinking water treatment plants' intakes at high concentrations. A second goal was to study the relationship between parasite concentrations and a variety of more easily measured water quality parameters (microbial or physicochemical) which could be used as risk indicators. Two aspects were particularly addressed: the influence of upstream waste water discharges, and the influence of rain fall and river floods on parasite concentrations. Preliminary results of an ongoing study are also presented: they show possible influence of non-point sources on parasite concentrations. Overall results show that parasite sedimentation in rivers is high, urban run-off and resuspension of particles could be at certain times the main factors responsible for peak pathogen levels in raw water.
Enhanced particle removal in drinking water treatment plants – case studies
Authors: Lipp P. , Baldauf G.
Published: May 2018

Measurements of parasites in surface waters in Germany showed that their presence is widely spread. Concentrations may reach values up to a maximum of 50 cysts per 100 l. Normally raw waters used for drinking water production show much lower values. In order to ensure sufficient parasite removal in drinking water treatment plants an enhancement of particle removal is required. For filtration processes parameters influencing particle removal are filter media, filtration velocity, flocculant dosage, preozonationand filter back wash. Moderate filtration conditions show best results. Three case studies show that preozonation, optimized energy input and use of flocculants improve particle removal. One case study shows results of the first ultrafiltration plant in Germany treating reservoir and spring water for drinking water production.
Removal of sulphite-reducing clostridia spores by full-scale water treatment processes as a surrogate for protozoan (oo)cysts removal
Authors: Hijnen W. A. , Willemsen-Zwaagstra J. , Hiemstra P. , Medema G. J. , van der Kooij D.
Published: May 2018

At eight full-scale water treatment plants in the Netherlands the removal of spores of sulphite-reducing clostridia (SSRC) was determined. By sampling and processing large volumes of water (1 up to 500 litres) SSRC were detected after each stage of the treatment. This enabled the assessment of the removal efficiency of the full-scale unit processes for persistent micro-organisms. A comparison with literature data on the removal of Cryptosporidium and Giardia by the same type of processes revealed that SSRC can be considered as a potential surrogate. The average Decimal Elimination Capacity (DEC) of the overall treatment plants ranged from 1.3–4.3 log. The observed actual log removal of SSRC by the unit processes and the overall treatment at one of the studied locations showed that the level of variation in removal efficiency was approximately 2 log. Moreover, from the actual log removal values it was observed that a low SSRC removal by one unit process is partly compensated by a higher removal by subsequent unit processes at this location. SSRC can be used for identification of the process conditions that cause variation in micro-organism removal which may lead to process optimization. Further research is necessary to determine the optimal use of SSRC in water quality monitoring for the production of microbiologically safe drinking water.
Production of high quality fuels using the enhanced Enersludge™ process
Authors: Skrypski-Mäntele S. , Bridle T. R. , Freeman P. , Luceks A. , Ye P. D.
Published: May 2018

The Enersludge™ process converts sewage sludge, biomass and other carbonaceous materials to re-usable fuels. Currently the low grade fuels namely char, reaction water and non-condensed gas are used to drive the process with the oil being classified as surplus fuel. Consequently oil quality is of paramount importance with regard to marketability of the Enersludge™ process. The new process comprises a single reactor followed by a catalyst cartridge to refine oil vapours. Oil quality can be controlled by type of catalyst, temperature and WHSV. Oil viscosity was used as a global oil quality indicator to benchmark the enhanced Enersludge™ process against its reactor predecessors. Oil viscosities as low as 3 cSt can be achieved which is equivalent to a tenfold reductioncompared to previous reactor designs. At the same time energy recovery in the oil has only dropped slightly.
The generation of CO2 in sewage sludge treatment systems: life cycle assessment
Authors: Hwang Y. , Hanaki K.
Published: May 2018

Life cycle assessment (LCA) on total sewage sludge treatment systems including thickening, anaerobic digestion, dewatering, and incineration/melting was performed to estimate a global warming impact as carbon dioxide (CO2) emission. As representative processes for the assessment, the most typical and widely used processes were selected. Generally, the life cycle of actual treatment facilities consists of three stages: construction, operation and dismantlement. In this study, the amount of CO2 produced from the life cycle steps of existing unit sludge treatment processes, was calculated by inventory analysis of input materials. In addition, for all processes investigated, individual CO2 emission units (CEUs), i.e. the amount of emitted CO2 for treating a unit weight of sludge, were also calculated. Byusing the obtained CEU matrix, it was possible to simulate the CO2 production from various types of complex treatment systems as well as to trace the dominant cause of CO2 production in individual treatment processes.
Management of land disposal and agricultural reuse of sewage sludge within the framework of the current South African guidelines
Authors: Snyman H. G. , Terblanche J. S. , van der Westhuizen J. L.
Published: May 2018

