bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstrating the integrity of a large scale microfiltration plant using a Bacillus spore challenge test
Authors: Trimboli P. , Lozier J. , Johnson W.
Published: May 2018

For protection against Cryptosporidium and Giardia New Zealand drinking water regulations established a goal of removal of all particles of 1μm and larger. The City of Tauranga, New Zealand, commissioned a 36 ML/d (9.5 mgd) microfiltration (MF) plant, the Joyce Road Water Processing Plant (JRWPP), to meet this stringent reduction goal. The plant consists of ten USF Memcor 90M10C units. This paper details a bacillus spore challenge test conducted on the JRWPP. The objectives were to (1) confirm that the plant could achieve the required 5 log reduction of particles, and (2) evaluate direct and indirect integrity testing methods as means to confirm log-5 particle reduction performance over the life of the plant. The test used Bacillus megaterium spores dosed into the feed water with the plant operated to maximise the challenge on the MF hollow fibre membranes. The results showed (1) the ability of an integral MF plant to reject Bacillus megaterium spores and achieve at least log 5.9 reduction in organisms; (2) Bacillus spores are a good medium for testing as they are robust, easy to handle, cultured in large quantities, and easily identified; (3) the spore challenge test cannot be economically used to monitor full-scale plant performance; (4) particle counting results correlated poorly with bacillus counts in feed or filtrate; and (5) the USF Memcor integrity test methods, which included a pressure hold test and a diffusive airflow test, underestimated spore rejection.
Adsorption performance of powdered activated carbon-ultrafiltration systems
Authors: Campos C. , Baudin I. , Lainé J.M.
Published: May 2018

The use of powdered activated carbon in combination with ultrafiltration membranes is attracting increasing interest for the removal of organic compounds in drinking water treatment. The overall adsorption efficiency of this hybrid membrane process strongly depends on the reactor configuration and its operating conditions. Identification of the operating conditions yielding optimum carbon performance can be facilitated by the use of mathematical models describing the adsorption process. In this study, the effect of various designs and operating parameters on the efficiency of the adsorption process is discussed using an adsorption model previously developed and verified by the authors. This discussion includes the effect of filtration time, membrane reactor volume, carbon dosing procedure, carbon dose and carbon particle size on the adsorption removal of two selected micropollutants and dissolved organic matter.
Development of advanced ceramic membrane filtration system combined with ozonation and powdered activated carbon treatment
Authors: Shioyama M. , Kawanishi T. , Yokoyama S. , Nuno M. , Yamamoto T.
Published: May 2018

Combining the Kubota Tank-Submerged type Ceramic Membrane filtration (TSCM) system with ozonation and powdered activated carbon (PAC) treatment, a new water treatment system, the advanced TSCM system, has been developed. It is a compact, maintenance-free and high performance system for water treatment plants in the small and medium size cities. In this paper, experimental results using 5.5m3/day demonstration plants are shown, and treatment performance is discussed mainly focussing on removal of disinfection by-products. Turbidity, color, total iron, total manganese and ammonia nitrogen were removed to below their detection limits. Accumulation of suspended solids including PAC at a maximum concentration of 8000 mg/L in the membrane tank increases biological degradation activity in the TSCM system. Furthermore, it was confirmed that the advanced TSCM system was able to effectively eliminate disinfection by-products and other organic contaminants in raw water. 75% of T-THMFP removal rate was obtained at only 10 mg-PAC/L dosage without the effect of ozone dosage, while the PAC treatment at 50 mg-PAC/L dosage prior to coagulation results in T-THMFP removals ranging from 40 to 60% (The Adoption Guideline of Advanced Water Treatment Facility, 1988). Therefore, it is concluded that the advanced TSCM system saves on the amount of PAC and is more cost-effective than the other conventional water treatment systems due to efficient utilization of the adsorption capacity of PAC.
Application of microfiltration for reuse of backwash water in a conventional water treatment plant - a case study
Authors: Song H. , Fan X. , Zhang Y. , Wang T. , Feng Y.
Published: May 2018

In conventional drinking water treatment processes, the amount of the filter backwash water covers nearly 3% of the total production. To reduce the water loss and waste discharge in the conventional drinking water treatment process, the Macao Water Supply Co. Ltd (SAAM) plans to recover the backwash water by Microfiltration (MF) membrane process as water resources are scarce and new environmental regulations are mandated in Macao. Generally, the filter backwash water from the conventional water treatment plant with sedimentation process is recycled to the source water to be treated again under certain conditions, and the sedimentation tank discharges most of the sludge. However, it is possible to recycle the backwash water directly to the inlet for direct filtration process due to the limitation of inlet turbidity. This paper describes how to apply MF technology to treat the backwash water of the direct filtration plant and to optimize MF operation. Without pre-treatment of the settling basin for backwash water, the operation of the MF pilot plant is proved to be stable and the permeate quality can meet EU drinking water standards. The pilot study shows that it is both economically and technically feasible to adopt MF technology in backwash water treatment. The main parameters to test MF process include flux, chemical cleaning duration and transmembrane pressure (TMP). They are 150-200 L/m2.h, 20 days and <1 bar respectively. The estimated cost including O&M and investment for a 1320-1760 m3/d backwash water treatment plant is USD 0.126-0.168/m3.
Membrane thickening of water works sludge
Authors: Gillighan A. , Judd S.J. , Eyres R.
Published: May 2018

