bluuebunny/crossref_metadata_2025 huggingface dataset:
Model reduction through boundary relocation to facilitate real-time control optimisation in the integrated urban wastewater system
Authors: Meirlaen J. , Vanrolleghem P.A.
Published: May 2018

Real time control is one of the possibilities to minimise the impact of the integrated urban wastewater system (sewer system and treatment plant) on the receiving water quality. Integrated control uses information about the river state to act in the sewer system or in treatment plant. In order to test and tune these integrated controllers, a simplified integrated model is needed. Even with these simplified models, the simulation times may be too long and further model reduction is needed.

In this paper, dependency-structure based model reduction is proposed as a technique to further reduce model complexity. Three steps are proposed: relocation of the upstream system boundaries to just upstream of the first control point, relocation of the downstream boundaries to just downstream of the last measurement point, and third, a further model simplification based on an analysis of the sensitivity of the control actions on submodel elimination. The effect of applying the different reduction approaches on the control strategy and on the resulting river water quality is discussed on the basis of a case study of the catchment of Tielt.
Practical identification of the dissolved oxygen dynamic in activated sludge plants
Authors: Suescun J. , Ayesa E.
Published: May 2018

This paper presents the application to a full-scale waste water treatment plant (WWTP) of a practical methodology to identify the oxygen supply and consumption terms, which regulate the dynamic behaviour of the dissolved oxygen concentration (SO) in activated sludge reactors. This methodology is based on a periodic adjustment of the selected model for oxygen mass-transfer coefficient (KLa) and a continuous estimation of the oxygen uptake rate (rO), maintaining constant the adjusted KLa model, in order to uncouple the effects that the consumption and supply terms have on the SO concentration.

The adjustment phase of the KLa model is based on typified excitations of the system through the aeration system of the plant, which allow the estimation of KLa for different values of the aeration intensity parameter, for instance, air flow rate in air diffusion systems, revolution speed in surface aerators, etc. Once the KLa model is adjusted, it is possible to evaluate the KLa value in process conditions at any time. The continuous estimation of rO is carried out starting from the oxygen mass balance in the activatedsludge reactor.

This practical methodology has been successfully verified in the Badiolegi WWTP in Azpeitia (Spain), which biological process consists of a double stage AB process, with two different aeration systems: fine pore air diffusers in the A-stage and surface aerators in the B-stage.
Utilisation of energy from digester gas and sludge incineration at Hamburg's Köhlbrandhöft WWTP
Authors: Thierbach R.D. , Hanssen H.
Published: May 2018

At Hamburg's Köhlbrandhöft WWTP the demand for external energy supply is minimised by state of the art sludge treatment. The sludge is subjected to thickening, anaerobic digestion, dewatering, drying and incineration. The digester gas is used in a combined gas and steam turbine process. The sludge incineration also produces steam, which is also used in the steam turbine that follows the gas turbine. The turbines produce electricity, partially expanded steam is used for the sludge drying process. Heat from the condensation of vapours from sludge drying is used to heat the anaerobic digesters. The overall process requires no external heat or fuel and produces 60% of the WWTP's electricity demand.
Feasibility of automatic chemicals dosage control – a full-scale evaluation
Authors: Devisscher M. , Bogaert H. , Bixio D. , Van de Velde J. , Thoeye C.
Published: May 2018

This contribution discusses the feasibility of automatic control for chemicals dosing in activated sludge systems. The evaluation is made on the basis of a full-scale implementation at the Lommel WWTP (Belgium) of an on-line controlled dosage system for iron chloride and external carbon source. The control laws are very simple and allow intuitive adaptation by the plant operators. The control system results in a significant reduction of the chemicals dosage, better effluent results and a lower sludge production. The implementation is furthermore cost-efficient.
Remote control system for the operation of 65 WWTPs
Authors: Teichgräber B. , Arendt P. , Brockmann H. , Obenaus F.
Published: May 2018

The present report discusses the monitoring system for approximately 340 facilities for water management of the Emschergenossenschaft and Lippeverband. It is based on the operation control system of the wastewater treatment plants (currently 61) and the pumping stations of the Lippeverband, which has been created since 1985. For the near future, the integration of the plants of the Emschergenossenschaft including storm-water tanks is scheduled. The current connection ratios of the WWTPs which are to be monitored vary between 500 and 1,940,000 Population Equivalents. The data recorded at each plant are transmitted to the allocated catchment area centre and then to the district centres. The encompassing monitoring centre serves the integrated control of all plants. The comprehensive remote control is managed through the presentation of relevant plant-type-specific system parameters. The investment costs of approximatelyt 33,000 €/plant and annual costs of 9,400 €/plant stand against a considerable increase of the operation safety and the reduction of manpower.
On-line instrument confirmation: how can we check that our instruments are working?
Authors: Lumley D.
Published: May 2018

