bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite-Difference Modelling for a One-Dimensional Rectangular Estuary
Authors: Sin Y. S.
Published: May 2018

A numerical method for the analysis of dispersion of pollutants in a one-dimensional rectangular estuary within a tidal cycle is presented. The finite-difference method is used to obtain a solution for the partial differential equation. An explicit scheme using multi-step procedure is adopted for solving the problem. It is shown that an analytical method is capable of predicting the dispersion of a slug load in the estuary as long as the effect due to the open boundary is negligible. However, the finite-difference method is required to study the dispersion effect of a continuous or variable pollutant source subjected to variable tidal velocity. The model developed is also applied in determining the effect of salinity intrusion within a tidal cycle due to different fresh water flows.
Anaerobic and Aerobic Submerged Bio-Filter System for Small Scale On-Site Domestic Sewage Treatment
Authors: Watanabe T. , Kuniyasu K. , Ohmori H.
Published: May 2018

In order to prevent water pollution and satisfy the demands for flush toilets in regions where a public sewerage system has not been in service, some on-site small scale domestic wastewater treatment processes called GAPPEI JOHKASOU have been developed to treat black water and gray water together in an individual house. Prior to its technical development, the characteristics of wastewater discharged from individual houses should be measured.

The possibility of application of anaerobic filter is examined for processing organic wastewater at low concentration like in domestic wastewater, and an anaerobic filteris successfully developed to lengthen the sludge removal interval, since the flow rate of wastewater from individual houses is characterized by a large variation.

It is difficult to serve the centralized treatment systems in many regions. Thus, a small GAPPEI JOHKASOU has been developed and propagated for by individual houses in such regions.
Specific Cake Resistance: Myth or Reality?
Authors: Tosun Ismail , Yetis Ulku , Willis Max S. , Chase George G.
Published: May 2018

The specific cake resistance is considered to be the key factor in the characterization of sludge dewaterability. The use of this parameter without knowing how it is derived and the conditions under which it can be used has been creating a great deal of confusion in the literature. Moreover, the lack of a universally agreed test method to determine its value causes additional problems. Hence, attempts to go from the laboratory data to the full scale industrial equipment using this concept may end up in failure.

This paper starts with the origin of the specific cake resistance in the historical perspective of filtration theory. Currently used experimental techniques in the determination of specific cake resistance are reviewed, advantages and disadvantages axe succinctly summarized. An alternative way of characterization of sludges using a resistance function rather than a specific cake resistance is proposed.
Approach to Thickening and Dewatering Using a One-Dimensional Finite Strain Consolidation Model
Authors: Leonhard D.
Published: May 2018

Gravity thickening and pressure filtration are described with a one-dimensional nonlinear finite strain consolidation model. Basic assumptions of a consolidation model are discussed. The consolidation coefficient κ for different types of sludges was found to vary less with solids concentration than the permeability and the compressibility. This leads to a simplified model. A comparison of model to experimental results reveals the basic validity of the outlined approach and serves to discuss the model limits. For pressure filtration a method to determine the κ-value of a given sludge from filter experiments is verified.
On the Origin of Specific Resistance to Filtration
Authors: Agerbæk Mikkel L. , Keiding Kristian
Published: May 2018

Specific resistance to filtration (SRF) is used extensively as a measure of dewaterability. The concept of specific resistance to filtration is based on Darcy's law and is usually interpreted as being of purely hydrodynamical character. This means that changes in electrokinetic properties, brought about by changes in pH and conductance, are not a priori expected to influence the specific resistance to filtration. It is shown that electrokinetic effects do indeed play an important role in the dewatering of bentonite suspensions as the measured values of SRF differ significantly when changing pH or conductance. A theory to understand the phenomena is proposed, but it is also shown that this theory is not adequate to understand the SRF measurements completely.
Anaerobic-Aerobic Treatment of Potato-Starch Wastewater
Authors: Abeling U. , Seyfried C. F.
Published: May 2018

Production of potato starch produces wastewaters with high concentrations of COD, nitrogen and phosphorus. The best known and most economical solution for the nearly full elimination of these substances is the two-stage anaerobic-aerobic treatment. The anaerobic pretreatment must only go so far as to maintain enough COD for biological nitrogen and phosphorus elimination in the aerobic stage. To optimize this process, several tests have been carried out on nitrification/denitrification by means of the intermediate product nitrite. The carbon consumption amounts to only 60% in comparison with denitrification via nitrate. The essential parameter for regulating the process is the concentration of free ammonia in the reactor. Concentrations of 1 to 5mg NH3/l inhibit the nitratation but not the nitritation. A separation of both partial steps is possible. The content of ammonia was controlled by means of continuous NH4 and pH measuring.

