bluuebunny/crossref_metadata_2025 huggingface dataset:
A study on membrane fouling due to algal deposition
Authors: Babel S. , Takizawa S.
Published: May 2018

Batch filtration experiments in dead-end mode were carried out to investigate the membrane fouling phenomenon due to Chlorella deposition and to analyse the effectiveness of pretreatment techniques to control membrane fouling. Experiments were also conducted to identify efficient and effective physical and chemical methods for cleaning the membrane. For both cellulose acetate and PVDF membranes, the effect of algal concentration was found similar. Initially when the deposition was less, the flux was high and the resistance was very low or negligible. As the deposition increased, the resistance increased exponentially. With further increase in deposition, the resistance increases linearly at a constant rate. Among the three pre-treatment techniques studied, coagulation with alum and ozonation were effective in controlling the fouling of membrane. Chlorine pretreatment was not effective in reducing the algal cake resistance because it brought about an extensive cell lysis. Photographs taken by Scanning Electron Microscope (SEM) showed damage to the cell surface architecture and release of organic matter to the medium after chlorination. Ozone pretreatment was more effective than chlorine in disintegrating only the extracelluar organic matter (EOM) without causing cell lysis, thus bringing down the algal cake resistance. Cleaning experiments after algal filtration without pre-treatment showed that physical cleaning was less effective than chemical cleaning. All four chemicals tested for membrane cleaning could reduce the cake resistance by more than 99%.
High-rate pond for treatment of piggery wastes
Authors: Costa R. H. , Medri W. , Perdomo C. C.
Published: May 2018

This work deals with studies on high-rate ponds, a batch working system that is followed by a filter pond where Chinese carp were introduced for piggery wastes treatment. COD removal values for the high-rate pond were in the order of 95% in the summer and 70% in the winter for an initial concentration of 2000 mg/L. Total nitrogen removal values ranged between 90% and 60%, respectively, in summer and winter periods for an initial concentration of 600 mg/L. Seasonal variations, which are mainly observed under differences of temperature, were shown to be not relevant for total phosphorus removal, a process that appears to depend mainly on increases of pH values over 8.5. An hydraulic retention time ranging between 15 to 20 days was found to be best for pond functioning. The plug flow model fits well to the pond's physical characteristics. The filter pond was shown to be a great potential process for removal of algae produced in the high-rate pond.
Development of membrane introduction mass spectrometry for monitoring trace organics in water
Authors: Sharara K. , Mansouri J. , Fane A.G. , Crisp P.T. , Calderon P. , Guilhaus M.
Published: May 2018

This paper describes the design of membrane inlet systems for detection of trace contaminants in environmental samples by Membrane Introduction Mass Spectrometry. A quadropole mass spectrometer equipped with a pervaporation membrane and a jet separator interface was used. The hollow fibre pervaporation membrane was mounted in a cell with transverse flow. Low-level (ppb-ppm) organic compounds (benzene, chloroform, 1,1,1-trichloroethane) in aqueous solutions in the absence or presence of a surfactant could be detected by this technique. The effect of feed flow rate, feed temperature and concentration on membrane performance including flux and enrichment were studied in both binary and multi-component solutions. Fluxes for organic compound increases with flow rate, temperature and feed concentration. Enrichment decreased with temperature. The presence of a surfactant reduced the flux at very high concentrations (Triton X-100; 18 g/l), but the effect was lower than expected. An example is given of industrial feed analysed using this technique.
Nutrient removal in the river basin of the Ruhr - a German case study
Authors: Bode H. , Klopp R.
Published: May 2018

In the catchment area of the Ruhr, restructuring and upgrading measures in the domain of wastewater and stormwater treatment have been under way since 1990 to successively implement the currently applicable legal requirements for nutrient removal. With 2.1 million inhabitants and a design capacity of 3.7 million population equivalents (PE), it is expected that approximately DM 2 billion still have to be invested from 2000 onward. With this it will be possible to further cut the nutrient load in the Ruhr River, that has been declining consistently since the 1970s: by about 25% for Ntotal and about 10% for Ptotal. The anticipated decrease in ammonia-nitrogen in winter is particularly important for drinking water production from the river water (bank filtration). Whether and to what an extent the expected decline in phosphorus concentrations will curb eutrophication in the Ruhr with its several impounded stretches remains to be seen. Further nutrient load reductions cannot be achieved by sewage treatment-related measures. Load balances underline the adverse impact of diffuse or non-point sources, in particular, for nitrogen. Some potential to further improve the situation is seen in minimizing the nutrient releases from agricultural practices.
Nutrient reduction policies and management strategies of the Chesapeake Bay water quality restoration program
Authors: Randall C. W.
Published: May 2018

The Chesapeake Bay Program is a unique, regional, federal-state-local partnership established in 1983 by a formal Agreement between six signatories, the states of Maryland, Pennsylvania and Virginia, the District of Columbia, the US EPA, and the Chesapeake Bay Commission, to protect and restore the Bay's ecosystem. The system of governance adopted provides for dynamic interaction between the signatories, and provides for input from the interested citizens, the local governments, and the scientific and technical community. The Agreement is periodically reviewed, amended and added to by new agreements, with the most recent being the 2000 Agreement, referred to as “Chesapeake 2000: A Watershed Partnership”. The new agreement, signed 28 June 2000, sets numeric goals to be accomplished during the next ten years, and includes land use policies and restrictions.
Feedforward control of the external carbon flow rate in an activated sludge process
Authors: Samuelsson P. , Carlsson B.
Published: May 2018

