bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the wastewater treatment plant of Rome airport
Authors: Gabrieli R. , Divizia M. , Donia D. , Ruscio V. , Bonadonna L. , Diotallevi C. , Villa L. , Manzone G. , Pana` A.
Published: May 2018

The wastewater plant of Rome airport, which receives all the sewage from the airport as well as the cess from aeroplanes, was analysed for microbiological parameters. From the bacteriological point of view, in the water and sludge samples the densities of the faecal indicator of pollution and the presence of Salmonella spp and Vibrio cholerae as bacteriological pathogens were determined. At the same time, samples were analysed for the presence of enteric viruses and phages. Overall, the mean reduction of the faecal coliforms was 96%, E. coli 92% and faecal streptococci 99%. Salmonella spp was identified in all but one of the final effluents and V. cholerae in 2/10. Enteric viruses were identified in all but one of the raw waters and in three samples of final effluent. Bacteriophages (somatic coliphage, F-plus phage and B40-8), were found in all the samples but irregularly. Phages and enteric viruses were also found in the prefilter membranes used for prefiltering the raw water samples.
Survival of legionella pneumophila and salmonella typhimurium in biofilm systems
Authors: Armon R. , Starosvetzky J. , Arbel T. , Green M.
Published: May 2018

Biofilms are found in many water supply systems where they form an environment in which different bacteria can be entrapped for long periods. Besides the aesthetic aspect, biofilm has a major contribution in biocorrosion, disinfection inefficiency and possibly may act as a reservoir for pathogenic and non-pathogenic microorganisms. In the present study, two pathogenic bacteria Legionella pneumophila and Salmonella typhimurium WG-49 were introduced into a biofilm simulation flow system supplied with sterile and non-sterile tap water. The survival of these microorganisms into the biofilm formed on glass and PVC coupons at two temperatures (24°C and 36°C) was compared in this system. On glass supports, under sterile conditions at 36°C, Legionella pneumophila sg3 decreased by 6 logs during 40d continuous recirculation. Under non-sterile conditions, L. pneumophila decreased by only half log <48d. S. typhimurium WG-49 under the same conditions showed an increase of 3 logs in the sterile system for 31d, while in the non-sterile system it dropped by only 0.5 log for 20d. At 24°C, L. pneumophila remained stable for >40d under sterile conditions. In non-sterile conditions, L. pneumophila dropped by 1 log for 35d. S. typhimurium, in a sterile system, remained almost unchanged, while in the non-sterile system an increase of 3 logs was observed for the first 21d and thereafter a decrease of 2 logs for the next 21d of the experiment. L. pneumophila on PVC coupons at 36°C survived better compared with glass support. The experimental data show that survival of pathogenic microorganisms into biofilm is variable and depends on many factors, making the survival prediction a difficult task. However, the survival results of L. pneumophila and S. typhimurium in time terms should raise important questions on their potential threat in water distribution systems.
Unique cultural methods used to detect viable cryptosporidium parvum oocysts in environmental samples
Authors: Slifko T. R. , Friedman D. E. , Rose J. B. , Upton S. J. , Jakubowski W.
Published: May 2018

Cryptosporidium parvum is an infectious enteric protozoan parasite that causes waterborne disease, severe gastroenteritis and is associated with high mortality in immunocompromised individuals. Detection of oocysts in water is very difficult and current methodologies do not determine viability. This project has focused on low level detection of Cryptosporidium parvum in environmental samples using a unique cultural method. Previously, cell culture methods have been used to assess the developmental stages of Cryptosporidium; however, no cultural methods have been employed with environmental samples. The percentage of viable oocysts can be estimated by detecting intracellular developmental stages of the parasite using fluorescently labelled antibodies. Other methods are not capable of low level detection or high sensitivity. We are evaluating detection of single foci of infection, indicating that one of the four sporozoites released from the viable oocyst has infected a single cell.
The status of UK methods for the detection of cryptosporidium spp oocysts and giardia spp cysts in water concentrates
Authors: Smith H. V. , Hayes C. R.
Published: May 2018

Current UK methods for the isolation and enumeration of Cryptosporidium spp oocysts and Giardia spp cysts in water concentrates are time-consuming and inefficient, providing minimal information regarding the biology of the organism. Minimising the portion of sample concentrate examined can reduce the level of confidence in the result obtained and this issue requires appreciation by the water regulators. Alternative methods for isolation and enumeration require corroboration with the established method using a variety of water types. Developments that increase information regarding the biology of these organisms should be encouraged. Not only does method performance (recovery efficiency, reproducibility etc), but also method significance (integrity of health, operational and regulatory assessments etc) require to be addressed. For Cryptosporidium the fluorogenic viability assay can not only assist in the decisions taken by health officials when oocysts are found in water supplies but also in designing catchment assessment and sampling policies for individual treatment plants, yet few laboratories are experienced in this assay.
Evaluation of drinking water treatment plant efficiency in microorganism removal by the coliphage, total coliform and H2S paper strip tests
Authors: Martins M. T. , Castillo G. , Dutka B. J.
Published: May 2018