As on-line instrumentation becomes increasingly important for operating modern wastewater treatment plants it is necessary to have diagnostic methods that can indicate sensor deviation at an early stage. Examples of on-line diagnosis methods used at the Rya WWTP (Göteborg, Sweden) are presented. These include on-line mass balance calculations and soft sensors, which make indirect parameter estimates. By comparing the estimates with the corresponding on-line sensors it is possible to make control decisions and to chose alternative strategies. These comparative methods are often useful for process monitoring and diagnosis as well. Some other soft sensor applications using exponential filters are also presented.
A novel strategy for cyanobacterial bloom control by ultrasonic irradiation
Authors: Lee T.-J. , Nakano K. , Matsumura M.
Published: May 2018

The application of ultrasonic irradiation to control cyanobacterial blooms was evaluated in actual eutrophic lake water. Ten prototype units of the Ultrasonic Irradiation System (USIS) were installed in the 32 ha Lake Senba, and the water and sediment quality were monitored for 2 years. By incorporating the ultrasonication process with the on-going strategy, particularly flushing with induction water, cyanobacterial blooms can be controlled effectively. In addition, a significant improvement in the conditions of the lake in terms of chlorophyll-a, COD and T-P was attained. Moreover, the feasibility of ultrasonic irradiation and bacterial assisted control of cyanobacterial blooms was also evaluated in laboratory conditions. The destruction of gas vacuoles brought about by ultrasonic irradiation promoted close contact between cyanobacteria and their lysing Myxobacter leading to immediate and accelerated destruction of the cells.
Selective inspection planning with ageing forecast for sewer types
Authors: Baur R. , Herz R.
Published: May 2018

Investments in sewer rehabilitation must be based on inspection and evaluation of sewer conditions with respect to the severity of sewer damage and to environmental risks. This paper deals with the problems of forecasting the condition of sewers in a network from a small sample of inspected sewers. Transition functions from one into the next poorer condition class, which were empirically derived from this sample, are used to forecast the condition of sewers. By the same procedure, transition functions were subsequently calibrated for sub-samples of different types of sewers. With these transition functions, the most probable date of entering a critical condition class can be forecast from sewer characteristics, such as material, period of construction, location, use for waste and/or storm water, profile, diameter and gradient. Results are shown for the estimates about the actual condition of the Dresden sewer network and its deterioration in case of doing nothing about it. A procedure is proposed for scheduling the inspection dates for sewers which have not yet been inspected and for those which have been inspected before.
Sustainable development of water services industry
Authors: Magara Y.
Published: May 2018

The world population is expected to increase up to 8 billion by 2015. Most of the cities in the world are scattered around the fresh water resources. These cities and villages have their own interests and they constitute a power order. Therefore, we have been trying to harmonize these cities and villages in the usage of fresh water resources and the discharging of wastewater as well, by using an engineering means of water treatment. However, fresh water resources, which are essential to our lives, have a constant amount of circulation with a period of one week to ten days.

The science and technology of the water environment should recognize the limit of fresh water resources for the sustainable development of society, because the water service industries are the essential infrastructure of the community. In order to implement an appropriate risk management it is necessary to identify the goal of environmental management considering the social, natural and economical conditions. The energy-dependent technologies should be reconsidered to consume less energy and undertake more resource conservation engineering. Water science and technology cannot supply all the answers, therefore more comprehensive water management systems should be developed by other sectors, such as the food production industry.
Simultaneous removal of nitrogen and phosphorus with A2/O process using immobilized media
Authors: Goto M. , Kuribayashi S. , Nonaka Y. , Yamazaki M.
Published: May 2018

It is necessary to introduce nitrogen and phosphorus removal processes in the existing wastewater treatment plants of Fukuoka City to improve the water quality of Hakata Bay. An A2/O (anaerobic-anoxic-oxic) process using immobilized media is proposed here, as a high-end technology to meet stricter discharge standards when faced with treatment space limitations. In order to investigate the applicability of the process, a pilot-scale study using municipal wastewater was conducted. Fluidized immobilization media were added to the aerobic reactor to maintain a high concentration of nitrifying bacteria and nitrification rate. Relationships between nutrient removal performance and varied operating conditions were examined. The results of the pilot plant test indicated that the process performs well for removal of nitrogen and phosphorus. Under the condition of HRT = 8 hr, it was possible to obtain an effluent water quality as follows: T-N<8.0 mg/L; T-P<1.0 mg/L.

It was observed that reaction time needed for a complete nitrification was shortened by the addition of immobilized media to the aerobic reactor, and longer reaction time would be needed for a completed phosphorus uptake process other than complete nitrification in an aerobic tank. Therefore, the phosphorus uptake rate, as well as nitrification process, should be considered as one of the important factors affecting the design parameters of an aerobic reactor.
Anaerobic acidification of a synthetic wastewater in batch reactors at 55°C
Authors: Yu H.Q. , Fang H.H.P.
Published: May 2018

Experiments were conducted to study the acidogenesis of a dairy wastewater in batch reactors at pH 5.5 and 55°C. There was a biased fermentation sequence for carbohydrate and protein, and the protein fermentation was delayed by carbohydrate. The production of hydrogen was exclusively from the fermentation of carbohydrate. Acetate and butyrate concentrations both increased rapidly at the beginning and peaked at some points, then declined in the reactors fed with 8 g-COD (chemical oxygen demand)/l, or higher concentrations. Butanol and propanol fractions increased with the substrate concentration. The metabolism shifted from the volatile fatty acid-producing pathways to the alcohol-producing pathways when the substrate concentration increased beyond 8 g-COD/l. The acidogenic biomass yield was in the range 0.19-0.25 mg-VSS/mg-COD.
The influence of artificial cutoff on a monitoring system and the water quality of the Keelung River
Authors: Lo S.L. , Kuo J.T. , Wang S.M.
Published: May 2018

