bluuebunny/crossref_metadata_2025 huggingface dataset:
Biodegradation of bisphenol A in the aquatic environment
Authors: Ike M. , Jin C. S. , Fujita M.
Published: May 2018

Biodegradation potential of bisphenol A (BPA) in the aquatic environments was investigated using 3 activated sludge and 44 river water microcosms. The biodegradation potential was exhibited by most of the tested microcosms; 3 activated sludge and 40 river water microcosms. However, only 6 river water microcosms could completely mineralize BPA, and the others showed accumulation of common metabolites which were detected as 2 peaks according to a high-pressure liquid chromatograph. In total 19 BPA-degrading bacteria were isolated from activated sludge and river water samples, and their BPA degradation property was also investigated. Although all the BPA-degrading bacteria could grow on BPA and remove about 70–80% of TOC derived from BPA, they accumulated 2 common metabolites, and they could not be removed by the prolonged cultivation up to more than 1 month. These 2 metabolites were identified as 2,3-bis(4-hydroxyphenyl)-1,2-propanediol and p-hydroxyphenacyl alcohol in the culture of a typical BPA-degrading bacterium. The experimental results suggested that BPA-degrading bacteria ubiquitously exist in the aquatic environments, but that they cannot completely degrade BPA, leading to the accumulation of more recalcitrant metabolites. For complete BPA degradation, the presence of microbes which can degrade the metabolites seems necessary together with BPA-degrading bacteria.
Development of the ELISAs for detection of hormone-disrupting chemicals
Authors: Goda Y. , Kobayashi A. , Fukuda K. , Fujimoto S. , Ike M. , Fujita M.
Published: May 2018

Six kinds of enzyme-linked immunosorbent assay (ELISA) systems were developed for the quantitative analysis of hormone-disrupting chemicals (HDCs), such as estrogen (ES: the total amount of estrone (E1), 17 β-estra (E2) and estriol (E3)), E2, bisphenol A (BPA), alkylphenol (AP), phthalate esters (PE) and chlorophenols (CP). To generate specific monoclonal antibodies against BPA, AP, PE, CP, hybridoma cells were produced by the fusion of mouse myeloma cells and spleen cells from mice immunized with carboxylated derivatives, while anti E2 monoclonal antibody was selected from those available on the market, and anti ES monoclonal antibody was purchased from Teikoku Hormone Mfg Co. Ltd. The detection limits of ES, E2, BPA, AP, PE and CP ELISAs were 0.1, 0.1, 5, 10, 200, 10 μg/L, when E2, E2, BPA, Nonylphenol (NP), Dibutylphthalate (DBP), 2,4-CP were used as standard, respectively, and the specificity of each ELISA was confirmed with the cross-reaction test using several compounds which have structural resemblance to the compounds of interest.
Accumulation of butyltin compounds and total tin in marine mammals
Authors: Takahashi S. , Le L. T. , Saeki H. , Nakatani N. , Tanabe S. , Miyazaki N. , Fujise Y.
Published: May 2018

Concentrations of butyltin compounds (BTs), including tributyltin (TBT) and its metabolites, di-(DBT) and monobutyltin (MBT), and total tin (ΣSn=organic+inorganic tin) were determined in various tissues and organs of marine mammals collected from Japanese coastal waters. Some marine mammal species from Hong Kong, India, Philippines, Black Sea and North Pacific Ocean were analyzed for comparison. Among the organs and tissues analyzed, concentrations of ΣBTs (TBT+DBT+MBT) and ΣSn were the highest in the liver. Concentrations of ΣBTs and ΣSn in most coastal species were higher than those in offshore species, indicating a greater input of tin compounds in coastal waters. Lower hepatic concentrations of ΣBTs and ratio of ΣBTs to ΣSn observed in pinnipeds may be attributed to higher metabolic capacity to degrade BTs and to their excretion through hair shedding. Age trends in accumulation of both ΣBTs and ΣSn showed increasing concentrations in immature growth stage and stable levels in mature animals.A significant correlation was observed between the hepatic concentrations of ΣBTs and ΣSn in marine mammals. These findings suggest a significant input and/or bioaccumulation of anthropogenic tin. A significant correlation was found between concentrations of ΣBTs (as well as ΣSn) in hair and liver of pinnipeds, suggesting that hair can be used as an indicator for monitoring butyltin contamination in the body of pinnipeds under non-killing condition.
Assessment of arsenic contamination in soils and waters in some areas of Bangladesh
Authors: Alam M. B. , Sattar M. A.
Published: May 2018