Biological nitrogen removal in an activated sludge process is obtained by two biological processes: nitrification and denitrification. Denitrifying bacteria need sufficient amounts of readily metabolized carbon. The objective of this paper is to develop an automatic control strategy for adjusting the external carbon flow rate so that the nitrate concentration in the last anoxic compartment is kept at a low pre-specified level. A simple model based feedforward control combined with a standard feedback PI controller is suggested. Simulation results show that the suggested controller, despite being simple, effectively attenuates process disturbances.
Stress protein expression in domestic activated sludge in response to xenobiotic shock loading
Authors: Bott C. B. , Duncan A. J. , Love N. G.
Published: May 2018

Using the Western blot immunochemical analysis method, the heat shock protein, GroEL, was found to be either induced or repressed in activated sludge microorganisms exposed to a range of xenobiotics. At the EC25 concentration, pentachlorophenol (PCP), cadmium, nickel, 2,4-dichloroaniline, benzoquinone, 2,4-dinitrophenol, and 1,1,1-trichloroethane all rapidly induced measurable GroEL expression, even though the time-dependent response for each of these compounds was somewhat varied. Toluene and hydroquinone resulted in repression of GroEL expression to levels below that measured in the control mixed liquor. For PCP concentrations at or exceeding the EC25, there was a significant and consistent increase in effluent volatile suspended solids from activated sludge sequencing batch reactors relative to unstressed controls. These preliminary results indicate that stress proteins may serve as sensitive and rapid indicators of toxicity which can adversely impact treatment process performance in activated sludge systems.
Impact of seeding with nitrifying bacteria on nitrification process efficiency
Authors: Plaza E. , Trela J. , Hultman B.
Published: May 2018

Seeding of nitrifying bacteria into the activated sludge process was studied both theoretically and experimentally. A simple model was developed for prediction of the effects of seeding of nitrifying bacteria from a separate stage into the activated sludge process. The purpose of seeding is to improve the treatment results and the process stability as well as to decrease the volume requirements of the process. Pilot plant studies were carried out at the Uppsala municipal wastewater treatment plant in order to evaluate the effects of seeding. One line was supplied with supernatant from dewatering of digested sludge and the nitrification process gave an activated sludge with a high fraction of nitrifying bacteria, suitable for seeding. The other line was supplied with pre-precipitated wastewater and with the excess sludge from the line treating the supernatant. The experimental results showed that nitrification could be obtained at sludge ages that would otherwise preclude nitrification. Performance relationships for the system developed, based on laboratory and on-line measurements were studied and are presented. The studies show that seeding may decrease the necessary volume needs for a stable nitrification process and that the effects could be predicted by use of a simple model.
Modification and expansion of a pure oxygen WWTP for biological nutrient removal (BNR)
Authors: Randall C. W. , Ubay Cokgor E.
Published: May 2018

A pure oxygen activated sludge system was converted to a VIP configuration BNR (biological nutrient removal) system wherein three of the five pure oxygen sections were retained, and performance was compared to that of a side-by-side air aeration MUCT (modified UCT) system. Because the pure oxygen BNR system could not obtain good nitrification, its treatment capacity had to be downgraded from 113,550 m3/d to a flow of only 60,000 m3/d. At the lesser flow, it was determined that adequate nitrification and improved denitrification could be accomplished in the pure oxygen system by continuously seeding it with 100% of the WAS from the MUCT system. Fortunately, while the capacity of the pure oxygen system had to be downgraded, it was determined that the capacity of the MUCT system was substantially greater than its design flow, and the combined system is capable of treating the entire design flow. However, this requires increasing the operating sludge age of the MUCT system. The pure oxygen BNR system performed better phosphorus removal than the MUCT system, both before and after seeding with the MUCT WAS. Apparently this was because the MUCT system was operated at a substantially higher sludge age than the pure oxygen system. However, both systems have consistently discharged effluent phosphorus concentrations of less than 2.0 mg/L TP, which is the Chesapeake Bay standard. Even with improved nitrification and denitrification in the pure oxygen BNR system, neither it nor the MUCT system have proven to be capable of meeting the Virginia Chesapeake Bay goal of 10 mg/L total nitrogen in the effluent.
Surface runoff pollution by cattle slurry and inorganic fertilizer spreading: chemical oxygen demand, ortho-phosphates, and electrical conductivity levels for different buffer strip lengths
Authors: Núñez-Delgado A. , López-Periago E. , Quiroga-Lago F. , Díaz-Fierros Viqueira F.
Published: May 2018

As a way of dealing with the removal of pollutants from farming practices generated wastewater in the EU, we investigate the effect of spreading cattle slurry and inorganic fertiliser on 8×5 m2 and 8×3 m2 areas, referred to surface runoff chemical oxygen demand (COD), ortho-phosphates (o-P) and electrical conductivity (EC) levels, and the efficiency of grass buffer strips of various lengths in removing pollutants from runoff.