The purpose of this study was to design a water quality monitoring network for the Keelung River in order to evaluate the effects of artificial cutoff across two bend channels. A steady-state water quality model was used to simulate the BOD and DO curves. The Kriging theory was applied to select the optimal locations for a water quality monitoring network. The sampling frequency was determined by the coefficients of variation of water quality and by considering the significance level and confidence interval. After calibration and verification of the water quality model, the model was applied and the simulation results indicated that the values of DO in the new channel would be higher than those of the old channel reaches. The critical point of the oxygen sag curve would shift to the mouth of river under Q75 low-flow conditions, and the BOD values in the new channel would also slightly increase. The results further indicated that more monitoring stations would be needed in the downstream reaches.
Continuous monitoring for Cryptosporidium - a novel approach to public health protection
Authors: Lloyd A. , Drury D.
Published: May 2018

Regulations requiring water utilities in England and Wales to carry out continuous monitoring for Cryptosporidium in treated water were introduced in June 1999. The rationale of the Regulations and the technical basis for the sampling and analysis are reviewed. The results of the first nine months of monitoring are summarised and compared with other equivalent data sets. The impact of the Regulations on water utilities operational practices and the implications for public health protection are discussed.
Monitoring of shallow sea environment by using snapping shrimps
Authors: Watanabe M. , Sekine M. , Hamada E. , Ukita M. , Imai T.
Published: May 2018

We examine the validity of pulse count of snapping shrimps for sea environmental monitoring. Snapping shrimps, which make a peculiar pulse sound, are found everywhere in the world. Pulse count can be achieved merely by recording their sounds for a few minutes by using a hydrophone without special biological knowledge. From field surveys and laboratory experiments, we found that the pulse count depends on water temperature when sea environment is normal, and it falls due to the occurrence of oxygen-deficient water. The results show that this method can be a useful index of the effect of water pollution on benthic animals in fixed-point observation.
Mass balance of a wastewater loaded canal system: case study of Bangkok
Authors: Banjongproo P. , Wett B.
Published: May 2018

A dynamic water quality model was applied in order to investigate self-purification processes in highly loaded canals in the centre of Bangkok, capital city of Thailand. Oxygen production by aquatic plants induces a significant diurnal variation of the dissolved oxygen concentration. The corresponding profiles of heterotrophic growth and BOD5 concentration demonstrate the limiting impact of oxygen shortage during night time. Both self-purification mechanisms - biological degradation and settling - are considered and water-sediment interactions are calculated. Simulation results and measurement data are summarized by mass balance schemes which offer a telling characterization of the complex system.
Study on generation of oxygen-depleted water based on stochastically-changing solar radiation intensity
Authors: Fujita K. , Hasemi H. , Tanaka K. , Lee I.-C. , Kusuda T.
Published: May 2018

To examine the generation probability of oxygen-depleted sea water in Hakata Bay, possible 20 time-series of different hourly-solar-radiation intensities were generated stochastically, and a numerical simulation on dissolved oxygen was carried out for each time series. The results of the model calibration followed the seasonal variation of observed water quality well, and generated cumulative-frequency-distribution curves of daily solar radiation agreed well with the observed ones. The simulation results indicated that the exchange of sea water would have a great influence on the DO concentration, and that the concentration could change more than 1 mg/L in a day. This prediction method seems to be an effective way to examine a solution to minimize fishery damages when DO is depleted.
Japanese experiences of environmental management
Authors: Matsuo T.
Published: May 2018

Japan experienced a very rapid industrialization and economic growth in the era of income doubling in 1960s and at the same time Japan experienced very severe damage from various types of environmental pollution. In this paper, historical development of population, GNP, energy consumption with classification of petroleum, coal and electric power, and CO2 emission are introduced as basic background data on Japanese development. The tragic experience of Minamata disease and Itai-itai disease caused by methyl mercury and cadmium, respectively, are introduced. In two tables, historical development of water pollution and air pollution are summarized. Regarding solid wastes management, the total mass balance in Japan and recent development in legislation framework for enhancement of recycling of wastes are introduced briefly.
Integrated centralized utility services to a chemical complex on Jurong Island, Singapore
Authors: Yan Y.G. , Wong P.C.Y. , Tan C.G. , Tang K.F.
Published: May 2018

SUT pioneered centralized utility services for the chemical industry on Jurong Island, which are cost-effective due to economies of scale, reliable due to inter-connection of satellite operations, and customer tailored for special requirements. The utility services range from the supply of steam and water, wastewater treatment, incineration, terminalling, service corridor to fire fighting. Among the services, water management achieves the complete cycle from wastewater treatment to effluent recycling.
Nitrogen removal using a vertically moving biofilm system
Authors: Rodgers M. , Burke D.
Published: May 2018

