bluuebunny/crossref_metadata_2025 huggingface dataset:
Membrane application to water purification process in Japan – development of hybrid membrane system
Authors: Watanabe Y. , Kimura K. , Suzuki T.
Published: May 2018

This paper deals with two recent developments made by the authors about the hybrid membrane systems applicable to the water purification. The performance of a hybrid MF membrane system with circulating powdered activated carbon and condensed sludge has been studied using a pilot plant. The powdered activated carbon was intermittently dosed to the system for adsorbing mainly the humic substances. Manganese ions and ammonia nitrogen were biologically oxidized by the iron-oxidizing bacteria and ammonia oxidizing bacteria inhibiting the condensed sludge. In the hybrid MF membrane system, decreasing rate of the permeability was much less than that of a conventional MF membrane process. This may result from the reduced organic loading to the membrane due to the adsorption of humic substances onto the powdered activated carbons. A novel UF membrane process was also developed, where the nitrifying bacteria are fixed on the surface of the rotating disk membranes. With this membrane process, the simultaneous performance of the strict solid-liquid separation and the biological ammonia oxidation are possible. In order to increase the washing efficiency, a small quantity of the sponge particles were introduced into the membrane chamber and then the disk rotational speed was increased. This membrane washing method using sponge particles was so effective that the filtration resistance due to the accumulated cake was completely cancelled.
Influence of molecular weight distribution of organic substances on the removal efficiency of DBPS in a conventional water treatment plant
Authors: Chang C-N. , Chao A. , Lee F-S. , Zing F-F.
Published: May 2018

The objective of this study is to investigate how the molecular weight distribution of the organic substances affects their treatment efficiencies and the reduction of disinfection by-products (DBPs) in the various unit operations of a full-scale water treatment plant. The results indicate that the membrane with a smaller molecular weight cut-off is more effective for removing the organic substances and its associated water quality parameters from the raw water. For example, using the membrane with a molecular weight cut-off of 0.5 K (500 daltons), the removal efficiency of DOC from the raw water sample can be as high as 88%. Removal efficiencies of other water quality parameters such as UV254 absorbance, THMFP and AOXFP are generally between 65–69%. When undergoing the various unit operations in the conventional water treatment plant, most organic substances are removed in the coagulation process followed by sedimentation.
Pond evaluation and upgrading in Mexico
Authors: Escalante V. , Moeller G. , Rivas A.
Published: May 2018

Half of the wastewater facilities constructed in Mexico for wastewater treatment and projected to be constructed in the next ten years, are waste stabilisation pond systems. The existing facilities have several problems in their operation. A national programme was developed by federal and local authorities responsible for sanitation and treatment for the monitoring and evaluation of the existing pond systems. The aim of the programme was the monitoring and evaluation of pond performance and effluent quality of a number of waste stabilisation ponds systems in different regions in Mexico and to upgrade and expand them if necessary. The programme was developed during 1998 and the specific sites selected were distributed within the country in the southern, central and northern part of Mexico. The evaluation of the specific ponds led to the production of a series of case studies on the various pond systems selected, that were discussed and jointly developed with local technicians in charge of the operation of the facilities. The case studies developed were: Gómez Portugal pond system located in the state of Aguascalientes, constituted by a baffled facultative pond; Guadalupe Victoria pond system located inthe State of Durango and constituted by a primary facultative, a secondary facultative and a third facultative pond; La Reforma pond system in Sinaloa, with two facultative ponds in series; González Ortega pond system in the State of Baja California Norte, with four anaerobic and four facultative ponds, and Chapilla pond system, located in the state of Chiapas. Plant effluents are intended for several purposes: irrigation and for discharge into receiving bodies. Effluent quality complies only with BOD limits, but not with microbiological limits established in national standards. For each pond, an upgrading plan is presented to comply with microbiological standards for discharge or for its use in irrigation.
Longitudinal distribution and vertical profile of pH, temperature and dissolved oxygen in a partially aerated facultative pond
Authors: Melo H. N. , Guimarães P. , Melo J. L.
Published: May 2018

The system consists of a partially aerated facultative pond with a polished area that treats the effluents of a soft drink industry in Brazil. This work concerns on the study of the longitudinal distribution as well as the analysis of the vertical profile of the main control parameters which exerts a direct influence on the metabolism of the system.

The results show the existence of a horizontal thermal gradient between aerated and polishing zones, which is more intense at the surface of the first 40 metres. The vertical profile did not identify a tendency to thermal stratification. The constant gradient vertical of 0.1°C in the aerated and polishing zones characterizes an almost isothermal condition.

The decrease of the effluent pH values was observed in the bottom layer of the pond. This indicates that the anaerobic digestion on the sedimented sludge incorporates acids in the liquid mass.

