bluuebunny/crossref_metadata_2025 huggingface dataset:
Resistance of bacterial cultures to non-oxidising water treatment bactericides by adaptation
Authors: Brözel V. S. , Pietersen B. , Cloete T. E.
Published: May 2018

Bacterial communities in water cooling systems treated with bactericides often become resistant to these bactericides. This has been ascribed to selection for resistant cells. Certain bacteria, having a high inherent susceptibility to water treatment bactericides become dominant in systems after bactericide treatment. We investigated the idea that bacterial isolates adapt to grow in the presence of bactericides. Pure cultures of Pseudomonas aeruginosa, P stutzeri and Bacillus cereus were cultured repeatedly in the presence of sub-inhibitory concentrations of 2,2′-methylenebis(4-chlorophenol), Na dimethyldithiocarbamate, isothiazolone and alkyl dimethyl ammonium chloride. All isolates adapted to grow in the presence of increasing concentrations of the bactericides. The phenomenon of development of bacterial resistance to water treatment bactericides was ascribed to adaptation and not to selection.
Water pollution control measures and water quality development in the Ruhr catchment 1972-1992
Authors: Imhoff K. R.
Published: May 2018

Since five million people have to rely on Ruhr water as a source for potable water supply, quality and quantity aspects of the river are very important for the region.

In the last 20 years, 2.1 × 109 DM have been spent for water quality control in the Ruhr basin. The most important types of plants and the progress in river water quality are described.
Modified culture methods for the detection of Vibrio spp. from estuarine waters
Authors: Toro A. , Gonzalez N. , Torres J. , Dvorsky E. , Toranzos G. A.
Published: May 2018

The purpose of this study was to improve and speed up the isolation and recovery of Vibrio spp. from water using modifications of the currently used culture techniques. Thiosulfate Citrate Bile Salts (TCBS) and Alkaline Peptone Salt Broth (APSB) media were modified by the addition of NaCl and Tris buffer. None of the modifications had a negative effect on the recovery of Vibrio spp. when compared to the unmodified media. The modifications giving the best results were 3% and 6% NaCl and Tris buffer 0.05 M at pH 8.4. Under these conditions, the background microflora was drastically reduced in both TCBS and APSB making the detection of the target colonies extremely easy. The presence of sulfur-producing microorganisms was reduced and in most cases completely eliminated. The use of a more selective medium also allows for an easier application of molecular techniques. Colony hybridizations are easily done, since the growth of interfering microorganisms is reduced. These studies are being expanded to include the detection of V. cholerae 01 and non-01 in waters from Latin American countries affected by the cholera epidemic.
The role of aquatic organisms in the management of river basins for sustainable utilisation
Authors: Chutter F. M.
Published: May 2018

The paper considers the several beneficial (provision of drinking water, fish, waste assimilation) and detrimental (overabundant plant life, habitat for pathogens and disease vectors) roles of the aquatic biota in general, before describing the use of the biota in river management through biomonitoring. This is followed by a description of a biomonitoring method called SASS which is based on the aquatic macro-invertebrate community. Results of using SASS4 are presented and show that SASS4 scores vary following water quality. SASS4 results are less expensive than the chemical analysis of water samples and represent water quality variation over a period of time. SASS4 has a role to play in the monitoring and assessment of water quality. It can be used as a substitute for chemical analysis in broad scale monitoring and allow chemical resources to be focused on sampling points where there would appear to be real water quality problems. Since river quality (both chemical and biological) reflects the manner in which the basin is managed, SASS4 provides key information pertinent to the management of river basins. It is concluded that river assessment based on the aquatic biota has an essential role to play in the management of river basins for sustainable utilization.
Studies on wild and vaccine strains of poliovirus isolated from water and sewage
Authors: Sellwood Jane , Litton Pamela A. , McDermott Jacqueline , Clewley Jonathon P.
Published: May 2018

The WHO Poliovirus Eradication Programme has renewed interest in the identification of wild and vaccine strains of poliovirus circulating in the community. One method of monitoring these strains is to study poliovirus isolates detected in sewage. To facilitate the isolation of poliovirus from sewage and eliminate the possibility of detecting the other enteroviruses, sewage was inoculated onto a transfected Mouse L cell line. This cell line contains the gene for the poliovirus receptor which allows poliovirus infection to take place but not that of other enteroviruses. This cell line is, however, too sensitive to the toxic elements of concentrated sewage to be of practical use.

