bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal Recovery from Wastewater Using Membranes
Authors: Fane A. G. , Awang A. R. , Bolko M. , Macoun R. , Schofield R. , Shen Y. R. , Zha F.
Published: May 2018

This paper outlines the requirements for metal recovery from wastewater, with particular reference to electroplating. The technical features of three alternative membrane processes are described. Nanofiltration is shown to separate ionic species on the basis of coulombic interactions or hydrated ion size, which leads to either a ‘charge' pattern or a ‘hydration' pattern of rejection. These rejection patterns provide ion selectivity. Ultrafiltration (UF), coupled with ion-complexing polymers or ion exchange resin, also provides efficient removal of metal ions, at high flux. The effectiveness of the UF-resin process is considerably increased as the resin size is decreased. Solvent extraction in a Liquid Membrane Contactor (LMC), which is based on microporous hollow fibre modules with aqueous and organic phases circulating through the shell or fibre lumens, achieves high fluxes of metal ions. A limitation of the LMC is the need to avoid phase leakage. The factors governing the critical displacement pressure and the effective transmembrane pressure are discussed. An LMC with a high packing density of fibres in the shell is preferred. Finally, the paper discusses criteria for selection of ‘user friendly' technologies for the electroplating industry. The membrane technologies, particularly in combined form, score highly except in terms of simplicity. This aspect needs further development.
Industrial Application of Formed-in-Place Membrane Ultrafiltration and Automated Membrane-Forming in the Treatment and Recycle of Rinse-Water during the Scouring of Raw Wool
Authors: Turpie D. W. F. , Steenkamp C. J. , Townsend R. B.
Published: May 2018

Fresh water consumption in the scouring of raw wool at a Mill in South Africa has been dramatically reduced by a combination of two factors, namely the purification and recycling of some of the wash water for reuse during rinsing, and the recycle of water from the firm's biological degradation ponds for use in the earlier stages of wool washing and in neutralising. Purification is undertaken by means of formed-in-place hydrous zirconium (IV) oxide membranes which are deposited automatically on porous sintered stainless steel supports. While about the same total quantity of water is used to wash the wool as traditionally, fresh water consumption on selected washlines has been reduced by approximately half.
Cake Formation in Cross-Flow Microfiltration Systems
Authors: Pillay V. L. , Buckley C. A.
Published: May 2018

Cross-flow microfiltration (CFMF) has potentially wide application in the processing of industrial and domestic waste waters. Optimum design and operation of CFMF systems necessitates a knowledge of the characteristic system behaviour, and an understanding of the mechanisms governing this behaviour. This paper is a contribution towards the elucidation and understanding of the behaviour of a woven fibre CFMF operated in the turbulent flow regime.

The characteristic flux-time curve and effects of operating variables on flux are presented for a limestone suspension cross-flow filtered in a 25 mm woven fibre tube. The phenomena contributing to the shape of the flux-time curve are discussed. A model of the mechanisms governing cake growth and limit is presented. Predicted steady-state fluxes show a notably good correspondence with experimentally measured values. It is also found that the flux may not be uniquely defined by the operating conditions, but may also be a function of the operating path taken to reach the operating point. This is of significance in the start-up and operation of CFMF units.
Tubular Reverse Osmosis Treatment of Secunda Mine Water: A Pilot Plant Investigation
Authors: du Plessis G. H. , Swartz J. A.
Published: May 2018

Secunda Collieries experience a positive water balance. Because of the zero discharge principle applied by Sasol and because it is rather difficult to build storage dams, desalination using a tubular reverse osmosis pilot plant was investigated. The objectives were to prove the technical feasibility of the process and to obtain enough information:to design a full-scale plant andto subsequently do economic evaluations regarding operating and capital costs.

With pretreatment consisting of flocculation/clarification and dual media filtration, excellent results were obtained. Average standard flux was 700 ℓ/m2.d at pressures of ca 4 MPa and at a water recovery of 70% (which was the maximum that could be obtained even with the addition of scale inhibitor). The importance of operating the system at feed water temperatures of ca 25°C was demonstrated. Salt rejection based on conductivity was very constant at ca 96% resulting in permeate conductivity values of ca 20 mS/m. Fouling, which was mainly inorganic in nature, was reversible and could be removed by citric acid washes and regular replacement of sponge balls.

Treatment of mine water using tubular reverse osmosis is a technically feasible process. However, further research is needed to improve overall water recovery.
Organic Stabilization and Nitrogen Removal in Membrane Separation Bioreactor for Domestic Wastewater Treatment
Authors: Chiemchaisri C. , Wong Y. K. , Urase T. , Yamamoto K.
Published: May 2018

In this study, organic stabilization and nitrogen removal were investigated using a household type hollow fiber membrane separation bioreactor of 6 2 1 volume. The process employed direct solid-liquid separation by hollow fiber membrane inside an activated sludge aeration tank. By providing highly turbulent conditions within the separation zone in conjunction with Jet aerating installation inside the membrane module, sludge accumulation on the membrane surface and inside the module can be reduced. Permeate flux obtained after 330 days of operation was 0.2 m/d under intermittent suction. High degree of organic stabilization was obtained in the system by operation without sludge wastage except for sampling purposes. Continuous and intermittent aeration modes were investigated in the study. The average effluent COD concentration of 20.8 and 16.5 mg/l were observed during continuous and intermittent aerating application respectively. Degree of nitrification depended upon DO concentration of mixed liquor during aeration period. Introduction of intermittent aeration enhanced total nitrogen removal up to 80% or more by simultaneous nitrification and denitrification, resulting in average of 4.9 mg/l of total nitrogen in the effluent. Increase in DO in aeration period from 1.5–2 mg/l to 4–5 mg/l improved percentage of nitrogen removal to more than 90%. Rejection of 4–6 log virus concentration by gel layer formed on the membrane surface was also observed.
Ultra- and Nano-Filtration in Advanced Effluent Treatment Schemes for Pollution Control in the Pulp and Paper Industry
Authors: Zaidi A. , Buisson H. , Sourirajan S. , Wood H.
Published: May 2018