Two potable water quality monitoring tests, the H2S paper strip test and coliphage test, were evaluated on Chilean raw potable source waters and drinking waters that had received conventional treatment to render them safe for drinking. Based on 108 samples in this study, it was found that the H2S paper strip provided consumers with equivalent to, or greater protection than, the total coliform MPN test. In treated water, a highly significant relationship (P =<0.0001) between total coliforms and H2S paper strip tests was observed. Significant relationships were also observed between total coliforms/coliphage and residual chlorine/H2S paper strip test. These studies provide evidence that the H2S paper strip test and the coliphage test are viable indicators of potable water quality and water treatment in two medium-sized cities in Chile.
Rapid PCR-based monitoring of infectious enteroviruses in drinking water
Authors: Reynolds K. S. , Gerba C. P. , Pepper I. L.
Published: May 2018

Currently, the standard method for the detection of enteroviruses and hepatitis A virus in water involves cell culture assay which is expensive and time consuming. Direct RT-PCR offers a rapid and sensitive alternative to virus detection but sensitivity is often reduced by PCR inhibitory substances and the requirement for small reaction volumes. Rapid methods for detection of infectious enteroviruses in PCR inhibitory environmental samples are being developed utilising an integrated cell culture/PCR approach (ICC/PCR). With this approach, 300–4001 of water were concentrated using charged filters followed by a modified 11, 1.5% BEV/glycine elution and organic flocculation reconcentration. Water concentrates were analysed by direct RT-PCR, conventional cell culture and ICC/PCR. For ICC/PCR, sample concentrates were incubated with BGM or FRhK cells for 24–48h. The cell culture lysates were collected following freeze-thaw cycles, centrifuged, resin column purified and PCR amplified. In this study viruses known to be present by cell culture analysis could not be detected by direct PCR. Using the integrated method, virus concentrations as low as 0.001MPN/l of original water were detected in samples which were previously inhibitory to direct PCR. In addition, confirmed enterovirus results were achieved as soon as 48h against 5–16d with cell culture alone. Therefore, the integrated approach overcame some of the traditional problems associated with conventional cell culture and direct RT-PCR by allowing rapid, confirmed detection of low levels of enteroviruses in PCR inhibitory samples.
Sensory evaluation of fish exposed to pulp and paper mill effluent: a case study of methods used for environmental effects monitoring
Authors: Redenbach Alan E.
Published: May 2018

The federal Environmental Effects Monitoring (EEM) program, a requirement of the Fisheries Act Pulp and Paper Effluent Regulations, requires sensory evaluation at Canadian pulp and paper mills where there have been historical complaints of fish tainting or reduced fishing efforts and there is no potential health hazard. Sensory evaluation tests were conducted at three mills in British Columbia. Each test component yielded considerable variability. Nevertheless, there were similarities in the results as defined by difference test methods, while the results of preference and acceptance test were less clear. Tainting, or taste impairment, occurred at one of three mills. Significant tainting of two fish species occurred within three hours and at exposure concentrations less than 0.08% (v/v) unbleached kraft effluent. Adult and juvenile fish appear to be attracted to and reside in effluent plumes immediately downstream of the outfall at some mills. Sensory evaluation may be the most sensitive monitoring tool available to assess and integrate effluent exposure with the usability of valuable sports, recreation, commercial and native fisheries resources. A proposal to focus EEM cycle 2 programs to evaluate the use of these fisheries resources is presented.
Physico-chemical and bacteriological characterization of wastewater from Mexico City
Authors: Jiménez C. Blanca , Landa V. Homero
Published: May 2018

This study was designed to characterize the behavior of the wastewater produced by Mexico City after being subjected to a physico-chemical treatment of Al2(SO4)3 and FeCl3 in a jar test simulation of an Advanced Primary Treatment (APT). Special attention was paid to the evaluation of the removal efficiency of suspended solids and of helminth eggs. The effluent thus obtained was first subjected to a simulated filtration process (through a fiberglass filter paper with an opening of 11 μm) and then it was disinfected with the use of two chemicals: sodium hypochlorite (NaOCl) and copper sulphate (CuSO4).

The use of both the Al2(SO4)3 (dose ranging from 25 to 40 mg/L) and the FeCl3 (varying from 20 to 40 mg/L) in combination with the filtration process proved to be quite effective in what refers to the removal mechanisms of helminth eggs. The concentrations recorded in each of the effluents fell always below the international regulations for irrigation reuse (<1 org/L as helminth eggs). The removal rates achieved for both coagulants were close to 99%.