The aim of this laboratory study was to establish the efficacy of a new experimental biofilm system for the removal of nitrogen from synthetic wastewater. The system consisted of six reactors in series: one anaerobic, one anoxic and four aerobic reactors. In both the anaerobic and anoxic reactors, a plastic cuboid module was repeatedly moved up and down in the wastewater, while being totally submerged at all times. In each of the aerobic reactors, an identical module to that used in the anaerobic and anoxic reactors was intermittently and repeatedly immersed in and lifted out of the wastewater. All the individual reactors had a bulk fluid volume of 28.2 litres and the average temperature of the wastewater was about 10°C. Each module consisted of crossflow corrugated plastic sheets with a surface area of 1.824 m2. The nitrate recycle flow from the fourth aerobic tank to the anoxic tank was twice the inflow to that tank. In the anoxic reactor, filtered COD was removed at an average rate of 2.22 kg COD/m3.d and nitrate-nitrogen was denitrified at a rate of 0.42 kg NO3-N/m3.d. The average nitrification rate in the second aerobic reactor was 0.12 kg NH4-N/m3.d. The new biofilm system was simple to construct and operate.
Adsorption of heavy metals from water using banana and orange peels
Authors: Annadurai G. , Juang R.S. , Lee D.J.
Published: May 2018

Liquid-phase adsorption removal of Cu2+, Co2+, Ni2+, Zn2+, and Pb2+ in the concentration range of 5-25 mg/L using low-cost banana and orange peel wastes was examined at 30 oC. Under comparable conditions, the amount of adsorption decreased in the order Pb2+ > Ni2+ > Zn2+ > Cu2+ > Co2+ for both adsorbents. The adsorption isotherms could be better described by the Freundlich equation. The amount of adsorption increased with increasing pH and reached a plateau at pH > 7, which was confirmed by the variations of zeta potentials. The application potential of such cellulose-based wastes for metal removal (up to 7.97 mg Pb2+ per gram of banana peel at pH 5.5) at trace levels appeared to be promising.
Photocatalytic oxidation technology for humic acid removal using a nano-structured TiO2/Fe2O3 catalyst
Authors: Qiao S. , Sun D.D. , Tay J.H. , Easton C.
Published: May 2018

A novel TiO2 coated haematite photocatalyst was prepared and used for removal of colored humic acids from wastewater in an UV bubble photocatalytic reactor. XRD analysis confirmed that nano-size anatase crystals of TiO2 were formed after calcination at 480°C. SEM results revealed that nano-size particles of TiO2 were uniformly coated on the surface of Fe2O3 to form a bulk of nano-structured photocatalyst Fe2O3/TiO2. The porous catalyst had a BET surface area of 168 m2/g. Both the color and total organic carbon (TOC) conversion versus the residence time were measured at various conditions. The effects of pH value, catalyst loaded, initial humic acid concentration and reaction temperature on conversion were monitored. The experimental results proved that the photocatalytic oxidation process was not temperature sensitive and the optimum catalyst loading was found to be 0.4 g/l. Degradation and decolorization of humic acids have higher efficiency in acidic medium and at low initial humic acid concentration. The new catalyst was effective in removing TOC at 61.58% and color400 at 93.25% at 180 minutes illumination time and for 20 mg/l neutral humic acid aqueous solution. The kinetic analysis showed that the rate of photocatalytic degradation of humic acids obeyed the first order reaction kinetics.
A culture-independent approach for studying microbial diversity in aerobic granules
Authors: Yi S. , Tay J.-H. , Maszenan A.M. , Tay S.T.-L.
Published: May 2018

This study reports the use of ribosomal-based molecular techniques to study the microbial diversity in aerobic granules. Aerobic granules at different growth stages (young, mature and old) were obtained from a laboratory scale sequential aerobic sludge blanket (SASB) bioreactor fed with glucose as the main source of carbon and energy. Deoxyribonucleic acid (DNA) was extracted from the young, mature and old granules. The polymerase chain reaction (PCR) was used to amplify the Eubacterial 16S ribosomal DNA (rDNA) and three clone libraries were constructed, corresponding to each of the three growth stages. The microbial diversity in each clone library was assessed by amplified ribosomal DNA restriction analysis (ARDRA). The results reveal that there was considerable diversity in each clone library and there were variations in microbial diversity among the three different clone libraries. This suggests a shift in the composition of the microbial communities. Microorganisms associated with 5 restriction fragment length polymorphism (RFLP) types (A, B, C, D and E) appear to play an important role in the development of aerobic granules.
Pond treatment and effluent reuse of sewage from an oil production site in an arid coastal environment
Authors: Smith E. , Hegazy S. , El-Aassar N.
Published: May 2018