The dissolved oxygen vertical distribution presents negative clinographic profile. The isolines in the aerated zone indicate good efficiency of oxygen transfer. In the polishing zone, concentrations above 2.0 mg/l were observed down to a depth of 1 m, possibly caused by photosynthetic activities.
Pilot-plant study of a high recovery membrane filtration process for drinking water treatment
Authors: Huang J.Y. , Takizawa S. , Fujita K.
Published: May 2018

Successful application of energy efficient dead-end micro-filtration (MF), which does not require recirculation like cross-flow filtration, depends on achieving high recovery rates. In this study, two different types of pilot scale membrane systems (horizontally and vertically stretched membrane filters) were evaluated based on the effects of pre-chlorination, intermittent chlorination and circulation flow by air-scrubbing. Additionally, the effects of operating factors including physical cleaning and chemical cleaning on membrane fouling were examined. The vertically stretched membranes showed better performance than horizontally stretched membranes at filtration fluxes of either 0.55 m/day or 0.78 m/day even under 2.6 to 27.5°C and raw water turbidity higher than 300 units, as long as intermittent chlorination (10 mg/l once a week) along with the circulation flow by air-scrubbing (once in 30 minutes) in the housing were employed. It was demonstrated that the vertically stretched membranes have been operated for one year without chemical cleaning of the membranes, wherein the recovery of raw water as a filtrate was 97.0% or 98.9%.
The application of a diagnostic methodology for the identification of hydraulic design deficiencies affecting pathogen removal
Authors: Vorkas C. A. , Lloyd B. J.
Published: May 2018

An intensive diagnostic methodology designed to evaluate microbiological removal deficiencies related to design defects was applied to a two-stage waste stabilisation pond system in Colombia. This evaluation included intensive monitoring of a range of physico-chemical parameters, an integrated assessment of faecal coliform removal and simultaneous hydraulic tracing of surface flow using oranges. The dispersion/advection effects and the hydraulic regime through the facultative pond were defined using a bacteriophage. This methodology facilitated the identification of the hydraulic flow patterns and short-circuiting together with the age distribution of the pond effluent. Observed differences between surface and sub-surface flow patterns were attributed principally to the fact that wind action opposed the natural input-output energy flow path. The concentration of phage leaving the pond in 6 hours represented 1% of the original dose, confirming the finding that a 2-log reduction of pathogen indicators could not be achieved. Three stages of intervention were identified as necessary for the performance to be improved to the level at which WHO reuse targets would be met.
Faecal coliform die-off in wastewater storage and treatment reservoirs
Authors: Athayde Júnior G. B. , Mara D. D. , Pearson H. W. , Silva S. A.
Published: May 2018

This paper describes faecal coliform (FC) removal in pilot-scale Wastewater Storage and Treatment Reservoirs (WSTR) in northeast Brazil. FC decay during the filling phase of WSTR was very reduced, suggesting that these reactors should be filled as quickly as possible, and subjected to the highest organic loading that will not cause odour emissions. The highest loading employed in this study was 659 kgBOD5/ha.d, causing no nuisance conditions. During the resting phase, FC decay rate decreased exponentially and Chick's law was modified. The time into the resting phase for FC to reach 103 cfu/100 mL ranged from 15 to 25 days as WSTR depth varied from 2.00 to 6.50 m. The performance of sequential batch-fed waste stabilization ponds (SBFWSP) in removing FC was compared to that of waste stabilization ponds (WSP) operated in series. It was shown that, in general, SBFWSP were cheaper than WSP in series, with the bacteriological quality of the effluent in the former being more reliably predicted than in the latter operational regime. When provision of volume to store the winter effluents is considered, a WSP system presents a higher benefit/cost ratio than a hybrid WSP-WSTR system, but the adoption of the latter can double the annual net return for a rainy season of 5 months for instance. In the case of use of the hybrid WSP-WSTR system, the net return would be US$ 0.17 – 0.22 per cubic metre of available wastewater, depending on the length of the rainy season (3 – 5 months considered) as compared to US$ 0.12 from the WSP system alone.
Ultraviolet light disinfection of wastewater stabilization pond effluents
Authors: Nelson K. L.
Published: May 2018

A reveiw of recent experiments on the particle-association of fecal coliforms in wastewater effluents and the effect that this has on UV disinfection is presented. The most significant finding is that a direct linear correlation was observed between the total number of particles with associated coliform bacteria and the residual coliform bacteria concentration after UV disinfection. In contrast to the other treatment systems, effluents from an aerated and a facultative pond system had very low numbers of particles with associated coliforms. Therefore, despite high suspended solids concentrations, the pond effluents were easily disinfected with UV because the majority of the coliforms were not associated with particles. More research is needed, in particular, on the effect of UV irradiation on algal solids and the implications for the discharge or reuse of pond effluents. The main factors affecting the costs of UV compared to chlorine disinfection are also discussed.
Pilot-scale membrane bioreactor and reverse osmosis studies for direct reuse of secondary textile effluents
Authors: Rozzi A. , Malpei F. , Bianchi R. , Mattioli D.
Published: May 2018

Post-treatment of secondary wastewater (80% textile, 20% municipal) was tested on a pilot scale low-pressure reverse osmosis (RO) module, to produce a polished effluent to be recycled into the textile factories. Two different flow sheets were used. In the first one, the feed to the RO was pre-treated in a coagulation and filtration unit. In the second one, a ZenoGem® membrrane hollow fibre reactor was used to separate the activated sludge from the permeate which was fed to the RO module. Experimental results are discussed as well as advantages and disadvantages of the two alternatives.
Nitrification potential of attached biofilms in dairy farm waste stabilisation ponds
Authors: Craggs R. J. , Tanner C. C. , Sukias J. P. , Davies-Colley R. J.
Published: May 2018