The experimental plot was a 15% sloped Lolium perenne pasture. Surface runoff was generated by means of a rainfall simulator working at 47 mm h-1 rainfall intensity. Runoff was sampled by using Gerlach-type troughs situated 2, 4, 6 and 8 m downslope from the amended areas.

During the first rainfall simulation, COD, o-P and EC levels were consistently higher in the slurry zone, more evidently in the larger amended area. During the second and third rainfall simulations, concentration and mass levels show a downslope drift into the buffer zones, with no clear buffer strip length attenuation.

Correlation between runoff and mass drift is clearly higher in the slurry zone.

Percentage attenuation in COD and o-P levels, referred to initial slurry concentrations - including rainfall dilution - were higher than 98%, and higher than 90% for EC.
Real-time control strategies for predenitrification - nitrification activated sludge plants biodegradation control
Authors: Suescun J. , Ostolaza X. , Garcia-Sanz M. , Ayesa E.
Published: May 2018

This paper presents the real-time control strategies developed to regulate both the ammonia and nitrate concentration in the effluent of the new Vitoria WWTP (Spain). Nitrate control aims at the optimal use of the denitrification potential at any moment. For this purpose, the proposed control algorithm continuously adapts the internal recycle flow in order to maintain a desired nitrate set-point in the anoxic zone. Ammonia control aims at maintaining the required average concentration of ammonia in the effluent by manipulating the Dissolved Oxygen (DO) set-point.

The control strategies have been based on a hierarchical structure where a high-level or supervisory control selects the set-point of the low-level or conventional controllers. The design of the controllers was carried out using the Quantitative Feedback Theory QFT for the design of robust control systems. Moving average values of some variables have been introduced in order to eliminate the perturbations associated with the daily 24-hour profiles. The controllers have been verified using long-time dynamic simulations based on a mathematical model previously calibrated in pilot plant. Influent load and temperature used in the simulations correspond to the real values measured in the full-scale WWTP during 12 months. The results obtained in the simulations show the good performance and stability of the control strategies independently from external disturbances. A short-time experimental verification of the controllers in pilot plant with real wastewater is also presented.
Biofilm structure and mass transfer in a gas phase trickle-bed biofilter
Authors: Zhu X. , Suidan M. T. , Alonso C. , Yu T. , Kim B. J. , Kim B. R.
Published: May 2018

Mass transport phenomena occurring in the biofilms of gas phase trickle-bed biofilters are investigated in this study. The effect of biofilm structure on mass transfer mechanisms is examined using experimental observation from the operating of biofilters, microelectrode techniques and microscopic examination. Since the biofilms of biofilters used for waste gas treatment are not completely saturated with water, there is not a distinguishable liquid layer outside the biofilm. Results suggest that due to this characteristic, gas phase substrates (such as oxygen or volatile organic compounds) may not be limited by the aqueous phase because transport of the compound into the biofilm can occur directly through non-wetted areas. On the other hand, for substrates that are present only in the liquid phase, such as nitrate, the mass transfer limitation is more serious because of the limited liquid supply. Microscopic observations show that a layered structure with void spaces exists within the biofilm. Oxygenconcentration distributions along the depth of the biofilms are examined using an oxygen microelectrode. Results indicate that there are some high dissolved oxygen zones inside the biofilm, which suggests the existence of passages for oxygen transfer into the deeper sections of the biofilm in a gas phase trickle-bed biofilter. Both the low gas-liquid mass transfer resistance and the resulting internal structure contribute to the high oxygen penetration within the biofilms in gas phase trickle-bed biofilters.
Simplified and Monod kinetics in one-dimensional biofilm reactor modelling: a comparison
Authors: Bonomo L. , Pastorelli G. , Quinto E.
Published: May 2018

A theoretical study supported by some experimental tests has been carried out with the aim of comparing one-dimensional (1-D) biofilm reactor models that use simplified (zero- and first-order) and Monod kinetics. Two different situations have been compared: one rate-limiting substrate with or without liquid film diffusion. The results obtained show that the use of a simplified kinetic approach compared to the Monod kinetic approach determines (1) an unjustified overestimate of the removal rate, especially for thin biofilms, and (2) an excessive overestimate of the liquid film layer thickness necessary to justify high kinetic orders. Even if recent research projects show that biofilm structure is more complicated than the one assumed in the modelling approach used in this study, nevertheless 1-D models still now continue to be the only ones that can reasonably support process engineers in biofilm reactor design, due to their intrinsic simplicity and the need for small sets of input data and parameters that can be obtained theoretically or often empirically.
Biological leaching of heavy metals from anaerobically digested sewage sludge using indigenous sulfur-oxidizing bacteria and sulfur waste in a closed system
Authors: Kitada K. , Ito A. , Yamada K. , Aizawa J. , Umita T.
Published: May 2018