The kraft pulp and paper industry is currently faced with the challenge of substantially reducing the discharge of conventional and toxic pollutants to the receiving environment without compromising its competitiveness. Ultrafiltration (UF) and nanofiltration (NF) are among the various unit processes that are being investigated by researchers interested in developing alternative schemes for meeting this challenge.

The objectives of the work presented here were: (i) to review the potential uses for UF and NF in the kraft pulp and paper industry and (ii) to evaluate the performance of eleven UF and NF membranes using a caustic extraction stage effluent from a kraft mill pulping softwood with a O D55/C45 EO H D bleaching sequence. The experimental work was conducted with two flat-sheets bench-scale units fed in parallel: a low shear and a high shear unit. The most promising UF membrane gave an average permeate flux of 9 m3m2d for a volume reduction factor (VRF) of 30, under high-shear conditions at 0.69 MPa. The associated COD rejections ranged from 85%–90% at a VRF of 1 down to 70–75% at a VRF of 30. While the results demonstrated in this study show promise, further research is needed to demonstrate the cost effectiveness of both high-shear and low-shear equipment for this application as well as options for the reuse or treatment of the diluted and concentrated streams produced by the UF/NF systems.
Evaluation of Nanofiltration for the Recovery of Brine from Sugar Liquor Decolourising Resin Regeneration Waste
Authors: Meadows D. M. , Wadley S. , Buckley C. A.
Published: May 2018

The recovery of brine from the regeneration effluent from cane sugar Liquor decolourising ion exchange resin by means of nano filtration has been investigated on a Laboratory and pilot plant scale. This effluent is produced at 80°C and contains up to 110 g/ℓ of sodium chloride and up to 6 g/ℓ (as total carbon) of organic matter. The SelRO MPT-30 membrane was selected for the pilot plant trials, which were carried out at 3 MPa and 45 °C or 60 °C. Point retention values ranged from (-2) to 15 % for sodium chloride and from 71 to 93 % for total carbon. Final water recoveries between 69 and 83 % were investigated. The sodium chloride recovery ranged from 64 to 81 % and the total carbon removal ranged from 79 to 89 %. Based on experiments using the salt-rich fraction of the effluent and a water balance over the regeneration system, it was calculated that a 30 % reduction in effluent volume and a 60 % reduction in salt consumption could be achieved. In the tests carried out so far, the use of the recovered brine in the regeneration of pilot resin columns did not lower the decolourising capacity of the resin.
Distribution and Seasonal Variation of Pesticide Residues in Yodo River Basin, Japan
Authors: Yamaguchi Y. , Fukushima M. , Fujita T. , Yamamoto T. , Yamada A.
Published: May 2018

Occurrence, distribution, seasonal variation and transport of pesticides in Yodo River basin, Japan were discussed. About 30 pesticides were detected in this study area. Their distribution and seasonal variation were distinguished in two groups by usage. Loads of pesticides applied to paddy field in agricultural area occupy the majority of load of downstream. In case of other pesticides, sum of tributaries flowed residential and urban area forms over 50%.
Characteristics of Pesticides Runoff from Golf Links
Authors: Sudo M. , Kunimatsu T.
Published: May 2018

The concentration and the loading rate of pesticides were investigated in a streamlet flowing through a golf links. The water samples were collected once a week for a year and during three storm runoff events (23.9-188mm). From the 50 weekly observations, the herbicides Simazin, Oxadiazon and Atrazine, and the insecticide Diazinon were detected. Atrazine, however, was not listed on the application record obtained from the golf links. The net average concentrations of pesticides discharged from the golf links were 0.92, 0.61, 0.28 and 0.04 µg/l, respectively, and their detection rates were 98, 60, 62 and 92%, respectively. Fenitrothion and Fenthion. though listed on the applications, were not detected. None of these pesticides contaminated the runoff water from the neighboring upstream forested area. The concentrations of pesticides varied to a great extent with each storm runoff event. The loading rates of pesticides caused by the storm runoff depended on the length of the period after the applications rather than being correlated with precipitation. Using the data obtained from the regular observation and the storm runoff events, the annual loading rates of Simazin, Oxadiazon, Diazinon and Atrazine were calculated as 1,590, 362, 99.0 and 295 g/km2/year. The loadings from only three storm events observed in the study occupied 22 - 100% of these annual loadings. The annual discharging rates of Simazin, Oxadiazon and Diazinon were 4.2, 1.5, and 0.98%, respectively.
Water Pollution by Cadmium and the Onset of Itai-itai Disease
Authors: Kasuya M. , Teranishi H. , Aoshima K. , Katoh T. , Horiguchi H. , Morikawa Y. , Nishijo M. , Iwata K.
Published: May 2018