The efficacy of ultrafiltration (UF) and microfiltration (MF) membranes was assessed for the concentration of actual waterworks sludges using crossflow tubular membranes operated at constant trans-membrane pressure. The MF membrane gave higher initial fluxes than the UF membrane but after 10 min of filtration the flux value and its decline tended to be very similar for both membranes operating under the same conditions. All membranes gave permeate product water of <0.2 NTU and <100ppb coagulant at all times. For both membranes mechanical cleaning, with sponge balls, was at least as effective as acid chemical cleaning, indicating that no significant permanent internal fouling occurred for these membrane materials. Hydraulic resistance data indicated a significant difference in the dynamic layer resistance between the two membranes. Whilst the UF membrane had a hydraulic resistance 3.7 times that of the MF membrane, the dynamic layer formed on the UF membrane during operation displayed a maximum hydraulic resistance almost nine times lower than that of the MF membrane operating under the same conditions. Correlation of cake resistance R versus feed solids concentration C for all the data generated for t>0 demonstrated reasonable agreement with the expression R∝ca where a=0.37 in the current study. This trend has been recorded in previous reported studies, a varying between 0.33 and 0.62 depending on sludge dewaterability.
Comparison of UV and chlorine pretreatment in pilot plant micro-filter membrane separation for drinking water
Authors: Huang J.Y. , Takizawa S. , Fujita K.
Published: May 2018

Methods to control bio-fouling, i.e. UV-irradiation and chlorination pretreatment were evaluated in dead-end membrane filtration. Pilot-scale experiments were carried out at Kosuzume Water Purification Plant, which is located at the Sagami River in Kanagawa Prefecture, Japan. As a result, both UV-irradiation and chlorination strongly suppressed the increase of transmembrane pressure and prevented bio-fouling. However, in the case of pre-chlorination, the membrane color changed from white to brown after a long use, causing irreversible membrane fouling due probably to manganese adsorption. Suspended solids removal by membrane filtration decreased the formation potential for CHCl3, but didn't affect the CHCl2Br and CHClBr2 formation potentials. Pre-chlorination, however, increased both CHCl2Br and CHClBr2 formation potentials, thus making up for the reduction in CHCl3 formation potential due to membrane filtration. UV-irradiation pretreatment combined with membrane filtration in the water purification process is regarded as an accessible method and was proved effective in controlling bio-fouling, which gave us a better water quality without increasing trihalomethanes in contrast to pre-chlorination.
Pilot scale studies on the removal of trace metal contaminations in drinking water treatment using chelating ion-exchange resins
Authors: Stetter D. , Dördelmann O. , Overath H.
Published: May 2018

Increasing nickel concentrations in groundwaters are causing treatment problems in some locations in Germany and other European countries. Ion exchange treatment using iminodiacetic acid resin was studied under various conditions in a pilot scale plant. Breakthrough curves show that nickel, cadmium and lead concentrations of below 100 μg/L can easily be reduced to 1% of the feed concentration. Assuming a minimum removal rate of 95% the treated volumes ranged from 75,000 bed volumes up to 195,000 bed volumes depending on flow rate and calcium concentration. The process has no impact on other chemical and microbiological water quality parameters. Ideally the feed water should be free from turbidity, iron and manganese, otherwise head loss will grow very fast because of high filtration rates and the small diameter of resin beads used in this process. Nevertheless, the ion exchange resin can be backwashed without increasing the metal concentration in the effluent. Ion exchange using iminodiacetic resins is therefore a suitable treatment process for the removal of heavy metals from drinking water.
Nitrification in rapid sand filter: phosphate limitation at low temperatures
Authors: van der Aa L.T.J. , Kors L.J. , Wind A.P.M. , Hofman J.A.M.H. , Rietveld L.C.
Published: May 2018

In winter 1995-1996 the RSF of AWS River-Lake Waterworks suffered from ammonium breakthrough. Research indicated that the nitrification was limited by stagnated growth of the nitrifying bacteria due to low phosphate concentrations at low temperatures (0-3°C). Phosphoric acid was dosed prior to the RSF (dose 35-50 μg PO43- -P.l-1) to stimulate bacteria growth. Two weeks after starting the addition, ammonium removal in the RSF had recovered.

AWS is conducting research on alternatives for production capacity extension. Several alternatives involve the construction of an additional RSF prior to the reservoir. Pilot experiments on RSF prior to the reservoir show that complete nitrification in these additional RSF is possible. The phosphate concentration should amount at least 10 μg PO43- -P.l-1.