Sacrificial land disposal and reuse in the agricultural sector are popular methods for disposing of excess sewage sludge in South Africa. These practices had to comply with the “Guide: Permissible Utilisation and Disposal of Sewage Sludge” (1991). These sludge guidelines were revised in 1997 with considerable amendments to the heavy metal loading and usage restrictions. The new guidelines are perceived to be overly restrictive, specifically with regards to some of the metal standards for sludge intended for unrestrictive use. The paper discusses the new South African sludge guidelines and the extent of compliance. Sludge data of 77 works is presented. The data indicates that not one of the wastewater treatment works could comply to the Cu (50.5 mg/kgdry), Pb (50.5 mg/kgdry) or Zn (353.5 mg/kgdry) in sludge intended for unrestrictive use. A case study is presented of a wastewater treatment works generating 2 tdry sludge/d. Under the new guidelines, the sludge needs to be applied to 515 ha/y in stead of 77 ha/y under the 1991 sludge guidelines. The process to revisit the 1997 sludge guidelines is discussed.
The activity of anaerobic biomass in thermophilic and mesophilic digesters at different loading rates
Authors: Zábranská J. , Štěpová J. , Wachtl R. , Jeníček P. , Dohányos M.
Published: May 2018

The thermophilic anaerobic process brings an acceleration of biochemical reactions and higher efficiency in the degradation of organic matter in comparison with the mesophilic process. The methanogenic activity of the thermophilic and mesophilic digested sludge was examined during the adaptation of full-scale digesters to an increasing temperature from 38 to 55°C.

The results proved a higher activity of the thermophilic sludge after the addition of glucose, acetate and propionate in comparison with the mesophilic sludge; the maximum methane production rates and the methane yield of the raw sludge were always higher under thermophilic conditions; the stability of the degradation process at an increased substrate load was also better. After the adaptation of anaerobic biomass to the temperature of 55°C, the responses of this culture to addition of simple substrates substantially changed, especially in favor of acetate and propionate degradation rates.
Enhancement of anaerobic sludge digestion by ultrasonic disintegration
Authors: Neis U. , Nickel K. , Tiehm A.
Published: May 2018

Biological cell lysis is known to be the rate limiting step of anaerobic sludge stabilization. Shear forces generated by high-power ultrasound can be used to disintegrate bacterial cells in sewage sludge. Thus the quantity of bioavailable dissolved organic substrate (Chemical Oxygen Demand) is significantly increased. As a result the subsequent sludge degradation is accelerated considerably. In our tests the fermentation process of sonicated waste activated sludge remained stable even at a very short digestion time of 4 days. The enhanced degradation rate resulted in a reduced volatile solids concentration of the digested sludges after the usual fermentation times.
Enhancing nitrification in North American activated sludge plants
Authors: Daigger G.T. , Parker D.S.
Published: May 2018

Many plant owners, operators and designers consider the nitrifying activated sludge process as being a high hydraulic residence time (HRT) process. However, in recent years a number of techniques have been developed to enhance the performance of activated sludge plants for nitrification. The result, when the proper combination of these techniques is used, can be a significant reduction in the biological process hydraulic residence time and a corresponding reduction in facility costs and space requirements. Several of these factors are discussed in this paper, including a discussion of the mechanistic basis for each technique and its impact on nitrification process sizing. Some full-scale North American examples are also discussed.
Reduction of microbial density level in sewage sludge through pH adjustment and ultrasonic treatment
Authors: Jean D. S. , Chang B.-V. , Liao G. S. , Tsou G. W. , Lee D. J.
Published: May 2018