The utilization of indigenous sulfur-oxidizing bacteria and sulfur waste was investigated in order to remove heavy metals from anaerobically digested sewage sludge economically. Indigenous sulfur-oxidizing bacteria existing in anaerobically digested sewage sludge were activated by adding elemental sulfur to the sludge and then the bacteria were isolated. It was found that indigenous sulfur-oxidizing bacteria could utilize sulfur waste generated by desulfurization of digestion gas as a substrate. Then, biological leaching of heavy metals from anaerobically digested sewage sludge was carried out using indigenous sulfur-oxidizing bacteria and sulfur waste. By adding sulfur waste to sewage sludge, sulfuric acid was produced by the bacteria and the sludge pH decreased. Heavy metals in sewage sludge were effectively removed owing to the decrease of pH. The optimum amount of sulfur waste added to decrease the pH sufficiently was 5g/L when the sludge concentration was 2%. It was presented that the biological leaching of heavy metals from sewage sludge can be carried out in a closed system, where all required materials are obtained in a sewage treatment plant.
Enhanced virus recovery from municipal sewage sludge with a combination of enzyme and cation exchange resin
Authors: Sano D. , Fukushi K. , Yano K. , Yoshida Y. , Omura T.
Published: May 2018

There is a great difficulty in virus enumeration in sewage sludge because viruses in sludge are firmly captured by sludge solids. In order to determine the precise number of viruses in sludge, an enhanced virus recovery method with a combination of an enzyme and a cation exchange resin (CER) was developed. Test viruses were seeded to a sample sludge obtained from a municipal wastewater treatment plant, and the sludge were incubated with various eluents. The quantity of eluted viruses in the liquid phase was then measured by the plaque assay technique. Using the eluent containing only water, CER, and CER with enzyme exhibited 0%, 19% and 39% of virus recovery, respectively. While the conventional USEPA method exhibited a virus recovery of 21%. Furthermore, viruses eluted by the eluent containing the CER and the lysozyme included not only surface-attached viruses but also solids-embedded viruses.
Heterogeneous catalytic ozonation of 2-chlorophenol queous solution with alumina as a catalyst
Authors: Ni C.H. , Chen J.N.
Published: May 2018

Heterogenous catalytic ozonation of 2-chlorophenol (2-CP) in the presence of γ-alumina as a solid catalyst has been investigated in this research. It showed that the rate for degradation of TOC could increase from 21% to 43%. The pseudo-first reaction constants of 2-CP could increase from 0.8688 min-1 to 0.1270, increasing by approximately 40%. At the same time, the consumption of ozone was only half that of ozone alone. This research also explored the effects of the catalyst dosage, pH values and removal kinetics of 2-CP. In addition, three consecutive running with the same catalyst revealed insignificant reduction of the activity. Furthermore, the elimination of toxicity was evaluated by Microtox® analysis. The detoxification was more stable and with good results.
Kinetics and toxicity of direct reaction between ozone and 1,2-dihydrobenzene in dilute aqueous solution
Authors: Zaror C. , Carrasco V. , Perez L. , Soto G. , Mondaca M. A. , Mansilla H.
Published: May 2018

The presence of toxic aromatic organic compounds in industrial wastewater affects the efficiency of conventional biological treatment. The oxidizing power of ozone represents an interesting pretreatment to reduce toxicity and increase biodegradability. At low pH, ozone is known to attack electron-rich structures by direct electrophilic reactions which open aromatic rings, and generate smaller oxidized compounds. This paper reports experimental results on kinetic and toxicity aspects of ozone direct reactions with 1,2-dihydrobenzene. This toxic compound is frequently found in cellulose bleaching effluents. Although the reaction pathway is rather complex, 4-carbon compounds, such as maleic acid, are readily formed during the first stage of ozonation. These 4-carbon compounds are further oxidized to form smaller molecules (mostly 2-carbon, such as oxalic acid). The apparent kinetics of 1,2-dihydrobenzene follows a second order law, with a rate constant around 0.36 (dm3 mmol–1s–1), at pH 2 and 20°C. Results show that the BOD:COD ratio increase five-fold as ozonation progresses. Furthermore, the mutagenicity of 1,2-dihydrobenzene totally disappears as the aromatic compound is destroyed by ozonation.
Monitoring of the microbial community of a sequencing batch reactor bioaugmented to improve its phosphorus removal capabilities
Authors: Dabert P. , Fleurat-Lessard A. , Mounier E. , Delgenès J.-P. , Moletta R. , Gordon J.-J.
Published: May 2018

The acclimatisation of an activated sludge to enhanced biological phosphorus removal conditions was followed after and without bioaugmentation with a low amount of phosphorus-accumulating sludge. Phosphorus removal yields were monitored by conventional analytical methods and microbial communities evolutions were followed by a finger printing molecular technique (PCR-SSCP). While the benefit of the bioaugmentation seems real at the level of the reactor parameters, bioaugmentation speeded up the installation of good and stable phosphorus removal yield, the establishment of the inoculated microbial community in the bioaugmented reactor is still unclear. Both the bioaugmented and the control microbial communities evolved in a similar way to end up with apparently comparable populations. At the time of the experiment, the results suggest that the microbial community inoculated for the bioaugmentation did not establish in the reactor but compensated for phosphorus accumulation until the acclimatisation of an endogenous microbial community arose.
The mechanism and design of sequencing batch reactor systems for nutrient removal - the state of the art
Authors: Artan N. , Wilderer P. , Orhon D. , Morgenroth E. , Özgür N.
Published: May 2018