In what refers to the disinfection accomplished with the use of NaOCl (from 4 to 17 mg/L as Cl2) and CuSO4 (from 3 to 5 mg/L as Cu), it was found to be an excellent supplementary process because less than 1000 CFU/100 mL were recorded and this value satisfies the international recommendations. The treatment as a whole showed removal efficiencies of 45% as COD, 73% SST, 99% helminth eggs, 99.99% faecal coliforms and from 7 to 87% in heavy metals.
Gross solids transport and degradation
Authors: Davies J. W. , Butler D. , Small J. L. , Sekuloski V. , Jefferies C.
Published: May 2018

The paper describes the first stages of a study of the origin, transport, and fate of sewer gross solids. The background to the project, its overall plan, and relevant previous studies are outlined. Progress to-date is described. A laboratory study of physical degradation of gross solids has confirmed general existing field observations that many sanitary solids undergo little degradation, whereas toilet paper and faeces are readily degraded. A study of solid advection and deposition in a laboratory pipe system has covered a wide variety of sanitary and artificial solids. The velocity at which sanitary solids are advected with the flow has been observed to be similar for most solids in spite of a considerable range of shapes and sizes. Pipe-full conditions, introducing the retarding effect of the pipe wall at the soffit, have tended to reduce solid velocities especially for floating solids. Generally the advective velocity of artificial solids of the same material and shape has not varied significantly with solid size. However size has had a clearer influence on deposition: with decreasing size, solids of the same density have been deposited at lower values of depth and velocity.
Biological nutrient removal at a very low-loaded activated sludge plant with high biomass concentrations
Authors: Kiuru H. J. , Rautiainen J. A.
Published: May 2018

The Laboratory of Environmental Engineering at the Helsinki University of Technology (HUT) carried out in 1991-1995 two successive full-scale research and development projects at the Pihlajaniemi WWTP of Savonlinna concerning biological nutrient removal from municipal wastewater. The projects have resulted in two reports in Finnish with quite large English summaries.

This WWTP was constructed originally (1978) as a conventional low-loaded activated sludge plant with the simultaneous precipitation of phosphorus. It was dimensioned for a sludge concentration of 3.5 kgMLSS/m3 in the aeration tanks. Six years later (1984) the plant was fitted with a tertiary stage of flotation filters in order to improve the removal of suspended solids and phosphorus. Nitrification was introduced to the activated sludge process of the plant in 1987. It could be done without any extension by using the sludge concentrations of 6-10 kgMLSS/m3 in the aeration tanks. In that way, this activated sludge process was converted into a very low-loaded one. The process became able to nitrify totally in the circumstances in which the wastewater temperature varies at the range of 4-20°C. The actual hydraulic as well as the BOD7-load of the plant are about 40% of the original dimensioned ones.

This activated sludge process of the Pihlajaniemi WWTP was modified in 1991-1993 for nitrogen removal and then in 1994-1995 for both biological phosphorus and nitrogen removal Denitrification was introduced to the process and the simultaneous precipitation of phosphorus in that was replaced by biological phosphorus removal still without any extension of the activated sludge process. The plant has now been operated over four years with biological nutrient removal exploiting the organic carbon compounds of the wastewater. A very little addition of some precipitant is used to improve the biological removal of phosphorus. The chemical and energy cost of the plant has been reduced by some 50% due to the introduction of biological nutrient removal.

The BOD7-value of the treated wastewater is mainly less than 3 mg/l (always less than 5 mg/l). The content of total phosphorus in the treated wastewater is usually less than 0.3 mg/l (always less than 0.5 mg/l). The content of total nitrogen in the treated wastewater is mainly 8-12 mg/l. Reductions for BOD7 and total phosphorus over 95% as well as that for total nitrogen about 70% are achieved.
A laboratory study of the erosion and transport of cohesive-like sediment mixtures in sewers
Authors: Tait Simon J. , Rushforth Peter J. , Saul Adrian J.
Published: May 2018

Surveys of sewers in the UK have indicated that many sewer systems have significant in-sewer deposits. Many of these existing combined sewers have been constructed at such a gradient and experience such a range of hydraulic conditions that over a period of time they experience repeated phases of sediment deposition, erosion and transport. Deposition of sediment in sewers with its consequent loss of discharge capacity can lead to the surcharging of sewerage systems and the premature operation of combined sewer overflows. The sudden erosion and transport of large quantities of deposited in-sewer sediments during periods of increased flow can significantly contribute to the pollution load imposed on receiving water courses and sewerage treatment plants. It is therefore important not only to be able to estimate the hydraulic performance of sewers but also the conditions under which significant erosion of deposited sediments occur. This paper reports on the rationale behind and the initial results from a laboratory study which aims to investigate the erosion and transport of “cohesive-like” sediment mixtures in controlled laboratory conditions. The choice of the sediments used was aimed at representing the characteristics of sewer sediment mixtures found in the field. These deposits have been found to exhibit a significant degree of cohesion not found in previously studied granular sediment beds.
Physiological, molecular and modeling studies of an aerobic denitrifier: microvirgula aerodenitrificans. Use of its properties in an integrated nitrogen removal plant
Authors: Patureau D. , Bernet N. , Dabert P. , Godon J.J. , Steyer J.P. , Delgenes J.P. , Moletta R.
Published: May 2018

