bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of ozonation and adsorption processes onto the chlorine demand of surface natural water
Authors: Ramírez Zamora R.M. , Seux R. , Durán Moreno A.
Published: May 2018

The aim of this work was to quantify the influence of the adsorption process, alone or coupled with ozone, in reducing the chlorine dose required in the disinfection stage of a drinking water treatment train. The raw water of the Blue reservoir (Paimpont, France) was fed to a pilot system consisting of a constant pre-treatment (coagulation–flocculation and sand filtration) but with different polishing processes (adsorption alone or combined with a pre-ozonation stage). Chlorine demand, at 2, 6 and 24 hours of reaction time, was determined for the effluent collected from the sand filter, according to the break-point method. The clarified and sand-filtered effluent was subsequently treated either by ozonation (15 min, 3 mg O3/L) coupled with adsorption (EBCT=8 min) or by adsorption alone. Two types of activated carbon were evaluated (NC35, coconut shell and PICABIOL, wood). The final effluents of these two treatment trains were collected to determine their chlorine demand. The adsorption process with PICABIOL halved the chlorine dose (2 mg Cl/L), compared with 4 mg Cl/L for the sand filtered effluent, required to obtain a residual concentration of free chlorine of 0.5 mg/L. Pre-ozonation coupled to adsorption also reduced significantly (by a factor of two and four depending on the type of GAC used) this chlorine dose, after 2, 6 and 24 hours of reaction time. Moreover, the residual chlorine content was the same for these three reaction times because ozone and activated carbon efficiently removed most of the reducing inorganic nitrogenous pollutants. The removal of aromatic organic compounds, quantified as Abs254 nm, by these processes decreased also significantly the calculated THM FP (trihalomethane formation potential) to the extent that this value for the ozonated and or adsorbed effluents has always been lower than the guideline proposed by the EPA (100 μg/L) for total THMs (yearly average).
A rapid small scale evaluation of ultrafiltration performance for surface water treatment at Alcantarilha's water treatment works (Algarve, Portugal)
Authors: Teixeira M. Ribau , Lucas H. , Rosa M.J.
Published: May 2018

A rapid small-scale evaluation of ultrafiltration (UF) performance with and without physical–chemical pre-treatment was performed to up-grade the conventional treatment used for drinking water production in Alcantarilha's water treatment works, Algarve, Portugal. Direct UF and pre-ozonation/coagulation/flocculation/sedimentation/UF (O/C/F/S/UF) were evaluated using polysulphone membranes of different apparent molecular weight cut-off (MWCO) (15–47 kDa). The results indicated that (i) UF is an effective barrier against microorganisms, including virus larger than 80 nm; (ii) for surface waters with low to moderate SUVA values, direct UF performance is equivalent or better than the conventional treatment in terms of residual turbidity, while UV254 nm and TOC residuals require the use of O/C/F/S/UF; (iii) the permeate quality improves with the membrane apparent MWCO decrease, especially for the direct UF, although the conventional treatment performance is never reached using UF; (iv) membrane fouling and adsorption phenomena are more severe in direct UF than in O/C/F/S/UF sequence (pre-ozonation decreases the membrane foulants by decreasing their hydrophobicity) and these phenomena increase with the membrane hydraulic permeability and, particularly, with the membrane apparent MWCO.
Application of hydraulic transients for leak detection in water supply systems
Authors: Covas D. , Ramos H. , Graham N. , Maksimovic C.
Published: May 2018

The current paper reports the investigation of two transient-based techniques for leak detection in water pipe systems using physical data collected in the laboratory and in quasi-field conditions. The first is the analysis of the leak reflected wave during a transient event and the second is inverse transient analysis (ITA). This was approached through the development of an inverse transient analysis tool and the collection of transient data for the testing and validation of this model. Two experimental programmes were carried out at Imperial College and in cooperation with Thames Water for the validation and testing of these techniques. Evaluation of the presence, location and size of leaks was carried out using the collected data. Transient-based techniques have been shown to be successful in the detection and location of leaks and leak location uncertainties depended on the leak size and location, flow regime and location where the transient event was generated. These leak detection methods are very promising for identifying the general area of the trunk main with leakage, and can be combined with other leak location techniques (e.g. acoustic equipment) to more precisely pinpoint the leak position. Transient-based techniques are particularly important for the diagnosis, monitoring and control of existing water supply systems, not only to detect leaks, but also to better understand the causes of pipe bursts and accidents, particularly when these are due to natural transient events.
Particles in the drinking water system: from source to discolouration
Authors: Vreeburg J.H.G. , Schaap P.G. , van Dijk J.C.
Published: May 2018

