bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of high sodium chloride concentrations on activated sludge treatment
Authors: Hamoda M. F. , Al-Attar I. M. S.
Published: May 2018

The performance and kinetics of the activated sludge process treating wastewaters of freshwater and salinewater (10 g/l NaCl and 30 g/l NaCl) origin were investigated using bench-scale, completely mixed reactors operated at different biological solids retention times (BSRT's) in the range of 3 to 20 d and organic loadings in the range of 0.5 to 2.0 kg COD/kg VSS.d. It has been found that the organic (COD or TOC) removal efficiency and the effluent quality of the activated sludge system were not deteriorated as a result of constant application of NaCl to acclimated biomass. However, the salinity of the effluent increased. The salt did not inhibit biomass growth under the experimental conditions studied but rather increased the biomass concentration in the reactors due to selection of salt tolerant microbial species. It has been demonstrated that kinetic models developed for the freshwater activated sludge system can be used successfully for the salinewater system. Biokinetic coefficients were determined which can be used for process design.
Biochemical characterization of wastewater by electrolytic respirometer
Authors: Sang Eun Lee , Yoon Soo Suh
Published: May 2018

The use of an electrolytic respirometer for characterization of chemical compounds and wastewater was studied. From the BOD curves generated by the respirometer, the first order biokinetic constant (K), ultimate BOD (BODu) and adaptation period were estimated. The estimated ultimate BOD values of the known chemical compounds were very close to the theoretical oxygen demand values. Using K values, the relative biodegradability of the chemicals could be compared while the adaptation period for each compound could vary with the type of seed micro-organisms used. It was found that BOD5 values determined by the conventional method have no or very little, if any, meaning as far as the biological characteristics of industrial wastewaters are concerned. The BOD curves for wastewaters consisting of 2 or 3 different compounds could be divided into several stages while those for the combined wastewaters could be expressed as one curve.
Electrochemical precipitation of chromium (Cr6+) from an electroplating wastewater
Authors: Kongsricharoern N. , Polprasert C.
Published: May 2018

This research was conducted in the laboratory to investigate an alternative of Cr removal from an electroplating wastewater using the electrochemical precipitation (ECP) process. The ECP unit consisted of an electrolytic cell made of two steel plates representing anode and cathode. The DC power source applied to the ECP unit had current (I) and electrical potential (E) of 3-6 A and 30-75 V, respectively. Electroplating wastewater used in the experiments contained Cr6+ in the range of 215-3860 mg/l, and the pH was 1.5. The parameters varied during the ECP experiments were: E, hydraulic retention time (HRT), Cr6+ concentration, conductivity and initial pH. The optimum ECP conditions found were electrical potential, 75 V; current, 4.8 A; HRT, 50 min; initial pH, above 3.2. Under these conditions, the Cr6+ concentrations remaining in the effluent were less than 0.2 mg/l. Sludge produced in the ECP unit had a sludge volume index (SVI) of 60-80, an indication of sludge settleability. X-ray fluorescence analysis of the ECP sludge revealed formation of Fe2O3 and FeCr2O4 as the main products. Power consumption of the ECP unit was found to be in the range of 14.7 - 20 kWh/m3 of wastewater. The economics of the ECP process was evaluated and compared with some conventional treatment processes for Cr removal.
Role of filter media in an anaerobic fixed-bed reactor
Authors: Miyahara T. , Takano M. , Noike T.
Published: May 2018

The relationship between the filter media and the behaviour of anaerobic bacteria was studied using anaerobic fixed-bed reactors. At an HRT of 48 hours, the number of suspended acidogenic bacteria was higher than those attached to the filter media. On the other hand, the number of attached methanogenic bacteria was more than ten times as higher than that of suspended ones. The numbers of suspended and deposited acidogenic and methanogenic bacteria in the reactor operated at an HRT of 3 hours were almost the same as those in the reactor operated at an HRT of 48 hours. Accumulation of attached bacteria was promoted by decreasing the HRT of the reactor. The number of acidogenic bacteria in the reactor packed sparsely with the filter media was higher than that in the closely packed reactor. The number of methanogenic bacteria in the sparsely packed reactor was lower than that in the closely packed reactor.
Minimising waste through bioenergetically and behaviourally based feeding strategies
Authors: Thorpe J. E. , Cho C. Young
Published: May 2018

Most species in aquaculture are new to cultivation and so behave like wild animals. They are products of evolution, with adaptations to specific habitat conditions. In the wild, food is not available uniformly throughout the day or the year, or in space, and rarely exceeds the fishes needs. Competition is energetically expensive, reducing growth efficiency. Consequently, feeding activity patterns have evolved, implying internal appetite rhythms, which optimise food intake under these various constraints. Salmonids can adapt quickly to short term variation in food availability, but show seasonal genetically determined anorexia. Rational feeding regimes in culture should take all such features into account. When appetite is high naturally, food should be presented so that it is economically indefensible - where every individual can eat, and where fighting does not pay. At periods of anorexia it will be prudent to offer no food. Manufacturers' feed tables are usually regimes devised to meet the bioenergetic needs of fishes, as they are understood in a physico-chemical sense. While useful first approximations, they do not take into account these evolutionary features of the fishes, and can lead to waste. Methods of presentation are described which allow the fish to determine when food shall be available, and in ways which, by diminishing the advantages of social dominance, ensure relatively even opportunities to feed for all individuals in the population. Allowing the fish to set the time-table reduces the likelihood of waste.
Effects of supplemental microbial phytase on phosphorus digestibility and utilization in rainbow trout (oncorhynchus mykiss)
Authors: Rodehutscord M. , Pfeffer E.
Published: May 2018