Dairy farm waste stabilisation ponds are a major source of ammoniacal-N to surface waters in New Zealand. Ammoniacal-N is of particular concern in New Zealand where native aquatic invertebrates appear to be very sensitive to ammonia toxicity. This paper investigates improvement of ammoniacal-N nitrification in dairy farm facultative ponds with mechanical aeration and provision of biofilm attachment surfaces. Biofilm was grown on surfaces at different depths (0.1 m, 0.2 m and 0.6 m) under three mechanical aeration regimes (no aeration, night-only aeration and continuous aeration). Nitrification potential of biofilm was determined as the rate of ammoniacal-N removal in bioassays with ammoniacal-N spiked pond water or culture medium under controlled conditions (20°C, pH 7.0, constant stirring, DO 2–3 g m−3, dark). The nitrification potentials (0.30 g N m−2 biofilm d−1 to 2.17 g N m−2 biofilm d−1) of biofilm-coated surfaces were largely controlled by oxygen availability and consistency of supply in the pond. Nitrification potentials were high where oxygen availability was high, such as close to the pond surface where atmospheric re-aeration and algal photosynthesis were prevalent. Nitrification potentials of biofilms incubated at depth were enhanced by mechanical aeration, with higher values achieved under the continuous aeration regime and at more turbulent sites closer to the aerator.
Bioaugmentation with the clc-element carrying Pseudomonas putida BN210 in a membrane separation bioreactor
Authors: Ghyoot W. , Springael D. , Dong Q. , Van Roy S. , Nuyts G. , Diels L.
Published: May 2018

For the removal of toxic and recalcitrant organic substances from wastewater, bioaugmentation with bacteria harbouring specific degradation pathways in activated sludge could constitute a relevant process. In this study, we examined the behaviour of a 3-chlorobenzoate (3CBA) degrading Pseudomonas putida BN210 carrying the self-transferable clc-element containing the clc-genes for 3CBA metabolism in a conventional activated sludge system (CAS) and a membrane separation bioreactor (MBR). It was shown that bioaugmentation in the MBR resulted in an increased resistance towards shock loading of 3CBA in terms of improved COD removal. Respirometry showed that the MBR sludge was less destabilized by 3CBA shock loadings than the CAS sludge. Molecular techniques including PCR-DGGE to follow strain BN210 and PCR using specific primer sets to follow the clc-element showed that strain BN210 was rapidly lost in both reactors or seems only to survive in low cell numbers. Other 3CBA degrading populations were observed in both CAS and MBR reactors.
Meeting stringent environmental and reuse requirements with an integrated pond system for the twenty-first century
Authors: Shelef G. , Azov Y.
Published: May 2018

AbstractIt is a long sought desire to modernize stabilization pond systems by increasing their efficiency to control malodors, to save land requirements and to improve their effluent quality, particularly for reuse purposes, while still capitalizing on natural energy saving processes such as anaerobiosis and photosynthesis. A full-scale demonstration modern integrated pond system was constructed in the town of Arad (22,000 inhabitants) located in the Negev desert of Israel. The integrated pond system is composed of the following units: (1) anaerobic covered ponds of which one is of the “submerged tent” novel design, including biogas collection and utilization for heating the bottom sludge; (2) two facultative ponds with internal recirculation; (3) a two stage rock filter to biologically remove excess algal biomass from the effluent; (4) three storage reservoirs operating in a sequential array of “fill, stay, draw”, and (5) a seasonal reservoir. The final effluent is aimed at irrigation of various agricultural crops.
Agronomic and health aspects of storage ponds located on a golf course irrigated with reclaimed wastewater in Tunisia
Authors: Bahri A. , Basset C. , Jrad-Fantar A.
Published: May 2018

In Tunisia, golf courses are irrigated with reclaimed wastewater stored in ponds for variable periods. The impact of storage on the sanitary and agronomic quality of the water was evaluated in two surveys conducted over one year. The water quality of the golf course ponds, operated as open ponds, was directly dependent on the flowrate and the quality of the new effluents. The faecal coliforms removal varied between 4 log. units at the end of winter and 1 log. unit in summer. Values exceeding the WHO guidelines (1989) (200 FC/100 mL) were recorded in the irrigation water. Reclaimed wastewater stored 20 days up to 8 months in two experimental closed ponds was in compliance with WHO guidelines throughout the year, i.e. 1000 FC/100 mL after a residence time of 5 to 10 days and 200 FC/100 mL after 40 days. A substantial loss of the water fertilizing potential was noticed after long storage. Storage increases the volume of water available for the dry season, and allows wider uses and unrestricted irrigation.A sequential use of the golf course ponds, with alternating closing and opening phases, would improve the water quality.
Acetate injection into anaerobic settled sludge for biological P-removal in an intermittently aerated reactor
Authors: Ahn K. H. , Yoo H. , Lee J. W. , Maeng S. K. , Park K. Y. , Song K. S.
Published: May 2018