Cadmium (Cd) from a zinc mine polluted Jinzu River basin, Toyama prefecture and produced a disease with severe bone pain (Itai-itai disease), from the early part of the 20th century. Cd caused renal tubular dysfunction and osteomalacia accompanied by osteoporosis. The main symptoms of the disease were bone pain, pseud fracture (Looser's zone), fracture, and renal tubular dysfunction. The pollution of paddy-field soil by Cd still remains and our epidemio1ogica1 studies of the inhabitants living in the Cd-polluted areas show the presence of renal tubular dysfunction and decrease of bone mass; characteristic of Itai-itai disease.
A Sensitive System (umu Test) for the Detection of Mutagenic Nitroarenes in Salmonella Typhimurium Strain Possessing Elevated Nitroreductase
Authors: Oda Y. , Shimada T. , Watanabe M. , Nohmi T.
Published: May 2018

A sensitive test system for the detection of mutagenic nitroarenes in a new tester strain Salmonellatyphlmurium NM1011 with a high nitroreductase activity has been developed. The tester strain was constructed by subcloning the corresponding gene into pACYC184 plasmid, and introducingthe plasmid into TA1535 harboring a fusion gene umuc‘-'lacZ (pSK1002). The strain enablesus to monitor expression of the SOS function umuC, by measuring the β-galactosidase activity in the cells. The sensitivity of the NM1011 was compared with that of parent tester strain (TA1535/pSK1002), or a nitroreductase deficient strain in seventeen mutagenic/carcinogenic nitroarenes. The newly developed strains with a high nitroreductase activity had about 4 times higher nitrofurazone-reductase activity than the parent strain, and was found to be highly sensitive to the compounds such as 2-nitrofluorene (2-NF), 1-nitronaphthalene (1-NN), 2-nitronaphthalene (2-NN), 1-nitropyrene (1-NP), m-dinitrobenzene (m-DNB), 4,4’-dinitrobiphenyl (4,4’-DNB), 3-nitrofluoranthene, 3,7- and 3,9-dinitrofluoranthene, 5-nitroacenaphthene (5-NA), 1,6-dinitropyrene, and 2,4-dinitrotoluene (2,4-DNT). On the contrary, the enzyme-deficient strain did not show considerable responses to 2-NF, m-DNB, 1-NN, 2-NN, 1-NP, 4,4’-DNB, 2,4-DNT, and 5-NA. These results suggest that a newly developed tester strain that has high nitroreductase activity is very useful for the detection of mutagenic nitroarenes contaminating the water and urban atmosphere.
Combined Effects of Chemicals: An Essential Element in Risk Extrapolation for Aquatic Ecosystems
Authors: van der Gaag M. A.
Published: May 2018

Joint toxic action of compounds in aquatic ecosystems is a factor that should be taken into consideration when environmental quality criteria are derived from the outcomes of toxicological tests in the laboratory. Many risk-extrapolation procedures calculate so-called ‘safe' environmental criteria for single compounds, regardless of possible interactions. However, additivity of toxic effects of different compounds, even at very low concentrations has been demonstrated by many different researchers. The possibility to integrate the aspect of joint toxic action into risk-extrapolation protocols is discussed against the background of the available scientific evidence.
Updating of OECD Guidelines for the Testing of Chemicals
Authors: Kitano M.
Published: May 2018

OECD's activity for the safety evaluation of chemicals is presented with its purpose and strategy.

The Updating of OECD guidelines for the ecotoxicological effect assessment is discussed in detail. OECD's approach for ecotoxicological effect assessment is also discussed.
Use of Radioactive Tracing Techniques to Identify Participate Deposits and Biological Effects of Urban Effluents Discharges from Sewage Outfalls
Authors: Romaña L.-A. , Brisset P. , Pagano G. , Amoux A. , Martin Y. , Caillot A. , Loarer R.
Published: May 2018

The discharge at sea of domestic effluents can present, in terms of its particulate phase, very different behaviors depending on the quantity discharged, on the type of purification treatment, as well as on the dumping method and on the dumping site. Consequently, it is extremely difficult to identify the relation between the deposits originating from the dumped waste and the modifications undergone by the substrate and by benthic populations. We have therefore focused our efforts on the particular case of East Toulon which is representative of most Mediterranean urban effluents discharges, in order to study the fate and impact of the particulate matter released by the sewage pipe (1,800 m long, 42 m deep) in the area close to its outfall.

The first phase consisted in searching for preferential deposit areas with the use of a radioactive tracer (hafnium) injected for 35 consecutive days on a continuous basis at the outlet of the physico-chemical purification plant. This tracer which fixes itself irreversibly on the particulate matter, was systematically tracked on the sea bottom with a sled carrying a nuclear detection probe. This enabled a cartography of deposits to be established both on a temporal (four times) and a spatial basis.