Polioviruses have also been isolated from river and seawater as part of three year surveys of sewage discharges into a river system and a coastal harbour. These isolates have been characterised using PCR amplification of a region of the VP1 gene followed by restriction fragment length polymorphism (RFLP) analysis. All isolates were vaccine-like although many poliovirus type 2 isolates had distinct PCR-RFLP profiles. The RFLP typing method is an efficient system for rapidly monitoring poliovirus isolates from the environment.
Occurrence of reoviruses in environmental water samples
Authors: Milde N. , Tougianidou D. , Botzenhart K.
Published: May 2018

Reoviruses are known to be present in water of different origin. The family of the Reoviridae includes viruses which are infecting not only humans but also animals and even plants. A differentiation between the reovirus types becomes possible by comparison of the electrophoresis pattern of their segmented dsRNA genome. The following presents the profiles of virus isolates from different environmental water samples which have been concentrated and their nucleic acids purified and analysed by SDS-PAGE. Reoviruses were frequently found in different environmental water samples but also in drinking water samples. The most frequently isolated reovirus was the serotype 1 followed by the serotype 3. The serotype 2 was not found in the analysed samples.
Environmental conditions of the water column in Haifa Bay, Israel, during September-October 1993
Authors: Kress N. , Herut B. , Angel D.
Published: May 2018

During September 1993, the water in Haifa Bay, Israel, turned brown and turbid, and a phytoplankton bloom was observed. Preliminary examination of the seawater showed very high concentrations of o-phosphate, nitrate and dissolved oxygen, and high pH values. In order to investigate this unusual occurrence and determine the environmental conditions that allowed for its development, the chemical and physical characteristics of the water column were measured, one during the unusual bloom in September and one during October 1993, after the bay appeared to have returned to normal. The distribution of nutrients and chlorophyll-a at the surface corresponded closely to that of the salinity and temperature, with high concentrations in the region close to the Kishon estuary, decreasing northward and westward. It was possible to determine that the Kishon river was the main source of the nutrients to the bay, originating from the effluents discharged into the river by a sewage treatment plant and nearby industries. During September, the input of nutrients from the Kishon to the bay was twice as in October, and this, together with favorable hydrographic conditions, most probably caused the unusual extensive phytoplankton bloom.
The cyclic activated sludge system for resort area wastewater treatment
Authors: Goronszy Mervyn C. , Slater Nigel , Konicki Dennis
Published: May 2018

Significant load variation is imposed on wastewater treatment infrastructure at resort centres. The type of resort centre plays a large part in both hydraulic and organic loading dynamics. Climatic conditions may also be a determining factor on the loading pattern. Holiday patterns also have a large impact upon loading dynamics. Performance of the Portage/Catawba Cyclic Activated Sludge System, located on the shores of Lake Erie, is described relative to the loading dynamics of the Summer/Winter populations.
Trace metals in sediments at the lower reaches of Mediterranean coastal rivers, Israel
Authors: Herut B. , Hornung H. , Kress N. , Krom M. D. , Shirav M.
Published: May 2018

Concentrations of mercury, lead, copper, zinc, cadmium, iron and partially chromium, manganese, nickel and aluminium, were recorded in surface sediments at the lower reaches of 11 rivers from the Mediterranean coastal zone of Israel, during 1988-1993. Excluding the lower Kishon river, no major contamination was found at most of the stations when trace metal concentrations were normalized against iron concentrations (trace metal/iron ratios) and compared to levels recorded in stream sediments from the southern drainage basin of the Kishon river. Minor enrichments found in part of the rivers are attributed to land-based point sources of pollution. Variations in trace metal concentrations at the estuaries are related to high influx of fine-grained sediments transported by heavy floods during rainy winters, which later are resuspended and transported seaward by bottom currents.
Water resources management in Greece: current status and prospective outlook
Authors: Angelakis A. , Diamadopoulos E.
Published: May 2018

The basic aim of this paper is to present the existing conditions and problems of water resources management in Greece. Water demand has increased tremendously over the past 30 years. Despite adequate precipitation, water imbalance is often experienced, due to temporal and regional variations of the precipitation, the increased water demand during the summer months and the difficulty of transporting water due to the mountainous terrain. Integration of reclaimed wastewater originating from the wastewater treatment plant effluents into the water resources management is proposed. This plan exhibits the potential for reducing the pollution loads entering sea or inland waters, while at the same time providing water for irrigation.
Competitive sorption of phosphate and marine humic substances on suspended particulate matter
Authors: Kaštelan-Macan M. , Petrovic M.
Published: May 2018

The sorption behavior of dissolved orthophosphate in the presence of background organics has been evaluated by studying the sorption on suspended particles (sand, calcite, bentonite and iron oxide). Humic and fulvic acids, that are the most significant component of organic substances in aquatic systems, were used as competitive solutes. Marine humic substances were isolated from the surface part of the sediment collected in Raska bay, Adriatic sea. Since the phenomena of phosphate fixation are especially important in estuarine waters, when fresh and saline waters undergo mixing in the coastal zone, the influence of salinity was studied. It was found that the following effects could be considered:

- reduced phosphate fixation due to favorable sorption of humic substances onto suspended particles,

- enhanced sorption induced by increased salinity and concentration of Ca2+-ions which enabled the bridging between sorbed humic acids and phosphate.
On-line quantification of settling properties with in-sensor-experiments in an automated settlometer
Authors: Vanrolleghem P. , Van der Schueren D. , Krikilion G. , Grijspeerdt K. , Willems P. , Verstraete W.
Published: May 2018

An on-line settlometer has been developed. Batch settling experiments lasting 40 min are performed in a model clarifier incorporated in the sensor (“In-Sensor-Experiment”). The descent of the sludge blanket interface is monitored and the settling characteristics are deduced. The hardware consists of a 10 litre Pyrex decanter, a stirring/wall-scraping mechanism, an external light source and a moving light-intensity scanner. Either stirred or non-stirred settling curves can be recorded.