Injecting acetate into the sludge layer during the settling and decanting periods was adopted to enhance phosphorus release inside the sludge layer during those periods and phosphorus uptake during the subsequent aeration period in a KIST Intermittently Decanted Extended Aeration (KIDEA) process. The relationship among nitrification, denitrification and phosphorus removal was investigated in detail and analyzed with a qualitative floc model. Dependencies of nitrification on the maximum DO level during the aerobic phase and phosphorus release on residual nitrate concentration during the settling phase were significant. High degree of nitrification resulted that phosphorus release inside the sludge layer was significantly interfered with nitrate due to the limitation of available acetate and the carbon sources from influent. Such limitation was related to the primary utilization of organic substance for denitrification in the outer layer of the floc and the retarded mass transfer into the inner layer of the floc. Nevertheless, effects of acetate injection on both denitrification and phosphorus release during the settling phase were significant. Denitrification rate after acetate injection was two times as high as that before acetate injection, and phosphorus release reached about 14 mg PO43--P/g MLVSS/hr during the decanting phase after the termination of denitrification inside the sludge layer. Extremely low level of maximum DO (around 0.5 mg/L) during the aerobic phase may inhibited nitrification, considerably, and thus nearly no nitrate was present. However, the absence of nitrate increased when the phosphorus release rate was reached up to 33 mg PO43--P/g MLVSS/hr during the settling and decanting phase, and nearly all phosphorus was taken up during subsequent aerobic phase. Since the sludge layer could function as a blocking layer, phosphorus concentrations in the supernatant was not influenced by the released phosphorus inside the sludge layer during the settling and decanting period. Phosphorus removal was directly (for uptake) and indirectly (for release) dependent on the median and maximum DO concentration during the aerobic phase, and those optimal values may exist within the range from 0.2 to 0.6 mg/L and 0.4 to 1.2 mg/L, respectively.
Data-based modelling and proportional-integral-plus (pip) control of nitrate in an activated sludge benchmark
Authors: Ghavipanjeh F. , Taylor C. J. , Young P. C. , Chotai A.
Published: May 2018

This paper presents the result of an investigation into the Proportional Integral Plus (PIP) control of nitrate in the second zone of an activated sludge benchmark. A data-based reduced order model is used as the control model and identified using the Simplified Refined Instrumental Variable (SRIV) identification and estimation algorithm. The PIP control design is based on the Non Minimum State Space (NMSS) form and State Variable Feedback (SVF) methodology. The PIP controller is tested against dynamic load disturbances and compared with the response of a well tuned PI controller.
Contribution of Pseudomonas spp. to phosphorus uptake in the anoxic zone of an anaerobic-anoxic-aerobic continuous activated sludge system
Authors: Atkinson B. W. , Mudaly D. D. , Bux F.
Published: May 2018

A continuously operated laboratory-scale (32 L) nitrification denitrification biological excess phosphorus removal (NDBEPR) activated sludge system (modeled on the 3-stage Phoredox configuration) was maintained for 140 d. The transition from a non-biological excess phosphorus removal (BEPR) sludge to one exhibiting a strong BEPR mechanism was monitored. Mixed liquor seed inoculum was obtained from a full-scale single aerobic activated sludge installation and subjected to conditions conducive to BEPR, i.e. increasing influent acetate (HAc) concentrations. At a sludge age of 10 d with 100% HAc feed, the system was capable of removing a maximum of ca. 40 mgPO4–P/L from the bulk liquid; P/VSS of ca. 0.27 (mgP/mgVSS); and VSS/TSS of 0.53 (mgVSS/mgTSS) in the aerobic zone was attained. Although typical BEPR phosphorus transformation patterns were routinely observed, i.e. anaerobic phosphate release and aerobic phosphate uptake, phosphate uptake in the anoxic zone was also recorded indicating the presence of denitrifying phosphorus accumulating organisms (DPAOs) in the sludge community. The microbial community was screened (using both isolation and direct methods of analysis) for the presence of Pseudomonas spp. as this genus is known to perform both polyphosphate accumulation and denitrification processes. Isolation of anoxic mixed liquor bacteria on solid media and identification using the API 20NE system resulted in the total dominance of the Pseudomonads (>50%). However, direct fluorescent in situ hybridizations (FISH) revealed that Pseudomonas spp. only constituted ca. 3% of the total bacterial community indicating that other bacterial genera are contributing to simultaneous polyphosphate accumulation and denitrification processes in the anoxic zones of NDBEPR systems.
Application of COD fractionation by a new combined technique: comparison of various wastewaters and sources of variability
Authors: Spérandio M. , Urbain V. , Ginestet P. , Audic M. J. , Paul E.
Published: May 2018

A new respirometric method for COD fractionation was applied to various wastewaters collected on French treatment plants. Great variations were observed especially in the readily biodegradable fraction (RBCOD) ranging from 1 to 16% of total COD. Variability of the results among the origin can be explained by the reactions occurring in the sewers. In one of the towns studied, the wastewater samples collected directly in the sewer show COD characteristics very different from the sewage which reaches the treatment plant. By analysing the same wastewater after aerobic and anaerobic storage, it was proved that RBCOD respectively decreased or increased significantly. Seasonal fluctuations were also quantified, showing that RBCOD fraction decreased from 75 mg/L to –15 mg/L during the summer whereas the variation of soluble fraction was less important.
Biological phosphorus and nitrogen removal in a sequencing batch moving bed biofilm reactor
Authors: Helness H. , Ødegaard H.
Published: May 2018