Conventional nitrogen removal processes are based on time or space separation of the two phases : aerobic nitrification and anoxic denitrification. According to the results obtained with a pure strain M. aerodenitrificans under discontinuous and continuous, aerobic and anoxic conditions, we propose to use its co-respiration properties in a single aerated system, in co-culture with a nitrifying population. We demonstrate the feasability of combining nitrifying microflora and the aerobic denitrifier under continuous and semi-continuous cultures. A mathematical model based on batch cultures was developed to help us control the M. aerodenitrificans cultivation and maintain it in a complex ecosystem. The specific detection and monitoring of the pure strain in the complex ecosystem was realized by fluorescent in situ hybridization with rRNA-targeted nucleic acid probe.
Adaptation of the simpletreat chemical fate model to single-sludge biological nutrient removal wastewater treatment plants
Authors: Boeije G. , Schowanek D. , Vanrolleghem P.
Published: May 2018

Many recent developments in municipal waste water treatment technology are directed towards biological nutrient removal. Chemical fate models which are used to predict the behavior of individual chemicals in waste water treatment plants (WWTPs), have until now not incorporated this aspect. In this paper, two modifications to the steady-state non-equilibrium Simple Treat modeling concept are presented. These focus on an improved description of sludge recycling, and on the presence of different redox zones in the biological reactor (aerobic, anoxic, anaerobic). The updated models were applied to three different WWTP designs, and simulation results were compared to measured values for the surfactant LAS.
A computational fluid dynamics (CFD) particle tracking approach to efficiency prediction
Authors: Stovin Virginia R. , Saul Adrian J.
Published: May 2018

Storage chambers play an important role in urban pollution management. They are frequently used in conjunction with CSO structures, where they reduce the number and magnitude of CSO spill events. However, one problem associated with the use of storage tanks at CSOs is the deposition of sediment. Techniques which enable engineers to design such chambers for minimal deposition are required.

In this paper the use of the particle tracking routine contained within the Fluent computational fluid dynamics (CFD) software for the prediction of sediment deposition in storage chambers is described. The paper details the way in which the particle tracking routine was configured to produce realistic efficiency results for the comparison of storage chamber performance. Consideration was given to the physical characteristics of the sediment, the injection location, the boundary conditions and a number of relevant simulation parameters. The sensitivity of efficiency prediction to the selection of these parameters is emphasised. The paper also demonstrates the potential application of particle tracking to the prediction of probable deposit locations.
Characterization of wastewater and activated sludge from European municipal wastewater treatment plants using the NUR test
Authors: Naidoo V. , Urbain V. , Buckley C. A.
Published: May 2018

Denitrification kinetics and wastewater characterization of eight different plants in Europe are discussed. Denitrification batch tests revealed three distinct rates except in the cases of Plaisir, Rostock and Orense where 4 rates were observed. The latter three plants revealed atypical rapid initial rates which were between 7 and 21 mgN/gVSS.h. All denitrification kinetics under non-limiting carbon conditions revealed fast first rates which ranged between 3.0 and 7.3 mgN/gVSS.h. Acetate was used to simulate denitrification kinetics with readily biodegradable COD present. Two subsequent rates were observed. Rates 2 and 3 ranged between 2 and 3 mgN/gVSS.h, and 1 and 2 mgN/gVSS.h, respectively. The RBCOD fraction varied between 10 and 19%, except for one of the plants where the value determined was 7%.
Evaluation of reversible fixed-film static-bed bio-denitrification reactors
Authors: Woodbury B. L. , Dahab M. F. , Miháltz P. , Csikor Zs.
Published: May 2018

This paper reports the results of a study to investigate the performance of fixed-film two-stage reversible bio-denitrification reactors operated at very short detention times for the removal of nitrates from contaminated groundwater. The results demonstrate that these systems imparted lower concentrations of organics and suspended solids into the treated effluent than traditional single-stage systems while maintaining higher levels of nitrate removal rates at HRT values as low as 30 minutes. The lower detention times translate into substantial reductions in capital cost on scaled-up systems. The results also demonstrate the ability of two-stage reversible flow systems to withstand the stresses associated with low HRT and flow cycle reversals.
Performance of a subsurface constructed wetland in Iran
Authors: Badkoubi A. , Ganjidoust H. , Ghaderi A. , Rajabi A.
Published: May 2018

The high capital, operational and maintenance costs of municipal wastewater treatment plants in Iran are a concern for the government. Wastewater treatments in natural systems have shown suitable methods for their low cost. The performance of a pilot-scale subsurface constructed wetland with Phragmites australis to treat municipal wastewater has been investigated. The purpose of this study was to determine the surface area requirement per person in an arid region to achieve an acceptable quality in terms of discharge standards.

Experiments were carried out in two cells (15 × 10 mxm) with media size ranging from 4-8 mm. One cell was used as blank (unplanted) and the other one was planted. Different hydraulic loading rates ranging from 5 to 20 L/min were used. Minimum land requirement was determined to be 1-2 m2/P.E. to reduce COD (86±4%), BOD5 (90±3%), TSS (89±4%), TN (34±6%), TP (56±5%) and fecal coliform (>99%).
Design considerations and applications for wetland treatment of high-nitrate waters
Authors: Baker L. A.
Published: May 2018