Processing of the raw data readily produces the zone or hindered settling velocity (Vs) and the (stirred) sludge volume ([S]SV). The latter can be combined with a sludge concentration measurement to determine SVI-values, and dSVIs if a dilution step is included.

Initial results are reported on a more elaborate interpretation of the data based on sedimentation models. The Takács et al. and Cho et al. models described the settling curves equally well. However, an identifiability analysis showed that not all parameters can be given unique values on the basis of the simple batch settling experiments applied in the work. More elaborate “In-Sensor-Experiments” are required to obtain complete identification.

Two years of practical experience with the device on pilot- and full-scale treatment plants revealed its robustness, low maintenance requirements and reproducible monitoring of settling curves.
Applications of a respirometry based toxicity monitor
Authors: de Bel M. , Stokes L. , Upton J. , Watts J.
Published: May 2018

The development of a respirometry based toxicity monitor is described which automatically tests samples of imported trade waste to indicate toxicity problems. The research concentrated on the development of a methodology to test acute toxicity on nitrifying sludge. The same method was used to test specific compounds that might affect the nitrification process of the activated sludge plant. The use of the respirometer to test the possible toxicity of influent (intake protection) is also described. Although the method was originally intended to test inhibitory effects of tanker discharges, only minor changes to the hardware or the software prove to be necessary to use the instrument for different applications.
Estimation of the respiration rate and oxygen transfer function utilizing a slow do sensor
Authors: Lindberg C.-F. , Carlsson B.
Published: May 2018

In this paper a software sensor for estimating the respiration rate and the nonlinear oxygen transfer functionKLa is presented. The respiration rate and the oxygen transfer function were estimated from measurements of the dissolved oxygen concentration (DO) and airflow rate by a Kalman filter. In particular, a filtering procedure was applied for the case when the DO sensor dynamic cannot be neglected. In the estimation scheme the time varying respiration rate was modelled by a filtered random walk model, and the nonlinearKLa function was modelled with an exponential model. A numerical study illustrated the advantage of the method. Also, real data were applied to the software sensor with promising results.
Delivery of microbial indicator organisms to coastal waters from catchment sources
Authors: Wyer Mark D. , Kay David , Dawson Helen M. , Jackson Gerry F. , Jones Frank , Yeo Janette , Whittle John
Published: May 2018

The introduction of ultraviolet disinfection of sewage effluent in Jersey has served to focus attention on other sources of faecal pollution responsible for subsequent compliance failures in coastal water quality in St Aubin's Bay. Studies of microbial concentrations (total coliforms, faecal coliforms and faecal streptococci) in streams draining to the bay showed concentrations to be elevated by an order of magnitude or more following rainfall. Detailed monitoring of indicator organisms during hydrograph events showed rapid increases in concentration with flow associated with the rising limb of the hydrograph and transport of suspended solids. Microbial budget estimates suggested that between 42 and 97% of microbial delivery was associated with high flows, which account for just 20% of the total discharge. Budgets also revealed the relative importance of different catchment inputs, revealing the low bacterial input associated with UV treated effluent which provided 48% of the total volume discharged to the bay. Implications for water quality standards are discussed with reference to catchment management planning.
Real time assessment of transient spills (rats)
Authors: Norreys Richard , Cluckie Ian
Published: May 2018

The influence of Combined Sewer Overflows (CSOs) on receiving water quality must be considered for comprehensive river basin management. Receiving water impact models are tools to assess the influence of intermittent discharges on water quality. Owing to the difficulty and expense of collecting data and a perceived requirement for a computationally fast model this relatively simple fast dynamic flow and pollutant routing model was developed. In this paper the flow and pollutant routing techniques are detailed for the construction of a dendritic model to represent many aspects of an urban watercourse. The flow routing is achieved with a combination of hydraulic and hydrologic techniques. The pollutant routing is undertaken using a variation of a Lagrangian routing technique to enable routing on a widely spaced flow grid. Results of the flow routing model and details of the complete models performance in a simulation of an English urban river system are given. The assessment of the model showed the pollutant routing technique to require some further refinement for real-time simulation and the Water Quality Index (WQI) was also found to be successful but required more sensitivity. As a whole the model was found to be too slow to be operated as part of a real time control scheme but was a useful tool for the assessment of multiple CSO impacts on a dendritic urban river system. The future development of RATS will involve a close association with the continuing development of radar based real-time control procedures for controlling strategic urban drainage systems in a climate of uncertainty.
Comparison among the most frequently used systems for wastewater treatment in developing countries
Authors: von Sperling Marcos
Published: May 2018