Potential effects of supplemental microbial phytase on digestibility and utilization of phosphorus (P) originating from plant materials were studied in trout. Diets were mainly based on soybean products and contained P only from plant materials. Concentration of total P was suboptimal and about 60% of total P were bound as phytate P. Diets were prepared either without enzyme supplementation or after supplementation with an Aspergillus niger phytase (1000 units/kg diet). Apparent digestibility of P was determined at a water temperature of 15°C. Utilization of P was measured in two growth trials at water temperatures of either 15 or 10°C. P retention of trout was measured using the comparative body analysis. At 15°C, both digestibility and utilization of dietary P were considerably improved when microbial phytase was supplemented. P digestibility and P utilization increased from 25 to 57% and from 17 to 49%, respectively. At 10°C, P utilization increased from 6 to 25%, but intake of the diet as well as growth rate of trout were very low, irrespective of whether phytase was supplemented or not. Practical relevance of the findings seems to apply only to diets in which protein is supplied almost entirely by plant products.
Evaluation of the effect of live haulage on metabolites and fillet texture of rainbow trout (Oncorhynchus mykiss)
Authors: Ostenfeld T. , Thomsen S. , Ingólfdóttir S. , Rønsholdt B. , McLean E.
Published: May 2018

Changes in metabolites and meat texture of pan-sized live rainbow trout (Oncorhynchus mykiss), were examined following commercial, international road haulage. Significant (P < 0.001) increases in water, NH4+ and pH were detected during haulage. Transportation decreased (P < 0.05) dark muscle glycogen and L-lactate. Textural parameters, including hardness, elasticity, and breakpoint of the raw fillet, were unaffected by the haulage process. Muscle pH increased (P < 0.05) both in fish exposed to starvation and transportation when compared to reference fish. The results obtained indicate that haulage has limited effects upon fish flesh quality.
Off-flavor as the consumer's measure of drinking water safety
Authors: McGuire Michael J.
Published: May 2018

If consumers detect an off-flavor in their drinking water, they are likely to believe that it probably is not safe. Water utilities will be defeating their best efforts to provide safe drinking water if they only meet health-related regulations and do not provide water that is free of off-flavor problems. The purpose of this paper is to explore the current U.S. regulatory environment and discuss how these regulations can adversely impact the control of off-flavors in drinking water. Utilities should adopt a water quality goal that allows them to not only meet the minimums of the regulations, but also meet the customer's highest standards - water that is free of off-flavors.
Evaluation of biological technologies for wastewater treatment in the pharmaceutical industry
Authors: El-Gohary F. A. , Abou-Elela S. I. , Aly H. I.
Published: May 2018

Wastewater from a pharmaceutical and chemical company provides the material of this study. The company produces drugs, diuretics, laboratory chemicals and others. The company is located 30 km north of Cairo, and discharges both industrial (1050 m3/d) and human wastewater (8400 m3/d) without treatment into a near-by evaporation pond. Reduction of pollutants in the wastewater down to permissible concentrations is necessary for the protection of ground water and the environment. Analysis of the combined wastes indicated that it is very acidic and contains high concentrations of organic compounds and total solids. Combined wastes were subjected to different treatment processes for final disposal into surface water, or reuse for irrigation purposes. Biological treatment of the combined wastes was carried out using both batch and continuous flow systems. The biological treatments included activated sludge process, fixed film reactor, and fixed film reactor followed by activated sludge process. Technical feasibility studies indicated that good quality effluent could be obtained using either extended aeration (20 hr aeration) or a fixed film reactor followed by activated sludge (11 hr detention time). Residual BOD5, COD, oil and grease concentrations in the treated effluent were complying with the National Regularity Standards. When constructional cost was considered, extended aeration was the first choice. Engineering designs of the proposed treatment options are included.
Adsorption equilibria of basic dyestuff onto palm-fruit bunch particles
Authors: Nassar M. M. , Hamoda M. F. , Radwan G. H.
Published: May 2018

Particles prepared from palm-fruit bunch have been used for the adsorption of a basic dye (BR 18) over range of initial dye concentrations and varying adsorbent particle size in the range of 106 to 300 m, using batch tests. The results revealed the potential for palm-bunch particles as low cost adsorbents. Uptake of the basic dye was higher at smaller adsorbent particle size. The adsorption isotherm follows both the Langmuir and Freundlich models. Values of the separation factor, R, indicate favourable for the basic dye - palm fruit bunch particles system, that is, 0< R <1 and Freundlich constant n >1.
Physiology and biochemistry of odorous compounds from freshwater cyanobacteria and algae
Authors: Jüttner F.
Published: May 2018