Biological phosphorus and nitrogen removal in biofilm processes have a potential advantage compared to activated sludge processes, because of less vulnerability with respect to sludge loss and because biofilm processes, in general, are more compact with a smaller footprint. Experiments have been carried out in a moving bed biofilm reactor operated as a sequencing batch reactor (SBR), with simultaneous nitrification, phosphorus uptake and denitrification in the aerobic phase. In order to achieve good phosphorus and nitrogen removal, the length of the anaerobic period should be tuned to achieve near complete removal of easily biodegradable COD in the anaerobic period, and the length of the aerobic period should be long enough for complete nitrification. The total COD-loading rate must be at the same time be kept high enough to achieve a net growth of biomass in the reactor.
Algae-removal performance of a fluidized-bed biofilm reactor system for lake water treatment
Authors: Tanaka T. , Tsuzuki K. , Nishijima N. , Takagi T.
Published: May 2018

The algae removal efficiency of a pilot plant – based on a fluidized-bed biofilm reactor system for treating – was investigated. This system does not require back-washing because the fluidized-bed suffers no clogging. Moreover, the system uses dissolved oxygen in the influent water for aerobic biological treatment without the need for additional aeration equipment. This, it is an easy-maintenance, low-energy system for purifying eutrophic lake water. The system was operated continuously at a flow rate of 1500 m3/d for nine months at Tsuchiura Port in Lake Kasumigaura. And concentrations of chlorophyll-a and dissolved oxygen in both the influent and effluent water were continuously monitored. In summer (August to September) when water bloom occurred, the average efficiency of chlorophyll-a removal was 64% at an average influent chlorophyll-a concentration of 137.8 μg/L. Over the entire experimental period of nine months, the average daily amount of removed chlorophyll-a was 40.3 g/d at an average influent chlorophyll-a concentration of 89.5 μg/L. By analyzing the relationship between the amount of removed chlorophyll-a and the consumption of dissolved oxygen, it was estimated that almost all of the algae trapped in the reactor was biologically degraded.
Dose-response assessment by a fuzzy linear-regression method
Authors: Lee Y. W. , Chung S. Y. , Bogardi I. , Dahab M. F. , Oh S. E.
Published: May 2018

Regression analysis has been used to characterize the relationship between an exposure dose and the incidence of an adverse health effect such as cancer. However, the regression rarely describes the true relationship due to uncertainties in dose-response data and relationships. Therefore, a method is developed to perform dose-response assessments by a fuzzy linear regression which explicitly exhibit these uncertainties. This method is applied to define the relationship between a particular nitrate dose to humans and its corresponding cancer risk.
Using the flexibility index to compare batch and continuous activated sludge processes
Authors: Hopkins L. N. , Lant P. A. , Newell R. B.
Published: May 2018

This paper considers the question of which is better; the batch or the continuous activated sludge processes? It is an important question because dissension still exists in the wastewater industry as toi the relative merits of each of the processes. A review of perceived differences in the processes from the point of view of two related disciplines process engineering and biotechnology, is presented together with the results of previous comparative studies. These reviews highlight possible areas where more understanding is required. This is provided in the paper by application of the flexibility index to two case studies. The flexibility index is a useful process design tool that measures the ability of the process to cope with long term changes in operation.
Robust soft sensors for SBR monitoring
Authors: Zyngier D. , Araújo O. Q. , Coelho M. A. , Lima E. L.
Published: May 2018

In wastewater treatment some process variables may be very difficult to measure directly because of the non-availability or excessive cost of sensors. An alternative is to use ‘soft sensors” that provide online estimates of these inacessible variables by calculations based on auxiliary measurable variables. Two such sensors are proposed based on extended Kalman filtering or neural networks that could enable this monitoring of nitrate ion, ammonium ion and carbonaceous matter concentrations during nitrification of wastewater.
Simple process for nutrient removal from food processing effluents
Authors: Raper W. G. , Green J. M.
Published: May 2018

Food processing effluents often contain high levels of nutrients, particularly N. Conventionally, anaerobic ponds are used to purify these effluents in Australia, giving cost-effective removal of BOD but little nutrient removal. It has become apparent that disposal by irrigation as presently practised normally exceeds sustainable N application rates, thus reduction of nutrient levels before irrigation is becoming mandatory. Meatworks effluent is often discharged to country town sewers, frequently accounting for 50-75% of the nutrient load. Meatworks effluents contain 1,000-4,000 mg/L BOD, 200-400 mg/L TKN and 20-50 mg/L P. Conventional BNR technology can readily remove nutrients from such effluents, either alone or in combination with anaerobic ponds but sludge handling on such a small scale poses economic problems.