The paper presents a series of tables, figures and charts which can be used for the preliminary selection of wastewater treatment systems, specially in developing countries. The systems analysed are: stabilization ponds, activated sludge, trickling filters, anaerobic systems and land disposal. Within each system, the main process variants are covered. A main summary table for quantitative analysis is presented, including easily usable information based on per capita values (US$/cap, W/cap, m2 area/cap, m3 sludge/cap). Other tables for qualitative comparison among systems are also included, one based on a one-to-five-star scoring and the other on a balance between advantages and disadvantages of the main treatment processes. The sludge treatment and disposal is also covered, including a comparative analysis based on a scoring system.
Design of grit channels controlled by parshall flumes
Authors: Marais Gerrit v. R. , van Haandel Adrianus C.
Published: May 2018

Grit removal is a necessary pre treatment step in sewage treatment. Grit can be separated from the liquid phase by gravity settling in a channel. For an adequate performance of the pre treatment unit, it is necessary that the liquid velocity in the channel is kept approximately constant, even when the flow rate varies. This can be accomplished by coupling a channel with a rectangular cross section to a Parshall flume, provided the channel bottom level is placed at a higher level than the flume base. The height of the step between the two devices depends on the magnitude and variation of the sewage flow. At low flow rates the step will start to act as a weir and can take over the function of the Parshall flume as the liquid velocity controlling device, thereby extending significantly the range of flow rates that can be degritted in the pre treatment unit.
CETREL's environmental management system (BS-7750): an advanced and innovative project
Authors: Pereira F. A. , Kauss A. B.
Published: May 2018

This paper analyses all of the activities carried out by CETREL to establish its Environmental Management System - EMS. This system encompasses all of CETREL's environmental protection efforts: treatment of industrial effluents and residues; environmental monitoring (soil, air, groundwater, rivers and the sea); wildlife preservation programme, environmental education programme, among other activities.

CETREL's EMS is a mid-sized system consisting of nearly 425 Instruments (244 Procedures and 181 Work Instructions). The size of the system was selected based on British Standard BS-7750, which provides the principal tools that will allow the organisation to continually maximise beneficial environmental effects while minimising adverse environmental effects.

Since the EMS in question is a voluntary one, the result of initiatives taken by CETREL itself, the system's design and architecture were chosen so that the Company's environmental standards would be more stringent than those in the environmental legislation, that is, stricter than the government-mandated environmental requirements.
Development of a respirometric assay to measure the transient load response of activated sludge to individual organic chemicals
Authors: Smets Barth F. , Fehniger Steven M. , Grady C. P. Leslie
Published: May 2018

This study described a new respirometric technique to monitor the transient response of activated sludge systems to individual synthetic organic compounds (SCOs). The assay used a fed-batch reactor system which contained mixed liquor from the parent reactor and received a biogenic feed and the target SOC at the same F/M ratio as was applied to the parent reactor. The fed-batch reactor was oxygenated using a hollow-fiber reaeration module to meet the steady-state oxygen demand. The reaeration module was characterized by means of KL a studies. The assay monitored the dissolved oxygen concentration profile after application of a shock load achieved by switching to a fed-batch feed with the target SOC at an elevated concentration. Mathematical descriptions of the transient profiles were derived and the experimentally observed dissolved oxygen profiles were subsequently compared to profiles predicted using extant kinetic parameters for SOC removal measured using an earlier developed assay. The use of the assay were complicated by the difficulty in maintaining a reaeration capacity at constant and low capacity. As a result, the adequacy of the measured extant kinetic parameters as predictors of the transient response could not be confirmed.
Treatment of TCE- and PCE-contaminated groundwater using UV/H2O2 andO3/H2O2 oxidation processes
Authors: Hirvonen Arja , Tuhkanen Tuula , Kalliokoski Pentti
Published: May 2018

The feasibility of O3/H2O2 and UV/H2O2 treatments the purification of groundwater contaminated with trichloroethylene (TCE) and tetrachloroethylene (PCE) was evaluated by laboratory and pilot-scale studies. Both methods showed rapid and extensive removal of the chlorinated ethylenes. Chloride measurements and by-product studies indicated a high level of mineralization. The health-based guidelines set by the World Health Organization were easily achieved for PCE and TCE as well as the predicted-no-effect-concentration (PNEC) values reached with extended treatment time. Owing to the partial stripping of TCE and PCE during ozonation treatment, UV/H2O2 was selected for further studies in a continuous-flow mode using a commercially available UV-sterilizor. The continuous-flow studies suggest UV/H2O2 could be useful for the purification of contaminated sites.
Extraction of sediment-bound chlorinated organic compounds: implications on fate and hazard assessment
Authors: Prytula Mark T. , Pavlostathis Spyros G.
Published: May 2018

Five methods were used for the extraction of hexachlorobutadiene and chlorobenzenes from a contaminated estuarine sediment. The following extraction methods were used: Soxhlet extraction, sonication and solvent extraction, sequential solvent extraction, saponification and solvent extraction, and supercritical fluid extraction. Soxhlet extraction resulted in better contaminant extraction efficiency and reproducibility. Most of the problems associated with the extraction methods were related to high water content and the inherent heterogeneity of the sediment samples. Drying and grinding of the sample greatly improved both extraction efficiency and reproducibility. Analyses of wet sieved and fractionated sediment samples indicated that the contaminants are not evenly distributed throughout the sediment organic fraction but rather predominate in the larger particle sediment fraction. The implications of quantification difficulties of sediment contaminants on the environmental fate and hazard assessment are discussed.
Morphological and lethal effects of mitomycin C, N-methyl-N′-nitro-N-nitrosoguanidine, benzo(a)pyrene and 4-nitroquinoline 1-oxide on a large unicellular indicator organism, Closterium ehrenbergii (green alga)
Authors: Hamada Jin , Kim Sang-Gil , Matsui Saburo
Published: May 2018