The soil samples and tubewell waters were collected from 25 locations representing five thanas of four districts of Bangladesh. The soils were collected from three depths viz. 0–15, 15–30 and 30–45 cm and tubewell waters were collected from same locations. The arsenic content of soils and waters were detected by Molybdenum blue method. The arsenic content in soils ranged from 1.27–56.68, 3.18–54.77, 1.27–50.95, 1.27–39.48 and 3.18–35.66 ppm in Chapainawabganj Sadar, Kustia Sadar, Bera, Ishurdi and Sarishabari thanas, respectively. Out of a total of 25 samples arsenic was detectable for 18 samples at 0–15 cm, 17 samples at 15–30 cm and 15 samples at 30–45 cm depth. One sample at 0–15 cm, 7 samples at 15–30 cm and 4 samples at 30–45 cm depth were found to be slightly contaminated. In tubewell water the arsenic content measured from Chapainawabganj Sadar, Kustia Sadar, Bera, Ishurdi and Sarishabari thanas were ranged 0.010–0.056, 0.010–0.071, 0.010–0.056, 0.010–0.056 and 0.025–0.071 ppm, respectively. Out of 25 water samples 17 contained variable amounts of arsenic where 6 sampling sites contained arsenic levels above 0.05 ppm, and these sites are Rajarampur of Chapainawabganj Sadar thana, Jordaha of Bera thana, Courtpara of Kustia Sadar thana, Nalgari of Ishurdi thana and Ijarapara of Sarisabari thana. Arsenic contained in soils was positively correlated with arsenic content in waters.
Multivariate analyses on heavy metal binding fractions of river sediments in Southern Taiwan
Authors: Yu K. C. , Chang C. Y. , Tsai L. J. , Ho S. T.
Published: May 2018

This study depicts the amounts of heavy metals (Cu, Zn, Pb, Cr, Co, and Ni) bound to four geochemical compositions of sediments (carbonates, Mn oxides, Fe oxides, and organic matters), and the correlations between various geochemical compositions and their heavy-metal complexes. Hundreds of data, obtained from sediments of five main rivers (located in southern Taiwan), were analyzed by using multivariate analysis method. Among the four different geochemical compositions, the total amount of the six heavy metals bound to organic matter is the highest. Zn is easily bound to various geochemical compositions, especially carbonates in sediments of the Yenshui river and the Potzu river (i.e., the heavily heavy-metal polluted sediments); Cr, Pb, and Ni are mainly bound to both Fe oxides and organic matter; Cu has high affinity to organic matter. By performing principal component analyses, the data points of organic matter and both Pb and Cu associated with organic matter cluster together in sediments ofthe Peikang, the Potzu, and the Yenshui rivers, which indicates both Pb and Cu might be discharged from the same pollution sources in these rivers. Moreover, correlations between any two binding fractions of heavy metal associated with Fe oxides in different rivers are not consistent, which indicates some factors including the binding sites of Fe oxides, the extent of heavy metal pollution, binding competitions between heavy metals may affect the amounts of heavy metals bound to Fe oxides. Furthermore, it should be noted that the amount of Pb bound to Fe oxides is highly correlated with the amount of Fe oxides in sediments of the Peikang, the Potzu, and the Yenshui rivers.
Persistent organochlorine pesticides and polychlorinated biphenyls in some agricultural and industrial areas in Northern Vietnam
Authors: Viet P. H. , Hoai P. M. , Minh N. H. , Ngoc N. T. , Hung P. T.
Published: May 2018

Organochlorine pesticide and polychlorinated biphenyl residues were determined in soils and surface sediments collected from Hanoi City, Viettri City and Halong Bay, which are representative of industrial and agricultural areas in northern Vietnam. Polychlorinated biphenyls (PCBs) and organochlorine insecticides such as DDT and its metabolites (DDTs) and lindane were detected in all samples analyzed, indicating the widespread contamination by these compounds in the environment of the north of Vietnam. Concentrations of DDTs and lindane were found to be highest in sediments from Halong Bay, followed by those in Viettri and Hanoi. PCB residues ranged from 0.64 ng g–1 120 ng g–1 (dry weight basis) in sediments and these levels were generally higher than those in soil samples. In general, higher concentrations of pesticides and PCBs were recorded in Halong Bay, suggesting the local sources in this area, probably from mining activities. High accumulation of DDTs in soils, sediments and biotafrom north to south Vietnam indicates that the recent input of DDT is still occurring throughout the country.
Embryonic development assay with Daphnia magna: application to toxicity of chlorophenols
Authors: Abe T. , Saito H. , Niikura Y. , Shigeoka T. , Nakano Y.
Published: May 2018

Cladoceran embryos, derived from Daphnia magna, were used for the developmental toxicity assay system of chlorophenols (CPs) and the quantitative structure-activity relationships (QSAR) studies. As the toxicity end point, the median effective concentration (EC50s) to reduce hatchability was estimated. The EC50s for embryo hatchabilities were found to be significantly correlated to acute immobilization toxicity (24-h EC50s) with juveniles, and the embryo assay appeared to be more sensitive to CPs with higher water solubility than the juveniles assay. The EC50s for embryos were correlated with six physicochemical parameters, and the Pow (n-octanol/water partition coefficient) gave a good correlation in simple linear regression analysis, as is frequently stated in toxicity studies with aquatic organisms. These results suggest that in vitro hatchability assay using D. magna embryos are useful for ecotoxicity screening of aquatic pollutants.
Waste stabilization pond use in Central America: The experiences of El Salvador, Guatemala, Honduras and Nicaragua
Authors: Oakley S.M. , Pocasangre A. , Flores C. , Monge J. , Estrada M.
Published: May 2018