A pond system consisting of two lines each of an anaerobic followed by facultative and maturation ponds is used to treat site sewage from oil and gas production operations in an arid coastal environment. The performance of the pond system was evaluated together with the suitability of treated effluent for reuse in local irrigation. Effluent from the pond system by-and-large satisfies criteria for irrigation of non-food crop plants with respect to chemical parameters. The primary problem is coliform bacteria levels which are an order of magnitude higher than preferred values. First-order decay rate constants for each pond were calculated from a mass balance model that assumes complete mixing and incorporates the considerable evaporation that occurs in this setting. While the anaerobic ponds of both lines exhibit suitable performance, rate calculations indicate that the facultative and maturation ponds of the East Line are performing better than the West. A tracer study of the facultative and maturation ponds indicates that some short-circuiting is occurring in the West Line. A field experiment of coliform transport in irrigated soil gives indications of short- and long-term risks associated with reuse of the effluent.
Use of image analysis to determine algal and bacterial biomass in a high rate algal pond following Percoll® fractionation
Authors: Cromar N.J. , Fallowfield H.J.
Published: May 2018

This paper reports the results of work to allow a more accurate enumeration, and gravimetric determination, of the relative proportions of algae and bacteria within the floccular matrix present in a High Rate Algal Pond (HRAP). Methodology involving a combination of physical and chemical treatments was used and the resulting material was separated using density gradient centrifugation. The “fractions” were analysed using microscopical image analysis. Each “fraction” was categorised as containing bacteria only, algae only or an association of bacteria and algae, the relative proportions of which were then determined by image analysis to enable a “true” gravimetric determination of the algal and bacterial components of HRAP biomass for the first time. The biomass from HRAPs operated both outdoors and in a glasshouse was examined over complete operational seasons to investigate environmental effects as well as possible effects of variation in COD loading rate and retention time on cell biovolumes and cell quotients.

In this study, the accurate assessment of both algal and bacterial biomass, determined as cell volume or dry matter, in addition to measurement of carbon and nitrogen has enabled the calculation of cell quotients. This allows a direct comparison between these values obtained from a nutrient-rich system and those published values obtained from systems with various nutrient status. Conversion factors obtained may also be of value for deriving inputs for computer models for the design and operation of high rate algal ponds.
Parasite removal by natural wastewater treatment systems: performance of waste stabilisation ponds and constructed wetlands
Authors: Stott R. , May E. , Mara D.D.
Published: May 2018

Parasite removal and low cost systems for wastewater treatment have become increasingly important requirements in developed and developing countries to safeguard public health from wastewater-associated intestinal diseases. Pilot and field-scale ponds and wetlands in Brazil and Egypt have been investigated for the fate and removal of eggs of human intestinal parasites from domestic wastewater. In northeast Brazil, parasite removal was investigated for a series of five waste stabilisation ponds treating raw wastewater. In Egypt, parasite removal was studied for Gravel Bed Hydroponic constructed wetlands treating partially treated wastewater. Influents to ponds and wetlands contained a variety of parasite helminth eggs (e.g. Ascaris, hookworm, Trichuris, and Hymenolepis spp.). The ponds consistently removed parasite eggs though rate of removal by individual ponds may have been related to influent egg numbers and extent of short-circuiting. Parasite eggs were reduced on average by 94% and 99.9% in the anaerobic and facultative ponds respectively. No eggs were found in effluent from the second maturation pond. In the wetland system, parasite removal varied with reedbed length. The majority of parasite eggs were retained within the first 25 m. Parasite eggs were reduced on average by 98% after treatment in 50 m beds and completely removed after treatment in 100 m beds.
Evaluation and modelling of helminth eggs removal in baffled and unbaffled ponds treating anaerobic effluent
Authors: von Sperling M. , Chernicharo C.A.L. , Soares A.M.E. , Zerbini A.M.
Published: May 2018

The paper evaluates and models helminth eggs removal in a combined UASB (Upflow Anaerobic Sludge Blanket) reactor - maturation pond system (one baffled and one unbaffled pond in parallel). The system is comprised of demonstration-scale units, treating actual domestic sewage from Itabira city, Brazil. The paper addresses the following points: (i) removal of helminth eggs from the wastewater in the system; (ii) comparison of the observed removal efficiency with the predictions using the Ayres et al. model; (iii) accumulation of helminth eggs in the sludge; (iv) viability of eggs in the sludge; (v) distribution of helminth species in the sludge. The removal efficiency of helminth eggs from the wastewater in both ponds was 100% for most of the time (0 counts in the final effluent). The predictions of helminth eggs removal according to the Ayres et al. model can be considered reasonable. After one year of operation, 88% of the eggs in the sludge remained viable. Helminth eggs counts in the sludge tended to decrease along the baffled pond length (from first to last compartment). The prevailing helminth species found in the sludge from both ponds was Ascaris lumbricoides.
Microelectrode array sensor for water quality monitoring
Authors: Gobet J. , Rychen Ph. , Cardot F. , Santoli E.
Published: May 2018

A versatile microelectrode array sensor for water quality monitoring has been developed. The array fabrication, based on batch microelectronic processes, results in a highly stable passivation of the silicon chip surface and provides the possibility to use a backside contact. Packaging was optimized for on-line water operation at high pressures. Examples of applications include chlorine monitoring in drinking water, ozone monitoring in deionized water, dissolved oxygen in activated sludge and preliminary measurements of trace arsenic.
Nutrient removal from piggery effluent using vertical flow constructed wetlands in southern Brazil
Authors: Sezerino P.H. , Reginatto V. , Santos M.A. , Kayser K. , Kunst S. , Philippi L.S. , Soares H.M.
Published: May 2018