The morphological and lethal effects of the mutagens such as mitomycin C (MMC), N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), benzo(a)pyrene (BaP) and 4-nitroquinoline 1-oxyde (4NQO) on both asexual (AR) and sexual reproduction (SR) of Closterium ehren- bergii were examined. Dimethyl sulfoxide (DMSO) was used as a solvent for MNNG, BaP and 4NQO at 0.03 %, the highest concentration which was not toxic to the alga. When MMC was administrated, the size of the vegetative cells increased by about 40 % at 10 - 30 mg/l. When MNNG was added, vacuoles appeared inside the cells at 3 mg/l became larger at higher concentrations, and many morphologically abnormal gametes were observed at 0.1 - 3 mg/l. When treated with BaP, the cells grew up to 2.5 mg/l which was the highest concentration of BaP soluble in DMSO, and the frequencies of the normal zygote formation decreased and those of the abnormal seemed to increase gradually at as low as 8 × 10−5 mg/l. When 4NQO was added, the cells stopped growing at 8 × 10−3 mg/l. In SR, the frequencies of the normal zygote formation decreased and those of the abnormal zygote formation or zygote forming gametes increased at 2.5 - 8 × 10−2 mg/l. When the susceptibility of C. ehrenbergii to the mutagens was compared with that of Bacillus subtilis, the former was more susceptible than the latter (e.g., 9800 times in BaP) except for the case in MMC.
Non-biodegradable wastewater compounds treated by ozone or ozone/UV - conversion monitoring by substance-specific analysis and biotoxicity testing
Authors: Schröder H. Fr.
Published: May 2018

The behaviour of polar, biochemically non-degradable organic compounds in waste waters dominated by textile waste water is followed in the waste water treatment process by means of substance-specific mass-spectrometric detection. Selected polar compounds of anthropogenic and biogenic origin are identified by tandem mass spectrometry. Oxidation by ozone (O3) and O3/UV respectively is carried out to increase the biochemical degradability. Compared to biochemically pretreated waste water the biochemical degradability of O3-treated waste water was tripled, but the sample treated by O3/UV showed complete inhibition. Comparing the contents detected by MS it is impossible to find any reason for this inhibition.

Some of the compounds developing during the oxidation process are characterized by selective MS/MS methods.

Untreated waste waters and those treated by biochemical or chemical-physical procedures are examined with help of biotoxicity tests. Here waste water treated by O3 and O3/UV respectively showed higher toxicity than untreated or biochemically treated waste water.
An evaluation of retention time and short-circuiting in waste stabilisation ponds using Serratia marcescens bacteriophage as a tracer
Authors: Frederick G. L. , Lloyd B. J.
Published: May 2018

A single dose of 10 litres of Serratia marcescens bacteriophage was introduced at the inlet of the Cayman Islands waste stabilisation ponds to trace residence time and dispersion through facultative and maturation ponds. The design retention time of the facultative ponds was 11.5 days for a daily flow of 2600 m3. However the study demonstrated that the average retention time was <2 days and the tracer's peak, representing about 1% of the total dose, was detected at the outlet after 3-6 hours. This short-circuiting was attributed mainly to the prevailing wind direction and the orientation of the lagoons including inlet-outlet arrangements. The residence time and short-circuiting was confirmed independently using a numerical model developed by Fares and based on the theory of shallow water equations for the simulation of spatial wind-driven circulation in a natural marine basin. The close agreement of the results of this experimental study with the numerical model, has fundamental implications for improving performance of ponds at the design stage. Given local wind conditions the model permits a rigorous pre-testing of design configurations which is likely to impact on dimensions and orientation in the future.
The performance of an innovative tropical experimental waste stabilisation pond system operating at high organic loadings
Authors: Pearson H. W. , Mara D. D. , Cawley L. R. , Arridge H. M. , Silva S. A.
Published: May 2018

In this study on the experimental pond complex at the Federal University of Paraiba in NE Brazil the organic loadings were were more than doubled to investigate the effect on pond performance. The results emphasise the tolerance of the pond system at high loadings without odour production or significant loss of efficiency in terms of BOD removal and bacterial pathogen removal, although nutrient removal by the maturation ponds was reduced. At high organic loadings baffled maturation ponds were more efficient at faecal coliform removal (FC). A minimum of 3 ponds in series are required to ensure maximum BOD removal. Shallow maturation ponds were also more efficient at FC removal although the depth of the facultative ponds had limited effect on BOD removal efficiency.
Low-cost upgrading of an over-sized waste water stabilisation pond system in Mindelo, Cape Verde
Authors: Johansson Per , Pernrup Marie , Rångeby Mikael
Published: May 2018