This work investigated the effects of using ultrasound and pH-value adjustment on the microbial density levels in sewage sludge, with total coliform and heterotrophic-plate-count (HPC) bacteria as the microbial indices. Application of ultrasound at a high intensity level could sufficiently disinfect both the total coliform and HPC bacteria. Adjustment of pH value could also disinfect the micro-organisms in the sewage sludge, but at a less efficient rate. For the present sewage sludge, the application of ultrasound of 0.33 W/mL level for 1-2 hours could make it a Class B sludge.
Prediction of full-scale dewatering results by determining the water distribution of sewage sludges
Authors: Kopp J. , Dichtl N.
Published: May 2018

Dewaterability of sewage sludge can be described by the total solids concentration of the sludge cake and by the polymer-demand for conditioning. Total solids concentration of the sludge cake depends on the physical water distribution. The various types of water in sewage sludge are mainly distinguished by type and intensity of their physical bonding to the solids. In a sewage sludge suspension four different types of water can be distinguished. These are free water, which is not bound to the particles, interstitial water, which is bound by capillary forces between the sludge flocs, surface water, which is bound by adhesive forces, and intracellular water. Only free water can be separated during mechanical dewatering. It can be shown, that thermo-gravimeteric measurement of the free water content leads to an exact prediction of full-scale dewatering results. Maximum dewatering results are reached by separating all free water during centrifugation. Polymer conditioning increases the velocity of thesludge water release, but the free water content is not influenced by this process. Furthermore it is not possible, to replace the measuring of the water distribution by other individual parameters such as ignition loss.
Cost optimisation of nitrogen removal in a compact nitrogen and phosphorus WWTP
Authors: Sagberg P. , Grundnes Berg K.
Published: May 2018

Based on overall mass balances for water, total nitrogen and organic carbon in the VEAS WWTP in 1997, alternative strategies for nitrogen removal are discussed based on cost optimisation. Marginal costs for biological removal are compared with total costs for side stream treatment by ammonia stripping. If the plant has sufficient capacity to meet the effluent requirements with biological removal alone, this study demonstrates that the price of methanol determines whether or not invetment in ammonia stripping still is a cost efficient solution.
Ozonation of sewage sludge prior to anaerobic digestion
Authors: Weemaes M. , Grootaerd H. , Simoens F. , Huysmans A. , Verstraete W.
Published: May 2018

Anaerobic digestion has traditionally been employed to reduce the mass and volume of waste sludge and to enhance the sludge dewaterability. In practice, anaerobic digestion of biosolids has a number of shortcomings, i.e. the low biodegradability of the microbial cells and the high retention times due to the rate limiting hydrolysis step. An oxidative sludge pre-treatment with ozone was therefore used to solubilize the organic compounds and increase their biodegradability. It is shown that the pre-treatment could significantly enhance anaerobic sludge digestion. Moreover, a novel approach in which the sludge was separated in a thickened sediment fraction and a supernatant was investigated. The sediment was digested anaerobically and the supernatant was treated aerobically. The overall COD-removal efficiency of the biosolids was 72%.
Composting and utilization of forest industry wastewater sludges
Authors: Rantala P.-R. , Vaajasaari K. , Juvonen R. , Schultz E. , Joutti A. , Mäkelä-Kurtto R.
Published: May 2018

Two different forest industry wastewater sludges were composted in piles. The piles were founded with leachate collection systems. The aim was to study the progress of the composting process, the amount and quality of leachates as well as the toxicity of the sludges and leachates. The sludges consisted of mixtures of primary and biosludge. The piles were monitored for eight months by physical measurements, chemical analyses and toxicity tests. The leachates were collected for six months. The lignin concentrations and the amount of mycelium were measured from the sludges and from the soil. Test plots and control plots were established to a field with different amounts of composted sludge in order to study the applicability of the sludges in agriculture. The results showed that both sludges were amenable to composting. The original sludges were toxic but the toxicity decreased during composting and all the sludges were proved to be non-toxic at the end of composting. The leachates were determined non-toxic and the heavy metal concentrations were low in both sludges and leachates. The sludges proved to be suitable for use as soil improver in agricultural plant production.
Operation costs and consumption of resources at Nordic nutrient removal plants
Authors: Balmér P.
Published: May 2018