A model has been developed to predict nitrification in RSF. The model confirms the results from both the River-Lake Waterworks' RSF as from the pilot RSF. The model is used for process control and scenario studies.
Problems related to particulate and dissolved components in water: the importance of organic matter
Authors: Bursill D. , van Leeuwen J. , Drikas M.
Published: May 2018

Natural organic matter (NOM) of microbial, animal and vegetable origin in reservoir catchments is the key factor influencing most, if not all water treatment processes. The character of the NOM and its involvement in water treatment processes requires greater understanding for determination of improved removal processes and interactions with other water contaminants. It is considered that a greater understanding of NOM reactions would lead to far better predictive capacity for water treatment designers and operators to minimise its impacts in treated water. Maximising the removal of NOM in the production of drinking water has many attractions such as minimising the formation of disinfection by-products and bacterial regrowth in the distribution system. By enhancing NOM removal, residual colour is also minimised. This paper provides an overview of work performed in Australia, on the issue of NOM removal from raw waters using conventional and novel technologies.
Performance and membrane foulant in the pilot operation of a novel biofilm-membrane reactor
Authors: Kimura K. , Watanabe Y.
Published: May 2018

We have developed a novel biofilm-membrane reactor (BMR) in which a nitrifying biofilm is fixed on the surface of a rotating membrane disk. With this reactor, both strict solid-liquid separation and oxidation of ammonia nitrogen can be simultaneously performed. Based on the results obtained in previous bench-scale experiments, a pilot-scale study was conducted using river water at a water purification plant. The results obtained in the pilot study can be summarized as follows. (1) By implementation of pre-treatment (coagulation and sedimentation) and simple membrane cleaning (sponge cleaning), the filter run could be continued for 17 months without any chemical washing. (2) Sufficient nitrification was observed when water temperature was high. Deterioration in nitrification efficiency during winter was reduced by the addition of phosphorus. (3) In addition to nitrification, biological oxidation of AOC and manganese can be expected with the BMR. In this study, both AOC and manganese concentration in the permeate decreased to a level less than 10 μg/L. (4) Irreversible membrane fouling, which was thought to be mainly caused by manganese, became significant as the operation period became longer.
Risk assessment for drinking water production: assessing the potential risk due to the presence of Cryptosporidium oocysts in water
Authors: Laîné J.M. , Démotier S. , Odeh K. , Schön W. , Charles P.
Published: May 2018

This paper presents an approach for assessing the risk of producing non-compliant drinking water (i.e. one of the quality parameters exceeds the standards fixed by legislation), taking into account the quality parameters of raw water and the process line of the treatment plant (technology, different failure mode and corresponding failure rate). Firstly, nominal and degraded modes of each step of the treatment line are analysed, in order to obtain transfer functions (which give output concentration of parameters in function of the input concentration) for each step of the treatment and each quality parameter, in nominal and degraded functioning. The transfer function of the whole treatment process can thereby be obtained by combination of transfer function of each step, and failure conditions of the whole treatment process and corresponding degraded global transfer function could be determined. Secondly, an inversion of both global function (nominal and degraded) permits to estimate probability for the resource to exceed thresholds fixed by regulation (in that case, a scenario of non-compliant drinking water exists), and to obtain a compliant water availability. Finally, this paper presents a software tool realised to evaluate the risk of non-compliant produced water, using the described methodology. Finally, an approach of risk assessment for Cryptosporidium is also presented. This method allows to identification and puts priorities for utilities presenting the highest risk.
Algae as surrogate indices for the removal of Cryptosporidium oocysts by direct filtration
Authors: Akiba M. , Kunikane S. , Kim H.-S. , Kitazawa H.
Published: May 2018

To evaluate the appropriateness of using algae as surrogate indices for the removal of Cryptosporidium parvum oocysts in conventional water treatment by rapid sand filtration, investigations on algal removal at eight water treatment plants and laboratory experiments using three species of algae and C. parvum oocysts were conducted. From the 5 years data collected from eight water treatment plants, the algal removal showed 0.63 - 1.83 log in coagulation and 1.66 - 4.17 log in sand filtration including coagulation. In jar tests, zeta potentials of flocs at an ALT ratio of 0.05 were -8.5 mV, -8.5 mV, -7.0 mV and -10.5 mV, and the removal rates at pH 7 were 2.05 log, 1.15 log, 1.51 log and 1.49-log for Microcystis viridis, Microcystis aeruginosa, Selenastrum capricornutum and C. parvum oocysts, respectively. In direct filtration tests, the removal rates of algae and C. parvum oocysts, except for M. aeruginosa, were around 3-log during the filtration time of 15-45 minutes when the best removal occurred. S. capricornutum, out of the three species of algae, showed almost the same coagulation characteristics as C. parvum oocysts and also behaved in a filtration pattern similar to C. parvum. From these results, algae were considered useful surrogate indices for the removal of C. parvum oocysts, and S. capricornutum was thought to be an appropriate one in rapid sand filtration.
A fast and sensitive nucleic acid extraction method for the detection of Cryptosporidium by PCR in environmental water samples
Authors: Dellundé J. , Pina S. , Jofre J. , Lucena F.
Published: May 2018