The process is suitable for many wastewaters with low COD/TKN ratios and high nitrogen concentrations. If there are undesired nitrite peaks in an aerobic treatment plant caused by high pH values and temperatures, specific nitrogen elimination by means of nitrite is a reliable treatment system.
Treatment of Citric Acid Wastewater for High Quality Effluent on the Anaerobic-Aerobic Route
Authors: Svardal K. , Götzendorfer K. , Nowak O. , Kroiss H.
Published: May 2018

A large citric acid factory is situated close to a rather small river, so the discharge of its wastewater caused severe water quality problems. A highly concentrated stream holds more than 90% of the total COD-load, the lowly concentrated stream about 80% of the flow. Anaerobic pretreatment of the highly polluted stream and additional aerobic treatment of all wastewater reduces the total costs to less than one third in comparison to the aerobic treatment alone. The anaerobic treatment is linked with several problems like high sulphate, high ammonia and high calcium concentration leading to H2S and NH3 toxicity as well as calcium carbonate precipitation, about 3 times more than biomass growth. A special anaerobic reactor (EKJ-reactor) was designed to realize an equal distribution of the wastewater in the sludge bed and to prevent sludge and lime deposition. In 1986 the first stage of the full scale treatment plant for the high concentrated wastewater consisting of an equalization tank, an anaerobic reactor (10 000 m3) and a highly loaded activated sludge plant (2 000 m3) went into operation. In 1987 a second anaerobic reactor was built. In 1988 an additional activated sludge plant with simultaneous nitrification-denitrification (aeration tank volume 15 000 m3) for treatment of all the wastewater was designed in order to keep the effluent concentrations within the strict effluent limits. This plant went in operation in 1990. The anaerobic reactors have shown very good results throughout all the five years of operation. At a COD loading rate of 3 to 7kg/m3·d) a COD removal of almost 90% could be achieved. Because of the high COD removal rate of the anaerobic stage, nitrification occurred in the first post-treatment plant but only to nitrite due to high ammonia concentration and high pH. In the second activated sludge plant stable nitrification was obtained. The content of NH4-N as well as NO2-N in the effluent is generally less than 2 mg/l. Some highly concentrated wastewater is fed directly into the second stage in order to obtain rather complete denitrification. So the NO3-N-concentration in the effluent can be kept below 20 mg/l (85% nitrogen removal) mostly.
Advanced Treatment and Food Production by Hydroponic Type Wastewater Treatment Plant
Authors: Furukawa K. , Fujita M.
Published: May 2018

Hydroponic type advanced wastewater treatment system, which consists of a water channel packed with porous concrete and hydroponic type cultivation tanks (HTCT). was developed and its applicability to advanced treatment of secondary effluent and polluted river and drain water was experimentally studied. Porous concrete (PC) provided enough interfacial area for reaeration and enough space for attached microbial growth and improved treatment capability of water channel tremendously. It was revealed that TOC could be removed efficiently under TOC loading rate of 80 mg-TOC/L-day. Owing to the high sludge entrapment capacity of PC, the observed sludge yield (Yobs) decreased to 0.25-0.33 g-MLSS/g-TOC. Crop yield of pak-bung plant during continuous treatment of effluent from water channel was proved experimentally to be 1.18 kg fresh weight/m2 ·month. Hydroponic cultivation of midi-tomato was succeeded by using the effluent from the water channel with low nutrient concentration which indicated that this advanced wastewater treatment process has a high applicational potential for direct purification of polluted river and drain water.
Permissible Charge of Nutrients and Organic Compounds in Relation to Other Processes in Reservoirs (Introduction to the Proceedings)
Authors: Lind Owen T.
Published: May 2018