Most large wastewater treatment plants in the Nordic countries have recently been extended for nutrient removal. Different process solutions have been employed. In order to compare consumption of energy, chemicals and manpower and costs, data have been collected from five treatment works with different process solutions. Energy consumption is in the range 31–47 kWh per population equivalent and year, and manpower consumption 50–130 man-years per million population equivalents. Net operation costs are 6–14 Euro per population equivalent and year. The data have been adjusted in order to make them as comparable as possible. The basis for comparison is discussed as well as the costs and resource consumption in relation to plant design and performance.
Anaerobic degradation of 1,2-dichloropropane in batch and continuous culture
Authors: Hauck R. , Hegemann W.
Published: May 2018

Microbial degradation of 1,2-dichloropropane (DCP) was studied in a laboratory scale continuous flow fluidized bed reactor using polyurethane foam cubes as a carrier for the mixed culture. The anaerobic enrichment culture derived from Saale River sediment and was immobilized prior to utilization in the reactor. The DCP degradation performance was monitored by direct gas chromatographic analysis. A variety of different co-substrates were investigated for their ability to support DCP dechlorination during reactor operation. Continuous DCP removal efficiencies over 90% were achieved with a model water at substrate loading rates of up to 700 μmol/(L · d) with methanol and sodium acetate as co-substrates at 24 h hydraulic retention time in the reactor. In batch experiments the degradation potential of the culture for other chlorinated organics, like 1, 2, 3-trichloropropane and dichlorodiisopropyl ether was investigated.
On the modeling of microbiological hydrolysis of organic solids
Authors: Terashima Y. , Lin S.
Published: May 2018

For the modeling basis of microbiological hydrolysis of organic solids, hydrolyzed quantity per unit time and unit surface area, namely hydrolytic flux was defined, and the hydrolytic models for estimating weight decrease of cubic and spherical organic-solids were derived. These models were verified and actual values of hydrolytic rate coefficients were obtained by the experiments, in which three sizes of cubic organic solid samples were made from each of rice cake, albumen congealed by heat, and beef tallow, submerged in reactors, and anaerobically hydrolyzed. Because the quantity of MLSS cannot correctly express that of the microbe in such reaction systems, the action of active anaerobe was estimated and evaluated based on ATP, in this study.
Biomineralisation of azo dyes and their breakdown products in anaerobic-aerobic hybrid and UASB reactors
Authors: Kalyuzhnyi S. , Sklyar V.
Published: May 2018

Batch toxicity and biodegradability of two azo dyes (Siriusgelb and Siriuslichtbraun) has been investigated. It was found that the former azo dye was significantly less toxic to methanogenic sludge than the latter one (IC50 are equal to 3.55 and 0.41 g COD/l, respectively). Neither of the azo dyes was biodegradable under aerobic conditions but both dyes were readily decolourised and slowly mineralised in anaerobic environments. In order to optimise the treatment strategy, the anaerobic and aerobic phases were combined into one single unit called the anaerobic-aerobic hybrid reactor. The performance of this innovative reactor was tested with a synthetic wastewater containing Siriusgelb and ethanol at 30°C and 56% removal of azo dye COD was achieved at volumetric load of 0.3 g azo dye COD/l/day. The effluent COD content could be attributed to the presence of non-biodegradable autooxidation products of Siriusgelb breakdown intermediates. A continuous biomineralisation of 2-aminobenzoic acid (2-ABA) – intermediate of the anaerobic decomposition of Siriuslichtbraun – was studied in a UASB reactor at 30°C. A high (>90%) removal of 2-ABA was achieved under volumetric loads of 1.5 g 2-ABA COD/l/day. However, a further increase in volumetric load led to a decrease in 2-ABA removal, probably due to low attachment ability of the bacteria responsible for primary decomposition of 2-ABA.
Successful and unsuccessful bioaugmentation experiments monitored by fluorescent in situ hybridization
Authors: Bouchez T. , Patureau D. , Dabert P. , Wagner M. , Delgenès J. P. , Moletta R.
Published: May 2018