Water discolouration in networks results from increased turbidity due to high levels of suspended particles. Hydraulic incidents such as pipe burst or hydrant use impose extra shear stresses on sediment layers in the network, leading to particle resuspension. The mass balance over a network or parts of the network may be used to analyse the different sources and accumulation processes; this article focuses on the contribution of the “mass in” from the pumping station as particles. Three analysis methods have been developed within the joint research program of the Dutch water companies (BTO-program): the continuous monitoring of turbidity, the Mass Settling Potential Method and the Resuspension Potential Method. The continuous monitoring of turbidity and particle counting enable an analysis of the relative contribution of sources for particles, e.g. corrosion of cast iron. The Mass Settling Potential and Resuspension Potential methods add insight into actual sediment load and actual discolouration risk. Further development of these methods will enhance knowledge of the origin and fate of particles in a network, enabling the formulation of effective measures against discolouration and associated water quality problems.
Assessing the relevance of intervening parameters on the per capita water consumption rates in Brazilian urban communities
Authors: de Lourdes Fernandes Neto M. , Naghettini M. , von Sperling M. , Libânio M.
Published: May 2018

The determination of the per capita water consumption is an essential step in the design of water supply systems. The present paper examines the influence of several variables on the per capita water consumption, based on 96 different towns in the Brazilian state of Minas Gerais. The set of samples was categorised firstly into five different classes and three distinct population intervals and, finally, was presented in overall terms. The paper also attempts to explain the relative influence of the intervening factors for each population range, and presents a multivariate regression model for the per capita water consumption rates for towns with populations ranging from 50,000 to 100,000 inhabitants. For this population range, the significant variables were: (a) percentage of water metering, (b) water tariff, and (c) energy consumption by commercial and industrial activities.
Sustainability and implementation of economic regulation in the Water Sector in Victoria, Australia
Authors: Farrier S. , Swier G.
Published: May 2018

The water industry in the state of Victoria, Australia underwent significant structural and pricing reforms in the 1990s. Now, attention is focussed on introducing independent economic regulation, and on the sustainable management of water resources. Experience in Victoria, Australia, provides an interesting opportunity to consider the challenges of reconciling independent economic regulation of profit focused businesses while meeting goals for sustainability in the most efficient way. We conclude that effective integration of sustainability and economic regulation requires consideration of the incentives in economic regulation; investment in defining and collecting data and information to support decisions; greater utilisation of market based instruments; wider and extended use of existing evaluation tools and more explicit linking of these tools to decisions about allocation of resources. However we consider that priority should be given to institutional arrangements; we consider that reform will be required to align arrangements with objectives and thus facilitate efficient and consistent decision-making.
Duly diligent utilities
Authors: Davison A.D. , Pryor E.L. , Howar G. , Deere D.A.
Published: May 2018

Increasingly, utilities need to think of their operations as businesses and as such, they are not only in the business of providing raw and drinking water, sewage services and stormwater services, they also need to acquit those operations in a manner consistent and compliant with the jurisdiction in which they operate. In this paper, we discuss the legal frameworks with which utilities should be familiar and show how having comprehensive and defensible risk management systems in place can demonstrate that a utility is conducting its business in a duly diligent fashion.
Innovative process using Fe0/CO2 for the removal of nitrate from groundwater
Authors: Ruangchainikom C. , Liao C.H. , Anotai J. , Lee M.T.
Published: May 2018

In this study, the Fe0/CO2 process was investigated for removing nitrate from aqueous solution, in terms of process efficiency, process operation mode, and post-treatment of the end product ammonium. The results show that nitrate at 30 mg/L could be removed from solution within 30 min under the conditions of 2 g/L Fe0 and 200 mL/min CO2 flow rate. Additionally, nitrite was not detected in treated solution, whereas ammonium is the predominant nitrogen-containing species. The normalized residual nitrate concentration decreased with increasing nitrate concentration (2.18–24.19 mg N/L). Nitrate removal was inhibited significantly in the presence of humic acid. Comparing operation modes, NO3− reduction efficiency with increasing number of batch operations in Mode 2 (treated solution was emptied and refilled with freshly prepared solution for the next batch treatment, containing the same level of nitrate as the previous batch) is better than that with Mode 1 (treated solution was retained in the reactor and spiked with concentrated nitrate solution to raise nitrate concentration to a level close to the one in the previous batch). However, to guarantee satisfactory nitrate removal in batch operation mode, zero-valent iron supplementation needs to be taken into consideration. For example, the nitrate removal efficiency without Fe0 supplementation is decreasing in the third batch, compared with those with supplements of 0.25 and 1 g/L. According to a preliminary study, the undesired end-product ammonium can be removed from solution by about 95% within 22.5 h with an air flow rate of 500 mL/min and a solution pH around 12; the ammonium concentration decreased from 6.4 to 0.3 mg 12 N/L. Stripping time can be further shortened by increasing air flow rate and using an efficient air diffuser.
Application of zeta potential measurements for coagulation control: pilot-plant experiences from UK and US waters with elevated organics
Authors: Sharp E.L. , Banks J. , Billica J.A. , Gertig K.R. , Henderson R. , Parsons S.A. , Wilson D. , Jefferson B.
Published: May 2018