Water is scarce in Cape Verde. In the city Mindelo almost all fresh water has to be produced by desalination of sea water. In this perspective, reuse of treated waste water for agricultural purposes is a very interesting alternative. The waste water stabilisation pond system in Mindelo is over-sized, with high evaporation and increasing salinity in the effluent water as a result. The salinity is already very high in the influent and with present process configuration the effluent is unusable for irrigation. The treatment plant has to be operated with less surface area to minimise the evaporation. This, on the other hand, means that an acceptable bacteriological quality in the effluent will not be achieved. By subdividing the ponds with removable plastic tarpaulins, a much smaller volume is needed to achieve this. The plastic tarpaulin can be moved and the process may be configured to different influent flows. The technique of subdividing ponds with a plastic tarpaulin is achieved at low cost and is very simple. The bacterial die-off constant, K, in the maturation ponds has been found to be around 2.65 d−1 at 26°C, which is comparable to results determined elsewhere. The bacterial die-off constant in the anaerobic pond was found to be much lower, 0.3 d−1. Operational strategies for different flows are presented.
Waste stabilisation pond decommissioning: a painful but necessary decision
Authors: Lawty Richard , Ashworth John de B. , Mara D. Duncan
Published: May 2018

The Mangere (Auckland, New Zealand) waste stabilisation ponds consist of three facultative ponds in parallel followed by a similarly sized maturation pond, covering a total area of 512 ha. The ponds were commissioned in 1960 and today serve a population equivalent of 685,000. The ponds are operated on a two-to-one effluent recirculation, which is considered to lead to an unstable treatment regime which results in occasional pond failure when they become anaerobic and smell. The ponds operate as tertiary treatment to a primary and secondary plant, the latter treating up to 40 percent of the flow; the combined stream is discharged to the ponds. The effluent from the ponds is discharged to the Manukau harbour, a partially closed tidal basin. To ensure the harbour does not suffer from algal blooms, a total nitrogen effluent standard of 10 mg 1−1 is being proposed by technical advisors. Although the ponds could be uprated to produce an effluent with < 1000 faecal coliforms per 100 ml, they will be unable to meet the nitrogen requirement. It is likely, therefore, that the ponds will be replaced by an activated sludge plant and UV disinfection.
The efficiency of a combined waste stabilisation pond/maturation pond system to sanitise waste water intended for recreational re-use
Authors: Jagals P. , Lues J. F. R.
Published: May 2018

Concern was expressed about the microbiological quality of irrigation water obtained from a combined sewage treatment facility. Treated effluent from the system is used to irrigate sports fields and public parks. This system primarily serves a community with well developed sanitation and also receives partially stabilised waste water from a neighbouring community with limited sanitation. Special concern was expressed for quality of irrigation water when certain stages of the system would be used as waste stabilisation pond system (WSP) during possible prolonged periods of main system failure. During such periods raw sewage would be discharged into such WSP from which irrigation water would still be withdrawn regularly. The pathogen removal efficiency of various parts of the total system including original WSP used within the system, was investigated. Faecal coliforms, male specific coliphages and presence of helminth eggs were used to indicate removal efficiency. Results proved that water from the activated sludge unit was sufficiently sanitised by tertiary treatment ponds (the original WSP). Indications are that the original WSP system was not as efficient in removing pathogens from irrigation water when used as emergency standby WSP.
Pathogen removal mechanisms in anoxic wastewater stabilization ponds
Authors: Almasi A. , Pescod M. B.
Published: May 2018

Anoxic wastewater stabilization ponds can reduce land requirements by as much as two-thirds of that required for facultative ponds and can avoid the environmental nuisances of odour and corrosion, compared with anaerobic ponds. When effluent reuse is to be considered, the aim of wastewater treatment is not only to reduce degradable organic matter but also to remove pathogenic microorganisms. There are many pathogenic agents in domestic sewage and determination of all of them is not practically feasible, so faecal coliform organisms are normally estimated as indicators of health risk.

It has been found that the volumetric organic loading on ponds affects pathogen removal inversely and temperature has a positive effect. This was confirmed in the present studies on “anoxic” ponds and, in addition, other environmental factors (light, pH, DO and ORP) were found to have influenced pathogen removal in these ponds, which were loaded in the range between conventional loadings for anaerobic and facultative stabilization ponds. However, pathogen removal in anoxic ponds was not found to be significantly better or worse than in anaerobic or primary facultative ponds and, therefore, maturation ponds would be required following anoxic ponds to achieve an effluent quality suitable for unrestricted irrigation.
Tube settling of high-rate pond algae
Authors: Nurdogan Yakup , Oswald William J.
Published: May 2018