Two nitrifying reactors were operated under the same conditions except that one was twice inoculated with the aerobic denitrifying bacteria Microvirgula aerodenitrificans. The first bioaugmentation induced a transient nitrogen loss. Fluorescent in situ hybridization revealed that the bioaugmented bacteria had been rapidly eaten by protozoa. The second massive inoculation unbalanced the ecosystem and resulted in an overgrowth of protozoa and perturbations of nitrification, whereas both parameters remained stable in the non bioaugmented reactor. To enhance the incorporation of the added bacteria to indigenous flocs, two strategies were then tested. First, coagulating and flocculating substances were added to the reactor just after bioaugmentation and second, the bacteria were embedded in alginate beads before inoculation. The latter strategy gave the best results. After break-up of the beads, alginate fragments, containing microcolonies of M. aerodenitrificans, were found to be incorporated into the existing flocs. Alginate beads offer a temporary protection against grazing and favor the adhesion of the exogenous bacterial microcolonies to the existing flocs. These beads therefore constitute a suitable bioaugmentation vector to incorporate a bacterial strain into activated sludge flocs.
New operational strategy for SBR technology for total nitrogen removal from industrial wastewaters highly loaded with nitrogen
Authors: Villaverde S. , García Encina P. A. , Lacalle M. L. , Fdz-Polanco F.
Published: May 2018

The present work deals with the upgrading of conventional Sequential Batch Reactor (SBR) technology for treating industrial wastewater. The aim is to obtain total nitrogen removal in a single SBR by implementing short aeration cycles. The operational strategy of conventional SBR consisting of a sequence of five phases (filling, aeration, stirring, settling and withdrawing) is simplified into a four phases sequence (filling, short cycled aeration, settling and withdrawing). This operational sequence has been proven to be adequate for total nitrogen removal from high strength wastewater containing nitrogen (up to 700 mg TKN/L) and organic matter (up to 2,000 mg COD/L). Short-cycled aeration allowed for a more efficient use of the oxygen supply for nitrification and the organic carbon content present in the wastewater for denitrification. The results here reported show that initially the tested technology is feasible and can report significant cuts in operation and maintenance when compared with conventional SBR processes. Total nitrogen removal up to 79% was attained treating the effluent of an UASB process designed for treating the wastewater of a potato starch factory. Total nitrogen removal capacities ranging between 0.2 and 0.65 kg of nitrogen per cubic metre per day are reported.
Monitoring and modelling an industrial trickling filter using on-line off-gas analysis and respirometry
Authors: Vanhooren H. , Demey D. , Vannijvel I. , Vanrolleghem P. A.
Published: May 2018

The process characteristics of an industrial scale trickling filter plant were quantified by means of a five day intensive measurement campaign with the use of on-line respirometry and on-line off-gas analysis. Respirometry was used to measure the readily biodegradable CODst and the off-gas sensor was used to monitor the O2 and CO2 content of the off-gases. To model the biodegradation in the filters, the model developed by Rauch et al. (1999) was used. It is based on the decoupling of two basic processes in biofilm systems, substrate diffusion and biodegradation. This model was extended with equations for the production and the pH-dependent liquid-phase equilibrium for inorganic carbon (IC). The measured effluent and off-gas concentrations could be followed very closely by the calibrated model. O2 and CO2 measurements revealed that the system was not always oxygen limited. The model calibration thus required the use of a very low value of the diffusion constant for readily biodegradable substrate.
Japanese experiences in water pollution control and wastewater treatment technologies
Authors: Matsuo T.
Published: May 2018

The history of water pollution control and environmental management in Japan is outlined. Particular attention is paid to Minamata disease and other impacts of industrial pollution, and the consequent development of environmental legislation. The growth of sewerage systems and more recently of wastewater and sludge reuse are noted, before considering the application of the concept of life cycle assessment, which is increasingly central to the minimisation of environmental impacts.
Integration of wastewater and OFMSW treatment cycles: from the pilot scale experiment to the industrial realisation – the new full scale plant of Treviso (Italy)
Authors: Pavan P. , Battistoni P. , Bolzonella D. , Innocenti L. , Traverso P. , Cecch F.
Published: May 2018

The paper presents the results from experiments on pilot scale plants concerning the possibility to integrate the organic waste and wastewater treatment cycles, using the light organic fraction produced via anaerobic fermentation of the organic fraction of municipal solid waste as a readily biodegradable organic carbon source for biological nutrient removal processes: the addition of the effluent from the fermentation unit as an external carbon source allows nitrogen and phosphorus removal of about 70–80% and the values of the effluent are in accordance with EC 271/91 Directive discharge limits. Maximal denitrification rate with fermenter effluent addition shows values close to those typical of pure methanol addition (0.3 kg N–NO3/kg VSS d) and double those obtained by primary settled sludges elutriate addition (0.14 kg N–NO3/kg VSS d). A full scale application of the approach (70,000 IPE), operating since July 1999 in northern Italy, is presented and an ASM 2 simulation is used to verify the behaviour of the whole real process.
Photooxidation of wool dye and TCP in aqueous solution using an innovative TiO2 mesh electrode
Authors: Li X. Z. , Yue P. T. , Mak C. L.
Published: May 2018