Freshwater cyanobacteria and algae are responsible for the formation of a wide spectrum of different odorous compounds that are frequently observed in natural waters and are the causes consumer complaints. The physiology and biochemistry of odorous compounds that are permanently in the cells or excreted into the environment are here described, as are the odorous compounds that are generated only after disintegration of the cells and are produced by the initiation of lipoxygenase and carotene oxygenase reactions.
Conceptual basis of wastewater nitrogen removal in sensitive coastal areas
Authors: Artan N. , Orhon D. , Sözen S.
Published: May 2018

Effective nitrogen control is required to safeguard the quality of receiving waters in sensitive zones. There are a number of process alternatives, but the most widely used is the suspended growth system having anoxic and aerobic reactors for nitrification and denitrification. Design of such systems is quite complicated because of severe fluctuations in wastewater quantity and quality. Kinetic evaluation of the denitrification process reveals a number of useful relationships between significant parameters such as denitrification efficiency factor, COD/TKN ratio, VD/V ratio. Design for nitrogen removal can be optimized by taking into account wastewater characterization and basic kinetic relationships.
The reactions of some sulfur compounds in water supplies in Perth, Australia
Authors: Wajon J. E. , Heitz A.
Published: May 2018

Some residents of Perth, Australia, receiving treated groundwater have complained of intermittent swampy, cooked vegetable odours in their drinking water. The compound primarily responsible is dimethyl trisulfide (CH3SSSCH3) which can be formed in the laboratory from the reaction of methyl iodide with thiosulfate (in the presence of iodine or sulfide) or with polysulfide (Sn2−). Addition of chlorine or sulfide to pre-formed S-methylthiosulfate (produced from the reaction of methyl iodide with sodium thiosulfate) at concentrations possibly expected in water supplies did not produce the swampy odour or only formed it slowly. Dimethyl trisulfide was formed upon the addition of methyl iodide to samples from each water supply system examined, even from those not prone to the formation of swampy odour, suggesting each contained polysulfide. Polysulfides and the reducing agents sodium oxalate, sodium borohydride and sodium thiosulfate reacted with dimethyl trisulfide in solution, removing 50-100% of that originally present.
Aspects of the European investment bank's experience in wastewater management
Authors: Bond P. D. R.
Published: May 2018

The role of the European Investment Bank (EIB) in financing viable long-term investments and their geographical and sectorial spread are briefly described. Its activities in the Mediterranean environmental field and the special actions taken jointly with the World Bank including structured technical assistance for project preparation are explained. Recent experience of the EIB in the wastewater sector covering the importance of the planning and institutional contexts as well as an analysis of typical problems and risks during implementation and operation are given.
In situ production of volatile odour compounds by river and reservoir phytoplankton populations in Australia
Authors: Jones Gary J. , Korth Wolfgang
Published: May 2018

The production of volatile odour compounds by freshwater phytoplankton was monitored weekly from November to April (summer period) 1990/91 at two sites: (1) Hay Weir pool on the Murrumbidgee River, NSW and (2) Carcoar Dam, near Blayney, NSW. During this period, the phytoplankton of the Murrumbidgee River was dominated by two species of the diatom Melosira, and the cyanobacterium Anabaena sp. Carcoar Dam was mostly dominated by the cyanobacteria Microcystis aeruginosa and Anabaena sp. The major odour compounds detected were geosmin, β-cyclocitral, β-ionone, geranylacetone, and 6-methylhept-5-en-2-one. Clmparison of multivariate statistical analyses of the volatile odour compound profiles and algal population data provided strong evidence for the hypothesis that the major source of many of these odour compounds was the phytoplankton. Total (intra+extracellular) geosmin concentration was strongly correlated with Anabaena abundance with no significant difference in geosmin production between sites. From the overall average of 10 fg geosmin cell−1 it is possible to predict that taste and odour problems, due to geosmin, may be experienced at Anabaena abundances of > 1,000-2,000 cells ml−1 in temperate Australian waters. β-cyclocitral concentration was correlated with Microcystis abundance at Carcoar Dam (10 fg β-cyclocitral cell−1), but with Anabaena sp. abundance at Hay Weir (2 fg cell−1).
Evaluation of odour removal by pilot-scale biological treatment process trains during spring runoff in an ice-covered river
Authors: Hrudey S. E. , Huck P. M. , Mitton M. J. , Kenefick S. L.
Published: May 2018

Biological water treatment has been shown to effectively remove biodegradable organic matter, chlorinated by-products and ozonation by-products from drinking water during a large pilot-scale study for the American Water Works Association Research Foundation using the North Saskatchewan River, at Edmonton. In addition to studying total organic carbon, assimilable organic carbon, chlorine demand, haloacetic acid formation potential, trihalomethane formation potential, adsorbable organic halide formation potential, chloral hydrate and aldehydes, this study used a flavour profile panel to follow the removal of odour through different process trains involving biological treatment during the annual spring runoff which has historically caused odour incidents in the water supply. Over the 5-week period of the study, the raw water was found to develop from a very mild grassy odour to a strong odour, variously characterized as septic, manure, musty, earthy and hay-like. The odour persisted and changed character to varying degrees through the various process trains under study. The results verified the futility of relying on a strictly oxidative treatment like ozone for odour removal as well as showing that biological treatment using granular activated carbon could produce an essentially odour-free effluent during a transient raw-water odour event.
Oxidation of odorous and nonodorous algal metabolites by permanganate, chlorine, and chlorine dioxide
Authors: Dietrich A. M. , Hoehn R. C. , Dufresne L. C. , Buffin L. W. , Rashash D. M. C. , Parker B. C.
Published: May 2018