At present little is known about the relationship between raw water characteristics, such as natural organic matter (NOM) content, and the universal applicability of coagulation optimisation through surface charge measurement. This research aims to investigate this issue by comparing case study sites in the US (Poudre River, Fort Collins, Colorado) and the UK (Albert Reservoir, Halifax) across periods of elevated organic levels. During the period of April to June 2004 in raw Poudre River water dissolved organic carbon (DOC) levels increased rapidly from 3.5 to 7.4 mg L−1 as a direct result of the spring snowmelt runoff, whereas at Albert reservoir, which is a moorland peat catchment, DOC concentrations varied between 7.8 and 10.1 mg L−1 during the period of January to March 2004. NOM is a highly heterogeneous mixture of organic compounds that vary with regards to acidity, molecular weight, hydrophobicity and charge density. XAD resin adsorption techniques were employed to fractionate the water into its hydrophobic and hydrophilic components. Results revealed that NOM composition and characteristics can vary both temporally and spatially, with increased DOC concentrations associated with both an increase in hydrophobic content and charge density. Optimising coagulation based on a zeta potential range (−10 to +5 mV) produced stable average DOC residuals for both locations, although the exact value is also dependent on the hydrophilic composition of the water and the coagulant used, with alum removing approximately 0.5 mg L−1 less DOC compared with ferric.
Removal properties of arsenic compounds with synthetic hydrotalcite compounds
Authors: Kiso Y. , Jung Y. J. , Yamada T. , Nagai M. , Min K. S.
Published: May 2018

The contamination of underground water with inorganic arsenic compounds has caused serious problems, particularly in developing countries. For water containing low-level arsenic compounds, an adsorption process may be more effective than other processes such as RO membrane and precipitation. In this study, the removal performance for arsenic compounds was examined with synthetic hydrotalcite (HTAL) compounds as an adsorbent process from the following viewpoints: the adsorption capacity, adsorption isotherm, the effects of pH and co-existing anions. The HTAL-Cl, which contains Cl− ions as an intercalate, showed very high adsorption capacity in the neutral pH region. The maximum adsorption capacity was 105 mg-As(V) g−1. The adsorption isotherm was approximated by the following modified Langmuir equation:The equation suggests that one mol of As(V) occupies two adsorption sites of HTAL-Cl, and the experimental result indicated that 2.64 mol of Cl− ions in the HTAL-Cl were substituted with one mol of As(V). The interfering effects of co-existing anions were relatively low, and the magnitude of the effects was observed in the order of HCO3− > HPO42− > SO42− > Cl−.
Advances in the use of low-pressure, hollow fiber membranes for the disinfection of water
Authors: Jacangelo J.G. , Madec A. , Schwab K.J. , Huffman D.E. , Mysore C.S.
Published: May 2018

Low-pressure membranes are often used for disinfection purposes. Using a simple bench-scale testing unit, several membranes were evaluated for their capability to remove microorganisms under specific conditions. Five hollow fiber modified polysulfone membranes ranging in molecular weight cutoff (MWCO) from 10,000 to 300,000 daltons and a 0.2 μm nominal pore size membrane were also evaluated. The 10,000 MWCO membrane removed less virus than the two 100,000 MWCO or the 300,000 MWCO membranes. The data from this study suggests that MWCO and specific flux may not, in all cases, be a good predictor of virus removal.
Deciding now what we want to be tomorrow as a key way of speeding the water business change
Authors: Parena R.
Published: May 2018

Normally, in every industrial context strategic decisions design the business expected evolution. Fine tuned balances between customer needs and resources' expected reward have to be pursued when economically evaluating how designed strategies impact on the Water Utilities' competitive position. With such a purpose, strategies have to care for both the economic value produced for the stakeholders and the options and actions required. Evaluating dimensional strategies' effectiveness in qualitative terms of market appraisal rather than in quantitative terms of growing bargaining power seems to be the best model to assess profitability and sustainability of designed strategies. Moreover, particular aspects affect the water business and need to be carefully considered when designing well-defined strategies aiming at speeding the required change. What efficiency is and then how to measure it is thus the major challenge for water managers.
Economic analysis of domestic, industrial and agricultural water demands in China
Authors: Zhou Y. , Tol R.S.J.
Published: May 2018

Demand management plays an increasingly important role in dealing with water scarcity in China. It is important to understand the level and pattern of water use in various sectors across the regions for any measures being put into effect. The aim of this study is to enhance the understanding of the factors that influence water demand by examining closely the water use in domestic, industrial and agricultural sectors. Using province level panel data from 1997 to 2003, the examination shows that the regional disparity in the level and pattern of water uses is considerable. The estimation of water demand shows that both economic and climatic variables have significant effects on water demand. The results suggest an income elasticity of 0.42 for the domestic sector, an output elasticity of −0.32 for industrial water use (per unit of output), and an output elasticity of −0.23 for irrigated agriculture (per land area).
Using a choice experiment to estimate non-use values: the case of Cheimaditida wetland, Greece
Authors: Birol E. , Karousakis K. , Koundouri P.
Published: May 2018