An innovative titanium dioxide (TiO2) mesh electrode was prepared by anodisation, in which 0.5 M sulphuric acid was used as electrolyte and titanium (Ti) metal mesh was anodised in a two stage anodic process. The innovated mesh electrode was examined using Raman spectroscopy to determine the formation of TiO2 layer when different potentials of 120 V, 140 V, 160 V, and 180 V were applied in anodisation. Microporous surface of the electrode was also examined using scanning electron microscopy. The photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation were studied using the new electrode for treating synthetic wastewater solutions of dye and trichlorophenol (TCP) respectively. The colour removal efficiency of 68% was achieved using the 160V-mesh electrode for treating wool dye solution after 80 minutes reaction time. However, it was found that a significant substrate adsorption on the surface of the mesh electrode could not be avoided when pH was below pHIEP of TiO2=6.3. In this condition, electrostatic adsorption occurred between the anionic substrate molecules and positively charged TiO2 surface. The adsorbed substrate anion occupied most active sites of TiO2 on the mesh electrode surface and significantly reduced the performance efficiency of photo-oxidation, when the TiO2 mesh electrode was reused. The experiment demonstrated that TCP adsorption on the mesh electrode could be significantly eliminated, when pH of TCP solution was adjusted to above 7. When raising pH in TCP photodegradation eliminated substrate adsorption, it was confirmed that PC oxidation with application of a potential bias could enhance the photo-oxidation rate and a repeatable photo-oxidation rate could be maintained when the same mesh electrode was reused in its following tests.
Characterisation by image analysis of anaerobic sludge under shock conditions
Authors: Alves M. , Cavaleiro A. J. , Ferreira E. C. , Amaral A. L. , Mota M. , da Motta M. , Vivier H. , Pons M.-N.
Published: May 2018

In the present work the characterisation by image analysis of anaerobic biomass under organic and hydraulic shocks was performed. The digester was fed with a synthetic substrate, containing 50% oleic acid (as COD). Organic and hydraulic shocks were performed by stepwise increasing the substrate concentration or by reducing the hydraulic retention time. In both cases the organic loading rate changed from 6 to 30 kg COD/m3.d. Hydraulic shock induced a fast decrease in the number of free filaments and in total filament length, which attained a minimum value 51 hours after beginning the shock. The initial filament values were not recovered 340 hours after the hydraulic shock. In the organic shock, the minimum values of these parameters were detected 200 hours after beginning the shock and initial values were recovered 840 hours after. During the hydraulic shock the methanogenic acetoclastic activity was directly correlated to the number and length of free filaments. This result suggests that filaments are predominantly acetoclastic bacteria, probably Methanosaeta.
Advanced treatment of dyehouse effluents by Fe(II) and Mn(II)-catalyzed ozonation and the H2O2/O3 process
Authors: Arslan I. , Akmehmet Balcioglu I. , Tuhkanen T.
Published: May 2018

Treatment of synthetic dyehouse effluent containing six reactive dyestuffs and their assisting chemicals by O3/Fe(II), O3/Mn(II), and O3/H2O2 advanced oxidation processes was investigated. All oxidation processes were capable of completely decolourizing the wastewater within 30 min. Decolourization proceeded fastest by the O3/Mn(II) process, whereas the O3/H2O2 combination was more efficient in the removal of DOC (Dissolved Organic carbon) and UV254nm which were 11 and 53%, respectively, for one hour treatment time. Application of Fe(II)-catalyzed ozonation provided an effective means of removing colour and COD (Chemical Oxygen Demand) by a five- and nine-fold enhancement, respectively, compared with conventional coagulation applied at the same coagulant doses. Formation of toxic oxidation products was not observed during the course of treatment with all investigated advanced oxidation processes.
An assessment of the toxicity of some pesticides and their metabolites affecting a natural aquatic environment using the Microtox™ system
Authors: Amorós I. , Connon R. , Garelick H. , Alonso J.L. , Carrasco J.M.
Published: May 2018

The conservation and preservation of aquatic ecosystems is of utmost importance due to the high diversity and density of species and their complex food network. The evaluation of the potential adverse environmental impact caused by pesticides entering water bodies is an important parameter in aquatic toxicity.