Loading of nutrients and organic matter is significant to the eutrophication of reservoirs. This paper identifies several features of reservoirs which determine the patterns of loading and the biotic consequences. The papers presented in the section with the above title at the Second International Conference on Reservoir Limnology and Water Quality, Ceske Budejovice, Czechoslovakia, 9-14 August 1992 are introduced.
In Vivo Fluorescence of Chlorophyll A: Estimation of Phytoplankton Biomass and Activity in Římov Reservoir (Czech Republic)
Authors: Vyhnálek V. , Fišar Z. , Fišarová A. , Komárková J.
Published: May 2018

The in vivo fluorescence of chlorophyll a was measured in samples of natural phytoplankton taken from the Římov Reservoir (Czech Republic) during the years 1987 and 1988. The fluorescence intensities of samples either with or without addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron, DCMU) were found reliable for calculating the concentration of chlorophyll a during periods when cyanobacteria were not abundant. The correction for background non-chlorophyll fluorescence appeared to be essential. No distinct correlation between a DCMU-induced increase of the fluorescence and primary production of phytoplankton was found.
Abundance and Distribution of Profundal Zoobenthos in Spanish Reservoirs: Differences between 1973/75 and 1987/88 Surveys
Authors: Real M. , Prat N. , Riera J. L.
Published: May 2018

This paper deals with the abundance and distribution patterns of profundal zoobenthos from 81 Spanish reservoirs which were sampled during mixing and stratification periods in 1973/75 and again in 1987/88. Our main aims are to explore the regional variability and to compare these two surveys, separated by 14 years. The densities of three major benthic groups were considered: Oligochaeta, Tanypodinae and other Chironomidae (basically Chironominae with some Orthocladiinae). While differences between reservoirs were highly significant for all three groups, differences between basins were only reflected by chironomids. Differences between surveys depended on the benthic group and the season. Between 1973/75 and 1987/88, Oligochaeta densities halved significantly in winter (all basins), tanipodins increased 1.7-fold in summer (northern and central Spain), while other chironomids significantly increased 1.8-fold in summer (northern and central Spain) and 1.6-fold in winter (all basins). The increase in chironomids accompanied by the decrease in oligochaetes was partly attributed to better oxygen conditions in the last survey.
Evaluation of Virus Removal in Membrane Separation Processes Using Coliphage Qβ
Authors: Urase Taro , Yamamoto Kazuo , Ohgaki Shinichiro
Published: May 2018

Virus removal in membrane separation processes was investigated by employing coliphage Qβ as a tracer. Several types of microfiltration membrane and ultrafiltration membrane were tested. Two types of filtration experiments were carried out; dead-end filtration and cross-flow filtration. The membrane surface deposits played an important role in the rejection of viruses in the filtration of activated sludge and pond-water, whereas acrylate polymer cake did not affect the rejection of Qβ. The leakage of ultrafiltration membranes was well examined by the high concentration of Qβ applied. The major part of the rejected coliphages were adsorbed onto the membrane and in its surface deposit.
Anaerobic Biodegradation of Phenol: Bacterial Acclimation and System Performance
Authors: Jianmin Wang , Guowei Gu , Chonghua Zhang
Published: May 2018

Bacterial acclimation in anaerobic phenol-bearing wastewater treatment processes is very difficult in general. New acclimation methods were studied through four parallel experiments with different inoculam. The study reveals that the sludge from aerobic phenolbearing wastewater plants may be used for anaerobic processes directly, and that the sludge adaptive time is only one-fifth of the traditional method. An anaerobic suspended-growth process was tested in a dynamic batch feeding operation. The study indicates that the anaerobic treatment process for high-concentration phenol-bearing wastewater has the advantages of low construction cost and energy consumption, easy operation, and high phenol removal efficiency.
Kinetic Studies of Adsorption-Desorption of Cd and Zn Onto Al2O3/Solution Interfaces
Authors: Lo K. S. L. , Leckie J. O.
Published: May 2018

The effects of external and internal mass transport limitations on zinc and cadmium adsorption onto the porous amorphous aluminium oxide/solution interfaces were studied. A modified two-stage rate model was used to interpret the experimental results. The rapid stage results from external surface film diffusion and internal diffusion into the near surface pores. The slow stage results from internal mass transport and extends over several days. The mass transfer-adsorption coefficients of the rapid stage are almost two orders of magnitude larger than those of the slow stage. The external mass transfer coefficients show an increasing trend with increasing pH, and appear to be affected by the charge/potential condition of the oxide/solution interface. The internal mass transfer coefficients indicate a uniform trend for both the zinc and cadmium results. The desorption rates and final metal ion solution concentrations are affected by the bulk solution pH. Film diffusion and internal diffusion are affected by the higher relative ratio of metal ion concentration to adsorbent concentration.
Intensification of a Pond System by Fibrous Carriers
Authors: Peishi Qi , Boazhen Wang , Fang Ma , Jinsong Zhang , Tingjun Li
Published: May 2018