This paper aims to assist policy makers in formulating efficient, effective and sustainable wetland management policies by providing them with the results of a non-market valuation technique using the Cheimaditida wetland in Greece as a case study. A choice experiment is employed to estimate the benefits of the non-use values of the Cheimaditida wetland that accrue to the Greek public. The results indicate that there are positive and significant non-use values of this wetland. These results can aid in the design of socially optimal policies for the sustainable management of the Cheimaditida wetland, with implications for other wetlands in Greece and the rest of Europe.
Analysis of water price determinants in France: cost recovery, competition for the market and operator's strategy
Authors: Garcia S. , Guérin-Schneider L. , Fauquert G.
Published: May 2018

This paper explores the effects of technical factors, competition and strategies of firms on the water price in France. From data on the procedures of delegation of water utilities, we estimate a price equation, taking into account the unobserved strategies of private operators and geographical effects. We show that the local strategy of the operator has a significant impact on the water price level and that neglecting it would lead to bias the effects of other factors.
Pricing irrigation water under asymmetric information and cost recovery constraints
Authors: Gallerani V. , Raggi M. , Viaggi D.
Published: May 2018

The objective of this paper is to discuss how policy makers may deal with irrigation water pricing under asymmetric information, positive transaction costs on payments and cost recovery constraints. The issue is dealt with through the development of a principal agent model and its application to a pilot case study in Emilia Romagna, Italy. The results show that using a menu of contracts may improve the overall social welfare derived from irrigation. However, differences in performance among instruments (and hence the choice of the optimal pricing strategy) are critically determined by the amount of the full cost of water and of transaction costs. Moreover, differentiation among farmers may encounter policy obstacles as a potential source of conflicts.
A design for a fresh water spot market
Authors: Raffensperger J.F. , Milke M.
Published: May 2018

This paper proposes a design for a fresh water spot market. The design has the groundwater of the New Zealand Canterbury Plains in mind, but would be appropriate for almost any region. In our market design, a market manager will operate a hydrology model and a Linear Program (LP), based on widely available software. The hydrogeology model calculates the effects of users' proposed abstraction rates. The LP finds allocations that maximise the sum of buyer and seller surplus, while satisfying environmental constraints expressed in terms of hydraulic heads and gradients in specific locations. The model produces a price for every location of interest. The price at a given location is the shadow price on the associated user's supply of water. Users are then charged their allocation times the market price at their location, and the market clears. We have written the software and are beginning testing.
Water reuse criteria in the United States
Authors: Crook J. , Surampalli R.Y.
Published: May 2018

Water reuse is well established in the United States, with uses ranging from pasture irrigation using reclaimed water that has received a low level of treatment, to augmentation of potable water supplies with highly treated reclaimed water. There are no federal regulations governing water reuse and criteria are developed at the state level. Criteria differ between states that have adopted regulations or guidelines, but criteria among states where water reuse is prevalent are similar and tend to be conservative, with public health protection being the most important consideration. The US Environmental Protection Agency (EPA) has published guidelines for water reuse that include recommended criteria for various reclaimed water applications.
Simple tertiary treatment systems
Authors: Escobar B. Moreno , Nieto M.A. Gómez , García E. Hontoria
Published: May 2018

There currently exists a wide range of systems for treating wastewater for reuse, with different levels of water quality and variable treatment costs. In view of this, it is appropriate to consider the most suitable alternatives in relation to the uses for which the treated water is intended. Accordingly, the research group ‘Microbiology and Environmental Techniques’ is studying various types of tertiary treatment with the aim of establishing which treatment is most suitable for specific uses. Results indicate that neither maturation lagoons nor macrofiltration systems should be employed as the only tertiary treatment before reuse. More exacting uses require more advanced technology, such as microfiltration and ultrafiltration, although it should be stressed that neither of these technologies is capable of eliminating dissolved substances. In this respect, reverse osmosis technology may provide a solution.
Membrane autopsies: helps to provide solutions to operational problems in reverse osmosis plants
Authors: López S. Gallego , del Vigo Pisano F. , Muñoz J. Shang
Published: May 2018

The problems of the need for water in the quantity and quality for the diverse uses that we require of it is one of the principal problems that we must address. More and more plants are installed for the production of water for potable, irrigation or industrial uses that employ membrane technologies, especially reverse osmosis. Moreover, with increasing frequency these techniques are also being employed in the recycling of waters from urban and industrial effluents.

Paralleling the development of these techniques and their new applications is the need for advances in understanding of the processes that affect their functioning and yield. Any reverse osmosis installation will in the medium or long term encounter problems of membrane fouling that necessitate cleansing. The cleansing protocol depends on the type of deposit (biofilm, organic matter, inorganic deposits or natural colloids) present in the membranes, which makes its characterisation indispensable.