A new protocol based on a combination of an excystation process followed by a nucleic acid extraction that combines the lysing and nuclease-inactivating properties of the chaotropic agent guanidinium thiocyanate and the nucleic acid-binding properties of silica particles is described for the extraction and purification of nucleic acids from Cryptosporidium. The application of nested and/or semi-nested PCR using different external and internal primers to DNA extracted by this method from seeded and naturally occurring Cryptosporidium oocysts concentrated and purified from environmental samples detects numbers of oocysts ranging from 20 to 50. The method is feasible, detects mostly excystable oocysts and no problems of inhibition of PCR were observed when applied to environmental samples.
In situ examination of microbial populations in a model drinking water distribution system
Authors: Martiny A.C. , Nielsen A.T. , Arvin E. , Molin S. , Albrechtsen H.-J.
Published: May 2018

A flow cell set-up was used as a model drinking water distribution system to analyze the in situ microbial population. Biofilm growth was followed by transmission light microscopy for 81 days and showed a biofilm consisting of microcolonies separated by a monolayer of cells. Protozoans (ciliates and flagellates) were often seen attached to the microcolonies. The biofilm was hybridized with oligonucleotide probes specific for all bacteria and the α- and β-subclass of Proteobacteria and visualized with a scanning confocal laser microscope. Hybridization showed that the microcolonies primarily consisted of a mixed population of α- and β-Proteobacteria. 65 strains from the inlet water and 20 from the biofilm were isolated on R2A agar plates and sorted into groups with amplified rDNA restriction analysis. The 16S rDNA gene was sequenced for representatives of the abundant groups. A phylogenetic analysis revealed that the majority of the isolated strains from the bulk water and biofilm were affiliated to the family of Comamonadaceae in the β-lineage of Proteobacteria. The majority of the strains from the α-lineage were affiliated to the family of Sphingomonadaceae. We were unable to detect any strains from the Pseudomonas genus and found a low abundance of bacteria affiliated to the γ-subclass of Proteobacteria where Pseudomonas and E. coli are positioned. The analysis revealed a high bacterial diversity in the water phase as well as the biofilm, but no strains were found in both environments.
International Report: Water losses management and techniques
Authors: Lambert A.O.
Published: May 2018

Since the 1991 IWSA International Report on “Unaccounted for Water and the Economics of Leak Detection”, the topic of management of water losses in distribution systems has received increased attention. This International Report seeks to present an overview of the “state of the art” in management of Water Losses, based on the Reports prepared by National Rapporteurs, the recent recommendations of the IWA Task Forces on Water Losses and Performance Measures, and improved concepts for modelling components of leakage and pressure: leakage relationships. The IWA Task Force recommendations provide overdue clarification and guidance on several issues that have caused persistent problems in quantifying Water Losses and comparing the effectiveness of their management. It is hoped that this Report will assist in the promotion of a more standardised international approach to the definition, assessment, monitoring and management of Non-Revenue Water and Water Losses.
Practical application of metric benchmarking in water supply systems
Authors: Cabrera E. , Arregui F. , Cobacho R. , Trull O.
Published: May 2018

Metric benchmarking has been widely quoted as a powerful management tool. However, as useful as metric benchmarking can prove, its actual application may present several inconveniences. These include internal resistance to the project, difficulties in finding a suitable partner, finding an appropriate set of indicators, actual data management and results analysis. This paper will present general guidelines to carry out a metric benchmarking project within the water industry, as well as some tools that may be used to overcome some of these difficulties.
Dealing with large particle counting data sets
Authors: Ceronio A.D. , Haarhoff J.
Published: May 2018

A particle count survey of 21 South African water treatment plants over a period of 15 months presented the authors with challenges similar to those experienced by other workers in the field. The amount of data generated was staggering and had to be dealt with in an orderly and structured way to derive the maximum benefit from the survey. Furthermore, the number of significant data points involved if the entire count is to be taken into consideration complicated interpretation of particle counting data. This led to the application of several data reduction techniques to reduce the number of significant parameters that had to be considered during analysis. The most common conventional method is the use of the total particle count larger than a given size, for example total count per ml > 2 μm. This method, however, negates one of the most powerful abilities of the particle counter, namely the ability to indicate particle size distribution. The application of the power law, a common alternative, provides a more detailed description but has its flaws. In this paper the authors illustrate how many particle counts were successfully handled in a purpose-designed database and how the power law concept was improved to provide a better particle counting data-reduction methodology.
Effect of pressure on bubble size in dissolved air flotation
Authors: Han M. , Park Y. , Lee J. , Shim J.
Published: May 2018

Although dissolved air flotation (DAF) has been successfully adopted for water and wastewater treatment, the fundamental characteristics of the process have not been fully investigated. According to recent theoretical work on DAF, bubble size is one of the most important factors that affect the efficiency of the process, with better removal efficiency when the sizes of both bubbles and particles are similar. In this study, a newly developed particle counter method (PCM) was introduced to measure particle sizes. To confirm its usefulness, the results were compared with those from image analysis. Then, using PCM, the size of bubbles in DAF was measured under various pressure conditions which are known to affect the bubble size the most (from 2 to 6 atmospheres). The bubble size decreased as the pressure increased up to a pressure of 3.5 atmospheres. Above this critical pressure, the bubble size did not decrease with further increases in pressure. According to these experimental results, it is not only costly, but also unnecessary, to maintain a pressure above 3.5 atmospheres if the goal is only to generate smaller bubbles.
Analysis of a clariflocculation process with a photometric dispersion analyser (PDA2000)
Authors: Rossi L. , Lubello C. , Poggiali E. , Griffini O.
Published: May 2018