Nitrate contamination is a serious problem worldwide. By providing an ample supply of carbon and an anaerobic environment, wetlands are a valuable low technology for treating nitrate-contaminated waters with low organic carbon concentrations. Denitrification is apparently limited by the C:N ratio, with ratios >5:1 resulting in >90% nitrate removal efficiencies. The denitrification rate constant, VNO3, varies in direct proportion to carbon supply. Several novel or emerging applications of wetlands include renovation of nitrate-contaminated aquifers (a pump-and-treat strategy), denitrification of nitrified sewage effluents, and treatment of irrigation return flows. Treatment of dual sources is also discussed. In arid regions with limited supplies of high quality water, nitrate treatment wetlands may play a significant role in the development of water resources.
Enhanced rapid gravity filtration and dissolved air flotation for pre-treatment of river thames reservoir water
Authors: Bauer M. J. , Bayley R. , Chipps M. J. , Eades A. , Scriven R. J. , Rachwal A. J.
Published: May 2018

Thames Water treats approximately 2800Ml/d of water originating mainly from the lowland rivers Thames and Lee for supply to over 7.3million customers, principally in the cities of London and Oxford. This paper reviews aspects of Thames Water's research, design and operating experiences of treating algal rich reservoir stored lowland water. Areas covered include experiences of optimising reservoir management, uprating and upgrading of rapid gravity filtration (RGF), standard co-current dissolved air flotation (DAF) and counter-current dissolved air flotation/filtration (COCO-DAFF®) to counter operational problems caused by seasonal blooms of filter blocking algae such as Melosira spp., Aphanizomenon spp. and Anabaena spp. A major programme of uprating and modernisation (inclusion of Advanced Water Treatment: GAC and ozone) of the major works is in progress which, together with the Thames Tunnel Ring Main, will meet London's water supply needs into the 21st Century.
Monitoring raw water quality and adjustment of treatment processes – experiences at the wahnbach reservoir
Authors: Hoyer Oluf , Schell Helmut
Published: May 2018

On-line monitoring of turbidity allows effective control of source and finished water quality. Fundamentals for particle destabilisation and removal are outlined and the application of the charge titration method for optimal online adjustment of the flocculant dosage is presented.
The stabilization of sewage sludge applied to agricultural land and the effects on maize seedlings
Authors: Snyman H. G. , de Jong J. M. , Aveling T. A. S.
Published: May 2018

The time for dewatered sludge to reach stability in terms of respiration after application to agricultural land was investigated and found that dewatered sludge applied at 16 ton/ha (dry) reached the background respiration rate of the soil, 50h after administration. Laboratory seedling experiments showed this stabilisation did not effect the effectivity of the sludge as a soil conditioner (growth of the maize seedlings) since seedling growth was similar whether seedlings were planted directly after, or 14 days after sludge was administered (after stabilisation). The beneficial effects of the sludge was significantly enhanced when doubling the dosage to 16 ton/ha in loam soil without heavy metal and salt accumulation in the soil or plant foliage. Laboratory studies of seedlings grown in 8, 24 and 72 ton/ha amended silica sand illustrated that the inorganic fertiliser (Hoagland's solution) affected seedling growth better in terms of root, leaf mass and shoot length but showed chlorosis. Apart from Zn the heavy metal concentrations in the seedling foliage were still similar to the positive control even at 72 ton/ha, clearly indicating the benefits of attempting to keep metals from entering the wastewater treatment plant.
Nitrification and low temperature in a raw water reservoir and rapid sand filters
Authors: Kors L. J. , Moorman J. H. N. , Wind A. P. M. , van der Hoek J. P.
Published: May 2018

Ammonium removal occurs in both the surface water reservoir and rapid sand filters of Amsterdam Water Supply. Nitrification in the reservoir is best modelled as a first order reaction with a temperature dependent breakdown coefficient. In moderate winters, the increase of ammonium concentration in the filter influent is compensated but stagnation of nitrification in the Winter of '95–'96 led to a two and half month excess of the ammonium maximum admissible concentration. Only after the start of phosphate dosing, full restoration of nitrification was achieved. A model to alert for ammonium breakthrough was developed based on growth characteristics of Nitrosomonas.
The influence of bioregulation on water quality of the prefiltered stagnant water reservoir eekhoven (Flanders, Belgium)
Authors: De Maeseneer Jan , Gille Lue , Meheus Jan
Published: May 2018

When the creation of a new safety reservoir for the drinking water supply of the Antwerp region was envisaged it was decided that a number of actions would be undertaken to create a favourable environment for bioregulation (biomanipulation). These were: the use of boulders for the side-walls instead of concrete or bitumen, first flooding with a shallow layer of water to leach out the minerals contained in the upper clay layer of the bottom floor, introduction of freshwater mussels and of a number of fish species (bitterlings, predators such as eels, pike-perch and pike) and of submerged, floating-leaved and emergent aquatic plant species. This paper is a report on the results of these bioregulation measures obtained so far.
Dimensions and scales
Authors: Lijklema Lambertus
Published: May 2018

Phenomena in the environment occur on a wide range of spatial and temporal scales. This puts certain demands on the ways we perform research and model systems. Transverse mixing in rivers and internal loading of lakes with phosphates are examples illustrating certain features. Time lags in both ecosystems and in society in combination tend to postpone the solution of environmental problems. Eutrophication serves as an example.
The E numbers of eutrophication - errors, ecosystem effects, economics, eventualities, environment and education
Authors: Moss Brian
Published: May 2018