The six algal metabolites, at concentrations of 20-225 μg/l, were oxidized with potassium permanganate, chlorine, or chlorine dioxide at doses of 0.25-3 mg/l. Flavor profile analysis (FPA) was used to determine the odors of the solutions before and after oxidation. Linoleic and palmitic acids, which are odorless compounds, were oxidized to odorous products by all three oxidants. The odor intensity of β-cyclocitral (grape, sweet tobacco) and phenethyl alcohol (rose, floral) was only slightly decreased by any of the oxidants. Oxidation by permanganate or chlorine either eliminated or greatly reduced the odors associated with linolenic acid (watermelon) and 2t,6c-nonadienal (cucumber); chlorine dioxide was ineffective at reducing the cucumber odor of 2t,6c-nonadienal. Oxidation, at doses typically applied for drinking water treatment, can result in the destruction of certain algae-related odors but in the formation of other odors.
Sulfate removal from indigo dyeing textile wastewaters
Authors: Kabdasli Isik , Tünay Olcay , Orhon Derin
Published: May 2018

Sulfate is an important parameter especially for discharges to sewer systems. The textile industry is a major source of sulfate. Some sulfate sources in the industry have material replacement alternatives. However in some sources, sulfate or species convertible to sulfate are the main materials. The indigo dyeing process involves sulfur species as main materials. In this study, indigo dyeing wastewaters which contain significant concentrations of oxidized and non-oxidized sulfur components are evaluated in terms of sulfate removal. The approach is a pretreatment at the source before being mixed with other wastewaters. The study is conducted in two steps. In the first step, conversion of species to either sulfide or sulfate is experimentally evaluated. While reduction to sulfide poses problems, oxidation of all species to sulfate is found to be applicable. In the second step sulfate precipitation using calcium, barium and lead is practiced. Calcium precipitation provides up to 30% sulfate removal and these results are supported with existing literature data. Barium sulfate and lead sulfate precipitation provided practically complete removal. Economical evaluation of alternative methods is also given.
Cheese whey and cheese factory wastewater treatment with a biological anaerobic–aerobic process
Authors: Malaspina F. , Stante L. , Cellamare C. M. , Tilche A.
Published: May 2018

Research on the anaerobic treatment of raw cheese whey started in 1990 with the objective of developing a technology suitable for medium size cheese factories that have growing disposal problems and cannot afford high investment costs for whey valorisation technologies (such as whey protein and lactose recovery, spray drying, etc.). In order to couple process stability and high loads, a new downflow-upflow hybrid reactor (DUHR) has been designed. The reactor was able to reach Bv values around 10 g COD·1−1·d−1, with 98% COD converted to gas and effluent soluble COD values close to 1,000 ppm; no external addition of alkalinity is required to maintain a stable pH that was constantly around 6.5-6.7 in the downflow pre-acidification chamber and around 7.5 in the bio-methanation upflow chamber. The high strength of the cheese whey treated gives an effluent that still contains high amounts of COD, ammonia nitrogen and phosphorus and therefore a post treatment is required in order to meet standard limits. Tests of post treatment were carried out during two years with a Sequencing Batch Reactor (SBR). The SBR was tested at various F/M values with different durations of anoxic-anaerobic-oxic cycles, obtaining, under certain conditions, more than 90% removal of COD, nitrogen and phosphorus.
Intermittent aeration of pig slurry – farm scale experiments for carbon and nitrogen removal
Authors: Bicudo José R. , Svoboda Ivo F.
Published: May 2018

A farm scale treatment plant was studied during a year. Four different aeration cycles were tested in order to optimise the process and to produce an effluent with low carbon and nitrogen concentrations. The treatment plant performance was not significantly affected by a 60% reduction of aeration times, from almost 20 hours per day to 12 hours per day. The high removal rates observed appeared to be related to the low aeration rates achieved through the intermittent operation of the aerator. The operation of the treatment system at very long sludge age resulted in almost complete removal of soluble biodegradable matter and up to 90% removal of soluble COD. The development of simultaneous nitrification/denitrification processes in the aeration tank resulted in very low ammonia levels in the final effluent and a reduction of over 95% in the TKN values. The energy input to the system was estimated to be, in average, 9 kWh/m3 of slurry. Activated sludge quality was monitored through microscopic examination and there was no evidence of an abundant or excessive growth of filaments within the reactor.
Nine years of full-scale anaerobic–aerobic treatment experiences with fermentation industry effluents
Authors: Çiftçi T. , Öztürk I.
Published: May 2018