Within the last 15 years 34 waste stabilization pond systems have been built in Central America in the countries of El Salvador (6 systems), Honduras (12 systems), Guatemala (9 systems), and Nicaragua (8 systems); these systems were built for municipalities with populations ranging from 5,000 to 80,000 persons. There are 14 additional systems in the final design phase or under construction in the region, including the first designs for large cities: a 162 hectare facultative system for Managua, Nicaragua (population (1,000,000); and a 168 hectare system for San Pedro Sula, Honduras (population (640,000). Monitoring data from Honduras and Nicaragua show that treatment efficiency is generally comparable to tropical pond systems cited in the literature in other parts of the world, although fecal coliform removal has not been as good as theoretically predicted and the desludging of facultative ponds has been a significant operational cost. While waste stabilization ponds are generally considered the technology of choice for municipal wastewater treatment within Central America, there are, nevertheless, problem areas that need to be addressed if waste stabilization pond use is to have continued acceptance and long-term sustainability. These areas of concern at the regional level are: i) design guidelines using parameters from data developed in Central America; ii) effluent guidelines that are realistic for pond effluents for reuse or surface water discharge; iii) monitoring programs focusing specifically on pathogen removal; iv) cost-effective grit removal and sludge removal from facultative ponds; v) improving designs for pathogen removal; vi) the need for centralized (El Salvador and Nicaragua) versus decentralized (Guatemala and Honduras) mechanisms for financing and operation and maintenance; vii) the development of comparative cost data for construction, operation and maintenance, pond desludging, and microbiological monitoring; and viii) the development of training programs for design, operationand maintenance, and monitoring.
Analysis of organic matter causing membrane fouling in drinking water treatment
Authors: Kaiya Y. , Itoh Y. , Takizawa S. , Fujita K. , Tagawa T.
Published: May 2018

A study was conducted on characteristics of membrane-fouling matter and chemical cleaning of fouled membranes. The membranes were those used for the filtration of raw water taken from the Lake Kitaura, Ibaraki, Japan. Analysis of the molecular weight distribution of extracted foulants by ultrafilters showed that 23% of organic matter was in the fraction exceeding a molecular weight of 100,000 daltons and 33% between 10,000 to 100,000 daltons. Analysis by gel permeation chromatography (GPC) revealed a void peak and five peaks at a molecular weight of less than 6,000 daltons. Assessment by Fourier transform infrared spectroscopy( FTIR) and pyrolysis gas chromatography mass spectrometry (Py-GC-MS) revealed that organic fouling matter contained polysaccharides, proteins, amino sugars and aromatic compounds that constitute humic substances. A comparison of the apparent molecular weight distribution and the FTIR spectra of both the raw water and fouled membrane extracts revealed the attachment of membrane-fouling matter nonexistent in the raw water, which was considered to be extracellular organic matter. Chemical cleaning of fouled membranes suggested that sodium hypochlorite and hydrogen peroxide were effective for the recovery of membrane permeability. In most of the experiments, the higher the cleaning temperature is between 5°C and 40°C, the more effective the chemical cleaning. However, chemical cleaning by a mixture of 1%-NaOCl and 4%-NaOH showed a comparable cleaning efficiency at 5°C as chemical cleaning at 40°C after two hours.
Separation of oil–water emulsion from car washes
Authors: Panpanit S. , Visvanathan C. , Muttamara S.
Published: May 2018

The potentials of UF and NF membrane processes have been evaluated for separation of oil water emulsion generated from car washing operations. Using membranes, wastewater can be effectively recycled and fresh water usage could be reduced. The parameters studied were membrane type, emulsifier types, pressure and competing compounds. Both an-ionic and non-ionic emulsifiers were used for the experimental runs. The Ca2+ and Mg2+ were used as the main competitive ions. Results indicate that a polysulfone membrane caused more flux reduction than the cellulose acetate and thin film polyamide membranes. Higher concentrations of emulsifier presented negative flux decline in both UF and NF membranes. However, the presence of nonionic emulsifier in oil emulsion caused more significant flux reduction than an anionic emulsifier. The NF membrane produced higher TOC removal and less fouling than UF. The results indicate that increased competitive Ca2+ and Mg2+ ions resulted in significant positive NF flux and TOC removal.
Hydodynamic behaviour and faecal coliform removal in a maturation pond
Authors: Brissaud F. , Lazarova V. , Ducoup C. , Joseph C. , Levine B. , Tournoud M. G.
Published: May 2018

A tracer test was performed in a 3,000 m3 and 1 m deep maturation pond located in the south of France. A retention time distribution was determined on the basis of tracer study. Tracer distribution into the pond was also monitored. Physico-chemical parameters and faecal coliform contents were measured at pond inlet and outlet and at 4 points in the pond. During the same period, two 20 m3 and 1 m deep pilot pools were set close to the pond and filled with inlet water. A die-off constant was calculated after the variations of feacal coliform contents observed in the pilot pools. The objective was to verify whether faecal coliform removal can be predicted from observed retention time distribution, assuming a first-order faecal coliform decay with a die-off constant determined in pilot pools. A very good prediction was achieved despite some uncertainties in the experimental data mainly due to pond operation and climatic conditions.
A comparative assessment of bacteriophages as tracers and models for virus removal waste stabilisation ponds
Authors: Vorkas C. A. , Lloyd B. J.
Published: May 2018