Accumulated experience is a precious commodity. Fifty years ago, Aldo Leopold succinctly expressed many of the principles of land management that contribute to minimising eutrophication. Lessons from his essay ‘Odyssey’ can be drawn and applied our current understanding of eutrophication. They include the importance of nitrogen vis a vis phosphorus, the relevance of a whole system treatment of the problem, the costs of the problem, the value of intact ecosystems in providing goods and services, and the future use of land in mitigating the problem on a world scale.
Alpha correction factors for static aerators and fine bubble diffusers used in municipal facultative aerated lagoons
Authors: Asselin C. , Comeau Y. , Ton-That Q. A.
Published: May 2018

The alpha correction factor (KLa process water/KLa clean water; where KLa is the volumetric oxygen mass transfer coefficient) was evaluated for 4 kinds of static aerators and 2 kinds of fine bubble diffusers used in municipal facultative aerated lagoons. For this purpose, a 40 m3 steel tank was filled (3.1 m side water depth) with clean or process water. The process water consisted of “mixed liquor” from a municipal facultative aerated lagoon divided into a cascade of four identical basins that were 3.5 m deep. Results showed that in the last three basins, the alpha correction factors were relatively high, being between 0.85 to 0.95 for any type of aeration device. In the first lagoon, however, the alpha correction factors were between 0.70 and 0.90 for static aerators and about 0.70 for fine bubble diffusers. Furthermore, at the inlet of the first basin, the alpha factor was as low as 0.59 for a static aerator and 0.26 for a fine bubble diffuser, due to the composition of the “mixed liquor”. It was shown that the alpha correction factor that should be used for the design of aeration systems for facultative aerated lagoons should be lower in the first basin of a series of basins and could be higher than 0.85 for the downstream basins.
Successful sidestream nitrification of digested sludge liquors
Authors: Jeavons J. , Stokes L. , Upton J. , Bingley M.
Published: May 2018

When digested sludge is dewatered for recycling to agricultural land or incinerated the centrate/filtrate liquors present considerable ammonia loads on the receiving sewage treatment plants which can compromise effluent standards. As an alternative to mainstream treatment at the sewage works sidestream treatments have been evaluated. At two incinerator sites sidestream ASPs processes have been chosen, and the outcome of modelling, laboratory studies and pilot plant operation are discussed, along with the design of the two plants and full scale performance.
Toxicity identification evaluation of ammonia, nitrite and heavy metals at the stensund wastewater aquaculture plant, Sweden
Authors: Adamsson M. , Dave G. , Forsberg L. , Guterstam B.
Published: May 2018

The Stensund Wastewater Aquaculture plant was built in 1989. The plant is contained in a greenhouse because of its northern location with a temperate climate. The plant receives wastewater from 40 persons and has a residence time of 30 days. The purification concept is to use a constructed aquatic food chain (algae, zooplankton and fish) combined with hydroponic culture of higher plants to further deplete the nutrients in the wastewater. However, the production of algae and zooplankton has not been working as expected from pilot studies. The purpose of this investigation was to study if toxic chemicals were limiting the production of zooplankton (Daphnia magna) in the aquaculture treatment system. Grab samples were taken at six sites and tested for acute toxicity to Daphnia magna and analyzed for BOD, COD, ammonium-, nitrite-, nitrate- and total nitrogen, total phosphorus and heavy metals (Cd, Cr, Cu, Ni, Pb, Zn). Toxicity to D. magna was also determined after addition of EDTA, sodium thiosulphate and pH adjustment of the water to 6, 7 and 8, in order to assess if heavy metals and/or pH-dependent toxicants were present. Potential toxicants, with concentrations high enough to intoxicate Daphnia magna, were Cu, ammonia and nitrite. Subsequent improvement of nitrification reduced the ammonia and nitrite concentrations as well as the toxicity. Furthermore, the improved production of algae and Daphnia at the Stensund Wastewater Aquaculture plant verified that the primary cause of toxicity was ammonia.
Use of non woven textile in intermittent filters
Authors: Roy Christiane , Auger Richard , Chénier Robert
Published: May 2018

Intermittent filters are widely used in North America for on-site wastewater treatment. However, availability or transportation of the treatment medium can become a limiting factor. The use of non-woven textile coupons, a light, and compressible material, to replace the sand or gravel has been tested. Test columns containing textile coupons over a height of 90 cm were operated at hydraulic loading rates (HLR) of 20 to 60 cm/d, with or without recirculation. During the eighteen months test period, the two most efficient columns, single pass (HLR = 20 cm/d) and recirculating (HLR = 60 cm/d), met treatment goals of 10 mg/l biological oxygen demand (BOD5) and total suspended solids (TSS). Detailed analysis of water quality at different depths and HLRs indicated that water detention time in the coupons might be a factor in organic matter removal. A new filter configuration was then developed to take advantage of this feature; it comprised three hydraulically independent layers of coupons. The new column was tested in the recirculating mode and in the single pass mode at HLRs of 123 and 188 cm/d respectively for six months. In both cases, BOD5 values at the effluent were below 10 mg/l; in the recirculation mode, TSS values were below 15 mg/l.
Comprehensive approaches to water management
Authors: van Rooy Peter T. J. C. , de Jong Joost , Jagtman Eric , Hosper S. Harry , Boers Paul C. M.
Published: May 2018