Santa Catarina State, southern Brazil, has the greatest swine breeding activities of Latin America. Generally, the piggery wastewater is treated in pond systems that are able to remove organic material according to local environmental legislation. However, these systems do not remove nitrogen and phosphorus efficiently. This work deals with a post-treatment system, using vertical flow constructed wetlands. The experiment was conducted in a swine production farm which has 45,000 animals. Although the pond system was able to partially remove the content of nutrients, their concentration in the effluent was high for environmental disposal. A four-bed vertical flow constructed wetland pilot plant, using Typha spp., was built. The pilot plant operated for 280 days for beds 2-4 (sand 2). However, the experiments with beds 1-3 (sand 1) were stopped after 111 days of operation, when a reduction in the wastewater drainage was observed. The beds with sand 2 showed a 33% COD removal, and about 49% of nitrification was observed from 111 days until the end of the operation. PO4-P removal was 45% with a loading rate of around 1.36 g m-2 d-1.
Investigation of pond velocities using dye and small drogues: a case study of the Nelson City waste stabilisation pond
Authors: Barter P.J.
Published: May 2018

The city of Nelson, New Zealand, has a 27 hectare oxidation pond as its primary wastewater treatment facility. Recent changes in the configuration of the pond and installation of a mixer/aerator raised concerns that pond treatment rates and effluent quality may be affected by high internal pond velocities and short retention times.

This paper presents the findings of an investigation into wastewater velocity and movement within the pond using qualitative dye dispersion and tracking of small-scale “holey-sock” drogues. Simultaneous deployment of drogues and dye allowed methods to be compared, since small-scale drogues have not commonly been used in wastewater ponds. Dye dispersion was assessed using low-level aerial photography from a tethered helium blimp to track short term movement and mixing, while a datalogger and fluorometer were used to measure pond retention time. Drogue movement was tracked in conjunction with the dye study from a small boat using hand-held GPS.

The dye study found that: (i) the first portion of pond influent discharged from the pond after 37.5 hours, substantially quicker than the theoretical pond retention time of 27 days. However, the measured retention time was with a mixer in place and the theoretical time was without a mixer; (ii) the position of the paddle wheel mixer/aerator was not optimally placed for mixing the influent and a quiescent region existed adjacent to the influent point; and (iii) the low-level aerial photography was an effective method of evaluating larger pond systems.

The “holey-sock” drogue studies showed that: (i) the drogues accurately followed the movement and velocity of dyed influent within the pond; (ii) wastewater velocity and movement was dominated by the paddle wheel mixer/aerator; and (iii) wind direction had a minor influence on wastewater velocity and movement in areas not directly affected by the paddle wheel mixer/aerator.

The study demonstrated that the combined use of dye and drogues was a relatively low-cost and effective means of determining internal pond velocities and movement. Future studies using similar methods will be useful in helping validate computer-modelled movement and velocity.
Multivariate on-line monitoring: challenges and solutions for modern wastewater treatment operation
Authors: Rosen C. , Röttorp J. , Jeppsson U.
Published: May 2018

In this paper, a number of challenges, which need to be overcome if multivariate monitoring of wastewater treatment operation is to be successful, are presented. For each challenge, one or several solutions are discussed. The methodologies are illustrated using an example from full-scale wastewater treatment operation. Some guidelines regarding choices of methods and implementation aspects are given.
On-line measurement data of wastewater systems via WAP mobile phones
Authors: Alex J. , Jumar U. , Schütze M.
Published: May 2018

In order to support the operation of wastewater systems a system was developed which allows us to access plant data by standard mobile devices such as WAP mobile phones. This system is suited to complement the standard application of alarm and message systems based for example on SMS or pager services. This technology provides useful options for mobile remote monitoring and remote control of automated plants. This technology is particularly appropriate for the use in remote facilities where no staff is available. The technology has been implemented succesfully and shows how standard IT and Internet technologies can be utilised to support the operation of spatially distributed plants with reasonable effort. Two implementations are presented which access plant data via WAP mobile phones and via mobile pocket PCs. First application experiences are presented.
A fatal waterborne disease epidemic in Walkerton, Ontario: comparison with other waterborne outbreaks in the developed world
Authors: Hrudey S.E. , Payment P. , Huck P.M. , Gillham R.W. , Hrudey E.J.
Published: May 2018

An estimated 2,300 people became seriously ill and seven died from exposure to microbially contaminated drinking water in the town of Walkerton, Ontario, Canada in May 2000. The severity of this drinking water disaster resulted in the Government of Ontario calling a public inquiry by Mr. Justice Dennis O’Connor to address the cause of the outbreak, the role (if any) of government policies in contributing to this outbreak and, ultimately, the implications of this experience on the safety of drinking water across the Province of Ontario. The circumstances surrounding the Walkerton tragedy are an important reference source for those concerned with providing safe drinking water. Although some circumstances are obviously specific to this epidemic, others are uncomfortably reminiscent of waterborne outbreaks that have occurred elsewhere. These recurring themes suggested the need for attention to broad issues of drinking water security and they present the challenge for how drinking water safety can be managed to prevent such tragedies in the future.
Temperature effect on UASB reactor operation for domestic wastewater treatment in temperate climate regions
Authors: Lew B. , Belavski M. , Admon S. , Tarre S. , Green M.
Published: May 2018