A multi-disciplinary sediment survey was then conducted, based on these results. Samples were collected at various distances from the outfall. In addition to standard parameters (particle size, matter content), the main toxicants originating from the discharge were examined. Finally, we used the same samples to carry out toxicological assays on sea urchins, based on sediment-induced alterations in embryogenesis, cell division and fertilization. Our findings revealed a non-monotonous trend in the embryo-toxicity of sediments which was satisfactorily consistent with the preferential deposit area of the (toxic) suspended matter originating from the discharge.
Comparison of the Purifying Efficiency of High Rate Algal Pond with Stabilization Pond
Authors: Picot B. , Bahlaoui A. , Moersidik S. , Baleux B. , Bontoux J.
Published: May 2018

Due to its high sanitary efficiency, treatment of wastewater by Stabilization Ponds (SP) is proposed for sensitive coastal areas (proximity to bathing areas, shellfish farming lagoons). This process, suitable for small communities with high summer populations, requires a large surface area. The objective of this study is to compare High Rate Algal Pond (HRAP) purifying efficiency with that of SP. We have experimented with a HRAP process, which by generating algal growth reduces the required surface area; our studies suggest this to be by a factor of 5. This process is particularly interesting for nutrient removal, especially nitrogen, and could be useful in coastal areas susceptible to eutrophication. Its sanitary performance is comparable to that of SP. Environmental factors and pond depth play a more important role in HRAP efficiency than retention time of water in the basins.
Wastewater Treatment of Greater Agadir (Morocco): An Original Solution for Protecting the Bay of Agadir by Using the Dune Sands
Authors: Bennani A. C. , Lary J. , Nrhira A. , Razouki L. , Bize J. , Nivault N.
Published: May 2018

The wastewater treatment by infiltration-percolation plant at Ben Sergao (a suburb of Agadir, Morocco) foreshadows the installation which will be able to be built for Greater Agadir (first fraction: 40,000 m3/d). The present plant treats 1,000 m3/d of highly concentrated raw effluents which after being decanted in an anaerobic stabilization pond are infiltrated into 5 infiltration basins of 1,500 m2 each, constituted by a bed 2 metres thick of eolian sand drained at its base.

The decanted water infiltrates at the rate of one metre per day. With this process 100 % of the suspended matter, and 95 % of the chemical oxygen demand are removed, 85 % of the nitrogen is oxidized. The parasites are entirely eliminated and the number of fecal coliforms and streptococci is made 10,000 to 100,000 times smaller. A series of experiments of irrigation by the treated effluents is under way.
Biotic and Abiotic Disappearance of Four PAH Compounds from Flooded Soil under Various Redox Conditions
Authors: Leduc R. , Samson R. , Al-Bashir B. , Al-Hawari J. , Cseh T.
Published: May 2018

Biotic and abiotic disappearance, mainly in terms of biodegradation and volatilisation respectively, of flooded soil contaminated with acenaphthene, acenaphthylene, fluorene and anthracene, was studied in erlenmeyer flasks and in bench-scale bioreactors. The erlenmeyer experiments were conducted under four different redox conditions. Disappearance kinetics followed zero order. Under aerobic and denitrifying environments, biodegradation of all four compounds occurred; the rates observed ranged from 0.38 to 0.53 ppm/day for the aerobic environment and from 0.29 to 0.35 ppm/day for the denitrifying one. However, no significant biodegradation occurred under the sulphate-reducing nor methanogenic environments. Aerobic abiotic losses were very significant; the ratio of the volatilisation to the biodegradation rates ranged from 2.4 to 3.6. The ratio of the aerobic to the denitrifying volatilisation rates ranged from 5.0 to 10.1. In the light of these results, the denitrifying environment was chosen for a further experiment to investigate the performance of a bench-scale bioreactor. Results showed that by enlarging the scale of the bioreactor approximately 8 times and simultaneously reducing the mixing intensity of the soil/water system, the biodegradation rates remained virtually unchanged. This study suggests that the denitrifying environment could play an important role in the development of an effective, economical and environmentally safe decontamination technology for treating PAH-contaminated soils.
Comparative Evaluation of Soluble and Insoluble Xanthate Process for Heavy Metal Removal from Wastewaters
Authors: Tare V. , Chaudhari S. , Jawed M.
Published: May 2018

Insoluble (ISX) and soluble starch xanthate (SSX) were synthesized in the laboratory from corn starch, and were used for metal [Cd(II), Cu(II) and Cr(VI)] removal from aqueous systems. Results indicate that soluble as well as insoluble xanthate processes are capable of meeting various effluent disposal standards. Metal removal by both the processes is maximum in the pH range 4 to 5. Mechanism of Cu(I I)-xanthate and Cr(VI)-xanthate interaction is also discussed. From overall comparison of the two processes it appears that theinsoluble xanthate process has an edge over the solublexanthate process in terms of metal removal capacity, reliability and ease of operation, particularly for cadmium removal. However, soluble xanthate process appears to be relatively less expensive compared to insoluble xanthate.
Treatment of Acidic Effluents with Limestone Instead of Lime
Authors: Maree J. P. , du Plessis P. , van der Walt C. J.
Published: May 2018

Traditionally acid mine water is neutralised with lime (Ca(OH)2) Limestone (CaCO3) can be used as an alternative to lime as it is much cheaper. The aim of this study was to investigate the practicality of using cheaper limestone (CaCO3) as an alternative. Beaker and semi-continuous studies were carried out to determine the quality of the water after lime treatment to various pH-values, the influence of CaCO3 dosage, particle size and aeration time on neutralisation rate and the effect of gypsum, magnesium, iron(II) and iron (III).