In this experimental study the clarification process of the drinking water treatment plant (WTP) of Florence (Italy) has been evaluated. At present, the most common way to optimise the clariflocculation process (best type and dosage of coagulants and mixing conditions) is the jar-test procedure which can give information about the final turbidity, and consequently the process efficiency, after a settling period in a batch procedure at laboratory-scale. An alternative method with a Photometric Dispersion Analyser (PDA2000) was recently introduced at the WTP to provide quick and continuous information (flocculation index, correlated with the flocs size) about the aggregation state of particles during a modified jar-test procedure. The PDA2000 was applied to a real suspension (namely Arno river water) providing useful data for the determination of best type and optimum dosage of coagulants. Furthermore a strong correlation between the removal efficiency of the turbidity and PDA a parameter derived from the PDA 2000 data (defined as the rate of the square root of the flocs size index and the maximum slope of the growing curve) was observed.
Color and suspended solid removal with a novel coagulation technology
Authors: Pak D. , Chang W.
Published: May 2018

A novel coagulation technology using atomized molten slag with ferrous sulfate has been developed to treat a turbid and colored water or wastewater. The atomized molten slag is produced by atomizing the molten slag from the steel-making process. The atomized molten slag has magnetic iron oxide in its constituent molecules so that it is magnetized. In this novel coagulation technology, the atomized molten slag acts as nuclei for coagulation process and weighting agent for the resultant floc. In this study, this new coagulation technology was compared with metal hydroxide flocs such as FeCl3 and PAC in treating textile wastewater. A batch settling test was conducted to investigate the settling characteristic of sludge formed with the atomized molten slag. The settling velocity of sludge formed with the atomized molten slag is almost ten times greater than that of sludge formed with FeCl3 or PAC. The coagulation using the atomized molten slag showed a higher removal rate of color, suspended solid, TOC, COD, TKN and T-P. The atomized molten slag is capable of adsorbing organic substance, ammonia and phosphate. This characteristic leads to higher removal rate than FeCl3 or PAC. The gel permeation chromatography of the wastewater treated using the atomized molten slag illustrated that this novel coagulation technology is more efficient in removing the particles with low molecular weight. The removal rates of color, suspended solid, COD, TOC, ammonia and phosphorous increase with increasing amount of atomized molten slag addition. Even though the atomized molten slag was overdosed, restabilization of particles was not encountered.
Development of a naturally derived coagulant for water and wastewater treatment
Authors: Folkard G. , Sutherland J.
Published: May 2018

Seeds of the pan tropical tree, Moringa oleifera Lam. (M. oleifera) contain water soluble, positively charged proteins that act as an effective coagulant (molecular weight 13 kDa and isoelectric pH 10-11). Treatment studies are reviewed using the extracts of the crushed seed kernel and of the presscake (solids residue remaining after oil extraction). M. oleifera seed was incorporated into a pilot scale treatment system as a primary coagulant to clarify river water of 400 NTU in the wet season. Over 90% turbidity removal was achieved in the sedimentation stage at a dosage of 100 mgL-1. The filtrate turbidity was maintained well below 5 NTU. Subsequent trials were conducted in an adjacent works operating at 60 m3h-1. Treatment performance was comparable to that of using aluminium sulphate. Inlet turbidities of 270-380 NTU were consistently reduced to below 4 NTU. A comprehensive study was undertaken to evaluate the potential of using M. oleifera coagulant within a contact flocculation filtration (CFF) pilot rig. A wide range of operating conditions was evaluated in order to establish the useful “working envelope” for this process combination (filtration rates 5-20 mh-1, initial turbidities 20-50 NTU). Principal results are presented. As a coagulant within chemically enhanced primary sedimentation (CEPS) of a mixed wastewater, M. oleifera dosed at 150 mgL-1 gave additional removals (compared to a plain sedimentation control) of 40% biochemical oxygen demand (BOD) and chemical oxygen demand (COD) and in excess of 80% for suspended solids (SS). Subsequent laboratory work coupled an upflow anaerobic sludge blanket reactor (UASB) to CEPS. M. oleifera coagulant in the CEPS pre-treatment unit beneficially increased the ratio of soluble COD to volatile SS by a factor of ten compared to plain sedimentation and by a factor of three when dosing ferric chloride. The UASB yielded more biogas and gave enhanced COD removal. Recent work on the extraction and purification of the active coagulant components is reviewed and the prospects for commercialisation are considered.
Family filter with iron-coated sand: solution for arsenic removal in rural areas
Authors: Petrusevski B. , Sharma S.K. , Kruis F. , Omeruglu P. , Schippers J.C.
Published: May 2018