The suitability of five strains of bacteriophage as hydraulic tracers and as models of pathogenic virus removal in waste stabilisation ponds was determined in vitro. The bacteriophages investigated included Serratia marcescens, Pseudomonas syringae, Erwinia amanas, and two phages of Erwinia amylovora. The study modeled the survival of these bacteriophages under the physico-chemical conditions typically encountered in WSP systems. This demonstrated that the selected phages, were greatly affected by increased pH and sunlight, but survived for sufficient time at moderate pH levels (6.5-8.5) to justify their use as tracers in full-scale WSPs. Furthermore, their survival/removal in adjusted physico-chemical conditions, suspended solids concentration and temperature, was comparable to human pathogenic viruses. It was concluded that these phages are potentially useful tracers and indicators for pathogenic viruses in WSPs.
Wastewater treatment using membranes: the North American experience
Authors: Côté P. , Thompson D.
Published: May 2018

Key features of the process consisting in coupling biological treatment with membrane separation are described for wastewater treatment. The process development started in the early 1970s with small flow rate applications for on-site commercial development applications and industrial wastewater treatment. The introduction of immersed membrane in the early 1990s allowed the process to be used for municipal wastewater treatment. The results from the 1st year of operation of a 3,800 m3/d plant are presented.
Two stage intermittent aeration membrane bioreactor for simultaneous organic, nitrogen and phosphorus removal
Authors: Seo G.T. , Lee T.S. , Moon B.H. , Lim J.H. , Lee K.S.
Published: May 2018

A submerged membrane bioreactor (SMBR) was operated in 2-stage intermittent aeration for simultaneous removal of organic matter, nitrogen and phosphorus. The system consists of two reactors with a total volume of 0.27 m3 (1st reactor 0.09 m3 and 2nd 0.18 m3). Real domestic wastewater was used as influent to the system. Membrane used for this experiment was hollow fiber polyethylene membrane with pore size of 0.1μm and effective surface area, 4 m2. The membrane was submerged in the 2nd reactor for suction type filtration. Experiment was carried out in two phases varying the time cycles of aeration and non-aeration. SRT was maintained at 25 days and HRT, 16–19 hours. MLSS concentration in the reactors was in the range of 2,700–3,400 mg/l. The MLSS internal recycling ratio was maintained at 100% of influent flow rate. When time cycles of aeration and non-aeration were set at 30/90 min and 60/60 min in reactor 1 and 2, the removal of BOD and COD was 98.3% and 95.6%, respectively. A relatively low nitrogen and phosphorus removal was observed in this condition (73.6% as T–N and 46.6% as T–P). However, with 60/60 min intermittent aeration conditions for both reactors, the removal rate of nitrogen and phosphorus for two weeks steady state were enhanced to 91.6% as TN and 66% as TP, respectively. Further a high organic removal (98% BOD and 96.2% COD) was achieved too. In these conditions, the membrane of flux declined from 0.1 m/d to 0.08 m/d and suction filtration was at 10–12 kPa for a month long operation period.
Sludge accumulation, properties and degradation in a waste stabilization pond in Mexico
Authors: Nelson K. L. , Jiménez B. C.
Published: May 2018

The sludge layer in a primary, facultative wastewater stabilization pond in Texcoco, Mexico was studied. Five sludge cores were taken in the pond, near the entrance, middle, exit, and at the midpoint about 5 m from each side. Each core was stratified into four subsamples and analyzed. Temperature, pH, ORP, and %VS decreased with depth (age) in the sludge layer, whereas ammonia and TS concentrations increased. The concentrations of fecal coliforms and viable helminth eggs also decreased with depth in the sludge layer, but significant concentrations of both organisms were still present in the oldest sludge, which is estimated to be over seven years old (average). From a sludge depth survey it was found that the majority of the sludge accumulated near the inlet of the pond. The average net sludge accumulation rate was estimated to be 24 mm/yr.
Phosphorus release from sediments of a deep wastewater stabilization pond
Authors: Ortuño J. F. , Sáez J. , Llorens M. , Soler A.
Published: May 2018

The fractional composition and potential mobility of particulate phosphorus was investigated in sediment from a deep wastewater stabilization pond. The predominant phosphorus fractions were Fe- and Al-bound P (NaOH-RP) and Residual-P (consisting mainly of organic P), which amounted to 35 and 34% of total phosphorus, respectively. A laboratory study was conducted to determine the influence of various environmental parameters (pH, redox conditions, biological activity and temperature) on phosphorus release from lagoon sediment. Phosphorus release was observed under both anaerobic and aerobic conditions. Anaerobic release was about 1.4-5 times greater than aerobic release. Phosphorus release was redox-sensitive and favoured by high pH values, up to 17.4% of total phosphorus being liberated anaerobically and at high pH. Biological activity favoured phosphorus release, since the amount released under non-sterile conditions exceeded that observed under sterile conditions.

Sediment phosphorus was fractionated before and after the release experiments. The NaOH-RP fraction was sensitive to pH and redox environmental changes, and was readily released under reduced conditions and at high pH. The mobility of the Residual-P fraction was enhanced in incubations involving biological activity due to the decomposition of the organic matter in the sediments, and NaOH–nRP (organic phosphorus) decreased by up to 45% during the incubation of non-sterile suspensions.
Treating faecal sludges in ponds
Authors: Strauss M. , Larmie S. A. , Heinss U. , Montangero A.
Published: May 2018