The rate of neutralisation is fast when stoichiometric dosages of lime are applied. If sufficient crystallisation is allowed, partial removal of sulphate is achieved, as well as complete removal of heavy metals, depending on the pH of the treated water. With limestone the rate of CaCO3 neutralisation depends on the dosage of CaCO3 and particle size. Aeration marginally accelerated the rate of neutralisation as a result of CO2 stripping. Partial sulphate removal is achieved as a result of CaSO4 crystallisation while magnesium, if present, co-precipitates with the CaSO4. Iron(III) and aluminium(III) are effectively removed but the rate of neutralisation is dramatically retarded by dissolved iron(II). Iron(III) has no influence on the rate of acid water neutralisation. During semi-continuous fluidised bed studies, CaCO3 in the limestone was completely utilised when the particle size was greater than 0.150 mm. The capital costs for lime and limestone neutralisation in a f luidised-bed reactor are similar, but the chemical cost in case of limestone neutralisation amounts to only 29% of that of lime.
Biotransformation in Soil of Chloroaromatic Compounds Related to Bleach Plant Effluents
Authors: Brezny R. , Joyce Thomas. W. , Gonzalez B.
Published: May 2018

The aim of the study was to examine the biotransformation of 6 chloroaromatic compounds in soil under laboratory conditions simulating the landspreading of sludges from the wastewater treatment of chlorine bleaching effluents. The soil samples were mixed with each of tetrachlorocatechol, -guaiacol, and −ve-ratrole (at 5 ppm concentration) and 4,5-dichlorocatechol, -guaiacol, and -veratrole (at 50 ppm). The samples were kept moist at 25 °C. The analytical methodology, directed to the examination of the transformation reactions of O-methylation and O-demethylation, comprised a modified extraction technique which enabled the recovery of chlorocatechols in reasonable yields (53 to 75%). The extracts, collected after 0,5,15, and 30 days of incubation, were analyzed by gas chromatography after acetylation. On kinetic curves, lag phases were observed in most instances. The half-lives (days) of the compounds in the “fast” stage were: TeCC: 9.6, TeCG: 6.1, TeCV: 24.8, DCC: 24.8, DCG: 4.3, and DCV: 4.1. Detection limits for O-methylation/demethylation products ranged from 0.3 to 4% of the starting concentration. O-Methylation was detected in TeCG (4.0% after 30 days), while O-demethylation was observed in DCV, TeCG and TeCV (45.5, 2.9, and 6.5% after 30 days, respectively). Especially fast and selective was O-demethylation of DCV with 77% recovery of DCC within 15 days. All of the starting compounds and biotransformation products were gradually disappearing from the soil and difference chromatograms showed no permanent accumulation of new chloroaromatic compounds after 30 days. The active role of microorganism in depletion of the test compounds from soil was proven in a control experiment with sterilized soil.
Hydrodynamics and Oxygen Transfer Characteristics in Activated Sludge Aeration Tanks
Authors: Fujie K. , Urano K. , Kubota H. , Kasakura T.
Published: May 2018

Spiral liquid circulation rate in the conventional aeration tank was investigated based upon the theoretical development of the hydrodynamics and the experimental observation. The effect of liquid circulation rate on the gas-liquid oxygen transfer and the oxygen exchange between the bubbling zone and the bubble-free zone in the aeration tank were clarified. The spiral liquid circulation rate at the liquid surface in the aeration tank was correlated as functions of the superficial gas feed rate, the diffuser depth and the bubble diameter generated from the air diffusers. The oxygen exchange resistance between the bubbling zone and the bubble-free zone was 3 - 5 % compared to the overall oxygen transfer resistance from the atmosphere to the bubble-free zone, while that in the deep aeration tank was significant. It was also clarified that the higher spiral liquid circulation rate increases the bubble ascending velocity and thus hinders the gas-liquid oxygen transfer.
Start up of Thermophilic UASB (Upflow Anaerobic Sludge Blanket) Reactors Using Micro-Carrier and Mesophilic Granular Sludge
Authors: Ohtsuki T. , Watanabe M. , Miyaji Y.
Published: May 2018

Two start-up methods of thermophilic UASB reactor were investigated for fast start-ups; one utilized micro-carrier as an initial support material and the other used intact mesophilic UASB granules as an initial seed. With both methods thermophilic granules having high activity were obtained in less than 3 months, even with acidified wastewater. Maximum sludge load for VFA substrate and sugar substrate were 3.2 and 0.9 kgCOD/kgVSS/day, respectively. Pre-acidogenesis was indispensable for high-performance treatment of sugar-containing substrate. It was proven that with a two-phase system sludge load could be raised to 3.0 kgCOD/kgVSS/day for sugar containing wastewaters. Some features of obtained sludge were examined, including maximum substrate utilizing activities, temperature dependence, pH dependence, and activity deterioration under lower loading conditions.
The Forecasting of Hydrogen Sulphide Gas Build-Up in Sewerage Collection Systems
Authors: Matos J. S. , de Sousa E. R.
Published: May 2018

The presence of hydrogen sulphide gas in sewerage collection systems is a common source of odour nuisance, corrosion of sewers and toxic atmospheres. The hydrogen sulphide build-up in the sewer air may be related to sulphide concentrations in the flowing sewage and with other factors, such as turbulence, aerodynamic conditions of the ventilating air now and roughness of the unsubmerged surfaces.