A “membrane autopsy” combines different procedures of analysis and tests capable of revealing information relating to the nature of the deposits and other aspects that can be associated with deficiencies in the functioning of the installations. In this way we have a toolkit able to compile the data necessary for the planning of new guidelines for the management of installations that will minimise or delay the appearance of the problems detected.
Improving operational efficiency by interconnecting regional water distribution systems
Authors: Shin E. , Park H. , Ryu T. , Kim J. , Yum K.T.
Published: May 2018

Since regional water supply systems (RWSS) in Korea are all separated and are tree-shaped networks, the reliability is low and operation is not efficient in an emergency. So connecting RWSS to each other can be a good option to improve the operation efficiency. This study has been initiated to evaluate efficiency looking at a pilot case. Expected shortage has been selected as a surrogate. In this study, we developed pipe failure probability equations which are suitable in Korea by considering material, diameter, year, and length. As a pilot case, the three systems of Jeon-ju (JJ), Bu-an (BA), and Seom-jin (SJ) are selected and we consider two connections: JJ–BA and JJ–SJ. In each connection we develop three alternative plans, and we conclude that connections of JJ–BA and JJ–SJ can improve the operational efficiency as much as 5% and 4%, respectively.
Bacterial Pollution of Marine Waters from the Disposal of Sewage and Sewage Sludge to Sea
Authors: Jones F
Published: May 2018

The disposal of sewage and sewage sludge to marine waters takes advantage of the natural purifying powers of the sea and has been accepted practice for many years in this country and elsewhere. Since these wastes contain large concentrations of faecal micro-organisms these activities inevitably result in bacterial contamination of the receiving waters. It is therefore surprising that only scanty information of such microbial pollution has previously been available. Recent work has been undertaken to rectify this situation and in response to national decisions. Three situations in the North West have been investigated and reported. Interpretation of the bacteriological results supports previous findings that sewage sludge dumped in Liverpool Bay has little or no effect on the bacterial quality of coastal waters, that the provision of a long sea outfall on the North Wirral peninsula has greatly reduced sewage pollution of the adjacent beach and its waters; that the quality of bathing waters along the Fylde coast are greatly influenced by the discharge of raw sewage from outfalls along its length and the turbidity of the sea during and after discharging.
Effect of Denitrification on the pH in Biofilms
Authors: Arvin E , Kristensen G H
Published: May 2018

The experiments in this study have confirmed that the pH inside a denitrifying biofilm may be considerably higher than the pH in the bulk liquid. This has been verified by simultaneous measurements of the pH at the rear of the biofilm and in the bulk liquid. The experiments were performed in a laboratory fixed film unit (rotating drum biofilm reactor).

A mathematical model is developed to describe the pH-profile in the denitrifying biofilm. The predictions made by the model were verified experimentally.

The diffusion coefficients of nitrate, carbon dioxide and bicarbonate were determined to be about 50% of the corresponding values in pure water.

The kinetic experiments performed as part of the verification studies result in kinetic parameter values in agreement with previous findings.

The pH increase is favoured by for example a low alkalinity and a deep active biofilm.
Nitrogen Control for the Partly Sewered Basin of Yodo River-Lake Biwa System
Authors: Iwai S
Published: May 2018

(a) New problems are proposed to the sources of water supplies in the downstream reaches of Yodo River, when sewage works up to the secondary treatment have been partly developed in Kyoto, the upstream area of the river. Also, (b) a new simulation process is exploited for the eutrophication of lake water. Upon applying the process to the Lake Biwa water, for which wastewater criteria were enforced even to legally control nutrients since 1979, a good fitness is recognized between observed data and computed results. The circumstances of the legal enactment of effluent quality standards of nitrogen etc by the Shiga Prefecture are introduced with the several concentration criteria, by way of example. Finally, (c) an advanced treatment process is required for the removal of nitrogen in organic wastewaters, in order to solve the problems proposed in (a) and to prevent the eutrophication stated in (b). A new process which was invented and named FDA(Facultative Denitro-Aeration) Process by the present author's group is explained and discussed. The result of application of this process to the nightsoil treatment plant at the City of Hikone is introduced, revealing that a potable effluent has been continuously obtained from the plant for the recent three years, with a slight rise in cost for construction, as well as for operation.
Operation and Performance of a New Activated Sludge Process: The Contact Stabilization Extended Aeration Hybrid
Authors: Paepcke B H , Jones P H
Published: May 2018

In this study the operation and performance of a contact stabilization process operating under the extended aeration mode is examined. Data was obtained during a detailed plant study carried out at a full scale municipal wastewater treatment plant. This new hybrid activated sludge process has good process stability like the conventional extended aeration process, but achieves this with a significantly smaller aeration tank volume and therefore lower cost.
Ammonia and Total Kjeldahl Nitrogen Removal in Aerated Lagoons
Authors: Pano A , Middlebrooks E J
Published: May 2018