Waste stabilisation ponds are a widely accepted and proven technology to treat wastewater. It is often stipulated (and also practised) that the design of ponds for faecal sludges (FS), septage in particular, should follow the same principles as for wastewater. Field research conducted by SANDEC and its partners at the Water Research Institute in Ghana, and information gathered from the scarce literature on FS treatment, however, has shown that design principles should be taken into consideration, which are specific to the treatment of FS. These principles depend on the type of FS to be treated and on the type of pond system envisaged. Issues dealt with in this article are the handling of FS solids; the role of anaerobic ponds in FS treatment; the anaerobic degradability of septage; and ammonia (NH3–N) toxicity.
Improvement of microfiltration performance in water treatment: is critical flux a viable solution?
Authors: Vigneswaran S. , Kwon D.Y. , Ngo H.H. , Hu J.Y.
Published: May 2018

In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.
Cross-flow microfiltration with high frequency reverse flow
Authors: Héran M. , Elmaleh S.
Published: May 2018

High frequency reverse filtration was evaluated while microfiltering a bentonite suspension, biologically treated wastewater and an activated sludge suspension through a 0.2 μm tubular ceramic membrane. Better results were obtained with a conventional internal layer filtration element than with an external skin membrane. However the technique was efficient in enhancing the permeate flux solely with the bentonite suspension. In the other cases, the flux was the same as in conventional cross-flow operation. Such a failure cannot be exclusively attributed to chemical interactions with the membrane since the permeate flux increased linearly with cross-flow velocity for all suspensions in conventional operation. Much research is then required to establish the technique applicability.
Tracer studies on a New Zealand waste stabilisation pond and analysis of treatment efficiency
Authors: Shilton A. , Wilks T. , Smyth J. , Bickers P.
Published: May 2018

This paper presents data collected from tracer studies undertaken at a facultative waste stabilisation pond in New Zealand. The dye used was rhodamine WT. The tracer studies were conducted using the stimulus-response technique to produce normalised curves of the hydraulic retention time distribution.

Two studies were undertaken. Comparison of the results shows a rapid rise to a high peak, followed by a slow, steady decrease with a long tail. The curves are similar to what would be expected from a mixed reactor suffering from short-circuiting. Although very similar for the majority of the study period, the two runs vary during the initial period.

The method described by Levenspiel, for analysis of non-linear reactions in reactors having non-ideal flow, was used to calculate treatment efficiencies from the tracer data.

It is evident from these calculations that the initial period of the tracer data, corresponding to small amounts of flow exiting with very short retention periods, accounts for the majority of the pollutant that escapes treatment in the pond system. For example, over half of the coliforms discharged untreated are due to the fraction of flow that exits the pond in a retention time of 24 hours or less. This highlights the potentially severe impact that short-circuiting has on attempts to achieve high treatment efficiencies. More generally it illustrates the importance of sound hydraulic pond design that avoids premature release of the wastewater. Further, in the context of pond hydraulics research it shows the importance of acquiring adequate data from the initial stages of a tracer study.
Improved fecal coliform decay in integrated duckweed and algal ponds
Authors: van der Steen P. , Brenner A. , Shabtai Y. , Oron G.
Published: May 2018

Algal growth in wastewater ponds has two contradicting effects on fecal coliforms (FC) decay. On the one hand, algal photosynthesis increases the FC decay due to increased pH and DO. However, on the other hand, attenuation of solar radiation by algal matter reduces the decay rate. It was therefore investigated if suppressing algal development could enhance the FC removal efficiency. Limiting the algal growth was accomplished by inserting duckweed ponds in between a series of algal ponds. Duckweed ponds are modified stabilization ponds, covered with a mat of small floating plants, that are known to remove algal from algal pond effluent.

The FC decay in a series of five shallow algal ponds was compared to FC decay in an integrated system of algal and duckweed ponds. The integrated system consisted of five mini-ponds (30 cm depth) in series: duckweed pond – algal pond – duckweed pond – algal pond – duckweed pond. The environmental factors that are known to affect FC decay were monitored and related to FC decay rates.

In the algal ponds of the conventional system the light attenuation by algal matter became rate-limiting for the FC decay. In the integrated system, the algal concentration in the algal ponds was reduced by the intermediary duckweed ponds. This was shown to increase the FC decay in the algal ponds of the integrated system considerably, compared to the FC decay in the algal ponds of the conventional system. An improved system of duckweed and algal ponds is proposed, that is expected to reduce significantly the area requirements of pond systems.
Parasite removal by waste stabilisation pond systems and the relationship between concentrations in sewage and prevalence in the community
Authors: Lloyd B. J. , Frederick G. L.
Published: May 2018

Waste stabilisation pond (WSP) performance for the removal of nematode eggs is generally considered to be excellent. In this paper, the performance of WSPs for parasite egg removal is reviewed. A simplified membrane filtration method for enumeration of parasites in sewage was introduced and applied to evaluate emergency anaerobic and permanent sanitation units in Bangladesh. With short retention times of 48-72 hours 99% egg removal efficiencies were achieved in the emergency unit using sewage from a cholera hospital complex. Permanent units gave poorer performance and, in a 23 day WSP system in Grand Cayman, it is possible that removal efficiency may have been impaired and hookworm eggs carried over to the final effluent. Evidence for carry over of eggs is critically re-assessed. Publications relating levels of prevalence of helminth parasites and concentrations in sewage are summarised, and data are interpolated to provide an understanding of the response-dose relationship. A classification of end emicity is proposed to assist in evaluating the success of helminth control programs.
Implementation of EU discharge guidelines at IVAR's Regional Wastewater Treatment Plant of North Jaeren, Stavanger, Norway
Authors: Tornes O.
Published: May 2018

Norway is a leading country on wastewater treatment comprising chemical precipitation processes. This is because Norwegian effluent standards to the North Sea have traditionally focused on phosphorus removal. In most cases, chemical treatment therefore has been considered to give lower investment and operating costs than biological treatment. Norwegian wastewater policy and management is based on the EU guidelines resulting from the EEA (European Economic Area) Agreement. According to the 1991 Urban Wastewater Treatment Directive, this will in most cases require secondary treatment. However, primary treatment can be accepted for plants larger than 10,000 PT with effluents to less sensitive coastal areas, if no negative environmental impacts can be proved.