The toxicity of the insecticide, Fenitrothion and two of its metabolites, 3-methyl-4 nitrophenol and 3-methyl-4-nitroanisole, and of the herbicides Thiobencarb and Molinate, commonly used in rice fields in Valencia near the protected area of lake Albufera, has been tested by using the Microtox™ system.

The 15 min EC50 values obtained with the marine luminescent bacterium Vibrio fischeri showed that the Thiobencarb was the most toxic of the three tested pesticides with an EC50 value of 0.03 mg/l. The EC50 values of the first two steps of the Fenitrothion hydrolysis indicated that while the first metabolite, 3-methyl-4-nitrophenol, was as toxic as its parent compound, a decreased toxicity was observed for the second metabolite, 3-methyl-4-nitroanisole.

In order to analyze the toxic effects of pesticides in complex mixtures the EC50 values of Fenitrothion, Molinate and Thiobencarb as pure substances and their mixtures were compared. The impact of the pesticides in the natural ecosystem was also studied and a protective effect of lake water was observed.
New approach to use of total coliform test for watershed management
Authors: Brion G.M. , Mao H.H. , Lingireddy S.
Published: May 2018

This study monitored surface water quality around a reservoir for a 2-year period. It was found that the total coliform test could be used in new ways, and in conjunction with other bacterial and viral indicators, to provide valuable information on the sources of fecal inputs and their potential impact on water quality. Two new approaches to the use of total coliforms were developed. Specifically, it was found that atypical colonies (AC) from the total coliform, membrane filtration test were invaluable input parameters for neural network models that could be trained to recognize and predict potentially hazardous fecal sources from agricultural activities. AC counts were also used in conjunction with total coliphage (TP) concentrations to create a reference index relative to domestic sewage to rank the level of fecal contamination at sites within the watershed. Atypical colonies isolated from total coliform tests of surface water samples were further classified with the API 20E system. The classification showed that the heterogeneous group known as atypicals consisted of three main groups of bacteria: modified coliforms, Aeromonas, and a mix of predominantly Vibrio and Samonella.
Controlling biofilm formation by hydrogen peroxide and silver combined disinfectant
Authors: Armon R. , Laot N. , Lev O. , Shuval H. , Fattal B.
Published: May 2018

Controlling biofilm growth in drinking and wastewater pipelines has attracted considerable scientific and technological attention over recent years. In this work, we have examined the biofilm control effectivity of a combined disinfectant comprised of hydrogen peroxide and silver ions. The performance of the combined disinfectant was compared to the effectivity of each of the ingredients alone and to the effectivity of chlorine disinfectant. Biofilm growth was investigated on uncoated and CaCO3 coated galvanized iron samples over prolonged exposure duration. It was found that the CaCO3 film does not significantly affect biofilm development. A combination of hydrogen peroxide and silver ions (30 ppm hydrogen peroxide and 30 ppb silver ions) were as effective in preventing film growth as hydrogen peroxide alone (30 ppm). Both compositions showed significant biofilm prevention effectivity as compared to silver ions alone. Biofilm prevention effectivity of chlorine (approximately 1 ppm) was considerably higher than that of the combined disinfectant. The bacteria that survived after 48 hours disinfection with hydrogen peroxide and the combined disinfectant showed high catalase activity hinting that hydrogen peroxide and the combined disinfectant may have a rather limited effectivity in continuous operation.
Enhancement of integrated water management and water reuse in Europe and the Middle East
Authors: Lazarova V. , Cirelli G. , Jeffrey P. , Salgot M. , Icekson N. , Brissaud F.
Published: May 2018

Municipal wastewater reuse, reclamation and recycling are essential to the development of sound water and environment management policies. In arid and semi-arid regions, wastewater reuse is a vital component of their development ensuring alternative water resources, sustainability, reduction of the environmental pollution and health protection. The purpose of this paper is to provide an overview of the role of wastewater reuse in thedevelopment of new integrated resource management strategy in Europe and the Middle East.