Laboratory scale trials showed that both BOD removal from meatworks effluent and sludge disposal could be achieved readily in conventional anaerobic ponds. The pond effluent, together with the town sewage if required, could be treated in a sequencing batch reactor (SBR) designed for nitrification/denitrification service. Optimisation of the anaerobic pond operation was required to ensure production of the minimum BOD:N ratio needed for N removal. This paper will describe the design and commissioning of two plants; a demonstration plant installed at a typical sized meatworks in Gippsland, Victoria, and a full scale plant for treatment of combined domestic sewage and effluent from a large meatworks at Longford, Tasmania. In neither case (for different reasons) has P removal yet been required. It was demonstrated that 98% of BOD and up to 95% N removal may be cheaply and readily achieved in the SBR. Where lagoons are used, levels of N suitable for river discharge can be achieved. P can be readily removed by alum treatment when required.
Modeling effect of remaining nitrate on phosphorus removal in SBR
Authors: Kazmi A. A. , Fujita M. , Furumai H.
Published: May 2018

Nitrate shock loading experiments were conducted in a bench scale SBR to investigate the effect of nitrate on phosphorus removal. After achieving satisfactory phosphorus removal under steady state operation, initial NO3-N concentration amounting to 10 and 20 mg /L was fed at the beginning of the cycle. It was observed that, 10 mg/L of NO3-N suppressed phosphorus release during the feed and mix phases. Organic consumption for denitrification lead to limited PHA storage by phosphorus removing bacteria, resulting in less PO4-P removal. For 20 mg/L, influent organic substrate was not sufficient even for complete denitrification, thus leading to the presence of higher NO3-N and PO4-P in effluent. To explain the dynamics of the nutrient removal system under the transient loading, a SBR model based on IAWQ ASM2 was implemented. After adjusting PHA contents, model simulations well predicted dynamic changes of nitrate and phosphate concentrations during a cycle. Based on the model simulations, competition of COD substrate among denitrification, fermentation and oxygen respiration were investigated by calculating their consumption rates during mixing phase. In addition, a nitrate disappearance model was proposed and implemented in conjunction with a settling model to predict remaining and effluent nitrate in a cycle of SBR. Furthermore, integrated model simulations highlighted the effect of remaining nitrate on phosphorus release considering different options of reactions in settling phase.
The effect of operating conditions on theperformance of soil slurry-SBRs
Authors: Cassidy D. P. , Irvine R. L.
Published: May 2018

Biological treatment of a silty clay loam with aged diesel fuel contamination was conducted in 8 L Soil Slurry-Sequencing Batch Reactors (SS-SBRs). The purpose was to monitor slurry conditions and evaluate reactor performance for varying solids concentration (5%, 25%, 40%, 50%), mixing speed(300 rpm, 700 rpm, 1200 rpm), retention time (8 d, 10 d, 20 d), and volume replaced per cycle (10%, 50%, 90%). Diesel fuel was measured in slurry and in filtered aqueous samples. Oxygen uptake rate (OUR) was monitored. Aggregate size was measured with sieve analyses. Biosurfactant production was quantified with surface tension measurements. Increasing solids concentration and decreasing mixing speed resulted in increased aggregate size, which in turn increased effluent diesel fuel concentrations. Diesel fuel removal was unaffected by retention time and volume replaced per cycle. Biosurfactant production occurred with all operating strategies. Foam thickness was related to surfactant concentration and mixing speed. OUR, surfactant concentration, and foam thickness increased with increasing diesel fuel added per cycle.
Intracellular dynamics of ribonucleic acid (RNA) and protein in microorganisms from periodically operated biofilters
Authors: Moe W. M. , Irvine R. L.
Published: May 2018

Conventional biofilters are designed and operated as continuous flow processes where the reactors receive a constant stream of contaminated air. Recent research has shown that periodically operated biofilters can remove a greater mass of contaminants during shock loads than equally sized continuously loaded biofilters. Preliminary experiments were conducted to investigate effects of periodic operation on physiological state of biofilter microorganisms. Relative concentrations of two macromolecular components of microbial cells, RNA and protein, were quantified in biosolids samples removed from biofilters operated under different periodic and continuous loading strategies. Preliminary studies presented herein suggest that the physiological state of the microbial population present in the periodically operated biofilter differs from that of those present in the biofilter operated continuously supplied air.
Biodegradation of high strength phenolic wastewater using SBR
Authors: Yoong E. T. , Lant P. A.
Published: May 2018

This investigation demonstrates the capability of a bench-scale sequencing batch reactor (SBR) to biodegrade an inhibitory substrate at a high loading rate. A SBR loading rate of 3.12 kg phenol.m3d-1 (2.1 g COD.g-1 MLVSS d-1) with a COD removal efficiency of 97% at a SRT of 4 days and a HRT of 10 hours was achieved; this rate was not reached before. The SBR was operated at 4 hours cycle, including 3 hours react phase. The synthetic wastewater of 1300 mg/L phenol was the sole carbon source.

Oxygen uptake rates (OUR) were monitored in-situ at various stages of the SBR. The oxygen mass transfer coefficient, KLa, of 12.6 h-1 was derived from respirometry.Use of respirometry in SBR aided the tracking of the soluble substrate through OUR.
The SBR process: an efficient and economic solution for the treatment of wastewater at small cheesemaking dairies in the Jura mountains
Authors: Torrijos M. , Vuitton V. , Moletta R.
Published: May 2018

The small cheesemaking plants in the Jura Mountains (N.E. France) need self-contained solutions for treating their wastewater. Any solution must suit the characteristics of the effluent produced by these small production units and be simple, robust and financially feasible in regard to both capital and running costs. Given this context, a technique based on an SBR was recommended and the operations of the first treatment plant established on an industrial scale, monitored for the first year, with particular attention paid to operating constraints. The results obtained show that the SBR is, from a technical point of view, perfectly adapted to treating cheese production wastewater, with purification levels at 97.7% for total COD and 99.8% for BOD5. In the course of this study, it has been shown that the SBR process, thanks to its simple design and operation, can easily be run by the cheesemaker who will need to devote a minimum of time to it.