The annual and seasonal removal of ammonia and total Kjeldahl nitrogen (TKN) in five aerated lagoons is evaluated. Relationships between the percentage removals of ammonia nitrogen and TKN and the hydraulic loading rates and the reciprocal of the hydraulic detention times are presented. The operating conditions, physical characteristics of the systems and the wastewater characteristics are discussed. Low hydraulic loading rates or long hydraulic detention times are required for effective ammonia nitrogen and TKN removals in aerated lagoons operating in cold climates.
Simultaneous in Situ Determination of Dissolved Gases by Gas Chromatography: II. Oxygen and Nitrogen in Activated Sludge Process Streams
Authors: Bilstad T , Lightfoot E N
Published: May 2018

A simple, reliable and accurate means for dissolved gas analysis, hitherto used only in clean water, is shown to be suitable for all process streams encountered in activated sludge waste treatment plants. This technique consists of exposing samples of helium across a gas permeable membrane to the solution of interest and determining the amount of each species transferred by standard gas Chromatographic procedures.

The technique appears to be the best available for the analysis of dissolved nitrogen and at least competitive to existing techniques for the measurement of dissolved oxygen. It should be possible to extend its use to any dissolved gas exerting a finite partial pressure.
Nutrients Removal and Recovery in a Two-Stage High-Rate Algal Wastewater Treatment System
Authors: Shelef G , Azov Y , Moraine R
Published: May 2018

Removal of wastewater borne nutrients by high rate algal ponds for the control of eutrophication in receiving bodies of water was studied under laboratory and outdoor conditions.

Due to limitations of areal productivity and stoichiometry of nitrogen/algal bio-mass and phosphorus/algal biomass only less than 40 percent removal of nitrogen and phosphorus from strong municipal wastewater can be expected through biomass incorporation in one-stage high-rate algae ponds. Nitrogen removal of 74 percent can be attained by supplementary removal through ammonia atmospheric evolution from pond surface while phosphorus removal of 95 percent is attained following algae flocculation with alum. A second-stage pond following a “coarse” algae separation is needed to exert the full incorporation of nutrients into algal biomass. Effluent from the second stage, following “refined” algae separation, contain less than 4 mg/ℓ and less than 0.5 mg/ℓ of nitrogen and phosphorus, respectively. The final second stage effluent sustained reduced further algae productivity even when resupplemented by N and P and only addition of other macro and micro nutrients triggered additional significant algae growth, indicating depletion of algae growth potential factors other than N and P by the preceding two stages. The possibility of recovering the removed nutrient in the form of biomass proteinaceous animal feed is also discussed.
Stability of Brestan in Tropical Waters
Authors: Odeyemi O , Ajulo E
Published: May 2018

Brestan (triphenyltin acetate) which is used for controlling fungal pathogens of economic crops in many tropical countries was investigated to assess its persistence in aquatic ecosystems. Sterile and nonsterile samples of freshwater, sewage, sea water, and soil were amended with 50 µg/ml or g brestan and incubated under greenhouse conditions. At selected periods of time, the residual brestan in each sample was extracted and assayed colorimetrica11y. After 28 weeks of incubation 76%, 75%, and 78% of the fungicide were still recoverable from freshwater, sewage, and sea water, respectively, while only 30% of the chemical remained in soil. Disappearance or metabolism of the pesticide was due less to biotic than to physico-chemical factors. TLC analysis showed brestan to be converted to the very stable triphenyltin hydroxide in both freshwater and sea water while the pesticide was probably metabolised to inorganic tin, monophenyltin, triphenyltin hydroxide and tetraphenyltin compound in both sewage and soil. Hence the fairly recalcitrant brestan has a relatively high pollution potential in streams and soil adjoining treated plots.
The Influence of Sediment - Water Interactions in an Impoundment on Downstream Water Quality
Authors: Grizzard T J , Randall C W , Jennelle E M
Published: May 2018

A program of in situ and laboratory studies was conducted in the Southwestern Region of Virginia, U.S.A. to determine the role of the deposited sediments of the Niagara Reservoir in affecting the quality of the flow of the Roanoke River above the headwaters of Smith Mountain Lake. Agronomic analysis techniques were adapted and applied to provide quantitative analysis capability for the sediments. The surficial sediments were observed to constitute a considerable reservoir of phosphorus, which, during the anoxic bottom conditions occurring during the summer months, caused an enhancement of concentrations in the water column. Conversely, during the winter months, the surficial sediments acted as a phosphorus sink, removing it from the water column. Laboratory microcosm studies made it possible to quantify the release and removal of phosphorus under aerobic and anaerobic conditions, and to observe the factors upon which the exchanges depended. The phosphorus interactions were found to be governed principally by sediment iron and organic matter content.