The Sequencing Batch Reactor (SBR) process for carbon and nutrient removal is subject to extensive research, and it is finding a wider application in full-scale installations. Despite the growing popularity, however, a widely accepted approach to process analysis and modeling, a unified design basis, and even a common terminology are still lacking; this situation is now regarded as the major obstacle hindering broader practical application of the SBR. In this paper a rational dimensioning approach is proposed for nutrient removal SBRs based on scientific information on process stoichiometry and modelling, also emphasizing practical constraints in design and operation.
Feedforward aeration control of a Biocos wastewater treatment plant
Authors: Wett B. , Ingerie K.
Published: May 2018

The Biocos strategy as a cyclical time controlled activated sludge system shows a great variability in operation and control. One topic such a type of treatment plant has to deal with is the optimum relation between aerobic and anoxic conditions. The aeration control has to adapt the length of the nitrification phases to the current constraints in order to save operational costs and maximise nitrogen elimination. Since wastewater treatment plants up to a certain size are usually not equipped with on-line nitrogen probes, influent flow and temperature can be taken as control parameters for the aeration system. The defined relation between influent flow and ammonia load is based on measurements and the relation between ammonia load and required aeration time is model based.
Dynamic control of a continuous-inflow SBR with time-varying influent loading
Authors: Yu R.-F. , Liaw S.-L. , Cho B.-C. , Yang S.-J.
Published: May 2018

The conventional sequential control of Sequencing Batch Reactor (SBR) is designed with fixed time periods for various operation phases. However, both of the flow rates and qualities of influent vary over time, therefore, a big capacity of wastewater equalization unit is required to cope with influent variability. Such an equalization unit increases the total treatment costs of the system, especially in a small-scale wastewater treatment system. Moreover, in using a SBR treating a time-varying influent loading with conventional sequential control, the system performance cannot be optimized. This paper presents the application of on-line ORP and pH monitoring to dynamically control a continuous-inflow SBR with time-varying loading of influent flow rates and water qualities. Experiential results show that the dynamic controlled SBR revealed not only achieved better substrate removal efficiencies, but also reduced treatment costs.
Biological ammonia removal from anaerobically pre-treated landfill leachate in sequencing batch reactors (SBR)
Authors: Yalmaz G. , Öztürk I.
Published: May 2018

The aim of the study was to investigate both the use of the SBR technology in biological ammonia removal from landfill leachate, and the suitability of raw landfill leachate as external carbon source in denitrification step. The SBR was fed with diluted leachate for the first 42 days and then the effluent of UASBR was used as the feed. The SBR was operated intermittently with a cycle time of 24 hours. The effluent NH4+-N values of less than 5 mg NH4+-N L-1 was consistently observed for the initial NH4+-N levels of as high as 1000 mg NH4+-N L-1. The nitrification rates for the first, second and third stages were found as 5.7, 46.8 and 102.8 mg NH4+-N L-1 h-1, respectively. The difference of the nitrification rates in the 2nd and 3rd stages originated from increasing adaptation of the sludge as well as increasing biomass concentration (10.5 mg NH4+-N g-1VSS h-1). No significant accumulation of NO2--N has been observed during the study and NO2--N/NOx--N ratios measured in the 1st aerobic phase and the SBR effluent were less than 7%. The denitrification rates for the second (raw leachate as carbon source) and the third (Ca(CH3COO)2 as carbon source) stages were determined as 45.7 mg NOx--N L-1 h-1 (or 9.85 mg NOx--N g-1VSS h-1) and 125.7 mg NOx--N L-1 h-1 (or 12.88 mg NOx--N g-1VSS h1), respectively.
The use of upflow anaerobic sludge blanket reactors in the treatment of poultry slaughterhouse wastewater
Authors: Del Nery V. , Damianovic M. H.Z. , Barros F. G.
Published: May 2018

This work studied the performance of the dissolved air flotation (DAF) system and the start-up and the operation of two 450 m3 UASB reactors in a poultry slaughterhouse in Sorocaba, Brazil. The DAF presented reduction efficiency of grease and fats, suspended solids and COD 50% higher. The reactors were seeded with non-adapted sludge. The average COD of the reactor influent was 2,695mg/L; and the initial organic loading rate (OLR) and the initial sludge loading rate at the start-up were 0.51 kg COD/m3.day and 0.04 kg COD/kg VTS.day, respectively. The start-up period was 144 days. During this time the reactor flow rate and OLR were gradually increased. At the reactor start-up, the maximum OLR value was 2.1 kg COD/m3.day, the COD reduction was higher than 80%, and the concentration of volatile fatsty acids (VFA) was below 100mg/L. The COD reductions, considering the reactor effluent raw COD and soluble COD were similar throughout the period studied in both reactors. The reactor effluent raw COD was approximately 10% higher than the soluble COD until the 225th day of operation. From the 225th day of operation this value increased 20%-30% due to the sludge washout. The effluent soluble COD reduction, the effluent VFA concentration and the operational stability attested the good performance of UASB reactors in poultry slaughterhouse wastewater treatment.
Removal of fecal indicator organisms and parasites (fecal coliforms and helminth eggs) from municipal biologic sludge by anaerobic mesophilic and thermophilic digestion
Authors: Rojas Oropeza M. , Cabirol N. , Ortega S. , Castro Ortiz L. P. , Noyola A.
Published: May 2018