For us to have sufficient amounts of good quality fresh water available in the 21st century, it is necessary that we find a different way of dealing with water. Awareness of this fact represents a first step in the right direction. Interactive planning can substantially contribute to this awareness and therewith to the solution of both physical and cultural bottlenecks. Interactive plan processes are complex. The challenge lies in being actively involved in this complexity. The IPEA methodology has been developed to support adequate completion of interactive plan processes. This methodology has already been applied in a number of plan processes, 25 of which were recently evaluated. From this evaluation it appears that applying IPEA helps to increase the clarity and the suitability of both processes and plans. The methodology also makes a positive contribution to levels of communication and interaction between the people and organizations involved in a plan process. Furthermore, IPEA leads to an increased acceptance of the contents of plans.
The experience of using a decision support system for nutrient management in Australia
Authors: Davis J. Richard , Farley Trevor F. N. , Young William J. , Cuddy Susan M.
Published: May 2018

Australia experienced an outbreak of algal blooms in the early 1990s that led to a concerted national program to reduce eutrophication. Most Australian States drew up nutrient management strategies which required catchment management groups to produce plans for nutrient reduction within their catchments. Most catchment management groups used the Catchment Management Support System (CMSS) to assist them in the preparation of these plans. CMSS is a simple decision support system developed by CSIRO (the national research organisation) which allows managers to assess the effects of Land Use and Land Management policies on nutrient loads. CMSS has been widely adopted by managers and community groups throughout eastern Australia and has been instrumental in drawing up many nutrient management plans. The program's success is attributed to its design features such as its simplicity of use, very low data demand, suitability for the specific institution task and the degree of documentation, training and support offered.

In this paper the application of CMSS to the Hawkesbury-Nepean Catchment in New South Wales is used to illustrate features of the decision support system, and its relevance to policy formulation.
Process control for nutrients removal using lamella sedimentation and floating media filtration
Authors: Zeghal Slim , Puznava Nelu , Subra Jean Philippe , Sauvegrain Patrick
Published: May 2018

The objective of this work is to provide an efficient method to control the dosing of chemicals in order to optimise the operation of the complete treatment train associating phosphorus precipitation in a lamellae separator followed by nitrogen removal in a Biostyr® filter with methanol addition. Four coagulation-flocculation tanks of 1.54 m3 total volume were used, followed by a lamellae primary tank of 0.65 m2 footprint and 5.4 m2 total settling surface. On-line measurements were used. The pilot was operated initially with no chemicals, at constant and variable flow. Different control strategies were sought. To help tune the controllers, step changes in chemicals dosing were made to identify the open-loop process transfer function at different flow rates. The system was then operated in closed loop. This proved to be an efficient means of operating the system. Future work will continue to test various control strategies.
Process modeling of ultraviolet disinfection
Authors: Blatchley Ernest R. , Do-Quang Zdravka , Janex Marie-Laure , Laîné Jean-Michel
Published: May 2018

Currently available process models for ultraviolet (UV) disinfection do not account for many of the fundamental physical phenomena that are known to affect reactor performance. A modeling approach was developed which employs numerical representations of hydrodynamics and the radiation intensity field; these simulations were accomplished by the methods of computational fluid dynamics and line-source integration. The modeling approach also allowed the identification of process characteristics which limited reactor performance. Based on the output of the models, two geometric modifications were developed and applied to a pilot-scale UV system that resulted in significant improvements in reactor performance. The results of this research illustrate the benefits of UV process analyses which incorporate detailed representations of the velocity and intensity fields.
Efficiency of adsorbents for removal of organosulphur compounds in water
Authors: Leong W. Y. , Teo E. H. , Lim C. H. , Tan Y. L.
Published: May 2018

Four carbonaceous adsorbents - Ambersorb XEN-563, Carbochem LQ830, Carbochem LQ1000 and Morganite FY5 - were evaluated in terms of adsorptive capacity for organosulphur compounds (thiodiglycol, ethyl 2-hydroxyethylsulphide, 1,4-thioxane, ethyl vinylsulphide) in water. The adsorption isotherms in single-solute and multi-component systems were fitted to Freundlich isotherms which give a first-cut estimation of the adsorptive capacities and breakthrough times. All four adsorbents demonstrated decreasing adsorptive capacity with increasing polarity of the adsorbates. Morganite FY5 and Ambersorb XEN-563 exhibited the highest adsorptive capacity for the selected adsorbates. The study was also extended to six non-carbonaceous adsorbents - Amberlite XAD-4 and XAD-7; Biobeads SM2, SM4 and SM7; and molecular sieve 13X. The overall efficiency of adsorption of the four vessicants was SM4 > XAD-4 > SM2 > SM7 > XAD-7 > 13X.
Water quality considerations in developing a new resource for water supply within the midlands of England
Authors: Smith D. J. , Crymble S.
Published: May 2018

Increasing demand for limited water resources within the Midlands of England resulted in a lower quality river being considered for water supply in an area of high urban and rural population. A comprehensive water quality monitoring programme was undertaken on the river to compare its quality with other sources used for water supply. Concurrent with the monitoring programme a series of laboratory scale trials began to assess how the river water could be treated, and the costs involved. A major consideration was the need to provide treated water by the summer of 1997, which precluded a complete new water treatment process from being designed.