This paper presents the results of nine years of experience in design and operating of full-scale anaerobic-aerobic treatment plants in a fermentation industry producing baker's yeast from sugarbeet molasses. The PAKMAYA Izmit Factory has a large two-staged treatment plant since 1986: anaerobic first stage and aerobic second stage. The anaerobic reactors were constructed as Upflow Anaerobic Sludge Blanket Reactors (UASBR) with internal and external sludge recirculation facilities. Average COD removals remain in the range of 75% in the mesophilic anaerobic stage. Average daily biogas production rates are as high as 20,000 m3/day. This treatment plant is one of the largest in the world in terms of biogas production. Similar systems were constructed later in two other factories of the same company (Cumaova-Bolu, Kemalpasa-Izmir). The biogas conversion yield is about 0.65 m3 per kg COD removed. The energy produced from the biogas used in the boiler houses is about 35% of the total energy requirement of the factory. The effluents from the anaerobic first stage are fed to the subsequent aerobic treatment system by mixing with low strength effluents of the factory. The aerobic second stage was designed and operated as an extended aeration activated sludge system. The COD removals of the aerobic stage are averaging at about 60 to 75%. This paper also discusses the operating problems encountered in the various stages of the treatment system and their solutions during the nine years of full-scale operation in three different treatment plants of PAKMAYA.
Manganese removal from acid coal-mine drainage by a pond containing green algae and microbial mat
Authors: Phillips P. , Bender J. , Simms R. , Rodriguez-Eaton S. , Britt C.
Published: May 2018

Acid mine drainage flowing from an underground seep, through an anoxic drain to an oxidation pond and then trickling filter was distributed among three treatment ponds for manganese reduction before releasing the mining water to a surface stream. Manganese was more effectively removed from the integrated green algae and microbial mat with limestone substrate pond (algae mat system) than from control ponds containing limestone or pea gravel substrates without mat. Although there was some Mn-cell binding, manganese was primarily deposited as precipitates at the pond bottom. Day/night and winter/summer manganese removal was essentially the same. The greater efficiency in Mn removal by the algae mat pond was most pronounced with higher flow rates and during the night. At 2 metres from the influent point of each pond, the algae mat pond removed 2.59 g manganese/day/M2, respectively, compared to 0.80 in the limestone pond and 0.37 in the pea gravel pond. Control ponds showed either Mn breakthrough or near breakthrough (Mn outflow releases > US Environmental Protection Agency regulations of 2 mg/L) during night-time sampling or when mine drainage flow exceeded 4.5 L/min.
Upgrading of facultative ponds to treat a toxic organic wastewater
Authors: Polprasert C. , Sookhanich S.
Published: May 2018

This study investigated the efficiency and performance of attached-growth waste stabilization ponds (AGWSP) treating a high-strength phenolic wastewater. The experiments employed 4 laboratory-scale pond units installed with an artificial attached-growth media. A control pond unit without attached-growth media (or WSP) was run in parallel for data comparison.

The experimental results revealed that the AGWSP units could remove about 99, 50, 45 and 28% of phenol when operated at influent phenol concentrations of 500, 1000, 1500 and 2000 mg/l (corresponding to organic loading rates (OLR) of 180, 360, 540 and 720 kg COD/(ha.day), respectively); these removal efficiencies were consistently higher than those observed in the WSP unit. The influent phenol concentrations of 1000-2000 mg/l resulted in some toxic effects and over loading to the pond system, causing the phenol removal efficiencies to decrease. The amount of phenol loss from the pond water through volatilization was found to be approximately 10%. A relationship between phenol removal rates (excluding volatilization) and phenol dosages to the AGWSP was developed. The superior performance of the AGWSP over the WSP appeared to be due to the biofilm biomass growing on the attached-growth media surface, resulting in increased potential biomass in the pond water.
A simple method for analysis of the performance of aerated wastewater lagoons
Authors: Bryant Curtis W.
Published: May 2018

An aerated wastewater stabilization lagoon, or any subsection of the overall lagoon, should function as an oxidation reactor, a clarifier, and a sludge digester. A relatively simple set of calculations can be used to evaluate these three functions for zones within a lagoon system. Only SBOD, TSS, and NH4-N or PO4-P measurements are needed to support the analysis. The evaluation should be limited to bacterially dominated zones of a lagoon system, i.e. lack of significant algal influence.
Nitrogen removal from waste treatment pond or activated sludge plant effluents with free-surface wetlands
Authors: Horne Alexander J.
Published: May 2018