In this work, two egg-shaped, 5L-volume, anaerobic sludge digesters were used, one under mesophilic conditions (35°C, M1), and the other under thermophilic conditions (55°C, T1). Both digesters were fed with the purged sludge from an anaerobic treatment plant (start-up period) and from an activated sludge plant (stabilization period), treating municipal wastewaters. The purpose of the study was to establish the technical feasibility of the anaerobic thermophilic sludge treatment comparatively, during the stages of start-up and stabilization of the process, for removing pathogenic microorganisms and parasites efficiently. The results show that, in both stages, the anaerobic thermophilic digester presents higher efficiency on the removal of pathogens and parasites, than the mesophilic digester. Anaerobic thermophilic digestion is close to complying with the EPA (1996) limits for “Class A” type biosolids, referring to the number of parasitic helminth eggs (0.25 HELarval/gTS), and to the pathogen indicator fecal coliforms (<1000 MPN/gTS). Therefore, the results show that thermophilic anaerobic digestion of biologic sludge may be considered as a suitable technology for the production of Class A biosolids, for further use in agriculture without restrictions.
Workshop 1 (synthesis): steps towards increased effectiveness in water use - possibilities and replicability
Authors: Bath Vincent J. , Lundqvist Jan
Published: May 2018

Inevitable increases in human needs and wants leading to mounting water stress necessitate that each unit of water is used as efficiently as possible. Excessive use of water cannot be accepted. Similarly, the least possible impact on water quality is a must. Yet, regional development and urgent social and environmental objectives may motivate an allocation of scarce water resources where the output is lower as compared to what could have been accomplished with an alternative allocation. In essence, the effective use of water presumes a broad and long-term perspective on societal development and environmental sustainability. Presentations illuminated that technical and institutional arrangements must be applied to reach an effective use. In practice, although not ncessarily in policy statements, technical arrangements continue to have a pivotal position in this regard.
Workshop 7 (synthesis): towards a recycling society: systems approach to small-scale reuse of human waste
Authors: Rahman Ausaf-ur , Drangert Jan-Olof
Published: May 2018

Population increase and growing quantities of human excreta create serious problems and high risks for people's health. Alternative solutions are becoming crucial to improve urban living conditions, and to shorten water and nutrient flows into circulation of used water and nutrient in human excreta. The speakers presented a wide range of experiences of “closing the loops” and thereby turning potential waste into productive use. The focus of the workshop deliberations was on simplifying the hygienisation of urine and faeces and the reuse in food production by using urine-diverting toilets, as well as innovative ways to recycle sewage after various stages of treatment.
Degradation of p-hydroxyphenylacetic acid by photoassisted Fenton reaction
Authors: Acero J.L. , Benítez F.J. , Real F.J. , Leal A.I.
Published: May 2018

The chemical decomposition of p-hydroxyphenylacetic acid, a phenolic pollutant present in agro-industrial plant effluents, has been investigated by means of the Fenton's reaction and the photoassisted Fenton's reaction, the so-called photo-Fenton system. The degradation levels achieved have been compared to those obtained by applying other Advanced Oxidation Processes, such as the combination UV/H2O2. The optimum pH to carry out the decomposition of this organic compound by either Fenton or photo-Fenton systems was found to be pH = 3. The presence of buffers such as phosphate impedes these processes due to the formation of ferric complexes.

A reaction mechanism, which allows calculating the contribution of the radical reaction to the global process, has been proposed. According to this mechanism, the dominant way of degradation of p-hydroxyphenylacetic acid is through its reaction with the OH radicals originated in the photolysis of H2O2 and, especially, in the Fenton's reaction.
Ozonation of Reactive Blue 81 in the bubble column
Authors: Ledakowicz S. , Maciejewska R. , Perkowski J. , Bin A.
Published: May 2018

The decolourisation process of the Reactive Blue 81 was carried out in a laboratory bubble column reactor with inner diameter 110 mm and working height 550 mm, equipped with a porous glass ozone diffuser (diameter 50 mm). A model of ozone absorption with the chemical reaction in the liquid phase was employed. It was found that the decolourisation proceeds in the fast pseudo first-order regime. The average value of the enhancement factor was calculated from the experimental results and compared with those calculated according to the theory of mass transfer with a second-order chemical reaction. In order to determine the intrinsic kinetics of ozonation, a stopped-flow technique was employed. The rate constant of the dyestuff reaction with ozone was determined as equal to 4.5 × 107 mol/(dm3.s).
Degradation of olive mill wastewater by the combination of Fenton's reagent and ozonation processes with an aerobic biological treatment
Authors: Beltrán-Heredia J. , Torregrosa J. , García J. , Dominguez J.R. , Tierno J.C.
Published: May 2018

Degradation of olive mill wastewater (OMW) by means of two chemical oxidation processes (Fenton's reagent and ozonation) and their consecutive treatments with aerobic microorganisms have been studied. Fenton's reagent treatment moderately reduces COD and to a greater extent the polyphenolic compounds. Ozonation contributed to low conversion of COD and moderate reduction of polyphenols. The aerobic biological treatments degrade to values higher than 70% and 90% for COD and polyphenolic compounds, respectively. A kinetic study has been carried out in each process, determining the representative kinetic parameters of each model.
On the need for engineering models of integrated chemical and biological oxidation of wastewaters
Authors: Ollis D.F.
Published: May 2018