The paper outlines the results from the monitoring programme, including some of the problem parameters such as pesticides at over 10 ug/l, and how some of the sources of these pollutants were identified. It also describes the treatment trials and explains how a water treatment process was developed which utilises disused gravel workings to provide bankside storage and a combination of powdered and granular activated carbon to remove organic pollutants.
Modeling spatial distribution of the unionid mussels and the core-satellite hypothesis
Authors: Lee Hooi-Ling , DeAngelis Donald , Koh Hock-Lye
Published: May 2018

This paper discusses the spatial distribution patterns of the various species of the Unionid mussels as functions of their respective life-cycle characteristics. Computer simulations identify two life-cycle characteristics as major factors governing the abundance of a species, namely the movement range of their fish hosts and the success rate of the parasitic larval glochidia in finding fish hosts. Core mussels species have fish hosts with large movement range to disperse the parasitic larval glochidia to achieve high levels of abundance. Species associated with fish host of limited movement range require high success rate of finding fish host to achieve at least an intermediate level of abundance. Species with low success rate of finding fish hosts coupled with fish hosts having limited movement range exhibit satellite species characteristics, namely rare in numbers and sparse in distributions.
Heavy metals in rivers and soils of central Chile
Authors: Schalscha B. Eduardo , Ahumada T. Ines
Published: May 2018

Industrial and domestic waste waters in Chile are discharged without previous treatment into rivers and other inland waters which are used to irrigate agricultural lands. The present study reports on results obtained when analyzing inland waters for Cd, Cu, Zn, Hg and As. Copper content was found to be high in most of the rivers studied and its sources were identifiable copper mining wastewaters. Cadmium and Zn levels are above accepted levels in some instances, whereas Hg and As content of river waters under study studied were found to be within accepted levels.

The more reactive chemical forms of heavy metals in soils irrigated with polluted waters, as determined by sequential extraction, were found to be the most abundant ones. These forms are easily bio-available.
Upgrading for nitrogen removal, using a combination of SBR (sequencing batch reactor) technique and unloading of existing biological stage
Authors: Rosén Björn , Ullman Anders , Ragnarsson Nils
Published: May 2018

Many waste water treatment plants in Sweden have been using pre-precipitation, which has considerably decreased the load on the existing activated sludge process. In many cases it has been possible to introduce predenitrification, with minor changes or increase of volume, in order to reach the required effluent values, which in Sweden varies between 10 and 15 mg Ntot/l as annual average value.

In treatment plants with anaerobic digestion of sludge, some 15–20% of the nitrogen load is recirculated with the return liquors from dewatering. Separate treatment of ammonia-rich return liquors has successfully been using SBR-technique for nitrogen removal, adding external carbon source, e.g. methanol or ethanol. The overall result is, however, not sufficient to meet the requirement, without additional action.

The use of SBR-reactors, designed for nitrification/denitrification of return liquors from dewatering of digested sludge, and part of the influent raw waste water, 20–30%, as a carbon source, has been proven most cost-effective, both from investment and operation cost point of view. The result is a considerably decreased load on the existing biological stage, making it possible to introduce pre-denitrification without any extension of reaction volumes. The paper presents the result from full-scale operation of some plants in Sweden.
The use of immersed membranes for upgrading wastewater treatment plants
Authors: Buisson H. , Cote P. , Praderie M. , Paillard H.
Published: May 2018

Membranes can be installed in the clarifier (or aeration tank) of an existing activated sludge plant to enhance the biomass separation function of the system, thereby effectively overcoming any operating constraints associated with sludge settleability. The resulting upgraded plant can be operated at high biomass concentrations (10–20 gMLSS/L), leading to an increase in its treatment capacity. The membranes also ensure a treated water consistently free of suspended solids and a superior disinfection performance. The system offers an enhanced operating flexibility, and allows to operate at high sludge ages leading to a low excess sludge production.

Such an immersed membrane activated sludge process (BIOSEP®) has been developed and applied to the treatment of raw sewage. When treating screened raw sewage with this process, with a sludge concentration of 15 gMLSS/L and a volumetric loading of 1.2 kgCOD/m3/d, a 96% COD reduction and a 95% Total Kjeldahl Nitrogen (TKN) reduction have been obtained. The disinfection performance of the system was over 6 Log removal for fecal coliforms. The resulting production of sludge was 0.20 kgMLSS/kgCOD.

Two desk case studies are given for 900 m3/day upgraded plants. In one case, the primary objective was to increase the treatment efficiency and develop nutrient removal for the original plant, while in the other case the primary objective was to increase the capacity of the original 460 m3/day plant.