In the present work, a mathematical model is presented for forecasting hydrogen sulphide gas build-up along gravity sewers, which is based on the analysis of a differential mass balance equation applied to a sewer reach. Good correlation was obtained, comparing the results of the model with experimental information collected in the Funchal main trunk sewer. Funchal city is the capital of Madeira, a Portuguese island in the middle of the Atlantic Ocean, and its main trunk sewer was put into operation at the beginning of 1980.
New Approach to the Emission of Flue Gases Caused by Sludge Incineration in the Netherlands
Authors: van der Vlies A. W. , te Marvelde J. H. B.
Published: May 2018

Recycling of sewage sludge will soon no longer be possible in The Netherlands, or will be possible only to a very limited degree. For that reason, part of the sewage sludge will have to be incinerated. This will happen particularly in those areas where tipping space is very limited. A sludge incineration plant is planned to be built in the town of Dordrecht, with a capacity of 45,000 tonnes dry solids per year. The plant will be subject to the very strict flue gas emission requirements of the Dutch Guideline on Incineration. The Guideline demands a sophisticated flue gas purification procedure.
Modeling Sludge Production Trends at Blue Plains Wastewater Treatment Plant
Authors: Bailey W. F. , Chang S. C. , Kornegay B. H. , Davies-Venn C. , Weinberger L. W.
Published: May 2018

The District of Columbia's Wastewater Treatment Plant at Blue Plains is undergoing a $400 million expansion and upgrade from 13.5 m3/s to 16.2m3/s. A large portion of this expenditure is for a permanent sludge management system. Both present and future sludge management plans feature multiple sludge processing and disposal options. To improve existing sludge operations and provide accurate planning for future facilities, sludge production models were developed from historical plant operating data. The historical data were evaluated and a macro and micro model developed for the Blue Plains WWTP. This paper describes the development, calibration, and application of the micro model which assesses the primary, secondary, nitrification, and chemical sludge production. The model also describes subsequent sludge treatment processes and indicates the quantity of sludge discharged from the various flow schemes and the total sludge generated and treated at the plant. During model calibration the predicted total sludge production was within 8.5 percent of the actual values for the six year period examined.
Influence of Combined Suspended and Fixed-Film Biomass in Anoxic Reactor on Nitrification-Denitrification Process
Authors: Drtil M. , Bodík I. , Tölgyessy J.
Published: May 2018

In single-sludge nitrification-denitrification process biomass is passed periodically through oxic and anoxic reactors. Nitrifying bacteria need oxygen for substrate oxidation. Behavior of these bacteria under anoxic conditions is still not sufficiently known. In this paper influence of retention time in anoxic reactor on nitrifiers has been studied. Optimum retention time for tested biomass was found to be 3 hours. A possible way to set-up this retention time is to increase denitrification rates by addition of support material of fixed-film biomass to anoxic reactor (e.g.polyurethane cubes). Increased denitrification rate results in decrease of necessary volume of anoxic reactor followed by increase of nitrification efficiency. Presence of fixed-film biomass has no influence on clarifier capacity and oxygen concentrations in oxic reactors. Theoretical aspects of this modification were confirmed in laboratory models with synthetic wastewater as substrate.
Effects of MCRT on Enhanced Biological Phosphorus Removal
Authors: Shao Y. J. , Wada F. , Abkian V. , Crosse J. , Horenstein B. , Jenkins D.
Published: May 2018

This paper presents the results of full scale experimental investigations into the fate of phosphorus in the Hyperion Treatment Plant, City of Los Angeles, CA, USA. For almost three decades, the activated sludge process, operated at standard rate has exhibited enhanced biological phosphate removal accompanied by initial anaerobic phosphate release and subsequent aerobic phosphate uptake. In 1989 when high rate treatment was initiated the enhanced phosphate removal and accompanying initial anaerobic phosphate release decreased and finally was eliminated. Phosphorus in the secondary effluent increased from 0.4 to 3.1 mg/l as the MCRT decreased from 3.1 to 1.5 days. Of added interest was the accompanying decrease in struvite (MgNH4PO4.6H2O(s)) build-up in the sludge dewatering processes downstream of the anaerobic digesters.
Nitrification, Denitrification and Biological Phosphate Removal in Sequencing Batch Reactors Treating Piggery Wastewater
Authors: Bortone G. , Gemelli S. , Rambaldi A. , Tilche A.
Published: May 2018

In Italy, because of the high concentration of animals in many agricultural areas, not all piggery manure can be landspread. Considering their chemical characteristics - high concentration in organics and nutrients -processes providing the removal of COD, N & P have to be adopted. Other aspects have to be considered with regard to cost saving and simple management.

In order to study a simple andreliable treatment system, two 51 bench-scale SBRs were built. Each reactor treated 500 ml/d of clarified (after centrifugation) piggery wastewater.

A cycle with the following alternating phases of reaction was chosen: first denitrification and phosphorus release, first oxidation-nitrification, second denitrification and second oxidation-nitrification. The systems showed good flexibility and enhanced removal of COD, N and P was easily reached modifying the duration of each phase. The best efficiency in N removal has been noticed in the reactor in which the feeding distribution was done in the two denitrification phases, allowing a better use of the organic substrate for the denitrifying bacteria. This confirmed that the limiting factor, in the removal of N from piggery wastewater, is represented by the too high ratio TKN/COD. Anyway good removals of COD (~93%), N (88-93%) and P(~95%) were obtained in both reactors. A relevant concentration of unbiodegradable COD - at the adopted HRT, SRT and reaction temperature - was still present in the effluent of both reactors (~300 mg/l).

Track studies allowed the evaluation of the nitrification and denitrification kinetic constants. Their values were higher than the ones reported in the literature. No inhibition of the nitrifying activity due to high concentration of N-NH4 (>80 mg N/l), was observed.