Furthermore, with treatment costs of around 2 centimes (0.33 US cent) per litre of milk delivered, the SBR process meets perfectly both the technical and financial conditions for treatment as laid down by the Federation of Cooperatives of the Doubs and Jura départements.
An integrated anaerobic - physico-chemical treatment concept for wool scouring wastewater
Authors: Peláez H. , Gutiérrez S. , Castro G. , Hernández A. , Viñas M.
Published: May 2018

The strong flow wastewater from a wool scouring industry is treated by a combination of anaerobic digestion and physico-chemical postreatment. Based on previous laboratory results (Gutiérrez et al., 1999), three anaerobic baffled reactors (ABR) of 300 m3 each were built, processing 60% of the strong flow of a wool scouring mill for about two years. COD and grease removal in the anaerobic reactors were 47-50% and 50-55% respectively, with an organic load between 8.9 and 6.7 kg COD/m3 d. The effluent of the anaerobic reactors was assayed with additives in an industrial decanter centrifuge. As results of these assays, all the effluent of the three reactors was sent to the decanter centrifuge after dosing additives. Overall COD and grease removal of the integrated system were 87% and 93% respectively. Dosage of coagulation-flocculation additives was optimized in a continuous flocculation device. The proposed treatment is cheaper and easier to control than others alternatives with COD removal higher than 93%.
Industry and water security: overarching conclusions
Authors: Stigson Björn
Published: May 2018

Fresh water is key to sustainable development. World Business Council for Sustainable Development members are addressing fresh water use 'within the corporate fenceline'. However, to address water issues 'outside the corporate fenceline' will require creative new public-private partnerships. Government's role is to provide sound framework conditions that will encourage businesses to invest time, staff and resources to address vital fresh water issues. Industry is committed to best practice within its internal operations and is ready to enter into partnerships to address broader fresh water issues.
Effect of inoculum-substrate ratio on the start-up of solid waste anaerobic digesters
Authors: Fernández B. , Porrier P. , Chamy R.
Published: May 2018

The anaerobic systems start-up for solid waste treatment is a fundamental step, especially for those with two phases. It is necessary to know both the waste characteristics and the inoculum conditions. The objective of this work was to study the inoculum-substrate ratio (ISR) influence as a previous step of the start-up of an anaerobic system for the solid waste digestion. During this research spent grain was chosen as residue, working at three different concentrations (7; 13 and 20% w/v), studying the ISR effect in terms of anaerobic degradability (AD) and specific methane productivity (SMP). The initial acetoclastic activities (A0) were calculated based on the equation which describes the methane accumulation during each test. The model constants were also calculated and were adjusted to the experimental data. The results showed that in general the ISR variation has less impact on AD than on SMP. While maximum AD were reached in those tests with high ISR, the greatest values of SMP were with the lowest values of ISR ratio. A low ISR caused a slow hydrolysis, although the methane production was fast. So, during the start-up of a two-phase anaerobic system an elevated ISR would not be necessary in order to reach a good AD and a good intermediate products production, because the hydrolysis and the VFA production must be optimised in the first phase of these systems. While in conventional systems, where phases are together, it is much better to optimise the methane production. The ISR and the SMP indicated which inoculum percentage would be interesting based on the objective of the whole system: methane or intermediate compounds (VFA) production. All this information is important during the conventional anaerobic reactors operation because these tests would show which ISRs avoid inhibition.
The role of institutional arrangements for more efficient water resources use and allocation
Authors: Kemper Karin E.
Published: May 2018

Water resources management requires an interdisciplinary approach to meet the challenges posed by ever increasing water demand and pollution. This paper discusses in which way appropriate institutional arrangements are complementary to technical interventions that aim to increase more efficient water use and allocation. Specific emphasis is given to water property rights as one of the determining factors in regard to the institutional framework. Issues such as the range of flexibility in designing property rights to water, the implications for pricing, enforcement and sanctioning mechanisms as well as for water trading and information needs are highlighted.
Workshop 2 (synthesis): balancing water and social challenges through restructuring of industry
Authors: Grau Petr , Fallenius Ulla-Brita
Published: May 2018

The workshop discussed the possibility of breaking the link between economic growth and environmental damage, and options that would encourage industry and government to take steps to reduce emissions, with 8 catalysts for change identified.
Workshop 6 (synthesis): making water everybody's business - the educational challenge
Authors: Chitale M. A. , Cederwall K.
Published: May 2018

Water awareness and communication are crucial for developing water security. Better knowledge and improved insight can lead to new ways of thinking and hence more effective handling of water-related problems. The outcomes of the workshop are summarised.
Anaerobic treatment for C and S removal in “zero-discharge” paper mills: effects of process design on S removal efficiencies
Authors: van Lier J. B. , Lens P. N.L. , Hulshoff Pol L. W.
Published: May 2018