Experimental examples of sequential chemical and biological oxidation treatment have been previously reviewed by Scott and Ollis, and economic estimates proposed by Esplugas and Ollis. Despite the prevalence of examples evident in these reviews and in recent conferences, very little use of kinetic models to codify and rationalize results on complex or simulated wastewaters has appeared. In consequence, models are not widely available nor have they yet received widespread acceptance as a method of analysis and reporting. To ameliorate this situation we here report a summary of important kinetic behaviors characteristic of individual chemical and biological kinetics, and provide experimental examples from recent works which illustrate the utility of such simple kinetic forms to construct two step treatment engineering models for complex wastewater and waters.
Photochemical treatment of simulated dyehouse effluents by novel TiO2 photocatalysts: experience with the thin film fixed bed (TFFB) and double skin sheet (DSS) reactor
Authors: Arslan I. , Balcioglu I.A. , Bahnemann D.W.
Published: May 2018

This study has been undertaken to provide a rather practical assessment of the heterogeneous photocatalytic treatment of two simulated reactive dye-bath effluents via three commercial TiO2 types (Degussa P25, Millennium PC 500 and Sachtleben Mikroanatas), which were employed in fixed film and suspended photochemical reactor configurations. The obtained results have clearly revealed that the inherent advantage of eliminating a proceeding photocatalyst separation step did not justify the significantly lower treatment performance of the thin film fixed bed (TFFB) reactor, which is directly reflected in the values obtained for percent photonic efficiencies (% ζ), first-order decolourisation rate constants (kd) and the collector area requirements per unit of mineralisation rate (CA/M), as compared to the more recently developed suspended double skin sheet (DSS) photoreactor. Generally speaking, Degussa P25 was found to be most efficient among the investigated TiO2 photocatalyst types.
Water quality characteristics of forest rivers around Lake Biwa
Authors: Fujii S. , Somiya I. , Nagare H. , Serizawa S.
Published: May 2018

Forest river surveys were carried out at upper streams of several rivers in the Lake Biwa watershed to understand the water quality characteristics of the rivers, and to find out their relationships with forest features such as geographical, geological and vegetational data. The results showed: (1) Forests have some purification functions for nitrogen and organic matter, but become sources for most of ionic species. (2) Main mineral species in forest rivers are Ca2+, Mg2+ and Na+, HCO3–, CO32–, Cl–, SO42– and SiO2. (3) Loading from forests was 0.4–7 kg/km2/d for TN and 0.01–0.3 kg/km2/d for TP. (4) River quality reflects the properties of each forest, and is unique to the place, especially in ionic species such as Ca2+ and Cl–. (5) A cluster analysis successfully categorized ionic components into several groups.
Reactive dyes decolouration by TiO2 photo-assisted catalysis
Authors: Lizama C. , Yeber M.C. , Freer J. , Mansilla H.D.
Published: May 2018

The photocatalytic degradation of three reactive azo dyes (yellow-2, orange-16 and red-2) and one anthraquinone reactive dye (blue-19) was studied. The reactions were carried out in a reactor with recirculation using TiO2 immobilised on glass Raschig rings (system A) and compared with a batch system using the catalyst in aqueous suspension (system B). Both reaction systems were irradiated with a 125 W, l > 254 nm lamp. The suspended TiO2 system was also studied using a 125 W 360 nm lamp (system C). Kinetic studies indicated a rapid colour removal, following the order B > A > C. The same trend was observed in COD and TOC removal profiles. The energy consumption per order of magnitude of catalytic degradation of the dyes was lower in the batch reactor (system B) than in the reactor with recirculation and immobilised TiO2 (system A).
Effects of subsurface heterogeneity on natural bioremediation at a gasoline spill site
Authors: Kao C. M. , Kota S. , Ress B. , Barlaz M. A. , Borden R. C.
Published: May 2018

A test cell of 3-m by 6-m located at the mid-point of a gasoline spill site was selected to test the hypothesis that the rate of hydrocarbon biodegradation is influenced by the spatial distribution of the electron acceptors, aqueous geochemistry, and microbial population. Multilevel samplers (MLSs) were installed at four corners of the test cell for groundwater sampling. Sampling ports were placed at 0.3-m intervals from 1.5 to 4.8 m below land surface (bls). A 0.91-m by 12.7-cm sediment core (from 3.3 to 4.2 m bls) in the center of the MLSs was collected. The core was cut into 7 sections, and each was used for sediment extractions, microbial enumeration, grain size distribution, and microcosm studies. Groundwater analytical results indicate that iron reduction was the dominant biodegradation process within this test cell. Iron-reducing process caused the preferential removal of certain compounds. Microbial enumeration results show that the distribution of microbial population varied with depth and sediment materials. Lower microbial population was observed in those sections with higher portion of clayey materials. The less permeable materials would limit the bacterial transport, decrease the bioavailability of Fe(III) to iron-reducing bacteria, and thus cause the low biodegradation activity. Results suggest that using blended sediments for biodegradation rate measurements may provide misleading results.
The study of rate improvement of trichloroethene (TCE) decay in UV system with hydrogen source
Authors: Choy W. K. , Chu W.
Published: May 2018