Specific studies on biological phosphate removal have been carried out. In spite of the high concentration of P in the biomass and the low concentration of P in the effluent, showing a surplus biological P removal, no P release was observed; this might have been masked by biologically induced chemical precipitation. In fact, piggery wastewaters are rich in metals and a high concentration of metal-bound P was analytically observed. However, a high concentration of polyphosphates has been analytically determined in the biomass. This should confirm the presence in the microbial community of bacteria performing the surplus P removal.
The Removal of Phosphate by Hydroxyapatite and Struvite Crystallisation in South Africa
Authors: Momberg G. A. , Oellermann R. A.
Published: May 2018

Nutrient removal by chemical means has, over the past decade, become an expensive practice owing to the scarcity of chemicals. A new method of phosphate removal by hydroxyapatite [Ca5(PO4)3OH] crystallisation has gained increasing interest as the need for the implementation of clean technology has become more apparent as we move into the environmentally conscious nineties. This method as well as another method, viz. struvite [NH4MgPO4-6H2O] crystallisation, will be discussed using results obtained from a laboratory scale study using three types of effluent, two demonstrating hydroxyapatite crystallisation and the third, struvite crystallisation. While it has been proven that phosphate crystallisation does work as a tertiary treatment (Van Dijk and Wilms, 1991) this paper will also show that the positioning of the crystalliser can vary to suit the need of the industry for which it has been designed.
Study of Factors Controlling Nitrite Build-Up in Biological Processes for Water Nitrification
Authors: Balmelle B. , Nguyen K. M. , Capdeville B. , Cornier J. C. , Deguin A.
Published: May 2018

Nitrification processes are well known for certain problems in connection with transient build-up of nitrite ions. Moreover, some works have shown interest in controlling the build-up of this ion, particularly when treatment procedures for nitrogenous pollution are of the nitritation-denitritation type. With this in mind, we have carried out a programme of research to check the main factors responsible for the accumulation of this ion, i.e. [NH4]o, T°, pH, and dissolved O2. The main results highlight the key role played by the free form N-NH3 and by the temperature. This research thus provides answers to a number of practical questions and allows us to envisage setting up new procedures for the treatment of nitrogenous pollution by fixed cultures.
Granular Activated Carbon Sequencing Batch Biofilm Reactor to Treat Problematic Wastewaters
Authors: Jaar M. A. A. , Wilderer P. A.
Published: May 2018

Experiments were conducted to study the performance of a reactor packed with granular activated carbon, and operated in a sequencing fill and draw mode. The reactor was inoculated with micro-organisms, loaded with a solution of 3-chlorobenzoate and thioglycolic acid. Oxygen was transfered to the microorganisms by means of silicon rubber tubings embedded in the activated carbon bed. Comparative studies were conducted with a continuous flow activated carbon filter and with a reactor packed with sand instead of granular activated carbon. Periodic operation of the granular activated carbon reactor provided superior results. High substrate removal efficiency was achieved as was high process stability under shock loading conditions, the latter mainly as a result of intermediate adsorption and subsequent decrease of toxic effects. After a period of 14 months of continuous operation the activated carbon had maintained about 90 per cent of its adsorptive capacity.
Coagulation with Prepolymerized Aluminium Salts and their Influence on Particle and Phosphate Removal
Authors: Ratnaweera H. , Ødegaard H. , Fettig J.
Published: May 2018

Based on coagulation experiments, electrophoretic mobility measurements, and literature studies, mechanisms for particle and phosphate removal during coagulation with coagulants of different basicities are discussed. In wastewater treatment, particles are expected to be removed by both the adsorption -charge neutralization and sweep floc mechanisms. However, when coagulating with low basicity coagulants, the dominant mechanism for particle removal is suggested to be the sweep floc mechanism, while the dominant mechanism for phosphate removal is adsorption-precipitation by initial formation of aluminium - hydroxo -complexes. When coagulants with high basicities are used, the particles are removed dominantly by the adsorption - charge neutralization mechanism, while phosphate removal will be favoured by adsorption of phosphate ions on to the hydrolysis products.
Physicochemical Treatment of Tropical Wastewaters: Production of Microbiologically Safe Effluents for Unrestricted Crop Irrigation
Authors: Gambrill M. P. , Mara D. D. , Silva S. A.
Published: May 2018

The objective of this work was to find an alternative wastewater treatment technology to that of waste stabilization ponds which was capable of producing an effluent safe for reuse in irrigation, but which did not require the large land areas of such a system. Single-stage lime treatment of raw domestic wastewater in a continuous-flow pilot-plant produced an effluent suitable for reuse in unrestricted irrigation by attaining the Engelberg/WHO guidelines of ≤ 1 intestinal nematode egg per litre and ≤ 1000 faecal coliforms per 100 ml. Such treatment was achieved for a mean hydraulic retention time in the sedimentation tank of less than nine hours. The principal mechanism of bacterial removal was physical entrapment and sedimentation to the sludge layer: high pH was only a secondary mechanism for faecal coliform destruction. Faecal coliforms acted as good indicators of the removal of salmonellae in the lime flocculation-sedimentation system, but intestinal nematode eggs were not reliable indicators of the removal of protozoan cysts.
Denver's Demonstration of Potable Water Reuse: Water Quality and Health Effects Testing
Authors: Rogers S. E. , Lauer W. C.
Published: May 2018