The deposited sediments of Niagara Impoundment showed a capacity to redistribute the impoundment influent nutrient load, causing an enhancement of the quantities released during the summer months, thus magnifying the impact on the waters of Smith Mountain Lake. The maintenance of aerobic benthic conditions could prevent the sediment releases from occurring. In the long term, sediment nutrients deposited in the past, without proper control, could provide a continuing source of phosphorus to the waters of Smith Mountain Lake, thereby reducing the effectiveness of upstream control of point and diffuse sources.
Slow Sand Filtration for Cercarial Control in North Cameroon Village Water Supply
Authors: Kawata K
Published: May 2018

People of North Cameroon must look for water at great distances from their homes during the dry season of the year. To provide water closer to villages series of internationally and bilaterally financed dams are being built to impound water in reservoirs. The Ministry of Health of the Government of the Republic of Cameroon is concerned that the dams do not increase health problems. One concern is the control of cercariae of human schistosomes. This paper reports on the literature survey on past filtration studies, presents data on filtration experiments, and gives design parameters for slow sand filtration plants to be built in North Cameroon.
The Nature of the Reactions between Chlorine and Purine and Pyrimidine Bases: Products and Kinetics
Authors: Gould J P , Hay T R
Published: May 2018

The reactions between chlorine and the bases uracil, cytosine and caffeine in aqueous solutions are under investigation. Caffeine yields a complex array of ring cleavage and rearrangement products in a relatively slow reaction. True ring chlorination with the production of 8-chlorocaffeine occurred in these systems but was a relatively minor process. The reaction was fairly slow, highly pH dependant, and yielded an array of labile combined chlorine species and chloride. Chlorine species analysis gave little evidence of the formation of carbon chlorine bonds. Uracil reacted rapidly with chlorine undergoing considerable true chlorination with the formation of a product consistant in character with 5-chlorouracil. Kinetically, the reaction was strongly pH dependant. While small quantities of chloramines were produced they were labile arising most likely as a result of ring cleavage. Cytosine produced a complex array of products including chromatographable organic chloramines. Fifty percent of chlorine added to cytosine was manifested as combined chlorine of high stability. Evidence for various N-chlorocytosines is presented.
Application to Estuarine and Coastal Waters
Authors: Gameson A L H
Published: May 2018

The principles underlying the mathematical modelling of parameters of pollution in estuarine and coastal waters are outlined in non-mathematical terms. Attention is drawn to some of the difficulties encountered – such as in assessing the inputs of relevant substances, evaluating coefficients of transformation processes, and ensuring that models can reasonably be used for predictive purposes. Two examples are given, one relating to dissolved oxygen in an estuary, the other to enteric bacteria in the sea. The application of models to the formulation of pollution control policies is reviewed.
Biological Effects of Oil Pollution
Authors: Clark R B
Published: May 2018

Pollution is defined as environmental contamination which has a deleterious effect, and in a biological context it is only mortality which has some impact at the level of the population or community that is important. Thus, very heavy mortality of the eggs and fry of commercial fish species may have no detectable effect on the commercial catch in future years. A reduction in the population of a species which is dominant in its community, on the other hand is likely to result in major ecological adjustment. Oil pollution does not appear to have reduced populations of commercial fish species or seabirds, the two groups of animals about which most fears have been expressed. The marine environment is subject to wide and erratic fluctuations which make it difficult to detect the impact of oil pollution unless the cause is obvious, even then some caution is necessary before attributing environmental change to pollution.
Physical-Chemical Methods of Treatment for Oil-Containing Effluents
Authors: Berné F
Published: May 2018

After a preliminary oil-removal by gravity in various types of oil-separators, the effluents from pipe-line terminals, de-ballasting units and refineries still contain, as a stable emulsion, significant residual hydrocarbon concentrations, varying from 25 to 300 mgl.

In order to bring these effluents to comply with the regulations governing their discharge either to the sea or to a river, or simply to be able to send them to a complementary biological treatment unit, it is necessary to submit such effluents to a polishing oil-removal process; such process, often called physical-chemical treatment, is necessary to remove the above mentioned residual, insoluble hydrocarbons and leave the soluble hydrocarbons only. Practically and depending on the case considered, the final total hydrocarbon content obtained should not exceed from 5 to 20 mgl−1. For this, there are several techniques based on dissolved air flotation, or filtration. These respective processes and their results are summarized hereafter by the authors who gathered them from experiments conducted on pilot plants and, most of all, from numerous industrial treatment plants in Europe and in America.
Water Pollution Control in Developing Areas: Problems and Needs
Authors: Simpson J R
Published: May 2018

Wholesome water supplies are essential for the control of many water-related diseases and pathogenic pollution is the most significant type of pollution in developing areas. Thus, the proper handling of wastes is necessary for complete control and data are presented on the fate of pathogens in various environments and waste treatment systems. High kills of pathogens can be achieved during storage in batch composting latrines, aerobic composting windrows and waste stabilisation lagoons.

While water-borne sewerage systems are highly convenient and quickly remove wastes from the immediate environment, they are expensive and sewage treatment is required before disposal. There are satisfactory alternative on-site and off-site excreta handling systems some of which can be adapted progressively as water service levels increase.