The presence of arsenic in groundwater is recognised as a threat to public health world-wide and specifically in rural areas of several developing countries due to variety of health-related problems observed in populations ingesting arsenic-containing water. Several arsenic removal technologies suitable mainly for centralised treatment are available or under investigation. However, point-of-use arsenic removal systems, suitable for application at household level appear to be the only feasible solution under conditions prevailing in rural areas of developing countries characterised in general by the absence of centralised water supply systems. Several household level arsenic removal units are commercially available and some of them are currently under testing in Bangladesh. Nevertheless there is still need to develop a more efficient and sustainable point-of-use arsenic removal unit. Very promising results were recently obtained in laboratory experiments with a simple “family filter” with iron-coated sand (ICS) or iron-impregnated granular activated carbon. The objective of this study was to establish methodology for assessment and selection of appropriate ICS for arsenic removal with “family filter”. An additional objective was to optimise and test further “family filter” with selected ICS. Batch and filtration laboratory adsorption experiments were conducted with five types of ICS originating from Dutch groundwater treatment plants and model and natural groundwater with high arsenic concentration. All ICSs tested demonstrated arsenic removal potential with removal efficiencies ranging from 50 to 100%. Short adsorption experiments can be applied to screen the suitability of different ICSs. Adsorption isotherm and filter runs are, however, needed to establish arsenic adsorption capacity of a particular ICS. Contact time was found to be the critical parameter for “family filter” design and performance. The “family filter”, very simple point-of-use treatment unit, equipped with an appropriate ICS demonstrated high arsenic removal potential and could be very attractive for arsenic removal in rural areas of developing countries.
Plastic tastes in drinking water: factors affecting the chemistry of bromophenol formation
Authors: Heitz A. , Blythe J. , Allpike B. , Joll C.A. , Kagi R.
Published: May 2018

A “plastic” or “chemical” taint, has recently emerged as a problem in drinking water in Perth, Western Australia. The taste occurs intermittently in zones receiving blends of treated groundwaters from several sources, generally only in boiled water. The compound primarily responsible is 2,6-dibromophenol (taste threshold concentration 0.5 ng/L). It was established that the relative ratios of phenol, bromide and chlorine, and pH are important determinants in whether the taste would or would not form and that the primary sources of phenol are plastic appliances, especially kettles and refrigerators (Heitz et al., 2001). However, bromophenol formation varied widely between waters from different sources, even though reaction conditions were ostensibly identical, and it was concluded that another, as yet unknown, factor must influence the reaction rate. This could account for observations that plastic taste only occurred in some groundwaters, but not in others. In the present study the effects of organic and inorganic nitrogen-containing compounds on phenol bromination rates were examined, with the view that this might give some insights into the nature of the unknown factor discussed above. These compounds slowed the rate of bromophenol formation, and results suggested that disinfection using chloramine, rather than chlorine, could prevent plastic taste problems.
Removal of color and estrogenic substances by fungal reactor equipped with ultrafiltration unit
Authors: Fujita M. , Ike M. , Kusunoki K. , Ueno T. , Serizawa K. , Hirao T.
Published: May 2018

Removal/degradation of color components and endocrine disruptors (EDs) by a bioreactor employing a white rot fungus Trametes hirsuta IFO4917 equipped with ultramembrane filtration (UF) unit was proposed and experimentally investigated. Among 20 white-rot fungal strains, T. hirsuta IFO4917 was screened as a most effective white-rot fungus for removal/degradation of color and EDs. This strain could effectively decolorize humic acid and degrade a wide range of Eds: bisphenol A (BPA), nonylphenol (NP), 17 beta-estradiol, estrone and estriol, although di-(2-ethylhexyl) phthalate (DEHP) could not be degraded. A bench scale (10 L), sequencing batch reactor using this fungus was developed and applied to decolorization of a melanoidin containing synthetic wastewater (4,200 color unit). The fungus was immobilized onto polyurethane foam cubes to stably maintain the biomass, and UF was applied to achieve a complete solid/liquid separation. The wastewater was decolorized in a main bioreactor and the resultant biologically treated wastewater was subjected to UF to obtain permeate as the effluent. The concentrate containing the remaining colored components with higher molecular weights was returned to the fungal bioreactor for further decolorization. In this fungal/UF system, 70% of the decolorization was constantly achieved at HRT of 2 days. The fungal/UF system was scaled up to a pilot-scale plant (200 L), and applied to the treatment of the secondary effluent from a night soil treatment process containing color components (1,000 color unit) and some EDs, NP, 4-t-octylphenol (OP), DEHP and benzophenone. 65-70% of decolorization efficiency was achieved at a 1.5 day cycle sequencing batch operation. NP, OP and benzophenone were removed efficiently with removal of 94%, 89% and 81%, respectively. However, the removal of DEHP was not so effective (45%).
The effect of particulate material and the loading of bacteria on a high dose PAC-MF system
Authors: Khan M.M.T. , Kim H.-S. , Katayama H. , Takizawa S. , Ohgaki S.
Published: May 2018