The performance of an upflow anaerobic sludge blanket (UASB) reactor was investigated for the treatment of domestic wastewater at different operational temperatures (28, 20, 14 and 10°C) and loading rates. For each temperature studied a constant CODt removal was observed as long as the upflow velocity was lower than 0.35 m/h: 82% at 28°C, 68% at 14°C and 44% at 10°C. At 20°C the COD removal increased with the HRT, reaching similar values as at 28°C for long HRT. At upflow velocities higher than 0.35 m/h, a reduction in total COD removal was observed due to washout of influent TSS. At 28°C, a constant 200 g sludge mass was observed and COD removal was attributed to biological degradation only. At lower temperatures, COD removal resulted from degradation and solids accumulation in the reactor. The increase in reactor sludge was greater as the temperature decreased and explains the similar overall COD removal efficiency at 28°C, 20°C and 14°C. During the transition from winter to summer conditions (10°C to 28°C), methane production initially increased due to the degradation of accumulated solids. Afterwards, methane production gradually declined and an increase in COD removal was observed, indicating that the TSS accumulated during the winter was exhausted and influent degradation remained.
Pollution reduction at wastewater treatment facilities through thermophilic sludge digestion
Authors: Zhou J. , Mavinic D.S.
Published: May 2018

Wastewater treatment facilities produce large amounts of sludge, which is a pollutant to the environment if not properly managed. Among the three most common methods (landfills, land application, incineration) of sludge disposal, thermophilic digestion to produce Class-A biosolids for land application is recognized as the most cost-effective, environmentally sustainable option. Full-scale experience revealed that thermophilically digested biosolids consumed a higher dosage of chemicals for conditioning and dewatering than conventionally (mesophilically) digested biosolids. This paper presents findings of a recent study to investigate how major operational parameters affect dewatering properties of thermophilically digested biosolids, and to search for the inter-relationship between digestion, characteristics of digested biosolids, and dewatering properties of thermophilic biosolids. Experimental work was carried out using bench-scale aerobic digesters. This study found that feed sludge composition has a significant effect on dewaterability. A higher content of secondary sludge resulted in poorer dewaterability in undigested and digested sludge. Dewatering properties are sensitive to a temperature effect. Such an effect is physical-chemical in nature. Excessive high shear results in significant deterioration in dewaterability. Thermophilic digestion resulted in a substantial increase in ammonia and phosphate concentrations, but these two factors seem to not have much impact on dewaterability. Instead, cellular biopolymers have a significant role in affecting dewatering properties of thermophilically digested biosolids.
Sulfidogenic volatile fatty acid degradation in a baffled reactor
Authors: Vallero M.V.G. , Lens P.N.L. , Bakker C. , Lettinga G.
Published: May 2018

The effect of staging the sludge bed on volatile fatty acid degradation by sulfidogenic reactors was evaluated in a baffled reactor. In a 5.4 l baffled reactor, containing three equal compartments, a volatile fatty acid (VFA) mixture (acetate:propionate:butyrate ratio 1:2:2 on COD basis; pH 8) was treated under mesophilic (30°C) and sulfidogenic (COD:SO42- ratio: 0.5) conditions for 38 days. At a specific sludge loading rate of 0.50 g COD.gVSS-1.d-1, a COD and sulfate removal of 85% and 30%, respectively, was obtained. In the baffled reactor, staging of the sulfidogenic VFA degradation occurred. Propionate and butyrate were mainly degraded in the first compartment. Their degradation was incomplete, resulting in elevated acetate concentrations in compartment I. In the second and third compartment of the baffled reactor, a net degradation of acetate took place. Acetate was the sole substrate present in compartment III and residual acetate concentrations of about 200 mg/l were present in the effluent at a specific sludge loading of 0.50 g COD.gVSS-1.d-1. Sludges with different maximum specific VFA and acetate degrading activities developed in the first and second compartment. These maximal specific activities were almost equal for sludge present in compartment II and III.
Assessing UV reactor performance for treatment of finished water
Authors: Bukhari Z. , LeChevallier M.
Published: May 2018