The need is stressed for proper training of operators and technicians, the maintenance of plant and the early control of industrial wastes.
Mine Water Pollution – An Overview of Problems and Control Strategies in the United Kingdom
Authors: Gordon Glover H
Published: May 2018

The management of water within the British coal mining industry and the means by which surplus waters are discharged to the environment without serious effect are described. The acquisition, use, treatment and re-use of water is discussed in detail with particular reference to the control of the volume and quality of surplus water generated.
Public Health and Water Quality Significance of Viral Diseases Transmitted by Drinking Water and Recreational Water
Authors: Cabelli Victor J
Published: May 2018

A review of the available information from case and outbreak reports and the results of prospective and retrospective studies revealed that the potential for the spread of viral diseases by the use of fecally contaminated drinking and recreational water has only been realized for infectious hepatitis and viral gastroenteritis. These two, however, are the most serious and prevalent, respectively, of the water-related diseases. A model is described for predicting the beach specific, swimming-associated rates and annual number of cases of gastroenteritis. The inputs are the swimming-associated, gastroenteritis rate-bathing water enterococcus density regression equation developed from the USEPA prospective epidemiologic-microbiologic studies and the distribution of enterococcus density estimates and annual number of swimmers at the beach in question. In general, the gastroenteritis rates predicted from the enterococcus model were less than those from the corresponding E. coli model. Detectable rates at the 75 percentile level and rates approaching or exceeding 5/1000 swimmers at the 90 percentile level were predicted for 7 and 14, respectively, of the 87 sampling station-beach associations. All but one of the fourteen stations were potentially impacted by known municipal wastewater discharges and two of the associated beaches were posted as unsafe for swimming. The inapplicability of the model to beaches impacted with small, immediate sources of fecal wastes or stormwater run-off is noted. The limitations in the use of findings from the analysis of outbreak reports in the evaluation and establishment of water quality criteria and, hence, the need for prospective, drinking water and shellfish epidemiological studies is discussed. The need for such studies also derives from the results of the bathing beach study in that they suggest that cases of gastroenteritis are occurring with acceptable drinking and shellfish growing waters. The need for tissue culture enumerative methods for the viral gastroenteritis agents and methodology for determining the biological decay coefficients for these agents and their indicators is noted.
Effects of Suspended Solids on Inactivation of Poliovirus by Chlorine
Authors: Kaneko Mitsumi , Igarashi Hideko
Published: May 2018

Attempts were made to indicate the protective effects of the suspended solids for inactivation of polioviruses in water by chlorine. Solids associated viruses, which were prepared by centrifugation after mixing polioviruses with sterilized kaoline or activated sludge and/or by elution with pH 8, 2% beef extract, were inactivated by chlorine. The activated sludge was found to absorb 96% of total poliovirus added, whereas 74% of the viruses added was absorbed to the kaoline. It has become clear that activated sludge which is porous in structure protects the viruses from inactivation by chlorine more effectively than kaoline does. When the concentration of the virus-containing solids was 10 mg/l, initial residual chlorine of 1.0 mg/l was not enough to get more than 3 log10 viral reduction with 30 minutes contact time. The concentration of 1.0 mg/l could affect inactivation of viruses seriously.
Ocean Disposal and Construction with Stabilized Coal Waste Blocks
Authors: Parker Jeffrey H , Woodhead Peter M J , Duedall Iver W , Carleton Herbert R
Published: May 2018

A multidisciplinary team of scientists at SUNY, Stony Brook is assessing the feasibility of using blocks of waste material from coal fired power plants for underwater construction, including building artificial fishing reefs. Experiments over the past five years, both in the laboratory and in the sea, suggest that coal waste blocks are environmentally acceptable in the ocean.

On September 12, 1980, a 500-ton reef was constructed in the Atlantic, consisting of 15,000 solid blocks of stabilized FGD sludge and fly ash from coal burning power plants. The blocks were fabricated in collaboration with Conversion Systems, Inc. (Horsham, Pennsylvania) at a commercial concrete block plant. In preparation for block fabrication, a combination of different coal waste mixes, stabilization additives, and curing procedures were screened to develop candidate mix designs. Experiments were conducted at research fsei1ities of the Besser Company in Alpena, Michigan to develop methods of successfully forming coal waste blocks with block making machines.

The demonstration disposal reef is being monitored to assess environmental impacts which may occur and their relation to structural integrity and chemical properties of the coal waste blocks. Blocks are tested ultrasonically in the sea and also returned to the laboratory for compressive strength measurements. After almost two years in the sea, gradual increases in strength have been documented.

The progress of biological colonization is also monitored and compared with existing reefs in the area. The fish, benthos, and encrusting organisms are sampled and analyzed for uptake of block components. Data from fish tagging surveys have indicated significant increases in the resident populations of various species of fish and lobster.