Due to their dynamic mode of operation, waste treatment pond and activated sludge plant effluents always contain quite large amounts of nitrogen relative to those found in natural lakes, streams, and oceans. Typical activated sludge plant effluents contain 25 mgl-1 N, mostly as ammonia. In most aquatic milieux, concentrations of ammonia > 1 mgl-1 N are potentially toxic to fish and other wildlife. Nitrification and denitrification of activated sludge plant effluent alleviates the ammonia problem at a considerable cost but the discharges still usually contain over 10 mgl-1 NO3-N which exceeds the WHO standard for drinking water. A great advantage of waste treatment pond effluents is that nitrogen is normally already present as nitrate or particulate-N (algae and bacteria), and nitrate concentrations are < 5 mgl-1 NO3-N. However, even 1 mgl-1 of nitrate-N is sufficient to cause eutrophication in unpolluted lakes, streams, and oceans and some of the particulate-N discharged will be recycled to give eutrophication downstream. Where sufficient diluting water is available, these higher effluent concentrations are not a problem. Unfortunately, clean diluting water is becoming a scarce commodity in many areas, particularly the 17 semi-arid states in the USA and in most developing countries where rainfall is needed for drinking water and wildlife support. One solution for nitrogen removal is new design for free surface constructed wetlands which have considerable potential for nitrogen polishing of waste treatment pond effluents. Particulate-N can be removed by using wetlands as large filters but the nitrogen often recycles and is released as ammonia in winter and spring. Denitrification of nitrate to N2 gas removes the problem permanently. In particular, the relatively low BOD, high nitrate and low ammonia effluent from some stabilization ponds is ideal for nitrate removal (denitrification) by free surface wetlands. Rates of nitrate removal of 200 to over 5,000 mg N m-2 d-1 can be achieved with initial nitrate values of 2-14 mgl-1 NO3-N. These rates are 1-2 orders of magnitude greater than occur in most natural lake, estuarine or wetlands sediments and can be mostly attributed to denitrification rather than growth of rooted plants. In two weeks 20 mgl-1 NO3-N can be reduced to less than 1 mgl-1. After wetlands treatment the water is suitable for release into water-depleted live streams or lakes where a low eutrophication potential is vital for native biota. It is recommended that pond effluent be routed thorough constructed wetlands whenever possible since both better water quality and wildlife benefits occur.
Upgrading effluent quality for lagoon-based systems
Authors: Melcer Henryk , Evans Brian , Nutt Stephen G. , Ho Anthony
Published: May 2018

To establish Best Available Technology Economically Achievable (BATEA) in non-urban communities which presently use conventional lagoon technology, an investigation was undertaken to evaluate alternatives which can be used to improve lagoon effluent and establish costs. Evaluated were the “Sutton” and the intermittent sand filtration or “New Hamburg” processes. The Sutton concept consists of a nitrifying extended-aeration plant followed by polishing lagoons, with waste sludge discharged into the lagoons. The New Hamburg concept consists of aerated or facultative lagoons, with the lagoon effluent sprayed intermittently over sand filters.

The Sutton plants produce an improved effluent quality relative to conventional facultative lagoons in terms of BOD5 and TSS concentrations. Increases in ammonia concentration across the polishing pond occur after 5-7 years of plant operation, suggesting a need to implement a regular program of sludge removal from the lagoon. The New Hamburg process results in a significant improvement in effluent quality in terms of BOD5, TSS, TP, TKN, NH3-N and H2S concentrations. Approximate capital costs for upgrading the existing conventional lagoons in Ontario to Sutton and New Hamburg process facilities are estimated at US $221 million and US $93 million, respectively.
Behaviour of air injection nozzles in dissolved air flotation
Authors: Rykaart E. M. , Haarhoff J.
Published: May 2018

A simple two-phase conceptual model is postulated to explain the initial growth of microbubbles after pressure release in dissolved air flotation. During the first phase bubbles merely expand from existing nucleation centres as air precipitates from solution, without bubble coalescence. This phase ends when all excess air is transferred to the gas phase. During the second phase, the total air volume remains the same, but bubbles continue to grow due to bubble coalescence.

This model is used to explain the results from experiments where three different nozzle variations were tested, namely a nozzle with an impinging surface immediately outside the nozzle orifice, a nozzle with a bend in the nozzle channel, and a nozzle with a tapering outlet immediately outside the nozzle orifice. From these experiments, it is inferred that the first phase of bubble growth is completed at approximately 1.7 ms after the start of pressure release.
Pilot plant testing of dissolved air flotation for treating Boston's low-turbidity surface water supply
Authors: Johnson B. A. , Gong B. , Bellamy W. , Tran T.
Published: May 2018

The Massachusetts Water Resources Authority (MWRA) supplies water to 2.5 million people in Eastern Massachusetts. Currently, the surface water supply is unfiltered. To determine the best way to comply with the Safe Drinking Water Act Amendments (SDWA), the MWRA initiated watershed protection and pilot treatment studies. This paper summarizes the major findings of the pilot treatment study. In particular, it compares the performance of dissolved air flotation with that of inline filtration, direct filtration, and contact adsorption clarification. Each process was evaluated for turbidity removal, filter production, particle reduction, disinfection byproducts, effect of ozonation, and coagulants. As a result of the piloting, a treatment process train consisting of dissolved air flotation, ozone, biological filtration, and chloramination was recommended.
Dissolved air flotation in Southern Africa
Authors: Offringa G.
Published: May 2018

A brief review is given of the historical development and current application of flotation technology in Southern Africa. Applications in water reclamation, sludge thickening, industrial effluents and water treatment are presented on the basis of some case studies and pilot investigations. Design philosophies followed are pointed out. Research and development performed and a few innovations by local engineers and scientists are highlighted. These include combination or integration of dissolved air flotation (DAF) with filtration, presettling and powdered activated carbon, a simple aeration nozzle, surface grids for float dewatering and stabilization, and a counter-current DAF.
Dissolved air flotation in the treatment of industrial wastewaters with a special emphasis on forest and foodstuff industries
Authors: Viitasaari M. , Jokela P. , Heinänen J.
Published: May 2018