The product water of the Denver (Colorado) Potable Water Reuse Demonstration Plant is compared to national and international standards for drinking water quality and with the high quality of the present drinking water supply. For parameters which cannot be analyzed or quantified, health effects testing is performed on concentrates of the existing and the innovative supplies. In order to determine relative risk, the health effects are assessed using the measures of chronic toxicity, carcinogenicity, and reproductive toxicity. For measurable constituents, the potable reuse product water equals or exceeds the high quality of Denver's existing drinking water. The preliminary results of the health effects testing demonstrate no health effects associated with either water. Potable reuse is shown to be an acceptable alternative water source which should be evaluated with other traditional supplies.
Agricultural and Municipal Use of Wastewater
Authors: Bouwer H.
Published: May 2018

Areas in relatively dry climates often have water shortages and there is competition between municipal and agricultural (irrigation) water use. The problem can be alleviated by using the water twice, first for the cities and then for agriculture after the municipal wastewater has been properly treated. There are now two sets of water quality standards for irrigation with wastewater: a stringent set for developed countries, and a less stringent set for developing countries. Also, more and more cities will have to use their wastewater internally for irrigation of parks, etc., and even for drinking. The latter requires advanced wastewater treatment. Part of this treatment can be supplied inexpensively by a groundwater recharge and recovery system, which also provides storage and enhances the aesthetics of direct potable reuse of wastewater by breaking the pipe-to-pipe connection. The renovated water from a recharge or “soil-aquifer treatment” system generally can be used as such for unrestricted irrigation, but potable use requires additional treatment.
Treatment of Domestic Sewage in Macrohydrophyte Ponds
Authors: Xu H. , Wang B. , Yang Q. , Liu R.
Published: May 2018

An experimental study was carried out on the treatment of domestic sewage by macrohydrophyte ponds, including water hyacinth and water peanut (AlterantheraPheloxiroides) ponds. The study indicated that both the water hyacinth and water peanut ponds were more effective and efficient in removing BODs (90-98%), TP (75-85%), PO4(90-99%), SS (90-95%), total bacteria (99.9-99.99%), and E. Coli (99-99.9%) in their growth seasons compared with the algae/bacterial symbiotic ponds with the pollutant removal rate constant ratio (k value in WHP or WPP/k value in ABP ponds) being: COD, 4.0-5.0, BOD5, 1.5-2.0, TN, 1.5-2.0, NH4+−N,2.0-3. 01 TP, 3.5-4.0; and PO43−2.8-5.7. The study found that the intensification effect was mainly ascribed to the microbial community in the root system, which was found to consist of Bacillus, Pseudomonas, Alcaligens, Brevibacterium, Ammonia fier, Nitrosonionas, Nitrobacter, and Denitrifier.

A mathematical model to describe the water flow pattern and BOD5 removal rule across the WPP pond based on the diffusion flow pattern model was developed with very low D values, which means that the water flow in the WHP and WPP ponds is near plug flow pattern.
Biofilms as an Aid to Nitrogen Removal in Sewage Treatment Lagoons
Authors: Baskaran K. , Scott P. H. , Connor M. A.
Published: May 2018

A pilot study of sewage treatment lagoons near Melbourne indicated that the best way to enhance nitrogen removal in such lagoons was to promote nitrification. Combined algal/bacterial biofilms grown on surfaces immersed in the lagoons showed potential for greatly increasing the extent of nitrification. A laboratory study was undertaken to determine the effect of pH, dissolved oxygen concentration, temperature and other factors on the nitrifying capabilities of such biofilms; effective nitrification was observed at temperatures down to 10°C, at pH's down to 5.5 and at dissolved oxygen levels down to 2.5 mg/L. Tanks containing biofilm-coated plates nitrified much more effectively than tanks containing only suspended microbial growths. At dissolved oxygen levels of 2-3 mg/L, up to 30% of the ammonia-nitrogen fed to tanks containing biofilm-coated plates was removed by denitrification. Photosynthetic activity in the biofilm greatly enhanced nitrification efficiencies at low dissolved oxygen levels.
Treatment Standards and Wastewater Discharge Fee in Germany
Authors: Imhoff K. R.
Published: May 2018

The Federal German Water Law of 1976 postulated for the first time that a license for the discharge of wastewater into public water courses might only be granted when the wastewater prior to the discharge is treated according to the actual standards. Also since 1976 it was decided that for the residual pollution of wastewater a pollution fee has to be paid.

Assuming certain loads per capita one can calculate that presently three pollution units have to be paid per capita and year for untreated domestic wastewater. One pollution unit is assessed with 50 DM per year in 1991 but the price will be increased to 90 DM per year in future.

Since the pollution units encompass COD, nitrogen, phosphorus, heavy metals and chlorinated carbon compounds the pollution unit is a very good tool to compare the effectiveness of treatment. For different drainage systems one can also calculate the residual pollution units per litre and second for low flow conditions.
Policies and Principles in Hong Kong's Water Pollution Control Legislation
Authors: Holmes P. R.
Published: May 2018

Hong Kong's water quality management policy aims to control direct environmental discharges and to limit the toxicity of sewer discharges so that ultimate effluents are not harmful. It bases pollution control standards on water quality objectives that will protect conservation goals. The main control mechanism is a licensing system. This allows the authority wide scope to specify treatment technology, but in practice the authority only sets pollution load limits, in line with the government's non-interventionist stance. Published standards for a wide range of receiving waters and effluent flow rates do not refer to the industrial or treatment processes from which the effluents arise. The standards aim to maximize the use of the foul sewerage system, to require pretreatment for toxins, and to allow economically efficient centralized treatment where appropriate. The law is effective to meet the policy goals, but a very slow pace of implementation has limited its practical value.