Stringent environmental laws in Europe and Northern America lead to the development towards closure of the process water streams in pulp and paper mills. Application of a "zero-discharge" process is already a feasible option for the board and packaging paper industry, provided in-line treatment is applied. Concomitant energy conservation inside the mill results in process water temperatures of 50-60°C. Thermophilic anaerobic treatment complemented with appropriate post-treatment is considered as the most cost-effective solution to meet re-use criteria of the process water and to keep its temperature. In the proposed closed-cycle, the anaerobic treatment step removes the largest fraction of the biodegradable COD and eliminates “S” as H2S from the process stream, without the use of additional chemicals. The anaerobic step is regarded as the only possible location to bleed "S" from the process water cycle. In laboratory experiments, the effect of upward liquid velocity (Vupw) and the specific gas loading rate (Vgas) on the S removal capacity of thermophilic anaerobic bio-reactors was investigated. Acidifying, sulphate reducing sludge bed reactors were fed with partly acidified synthetic paper mill wastewater and were operated at 55°C and pH 6. The reactors were operated at organic loading rates up to 50 g COD.l−1.day−1 at COD/SO42- ratios of 10. The effect of Vupw was researched by comparing the performance of a UASB reactor operated at 1.0 m.h−1 and an EGSB reactor, operated at 6.8 m.h−1. The Vupw had a strong effect on the fermentation patterns. In the UASB reactor, acidification yielded H2, acetate and propionate, leading to an accumulation of reducing equivalents. These were partly disposed of by the production of n-butyrate and n-valerate from propionate. In the EGSB reactor net acetate consumption was observed as well as high volumetric gas (CO2 and CH4) production rates. The higher gas production rates in the EGSB reactor resulted in higher S-stripping efficiencies. The effect of Vgas was further researched by comparing 2 UASB reactors which were sparged with N2 gas at a specific gas loading rate of 30 m3.m−2.day−1. In contrast to the regular UASB reactors, the gas-supplied UASB showed a more stable performance when the organic loading rates were increased. Also, the H2S stripping efficiency was 3-4 times higher in the gas-supplied UASB, reaching values of 67%. Higher values were not obtained owing to the relatively poor sulphate reduction efficiencies.
Combined anaerobic/aerobic (UASB + UBAF) system for organic matter and nitrogen removal from a high strength industrial wastewater
Authors: Lacalle M. L. , Villaverde S. , Fdz-Polanco F. , García-Encina P. A.
Published: May 2018

The paper presents the experimental results collected from seven months of operation of a combined anaerobic/aerobic system treating an industrial effluent with averaged content of organic matter and nitrogen of 10.4 g COD /L and 790 mg NKT /L, respectively. The system was formed by an upflow anaerobic sludge blanket (UASB) and an upflow biological aerated filter (UBAF) connected in series, with a recycling line of the UBAF effluent into the UASB for its denitrification. The best results were obtained when operating the two reactors, UASB and UBAF, with hydraulic retention times (HRT) of 3.3 and 1.3 days, respectively, and a recycling ratio of 6.7. Under these conditions the system removed 98% of the organic matter and ammonia and 91% of the total nitrogen entering the system.

The activity of the different microorganisms was followed through activity assays consisting of measuring the consumption or production rate of any specific substrate or metabolism product. Thus when operating the system under the aforementioned conditions the reported values for the specific activity of methanogenic microorganims and denitrifiers coexisting in the UASB were 1.05 g COD/g VS d and 32.08 mg NO3−-N/g VS d, respectively. While the activity of ammonia and nitrite oxidisers within the UBAF were 47.65 and 4.36 mg O2 /g VS h, respectively.
Methanogenic activity measurements by the MAIA biosensor: instructions guide
Authors: Rozzi A. , Remigi E. , Buckley C.
Published: May 2018

The MAIA (Methanogenic Activity and Inhibition Analyser) is a titration (pH-stat) biosensor designed to determine the activity and inhibition related to acetoclastic methanogens. The main operational problems encountered in using this instrument are described.
The erosion of organic solids in combined sewers
Authors: Ahyerre M. , Oms C. , Chebbo G.
Published: May 2018

Many studies undertaken on urban catchments show, thanks to indirect approaches, that the contribution of eroded sewer sediments to pollution of combined sewer overflows is significant and highly organic. An in situ study of the erosion of sewer sediments has been implemented to validate those results with a direct approach and to observe the processes of erosion.

Two experiments have been carried out on a 150 m length of combined sewer in “Le Marais” catchment in Paris, in order to determine the rate of erosion and the nature of the particles eroded by an injection of drinking water in the sewer system. Hydraulic and quality parameters have been measured in situ.

Those injections have shown that the rate of erosion is important (maximum rate of 146 g/s) at each stage of the injection, which has been conducted in three stages with a maximum flow of 370 m3/h. The erosion does not only occur locally but happens along the entire length of the section even at low shear stresses (0.5 N/m2). The eroded particles are highly organic (VS=54–86%) and their loads in volatile solids, COD, BOD5 decrease as the flow increases.

So, this work confirms, by direct measurements, that eroded sewer sediments are a significant source of organic matter that contribute to combined sewer overflow.