The effluent of a high-rate pond (HRP) may contain 200 to 400 mg/L of algal suspended solids (SS). Microalgae must be separated before the effluent is discharged. Gravity sedimentation is usually the first method considered in algal wastewater treatment systems. However, required overflow rates (OFRs) to remove algae in the conventional clarifiers are too low. Therefore, the shallow-depth sedimentation concept was studied for the separation of Micractinium from HRP effluent in order to increase the OFRs of gravity settling equipment. Using the orthogonal squares experimental plan, the design parameters, such as OFR, tube diameter, tube length, and inclination, were evaluated for algal SS removal. A circular upflow clarifier was run as a control. At an OFR of 8.15 L/m2 · min (0.2 gpm/ft2), SS removal efficiencies of tube settling and upflow clarifier were 80% and 18%, respectively. When the OFR was increased to 16.3 L/m2 · min (0.4 gpm/ft2), SS removal efficiencies decreased to 61% in tube settler and to 11% in upflow clarifier. SS removal efficiencies of tube settlers were 40% at 30.6 L/m2 · min (0.75 gpm/ft2) and 20% at 71.3 L/m2 · min (1.75 gpm/ft2). A linear relationship exists between removal efficiency and the diameter and length of tubes. The relationship is parabolic for the inclination of tubes and the OFR. The overall algae removal efficiency increased with the tube length but it was an inverse function of OFR, tube diameter, and inclination. At an OFR of 12.2 L/m2 · min (0.3 gpm/ft2), algae removal efficiencies were 7 to 8 times better than that of upflow clarifier. It was demonstrated that OFR in a gravity settler could be increased 4 to 5 times using tube settlers.
Clay liner materials for land disposal of hazardous non-metal wastes
Authors: Lo I. M.-C. , Liljestrand H. M. , Khim J. , Shimizu Y.
Published: May 2018

Simple land disposal systems for hazardous and mixed wastes contain heavy metal cationic species through precipitation and ion exchange mechanisms but typically fail by releasing soluble organic and inorganic anionic species. To enhance the removal of anions from leachate, clays are modified with coatings of iron or aluminium cations to bridge between the anionic surface and the anionic pollutants. A competitive surface ligand exchange model indicates that surface coatings of 10 meq cation/gm montmorillonite under typical leachate conditions increase the inorganic anion sorption capacity by at least a factor of 6 and increase the intrinsic surface exchange constants by more than a factor of 100. Similarly, metal hydroxide coatings on montmorillonite increase the organic anion sorption capacity by a factor of 9 and increase the intrinsic surface exchange constants by a factor of 20. For historical concentrations of non-metal anions in US hazardous and mixed waste leachate, sorption onto natural clay liner materials is dominated by arsenate sorption. With cation coatings, anion exchange provides an effective removal for arsenate, selenate, phenols, cresols, and phthalates. Engineering applications are presented for the use of modified clays as in situ barriers to leachate transport of anionic pollutants as well as for above ground treatment of recovered leachate.
Treatment of silk and lycra printing wastewaters with the objective of water reuse
Authors: Rigoni-Stern S. , Szpyrkowicz L. , Zilio-Grandi F.
Published: May 2018

This paper concerns the treatment of wastewaters produced during printing matrix washing and by dyestuff leakage in the silk and Lycra printing industry. The objective was to obtain effluent of a quality that would allow water reuse. The raw wastewaters contained a high concentration of ammonia nitrogen (from urea, ammonium sulphate and tartrate used for the dyestuff preparation together with organic compounds. A high BOD5COD ratio determined the possibility of a biological treatment of the wastewaters by nitrification-denitrification. To achieve complete denitrification, however, it was necessary to add an external carbon source. A mixture of methyl and ethyl alcohols from pharmaceutical industry wastes was used to achieve a BOD5N ratio of about 3.5. High temperature (23-26°C) and low inhibition enabled good rates of treatment to be achieved in a single-sludge system, equal to 0.042 kgN/kg MLVSS × day and 0.12 kgN/kg MLVSS × day, respectively for nitrification and denitrification. After this stage the effluents were characterized by COD <120 mg/L, BOD5 <25 mg/L, N-NH4 <10 mg/L, N-NHO3 <12 mg/L, N-NO2 <0.3 mg/L values which meet Italian discharge standards. A subsequent quartz filtration and UV sterilization allowed the wastewaters to be reused for washing purposes within the factory. At the final stage of the wastewater treatment it was possible to economize by reusing industrial wastewaters by 30-40%. No problems connected with a gradual accumulation of the recalcitrant or toxic compounds were encountered in the reuse of treated wastewaters and their subsequent biological treatment during 10 months of full scale plant operation. Residual colour removal was however necessary if the wastewaters were also to be used for the preparing of dyes. Laboratory experiments to remove colour using ozone treatment were conducted. A dose of 20 mg/L of ozone was introduced prior to filtration. This step eliminated not only the residual colour but also the residual non-ionic surfactants. As the final result of the treatment it will be possible to use wastewaters not only for washing purposes but also for preparation of the printing colours; it is calculated that economies of 60-70% of process water will be possible.
Laboratory study and computer model development related to gross solids' movement in combined sewers
Authors: Davies John W. , Xu Yanli , Butler David
Published: May 2018

Significant problems in sewer systems are caused by gross solids, and there is a strong case for their inclusion in computer simulation models of sewer flow quality. The paper describes a project which considered methods of modelling the movement of gross solids in combined sewers. Laboratory studies provided information on advection and deposition of typical gross solids in part-full pipe flow. Theoretical considerations identified aspects of models for gross solids that should differ from those for dissolved and fine suspended pollutants. The proposed methods for gross solids were incorporated in a pilot model, and their effects on simple simulations were considered.
Sediment transport modelling in combined sewer
Authors: Huseng Lin , Le Guennec Benoit
Published: May 2018