The main objective of the Regional Water, Sewerage and Waste Company (IVAR) is to comply with the prevailing effluent limits at lowest possible cost. During the past four years, IVAR has therefore undertaken comprehensive optimising of the precipitation process including full-scale experiments with different coagulant dosing control systems and different types of coagulants. IVAR also accomplished a feasibility study of introducing biological treatment as an alternative to chemical treatment. Under the prevailing frame conditions of discharge requirements and sludge deposit costs, it is not economically feasible to change to organic coagulants or biological treatment. This conclusion might have to be altered later resulting from the implementation of new EU regulations and increasing sludge deposit costs.

This paper presents results from full-scale experiments, extracts from the feasibility study and a comparison of costs. Furthermore, the practical consequences of implementing the EU-guidelines are discussed.
A molecular method to study population and activity dynamics in anaerobic digestors
Authors: Delbès C. , Leclerc M. , Zumstein E. , Godon J.-J. , Moletta R.
Published: May 2018

The applicability of a new molecular fingerprinting method (Single Strand Conformation Polymorphism) to study the microbial populations of anaerobic digestors was investigated. After extraction of total nucleic acids, the 16S rDNA and 16S rRNA molecules were amplified and the amplicons were separated by SSCP electrophoresis. Characteristic and complex peak patterns were obtained, where each peak could be correlated with the 16S rDNA sequence of one micro-organism. The rDNA peak patterns should consist of the most abundant sequences and thus would reflect the diversity of prominent species of different digestors. Ribosomal DNA patterns were compared to rRNA patterns and revealed the bacteria that were the most active metabolically. The SSCP method also revealed dynamic changes in the presence and activity of populations, following perturbations such as an acidic shock which caused an increase in activity of two species. After cloning the 16S rDNA, the species corresponding to the peaks of interest, such as the archaeal species, could be identified by screening the clones according to their SSCP patterns and sequencing the 16S rDNA.
Anaerobic degradation of 2,4,6-trinitrotoluene in granular activated carbon fluidized bed and batch reactors
Authors: Moteleb M. A. , Suoidan M. T. , Kim J. , Davel J. L. , Adrian N. R.
Published: May 2018

In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produced pink water waste stream containing trinitrotoluene (TNT). The synthesized waste consisted of 95 mg/l-TNT, the main contaminant in pink water, which was to be co-metabolized with 560-mg/l ethanol. Granular activated carbon was used as the attachment medium for biological growth. TNT was reduced to a variety of compounds, mainly 2,4,6-triaminotoluene (2,4,6-TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), and 4-amino-2, 6-dinitrotoluene (4-A-2,6-DNT). These conversions resulted through the oxidation of ethanol to carbon dioxide under anoxic conditions, or reduction to methane under methanogenic conditions. The anaerobic reactor was charged with 1.0 kg of 16×20 U.S. Mesh Granular Activated Carbon (GAC) and was pre-loaded with 200g of TNT prior to the addition of the mixed seed culture. During the first three weeks of operation, ethanol was completely degraded and no methane was produced. Effluent inorganic carbon revealed stoichiometric conversion of the feed ethanol to dissolved inorganic carbon with accumulation of carbon dioxide in the headspace of the reactor. GAC extraction showed incremental reduction of the nitro groups to amino groups, with 2,4,6-TAT as the final product. After three weeks, the oxygen from the nitro groups was depleted and methane production commenced. The reproducibility of this phenomenon was confirmed by repeating the experiment in the same manner using an identical AFBR. Furthermore, serum bottle tests were conducted using TNT loading ratios of 0.2, 0.4, 0.8, 1.0 g-TNT/g-GAC as well as experiments in the absence of GAC. Similar behavior to that of the columns was observed, with degradation rates varying according to the particular condition. GAC greatly enhanced the degradation rates and the higher TNT loading resulted in slower degradation rates of ethanol.
Contribution of P-bacteria in biological nutrient removal processes to overall effects on the environment
Authors: Hao X. , Heijnen J. J. , Qian Y. , van Loosdrecht M. C.M.
Published: May 2018