Recently, use of low levels of medium- and low-pressure ultraviolet light for successful inactivation of Cryptosporidium parvum oocysts has generated tremendous excitement in the water industry. Accurate delivery of the target dose, lamp performance, sensor stability and impact of water characteristics are some factors that could impact disinfection efficacy, in turn influencing decisions on application of this technology. To this end, American Water Systems, the largest investor owned water utility in the US, has responded to some of these challenges by ascertaining the long-term feasibility of applying UV for treatment of finished water. A 4 × 1 UV reactor with a 12 inch (0.3 m) diameter was installed after granular activated carbon filtration and was operated with a finished water flow rate of 600 gpm (2,700 L/min). Over a 12-month period, various chemical (THM, HAA, UV254, DOC, TOC, metals, nitrate, nitrites) and physical measurements (lamp voltage, current, sensor measurements) were monitored to define their impact (if any) on the operation of the reactor. MS2 bacteriophage challenge studies were conducted with various lamp configurations and lamp age. These inactivation data demonstrated high levels of correlation with controlled bench scale inactivation data. For C. parvum oocysts, bench scale studies were performed with a modified in vitro infectivity assay using HCT-8 cells, an enhanced infectivity protocol and with either immunofluorescence or quantitative PCR based detection. While both assays indicated increasing infections levels of HCT-8 cells with increasing oocyst inocula, UV treatment of oocysts produced markedly different infectivity responses. Based on the data generated in this study, one in vitro infectivity assay was selected to demonstrate >3 logs inactivation with low UV doses (5 mJ/cm2 -10 mJ/cm2).
Artificial neural network modelling: a summary of successful applications relative to microbial water quality
Authors: Brion G.M. , Lingireddy S.
Published: May 2018

Artificial neural networks (ANN) are modelling tools that can be of great utility in studies of microbial water quality. The ability of ANNs to work with complex, inter-related multiparameter databases and provide superior predictive power in non-linear relationships suits their application to microbial water quality studies. To date ANNs have been successfully applied (a) for the prediction of peak microbial concentrations, (b) to sort land use associated faecal pollution sources and relative ages of runoff and (c) towards the selection and study of surrogate parameters. Predictions of peak microbial contamination or faecal pollution sources have been greater than 90% accurate. The importance of a subgroup of organisms that are isolated by the total coliform membrane filter test on m-Endo media in defining faecal sources was revealed through parameter selection exercises. The result is the definition of a new bacterial ratio that can be directly related to the age of faecal contamination in animal impacted runoff.
Comparison of the biodegradability of the grey fraction of municipal solid waste of Barcelona in mesophilic and thermophilic conditions
Authors: Mace S. , Bolzonella D. , Cecchi F. , Mata-Alvarez J.
Published: May 2018

The results of the start-up of two digesters in mesophilic and thermophilic conditions, together with its steady results at several organic loading rates are described. A kinetic study is also carried out which allows one to estimate the ultimate methane production, together with the first-order kinetic constant. Operation at thermophilic temperature yields better results as it allows a more loaded reactor and the methane production is slightly higher.
Sewer sediment management: some historical aspects of egg-shaped sewers and flushing tanks
Authors: Bertrand-Krajewski J.-L.
Published: May 2018

This paper presents a historical review of some concepts and techniques used to manage sewer sediments and to cleanse sewers. Two aspects are illustrated: i) the use of egg-shaped and similar types of sewers in order to ensure self-cleansing velocities even during low flow periods, and ii) the use of flushing tanks to scour deposited sediments and keep sewers free of deposits. After a brief survey of antecedent periods, the paper focuses on the evolution since the middle of the 19th century. Mainly based on French and English complementary examples, because both countries were leaders in the development of urban drainage in the period 1840-1880, the paper also provides information from Germany and the USA and shows that some aspects remained rather unchanged during 150 years while other have been completely revised during the same period.
Phthalic acid esters found in municipal organic waste: enhanced anaerobic degradation under hyper-thermophilic conditions
Authors: Hartmann H. , Ahring B.K.
Published: May 2018

Contamination of the organic fraction of municipal solid waste (OFMSW) with xenobiotic compounds and their fate during anaerobic digestion was investigated. The phthalic acid ester di-(2-ethylhexyl)phthalate (DEHP) was identified as the main contaminant in OFMSW in concentrations more than half of the threshold value for the use as fertilizer on agricultural soil in Denmark. Analysis of DEHP in samples before and after large-scale anaerobic digesters revealed higher concentrations of DEHP per kg dry matter in the effluent than in the influent. The concentration of DEHP and DBP (dibutylphthalate) in OFMSW was monitored in the influent and effluent of anaerobic thermophilic (55°C) and hyper-thermophilic (68°C) laboratory-scale reactor systems. In the thermophilic reactors with a hydraulic retention time (HRT) of 15 days 38-70% of DBP was removed, but no consistent removal of DEHP was observed. However, after treatment of the effluent from the thermophilic reactor in a hyper-thermophilic digester (HRT: 5 days) 34-53% of the DEHP content was removed and the DBP removal was increased to further 62-74%. Removal rates (kh) of DEHP and DBP were found to be 0.11-0.32 d-1 and 0.41-0.79 d-1, which is much higher than in previous investigations. It can be concluded that the higher removal rates are due to the higher temperature and higher initial concentrations per kg dry matter. These results suggest that the limiting factor for DEHP degradation is the bioavailability, which is enhanced at higher temperature and higher degradation of solid organic matter, to which the highly hydrophobic DEHP is adsorbed. The investigated reactor configuration with a thermophilic and a hyper-thermophilic treatment is, therefore, a good option for combining high rate degradation of organic matter with high biogas yields and efficient reduction of the phthalic acid ester contamination.