The effects of particulate material, their size distribution and the loading of total bacteria based on the age distribution of powdered activated carbon (PAC) were investigated in a hybrid membrane process consisting of an immersed microfiltration membrane system in a completely aerated reactor containing high concentration (40 g/L) of PAC. The laboratory-scale experiments on PAC-MF system were carried out using actual surface water (Tama River, Tokyo), before and after the treatment by a biofilter media. As a result of continuous filtration and backwash experiments, improvement of filtrate water quality and controls of membrane fouling were demonstrated by the addition of PAC. 52% of the PAC fell into a particle size between 22 μm and 45 μm. PAC larger than 125 μm and smaller than 22 mm were 6% and 4% respectively. Due to continuous aeration and Brownian motion of the particles, the size of the PAC inside the reactor was becoming smaller day by day. After 162 days of operation, the particle size from 1-10 μm was higher, which is the suitable size range for the adsorption of bacteria. At the same time, the number of total bacteria was also increasing inside the reactors. The membranes were fouled shortly during end of the operation due to the heavy load of fine particles and high accumulation of bacteria. However, PAC acts as an adsorbent media inside the reactors that causes successive accumulation of total bacteria.
The role of pH on the ultrafiltration for drinking water production in Algarve (Portugal)
Authors: Ribau Teixeira M. , Lucas H. , Rosa M.J.
Published: May 2018

The effect of the pH on the ultrafiltration performance of natural surface waters with moderate NOM content was evaluated at a laboratory scale using a plate-and-frame polysulphone membrane of 47 kDa MWCO. The results at three different pH values (acid, neutral and basic) demonstrated the important role of the pH on the ultrafiltration (UF) performance controlling the membrane - fouling matter interactions. The higher fluxes and lower natural organic matter (NOM) rejections obtained, at basic pH when compared to acid pH, are explained in terms of the variation of membrane and NOM charge, due to electrostatic repulsion and adsorption effects.
Evaluation of Scenedesmus quadricauda as a surrogate of Cryptosporidium oocysts removal in direct filtration
Authors: Kim H.-S. , Kobayashi Y. , Akiba M. , Kunikane S.
Published: May 2018

A comparative study on the evaluation of a Cryptosporidium removal surrogate was conducted using Scenedesmus quadricauda, green algae. Bench-scale direct filtration experiments were carried out at various initial concentrations: 500-5,000 oocysts/ml for C. parvum oocysts and 500-10,000 cells/ml for S. quadricauda. From the results, algal cell or Cryptosporidium oocyst counts of the filtrates (C) increased in proportion to their initial concentrations (C0). However, no significant differences in C/C0 profiles were observed over the examined range of the initial concentration, which implied that the removal efficiencies for S. quadricauda cells and C. parvum oocysts were not related to the initial concentrations. Examination of the deposition in the sand filter showed that a large part of S. quadricauda cells or C. parvum oocyst counts were captured in the upper layer of the sand filter, and the deposition rates were gradually reduced along the filter depth. Total cell or oocysts counts deposited in the sand filter increased commensurate with the initial concentration for both microorganisms. The ratio of the deposited cell or oocyst counts to the deposited amounts of flocs showed quite similar values between S. quadricauda and C. parvum, which meant that these two microorganisms were alike in their removal behavior. From these similar characteristics of removal, S. quadricauda was thought to be a reasonable and reliable surrogate of C. parvum oocysts removal in sand filtration.
Treatment of humic surface water at cold temperatures by ozonation and biofiltration
Authors: Melin E. , Eikebrokk B. , Brugger M. , Ødegaard H.
Published: May 2018

A small full-scale ozonation/biofiltration plant was operated for 1.5 years in mid-Norway. A three-media biofilter was used to remove biodegradable organic matter from ozonated water. The biofilter contained granular activated carbon (GAC), phonolith and CaCO3 and was operated at 26-30 min. empty bed contact time. The water temperature varied between 2 and 14°C but the biofilter was operated most of the time at temperatures below 10°C. Total phosphorus concentration in the raw water was also very low (1.1-2.0 μg L-1). Batch tests showed that low phosphorus concentration and low temperature are potential limitations for microbial growth and organic carbon removal. Initially, the GAC adsorbed organic carbon while the microbial activity was building up. Most of the adsorption capacity was used after 1.5 months of operation. After this period, 14-33% of the TOC was removed (average 23%). Although the overall TOC removal in the process was modest, average BDOC removal of 55% was observed even at 3°C. Ozonation was effective in reducing colour with average removal of 80%. The results show that significant biological activity can be achieved and maintained in biofilter treating ozonated water even at low temperatures and phosphorus limited conditions.
Occurrence of haloacetic acids in chlorinated drinking water
Authors: Singer P.C.
Published: May 2018

Haloacetic acids (HAAs) are a second major class of disinfection by-products (DBPs) arising from the chlorination of drinking water. They have not been studied as extensively as the trihalomethanes (THMs), but in many waters they are found at concentrations equal to, or greater than, the concentration of THMs. Health effects research suggests that some HAA species are more harmful than THM species. This paper summarizes a number of the author's recent investigations concerning the formation, occurrence, stability, and control of HAAs in chlorinated drinking water. A number of examples linking observations made under controlled laboratory conditions to field-scale observations are presented, and the significance of the findings to water treatment practice is discussed.
Relationship between trihalomethanes and haloacetic acids with total organic halogen during chlorination
Authors: Pourmoghaddas H. , Stevens A.A.
Published: May 2018