P-bacteria can combine denitrification and P-uptake. This category of P-bacteria is abbreviated DPB. Use of DPB in BNR processes, instead of obligate aerobic PAOs, reduces oxygen consumption. Moreover, less COD is needed for the nitrogen removal. Non-required COD can be removed by presettling and used for methanation. This leads to a lower sludge production. As a result, CO2 emissions are reduced owing to less net energy consumption. Simulation for a planned WWTP with the BCFS® process indicates that DPB can save 53-59% of required COD. The optimal ratios of COD/N and COD/P for simultaneous N and P removal are determined to be 3.9~4.5 and 32.2~35.2 at 12~20°C. 80-95% of particulate COD can be removed from the influent, thereby CH4 production is increased by 154-271%, and the total volume of reactors can be reduced by about 50% compared to a minimised process design. Less net energy consumption over the whole WWTP contributes to a net reduction of the total CO2 emissions up to 16-21%. The energy production from CH4 is excessive enough to balance the energy consumption from aeration, dewatering and incineration. It is concluded that contribution of P-bacteria to saving COD has overall positive effects on the environment.
The SHARON®-Anammox® process for treatment of ammonium rich wastewater
Authors: van Dongen U. , Jetten M. S.M. , van Loosdrecht M. C.M.
Published: May 2018

The treatment of ammonium rich wastewater, like sludge digester effluent, can be significantly improved when new biotechnological processes are introduced. In this paper, the combination of a partial nitrification process (SHARON®) and anoxic ammonium oxidation (Anammox®) process for the treatment of ammonia rich influents is evaluated. Herein the combined process has been studied with sludge recycle liquor from the WWTP Rotterdam-Dokhaven. The SHARON process was operated stably for more than 2 years in a 10 l CSTR under continuous aeration with a HRT of 1 day. The ammonia in the sludge liquor was converted by 53% to nitrite only. During the test period no formation of nitrate was observed. The effluent of the SHARON process was ideally suited as influent for the Anammox reactor. The Anammox process was operated as a granular sludge SBR-process. More than 80% of the ammonia was converted into dinitrogen gas at a load of 1.2 kgN/m3 per day. Planctomycete-like bacteria dominated the mixed community of the Anammox reactor, and only a small percentage of the population consisted of aerobic ammonium-oxidizing bacteria. This showed that the ammonium-oxidizers in the effluent of the SHARON process did not accumulate in the SBR. The test period showed that the combined SHARON-Anammox system can work stably over long periods and the process is ready for full-scale implementation.
Nutrient removal from low strength domestic wastewater in sequencing batch biofilm reactor
Authors: Altinbas U.
Published: May 2018

Nutrient removal was investigated in a packed bed column, which was operated by changing of aerated and non-aerated periods. Good removal efficiencies for nitrogen and phosphorus were obtained at long aeration period. Highest nitrification efficiency was observed in run3 because the aeration period was enough to allow nitrification. NO3 concentration was not significantly changed during the cycle, because of simultaneous denitrification during aerobic stage. Nitrogen and phosphorus removal efficiencies reached to 71 and 74% in run3 respectively. Effluent concentrations of TKN, Tot.P, NH4 and NO3 were found as 3.8, 3, 1 and 2.5 mg/l respectively.
Denitrification potential enhancement by addition of anaerobic fermentation products from the organic fraction of municipal solid waste
Authors: Bolzonella D. , Innocenti L. , Pavan P. , Cecchi F.
Published: May 2018

The aim of this study is to demonstrate the denitrification potential enhancement determined by the addition of the anaerobic fermentation products from the organic fraction of municipal solid waste in BNR wastewater treatment plants. The denitrification potential rose from 6 to 17 mgNO3-N/l thanks to the good performances showed by the fermentation products in the denitrification step: a typical maximum denitrification rate of about 5 mgN/gVSS d was observed. This value is similar to those obtained by using pure organic substrates. The denitrification capacity increase is determined by a significant increase of Ss and Xs availability in the influent due to the anaerobic fermentation products addition which leads to an influent COD increase equal to 68% of the total load: this value is significantly higher than the one obtained by fermentation of primary and/or waste activated sludge (3-5%).
A new concept for storm water treatment: full-scale experience in Flanders
Authors: Carrette R. , Thoeye C. , Ockier P.
Published: May 2018

Current practice in Flanders (Belgium) is to limit the hydraulic capacity of the wastewater treatment plant to 6Q14. A maximum of 3Q14 is treated in the activated sludge system, the excess flow undergoes only physical treatment (stepscreen, sand trap and settling). This paper focuses on an alternative storm management operation strategy aiming at maintaining plant performance and reducing the total pollutant discharge towards the receiving waterbody. Given the observed dilution of incoming wastewater under storm conditions, the idea was put forward that higher hydraulic loadings could be treated within the biology if additional secondary clarifier volume was supplied. The new storm operation strategy would consist of treating 6Q14 biologically using the available storm tanks as additional clarifier volume. The outcome of this study clearly shows that 6Q14 can be treated biologically using the storm tank as an extra clarifier. It was shown that doing so the overall pollutant discharge was significantly reduced. The proposed strategy does not entail any extra operational costs. On the contrary it offers a potential cost saving of 244 million Euro in view of a possible future change of environmental legislation regarding storm tank spill frequencies.
Wastewater treatment and nitrogen removal using submerged filter systems
Authors: Chui P. C. , Terashima Y. , Tay J. H. , Ozaki H.
Published: May 2018

The performance of two submerged filter systems: a two filters-in-series system and a single combined filter system, in treating a strong nitrogenous wastewater with nitrogen concentration of 480 mg/L was evaluated. Both systems were equally effective in removing up to 90% of nitrogen and 98% of COD from the wastewater for loading rates up to 5 kg COD/m3.d and 0.5 kg N/m3.d. The second system in which anaerobic, anoxic, and aerobic zones were incorporated in a single filter offers a greater flexibility in treatment in that by repositioning the locations of the aeration point and effluent recycling inlet, the zonal volumes can be altered easily to treat wastewaters with different COD and nitrogen concentrations.
Development and verification of design and operation criteria for the step feed process with nitrogen removal
Authors: Larrea L. , Larrea A. , Ayesa E. , Rodrigo J. C. , Lopez-Carrasco M. D. , Cortacans J. A.
Published: May 2018

The step feed process with three stages of denitrification-nitrification reactors has been studied using simulations in order to develop criteria for the optimum selection of the design parameters and to propose efficient operational strategies. To verify the simulation results experimental studies in a pilot plant of 1100 litres were carried out.