The suspended solids separation is an essential element in almost any wastewater treatment system. If sedimentation, dissolved air flotation and filtration are compared, flotation has both the largest operational ranges concerning influent suspended solids concentration and particle size, and load bearing capacities. When considering the suitability of flotation as a wastewater treatment process, important factors are the effluent and sludge qualities, operation and costs. To get a comprehensive conception of flotation, those factors are presented and discussed. Flotation is widely used in forest industry wastewater treatment, as well as in process water recirculation. It is also proven technology in foodstuff industry wastewater treatment. Several cases from both industries are presented.
Gene exchange in drinking water and biofilms by natural transformation
Authors: Lisle John T. , Rose Joan B.
Published: May 2018

A naturally competent Acinetobactercalcoaceticus system has been developed to investigate the frequency of gene exchange by natural transformation in drinking water and biofilms. We report here 1) the first demonstration of bacterial transformation in drinking water, with and without disinfectant residual (respective transformation frequencies: 6.59×10−7 and 8.81×10−7), 2) that disinfectant residual had no effect on the ability of these bacteria to exchange plasmid resident genes and 3) the development of a bacterial system to characterize natural transformation in biofilms.
Development of a colorimetric protein phosphorylation assay for detecting cyanobacterial toxins
Authors: Ash C. , MacKintosh C. , MacKintosh R. , Fricker C. R.
Published: May 2018

A new colorimetric assay is described, based on inhibition of protein phosphotases, that enables the rapid, simple and sensitive determination of the concentration of toxins from cyanobacteria.
Removal of hepatitis a virus (HAV), poliovirus and MS2 coliphage by coagulation and high rate filtration
Authors: Nasser A. , Weinberg D. , Dinoor N. , Fattal B. , Adin A.
Published: May 2018

Filtration is considered a mandatory operation unit for the production of pathogen free drinking water from surface sources. This study was undertaken to determine the removal efficiency of enteric pathogenic viruses (hepatitis A virus and poliovirus) by high rate filtration and to determine the suitability of F+bacteriophages as index for the removal of these pathogens. A jar test was used to determine the optimal flocculation dose to be used in the high rate filtration experiments. At an alum concentration of 30 mg/l, the greatest reduction was observed for HAV (88.4%) as compared with poliovirus 1 (47%) and turbidity (61%). Addition of 1 mg/l cationic polyelectrolyte improved the reduction of HAV to 98.3% by flocculation, while the removal of polio 1 and turbidity was not improved. The presence of humic acid at a concentration of 15.3 mg/l interfered with flocculation performance of HAV and turbidity, while the addition of the cationic polyelectrolyte reduced the interference appreciably. High rate filtration (20 m/hr) using a 100 cm long sand column, resulted in reduction of 99%, 93% and 80% of turbidity, MS2 and poliovirus 1, respectively. Addition of polyelectrolyte enhanced the removal of viruses and turbidity. In the presence of humic acid no virus removal was observed by high rate filtration, whereas turbidity removal was unaffected. The removal of MS2 was similar to that of HAV rather than poliovirus 1. High rate filtration was found efficient for the removal of pathogenic viruses and turbidity from surface water. Under all conditions tested the removal of turbidity was greater than that of viruses.
A framework for integrated river basin management
Authors: Burton J.
Published: May 2018

A framework for integrated river basin management was designed in consultation with African managers in 1990–1991. It was used as a training guide at five regional seminars organized in 1992–1993 by the Large River Management Project of the Francophone Summit (Paris). It begins with an extensive documentation phase to produce an integrated diagnosis of the river basin, moves into a planning phase and ends with an action and monitoring phase. Integrated river basin management is feasible but the real challenge lies with the lack of information and the need for a people-oriented approach.
Role of non-point sources in the development of a water quality management plan for the Mgeni River catchment
Authors: Pegram G. C. , Bath A. J.
Published: May 2018

Integrated river basin management depends upon information about existing and potential water quality problems. In the Mgeni River basin, the major water quality problems are sediment, nutrient and bacterial with at least 85 percent of the total contamination derived from non-point sources. This paper shows that it is of paramount importance that the development of management objectives and approaches be based on the understanding, quantification and interpretation of the seasonal and spatial variation in export from non-point source areas. Management and analysis requires the grouping of all non-point source areas into diffuse, concentrated and incident sources, with the emphasis on the source area and pollutant delivery rather than the water quality response. Traditionally monitored data is not sufficient for detailed interpretation of non-point source pollution. Comments are made regarding the problems associated with obtaining representative loading data for non-point sources. The choice of appropriate analysis techniques, which assist in the interpretation of the available data, is based upon an assessment of the information requirements for management, the conditions and the water quality problems in the study catchment. GIS-based basin scale and individual source area maps of pollution potential and export are used to support the time-series of catchment export. These techniques will be incorporated into the management information system (MIS).
Distribution comparison between coliphages and phages of anaerobic bacteria (Bacteroides fragilis) in water sources, and their reliability as fecal pollution indicators in drinking water
Authors: Armon R. , Kott Y.
Published: May 2018