The photosensitization of trichloroethene (TCE) in the presence of hydrogen source of surfactant and photosensitizer was investigated. Photolysis experiments were conducted with a Rayonet RPR-200 merry-go-round photoreactor at 253.7 nm. Solutions containing fixed amount of TCE and surfactant Brij 35 were exposed to UV illumination with different concentrations of acetone (ACE). Quantum yield in solution with surfactant Brij 35 and optimum ACE dosage is about 25 times higher than that in Brij 35 alone. However, with an excess ACE dosage, it would act as a light barrier which attenuates the light intensity for TCE photodegradation. A mathematical model is therefore developed for the prediction of TCE photodegradation in Brij 35 solution containing various ACE concentrations, in which the remaining fraction of TCE (C/C0) in the system can be determined. Apart from the direct photodegradation, photosensitization is postulated to be another major pathway contributing to the overall decay.
Fluorescence spectroscopy and molecular weight distribution of extracellular polymers from full-scale activated sludge biomass
Authors: Esparza-Soto M. , Westerhoff P. K.
Published: May 2018

Two fractions of extracellular polymer substances (EPSs), soluble and readily extractable (RE), were characterised in terms of their molecular weight distributions (MWD) and 3-D excitation-emission-matrix (EEM) fluorescence spectroscopy signatures. The EPS fractions were different: the soluble EPSs were composed mainly of high molecular weight compounds, while the RE EPSs were composed of small molecular weight compounds. Contrary to previous thought, EPS may not be considered only as macromolecular because most organic matter present in both fractions had low molecular weight. Three different fluorophore peaks were identified in the EEM fluorescence spectra. Two peaks were attributed to protein-like fluorophores, and the third to a humic-like fluorophore. Fluorescence signatures were different from other previously published signatures for marine and riverine environments. EEM spectroscopy proved to be a suitable method that may be used to characterise and trace organic matter of bacterial origin in wastewater treatment operations.
In situ detection of cell surface hydrophobicity of probe-defined bacteria in activated sludge
Authors: Nielsen J. L. , Mikkelsen L. H. , Nielsen P. H.
Published: May 2018

The surface hydrophobicity of different types of bacteria in activated sludge were investigated under in situ conditions by following the adhesion of fluorescent microspheres with defined surface properties to bacterial surfaces (the MAC-method). This technique was combined with identification of the bacteria with fluorescence in situ hybridization with rRNA-targeted oligonucleotides (FISH) and could thus be used for characterization of surface properties of probe-defined bacteria directly in a complex system without prior enrichment or isolation. This MAC-FISH technique could be used for single bacteria as well as filamentous bacteria. In the investigated activated sludge from an industrial wastewater treatment plant, two types of filamentous bacteria dominated. One morphotype consistently attracted only very few hydrophobic microspheres, indicating that the thin sheath of exopolymers around the cells had a hydrophilic surface. Use of a hierarchical set of gene probes revealed that these filaments were sulphide oxidising Thiothrix spp. The other predominating filamentous morphotype had a thick, very hydrophobic exopolymeric sheath. This filamentous bacterium was found to belong to the alpha-Proteobacteria. The relevance of the significant differences in surface hydrophobicity for the two morphotypes in respect to substrate uptake and floc formation is discussed.
Modelling of activated sludge acclimisation to a non-ionic surfactant
Authors: Carvalho G. , Nopens I. , Novais J. M. , Vanrolleghem P. A. , Pinheiro H. M.
Published: May 2018

A model is proposed to describe activated sludge acclimatisation to a non-ionic surfactant. The model was calibrated automatically, using WEST, a specific software environment for wastewater treatment model building, simulation and parameter estimation. The assays have been performed in a sequencing-batch reactor (SBR), using a non-ionic surfactant as sole carbon source and non-acclimatised sludge. The best fitting model was based on the assumption of three sequentially degraded COD fractions, where the second fraction is a metabolite of the original molecule and the third fraction is a more slowly biodegradable metabolite resulting from the secondary degradation. For primary degradation, hydrolysis with no associated growth was assumed. The growth of microorganisms responsible for degradation of the second and third COD fractions was presumed to follow Haldane and first order kinetics, respectively. The model was able to fit four consecutive assays of the same acclimatisation process, using Brij 30 as carbon source, with different food/microorganism ratios. The parameters obtained showed that the (self-)inhibition of the growth on the second COD fraction decreased along acclimatisation.
Study on real time control of non-point pollutants discharged from urban areas during a storm event
Authors: Yamada K. , Kim T.-S. , Nakamura K. , Nomura J.
Published: May 2018

In this research, we installed the storm water storage tank, which has three functions: pollutant control, flood control and water use, to the end pipe of a separate system. We examined the effect of real time control (RTC) introduction with the scenario selection in the study area in the catchment basin, which has measured data. As a result, a latter period centering-type case is satisfied with the pollutant reduction by the RTC and also at the water use tank, the best control settles COD concentration at about 0.45 mg/l. It was clarified how to use a RTC method as a measure of the discharge problem from an urban area during a storm event.