The simulation studies showed that the optimum influent flow distribution to the three anoxic reactors is in the range of 40-40-20% and 33-33-34% depending on the wastewater characteristics and effluent requirements. These two latter conditions and in turn the influent flow distribution determine the anoxic and aerobic reactor volumes. The reduction of the dissolved oxygen in the two first aerobic reactors and the use of facultative zones in the final D-N stage are proposed as operational strategy. The experimental results proved the validity of the criteria developed for design and operation. A high capacity of the IAWQ activated sludge model No. 1 to predict the performance of the step feed process was observed.
Simultaneous nitrification and denitrification in biofilters with real time aeration control
Authors: Puznava N. , Payraudeau M. , Thornberg D.
Published: May 2018

The aim of this article is to present a new biological aerated filter (BAF) for nitrogen removal based on simultaneous nitrification and denitrification. Contrary to the systems which integrate both an aerated and a non-aerated zone to allow complete nitrogen removal in one compact or two different units (pre-denitrification and nitrification), this upflow BAF system is based on the principle of simultaneous nitrification and denitrification since the filter is completely aerated. The denitrification process is possible due to the diffusion effect which dominates biofilm processes. The real time aeration control allows us to maintain a low dissolved oxygen value (0.5 to 3 mg O2/l). In this case, the biofilm will not be fully (or less) penetrated with oxygen and denitrification will be carried out in a large part of the biofilm. Therefore, nitrification and denitrification is running simultaneously in different depths of the biofilm. By using 50% less air this BAF gave the same results (less than 20mg TN/l) on pilot plant as a classical nitrification and denitrification BAF (Toettrup et al., 1994). Less recirculation was necessary to achieve the same denitrification.
Single stage biological nitrogen removal by nitritation and anaerobic ammonium oxidation in biofilm systems
Authors: Helmer C. , Tromm C. , Hippen A. , Rosenwinkel K.-H. , Seyfried C. F. , Kunst S.
Published: May 2018

In full scale wastewater treatment plants with at times considerable deficits in the nitrogen balances, it could hitherto not be sufficiently explained which reactions are the cause of the nitrogen losses and which micro-organisms participate in the process. The single stage conversion of ammonium into gaseous end-products – which is henceforth referred to as deammonification – occurs particularly frequently in biofilm systems. In the meantime, one has succeeded to establish the deammonification processes in a continuous flow moving-bed pilot plant. In batch tests with the biofilm covered carriers, it was possible for the first time to examine the nitrogen conversion at the intact biofilm. Depending on the dissolved oxygen (DO) concentration, two autotrophic nitrogen converting reactions in the biofilm could be proven: one nitritation process under aerobic conditions and one anaerobic ammonium oxidation. With the anaerobic ammonium oxidation, ammonium as electron donor was converted with nitrite aselectron acceptor. The end-product of this reaction was N2. Ammonium and nitrite did react in a stoichiometrical ratio of 1:1.37, a ratio which has in the very same dimension been described for the ANAMMOX-process (1:1.31±0.06). Via the oxygen concentration in the surrounding medium, it was possible to control the ratio of nitritation and anaerobic ammonium oxidation in the nitrogen conversion of the biofilm. Both processes were evenly balanced at a DO concentration of 0.7 mg/l, so that it was possible to achieve a direct, almost complete elimination of ammonium without addition of nitrite. One part of the provided ammonium did participate in the nitritation, the other in the anaerobic ammonium oxidation. Through the aerobic ammonium oxidation into nitrite within the outer oxygen supplied layers of the biofilm, the reaction partner was produced for the anaerobic ammonium oxidation within the inner layers of the biofilm.
Increased toxicity of textile effluents by a chlorination process using sodium hypochlorite
Authors: Chen C.-M. , Shih M. L. , Lee S.-Z. , Wang J. S.
Published: May 2018

Chlorinated textile effluents were tested for their toxicity using different bioassays. These assays were the Microtox® assay, daphnia (Daphnia similis) 48-hr survival test, medaka embryo 14-day and juvenile 96-hr survival tests, and tilapia (Oreochromis mossambicus) juvenile 96-hr survival test. By comparing the results of toxicity tests on water samples collected at the instream prior to the chlorination process and at the outlet of the wastewater treatment facility, we found that wastewater toxicity was obviously increased by chlorination using NaOCl as the oxidant, as evidenced by the different bioassays used. Because no significant difference was observed in water chemistry, such as pH, DO, and conductivity, the induced-toxicity may be partially attributable to residue chlorine or other chlorinated compounds generated by chlorination. Future studies are warranted to identify the cause of the increase in the textile wastewater toxicity.