E. coli somatic and male specific bacteriophages and Bacteroides fragilis bacteriophages had been surveyed in drinking water for three years. Concurrently, coliforms and fecal coliforms bacteria were also measured. Occasionally several large drinking water volumes were tested for enteric viruses and the above bacteriophages. Sampling site cluster shows good correlation between bacteriophages and bacterial indicators, as pollution index. Water from the three main supply sources showed increased bacteriophage presence as follows: well > lake >spring. Mixture of the three water supplies revealed different contamination frequency. Bacteriophages' presence in drinking water presumably points to contamination of these sources. Results of a different study on groundwater aquifer recharged with reused water, and retained for more than 20 months before being drawn out, showed absence of these bacteriophages. The current results correlate with other studies, indicating that filtration is a necessary step in water treatment. With the introduction of full scale filtration units in the near future, it is expected to find a decline in the presence of these bacteriophages in drinking water in Israel. Following additional studies, use of suggested E. coli bacteriophages of type male-specific (F+) similar to coliforms and B.fragilis bacteriophages to fecal coliforms as pollution index of drinking water, in addition to classical indicators.
Development of a method to selectively isolate pathogenic Leptospira from environmental samples
Authors: Wilson Richa , Fujioka Roger
Published: May 2018

Current isolation methods are incapable of selectively recovering pathogenic Leptospira from environmental samples which contain saprophytic Leptospira. In this study the Faine's Test and the Modified Faine's Test, both of which simulate internal body conditions, were evaluated to promote the growth of the pathogen in vitro while inhibiting the growth of the saprophyte. Only the saprophytic Leptospira were found to be inhibited by the test conditions provided. These tests were used for the isolation of pathogenic Leptospira from soil and stream water samples. Preliminary data suggest that Faine's Test and the Modified Faine's Test may be useful in serving this purpose.
A comparison of culture methods for the detection of Salmonella in wastewater sludge
Authors: Hu C. J. , Gibbs R. A.
Published: May 2018

A comparative study was undertaken of three enrichment broths and three plating media to determine their efficiency in isolating Salmonella from wastewater sludge samples. These samples were raw, digested and dewatered sludge from wastewater treatment plants and composted sludge from a composting facility.
Detection of adenovirus and enterovirus by PCR amplification in polluted waters
Authors: Girones R. , Puig M. , Allard A. , Lucena F. , Wadell G. , Jofre J.
Published: May 2018

Several systems for virus recovery from environmental samples and extraction of nucleic acid were tested by adding adenovirus 2 and poliovirus 1 to different sewage samples. The most promising method involved: concentration of viruses by centrifugation, and elution of the pelleted viruses by treatment with 0.25 N glycine buffer pH 9.5. The nucleic acids were extracted by adsorption of RNA and DNA to silica particles. One aliquot was directly used for a two-step PCR in a nested fashion, with specific primers for all adenoviruses; the other aliquot was used to synthesize cDNA and a nested two-step PCR with specific primers for enteroviruses. The specificity and sensitivity of the selected primers were evaluated, the 47 human adenovirus serotypes were identified and 24 different enterovirus strains were recognized. The sensitivity of the nucleic acid extraction, cDNA synthesis and nested PCR amplification was estimated to be between 1 and 10 viral particles. Sewage and polluted river samples were analyzed showing, as expected, a much higher number of positive samples by the method described than by tissue culture analysis, a high prevalence of hepatitis A virus in sewage and the adenoviruses as the most commonly detected virus in the environmental samples analyzed.
Use of RT seminested PCR to assess viral contamination in Caribbean rivers (Martinique)
Authors: Le Guyader F. , Menard D. , Pommepuy M. , Kopecka H.
Published: May 2018

RT seminested PCR was used to detect enterovirus and hepatitis A virus RNA in polluted surface water in a Caribbean island. Similar results were obtained from samples with or without PEG concentrations: viral RNA being detected in about 60% of river samples. No correlation was found with bacterial contamination, but some inhibitors may have been present. PCR would seem to be a good tool for monitoring surface water pollution.
Studies on the prevalence of giardia cysts and cryptosporidium oocysts in South African water
Authors: Kfir R. , Hilner C. , du Preez M. , Bateman B.
Published: May 2018

The levels of Giardia cysts and Cryptosporidium oocysts in 650 environmental water samples were investigated. Cysts and oocysts were found in all types of water tested. The presence of Giardia cysts exceeded Cryptosporidium oocysts both in the number per sample and the number of positive samples. Almost 50% of sewage samples studied contained Giardia cysts and 30% contained both Giardia cysts and Cryptosporidium oocysts. Treatment of sewage resulted in a reduction in the percentage of samples containing cysts and/or oocysts (30% of treated effluent samples were positive for Giardia and 25% had both cysts and oocysts). Higher numbers of Giardia cysts were found in surface water samples than in either sewage or treated effluents (55% of surface water samples were positive). However, the number of cysts isolated per surface water sample was lower on average. Most water purification plants showed effective removal of cysts and oocysts. However, 13% of potable water samples contained protozoan parasites, indicating occasional failure of the purification processes and the need for monitoring final treated water.