The classical solid transport theory has been used to analyse the experimental results obtained from the No. 13 combined sewer trunk of Marseille for more than two years. This study demonstrates that the sediment transport phenomena in a combined sewer trunk are nothing other than the classical ones. A numerical model has been established according to the analyses. Based on a permanent flow regime, this model considers not only the effects of the real channel geometry, non-uniform particles size, but also the coexistence of mineral and organically materials. Some particular sediment transport phenomena such as the armouring of bed have also been taken into account. It also shows that although the influence of the suspension particles is not necessarily considered, the simulation including the variations of particle density with each granular fraction may be improved.
Comparison between O3/VUV, O3/H2O2, VUV and O3 processes for the decomposition of organophosphoric acid triesters
Authors: Echigo Shinya , Yamada Harumi , Matsui Saburo , Kawanishi Shosuke , Shishida Kenichi
Published: May 2018

O3/vacuum ultraviolet (VUV, ultraviolet radiation by a low pressure mercury lamp at 185 and 254 nm), O3/H2O2 and VUV processes rapidly decomposed organophosphoric acid triesters (OPEs) dissolved in distilled water as compared to simple ozonation. The O3/VUV process was the fastest of the three advanced oxidation processes (AOPs) for the decomposition of 1 mg/l of OPEs in pH 7.5 phosphate buffer solution (0.5 mM). However the difference between the pseudo-first-order rate constants of the O3/VUV and O3/H2O2 processes decreased in the condition of increasing OPEsw concentration, and the efficiencies of the two processes were almost the same at an initial concentration of 20 mg/l. Contrary to results in distilled water, in an effluent from a solid waste landfill site, the O3/H2O2 process was the fastest. This is manily due to the absorption of VUV radiation by nitrate ion. WE confirmed that nitrate ion of more than a few mg/l strongly interfered with the generation of hydroxyl (OH) radicals from VUV radiation while the O3/H2O2 process was not affected. The use of an ESR-spin trapping technique revealed that AOPs generated more OH radicals than ozonation alone, and the detection of hydrogen atom confirmed that VUV radiation directly generated OH radicals from water.
An innovative process for waste water treatment: the circulating floating bed reactor
Authors: Lazarova V. , Manem J.
Published: May 2018

Increasing volumes of wastewater combined with limited space availability and progressively tightening European standards promote the development of new intensive biotechnologies for water treatment. Fixed biomass processes offer several advantages compared with conventional biological treatments: higher volumetric load, increased process stability and compactness of the reactors. The purpose of this paper is to present a new concept of gas-lift mobile bed, the circulating floating bed reactor (CFBR). The reactor design is simple and does not require any complex technical devices (easier effluent and air-flow distribution, no primary settling, no back-washing).

This new process is studied and developed in an industrial-scale prototype. The optimum hydrodynamic characteristics of the CFBR (liquid circulation velocity 0.3-0.4 m s−1, kLa 50-300 h−1, average mixing time 85 s) were not deteriorated by the high solid hold-ups (up to 40% v/v) of the floating media. On the contrary, three-phase operating improves the local gas hold-up in the downcomer. Improved hydrodynamics in the CFBR guarantee high nitrification rates and operation stability either in tertiary (up to 2 kgN m−3 d−1) or secondary (up to 0.6 kgN m−3 d−1) nitrification. The results show that nitrification is the limiting step in simultaneous C+N treatment. The negative effect of the increasing C/N ratio is more pronounced than stepwise decreasing of the temperature. The study of the biofilm composition and activity shows an effective control of the attached biomass growth by the high liquid circulation velocity.

It is concluded that this new three-phase bioreactor ensures not only an enhanced process stability and biological reaction rate through an effective biofilm control but also guarantees an excellent synergy between hydrodynamic and biological performances. These advantages are highlighted by the simplicity of the reactor design. Thus, this innovative technology will be an attractive solution for intensive wastewater treatment for nitrogen and carbon removal.
The relationship between settling velocity grading and the characteristics of the contributing catchment
Authors: Tyack J. Naomi , Hedges Peter D. , Smisson Robert P. M.
Published: May 2018

A method for measuring the settling velocity gradings of both storm and dry weather flow (DWF) sewage was investigated. This method was then used experimentally to determine whether a relationship exists between the settling velocity grading of a sewage as it enters a treatment works and the characteristics of the contributing catchment.

The problems associated with the collection of data on the characteristics of the contributing catchments are discussed. These include the availability of up to date information within the water companies and the time consuming nature of collecting full sets of information for a particular wastewater treatment works.

An S-shaped curve was fitted to all the settling velocity gradings produced during the research. Relationships relating the curve constants to the catchment characteristics were derived using multiple regression techniques. The methodology was proved, but the model was not sensitive enough to be used successfully as a predictive tool without further analysis involving either more sites and/or a more careful selection of the test sites.