The effects of bromide ion, pH and reaction time on the formation of four trihalomethanes, nine haloacetic acids and total organic halogens in chlorinated drinking water have been investigated. In this extensive study, the relationship of total trihalomethanes and total haloacetic acids with total organic halogen have been evaluated. The study determined the concentration range of nine haloacetic acids and four trihalomethanes as a percentage of total organic halogen. The results showed that the percentage of total organic halogen made up of total trihalomethanes plus total haloacetic acids significantly increases with increasing bromide ion concentrations and pH. These observations suggest that both a higher bromide concentration and pH cause the formation of mainly brominated trihalomethanes with the reduction of haloacetic acids which could be identified and quantified by current USEPA methods.
Biologically enhanced granulated activated carbon (BAC) filtration of a mixed industrial/domestic tertiary effluent for reuse
Authors: Antonelli M. , Bonomo L. , Bianchi R. , Rozzi A.
Published: May 2018

Biologically enhanced granular activated carbon (BAC) is a promising wastewater post-treatment to produce a purified effluent suitable for recycle in the textile industry. Three small pilot scale filters were used, filled with three media (two adsorbent media and one non-adsorbent), to compare two different GACs and quantify the biomass contribution to organic removal and colour abatement. A demonstrative scale filter was tested in parallel to evaluate the influence of hydraulic parameters on BAC process efficiency. Biomass contribution was significant when an acclimated biofilm grew on particles; in all cases, wastewater decolorising was due to physical-chemical adsorption only; higher hydraulic load negatively affected the polishing process. Laboratory and semi-industrial scale tests were performed on textile fibres and fabrics using samples of the effluent from the demonstrative filter. The tests confirmed the suitability of the treated water for textile reuse.
Low energy treatment system for brewery wastewater reuse
Authors: Parameshwaran K. , Fane A.G. , Cho B.D. , Moosbrugger R. , Kim K.J.
Published: May 2018

A pilot plant consisting of UASB, SBR and microfiltration in series was operated for 15 months to study a low energy treatment option for brewery effluent. The UASB was loaded up to 18 kg/kL.d. However for trouble free operation the loading had to be limited to 14 kg/kL.d. More than 80% of the feed COD was removed in the anaerobic process and a further 60% COD removal was observed in the aerobic process. An air backwashable microfiltration unit was used to remove suspended solids so that the treated water could be reused. The membrane unit was optimised by operating under dead-end, controlled flux conditions (permeate pumping) and air backwashing at set transmembrane pressure (TMP) (in practice the membranes are backwashed at set time interval). Operating energy cost calculations for the membrane system showed that the unit needs to be operated at low flux (say 20 to 30 L/m2.h) to have a low energy demand. However this necessitates a large membrane area. Optimisation for capital and energy cost indicates that the unit needs to be operated at more than 60 L/m2.h depending on the maximum TMP specified. The system energy balance was also calculated. The energy needed for the operation of all units less the energy gained from methane gas generated indicates that the system could yield a net energy of 2.5 kWh/kL water treated. The treated effluent had a turbidity of less than 1.2 NTU and the BOD5 less than 20 mg/L.
On-site water recycling systems in Japan
Authors: Yamagata H. , Ogoshi M. , Suzuki Y. , Ozaki M. , Asano T.
Published: May 2018

Non-potable urban water reuse is Japan's main water reuse practice, which includes water for environmental uses, in-stream flow augmentation, toilet flushing, and industrial reuse. On-site water recycling systems reclaim wastewater on site as well as harvest rainwater in one or more large buildings and distributing the reclaimed water within the buildings for non-potable reuse. Based on our survey conducted in 1999 on current status of on-site water recycling systems in 23 wards of the Tokyo Metropolitan Government District, the following findings are reported in this paper: (1) on the average, 61% of non-potable water demand is met by reclaimed water, and the deficit is made up by tap water from city water supply, (2) biological treatment or ultrafiltration processes can provide reliable treatment and suitable water quality. Some technical problems such as odor from on-site treatment facilities have occurred in a few buildings, (3) there has been no serious accident involving human health by accidentally ingesting reclaimed water, and (4) there is a scale merit in the construction cost of on-site water recycling systems. An on-site wastewater recycling system larger than 100 m3/d is more economically justifiable when compared to a conventional domestic water supply system. An on-site water recycling system can provide an effective, safe, and economical urban water resource for non-potable water reuse applications.
Wastewater reclamation through a physical-chemical pilot and two disinfection systems (ozone and chlorine dioxide) combination
Authors: Folch M. , Huertas E. , Tapias J.C. , Salgot M. , Brissaud F.
Published: May 2018

The DRAC, (“Desinfecció i Reutilització d'Agües Residuals a Catalunya”, Wastewater disinfection and reuse in Catalonia - Spain), project is included in a RDD (Research, Development, and Demonstration) program. The project arises from the necessity to define reclamation treatments guaranteeing an effluent with enough quality to be reused with a minimal microbiological risk. This paper presents the first results obtained from the combination of a physical-chemical pilot and two disinfection pilot systems: ozone and chlorine dioxide. The combination of physical-chemical and disinfection systems allows the use of lower doses of disinfectants, thus minimising the negative impacts of the whole process and improving the reliability of the reclamation facilities.