A study was carried out on the intensification of a pond system, consisting of an anaerobic pond, a facultative pond and a polishing pond, in Anda City, Heilongjiang Province, by fibrous carriers packed in the anaerobic pond, by means of which the performance of the pond system was remarkably improved with higher removal capacities and efficiencies for SS, BOD5, COD, TN, TP and bacteria, compared with the conventional system. The mechanism for the intensified effect was found to be ascribed to the increase of biomass in the form of biofilm attached to the surface of the fibrous carriers and more even distribution of the biomass in the pond. A mathematical model based on the complete mixed flow pattern was developed both for the intensified and conventional anaerobic pond, and the organic degradation rate constant value K in the former was found to be much greater than that in the latter. The microbial communities in both the ponds were also observed.
Pilot Plant Studies on Filtration of Raw Sewage Using Floating Filter Media and Multiple Filter Column Inlets
Authors: Mouri Mitsuo , Niwa Chiaki
Published: May 2018

The characteristics and performance of solid-liquid separation of raw sewage using floating media and multiple inlets were studied using pilot-scale equipment. Particles over 7 µm, representing approximately 80% of SS and 50% of BOD in raw sewage were efficiently removed. Smaller particles and soluble components, comprising a large part of total BOD, were difficult to remove by filtration. The maximum SS removal ratio (SSRR) and SS quantity removed per unit filter surface (SSR) was achieved using a medium size of 5.5 mm and a filtration rate of 150 µm/d. Inlet switching to a lower position significantly extended the filter run lengths and increased the total SS removed by filtration. Using 5.5 mm filter particles and a 150 m/d filtration rate, 80-89% of SS was removed, 38-42 kg of SS was removed per unit filter sectional area, and filter runs were 55-65 hours. The backwash-filtrate ratio was around 2%. The space requirement of this system will be significantly smaller than the ordinary primary treatment system judging from the trial design of a prototype plant.
Standardisation of Small Wastewater Treatment Plants for Rapid Design and Implementation
Authors: Crabtree H. E. , Rowell M. R.
Published: May 2018

Severn Trent Water was faced with the problem of rapidly implementing a massive capital investment programme to replace a large number of its small sewage treatment works. To meet the investment targets it was necessary to streamline the process of planning, design, construction and overall procurement of plant and equipment.

Key elements in achieving these targets were seen as:Standardisation of treatment processes and plant to reduce design times and construction periods and to guarantee performance.Use of standard specifications and procurement practice to ensure rapid acquisition of plant to the required design standards.

The Company's experience of operating a large number of different types of sewage treatment plant was used to standardise treatment processes for small works on the rotating biological contactor (RBC) and the reed bed.
The Role of Particle Size Distribution in the Performance and Modelling of Filtration
Authors: Mackie R. I. , Bai R.
Published: May 2018

The paper examines the importance of size distribution of the influent suspension on the performance of deep bed filters and its significance with regard to modelling. Experiments were carried out under a variety of conditions using suspensions which were identical in every respect apart from their size distribution. The results indicate that the presence of coarse particles does increase the removal of fine particles. Deposition of fine particles leads to a greater headloss than deposition of large particles. Changes in size distribution with time and depth play an important role in determining the behaviour of a filter, and models of both removal and headloss development must take account of this.
A Training Program for Operators of Small Wastewater Treatment Plants
Authors: Kerri K. D.
Published: May 2018

Operators of small wastewater treatment plants frequently live in remote areas where operator training is not readily available. A training program has been prepared using the techniques of self-instruction, wherein an operator reads a short section of the training material, writes the answers to questions in a notebook, and compares the written answers with suggested answers. The training materials were developed by experienced operators following extensive field studies. First, operators (subject matter experts) for each treatment process prepared an outline of what knowledge and skills (need-to-know criteria) they expected their operators to possess to safely operate and maintain each treatment process in the training manual. Draft chapters were then field tested using operators with varying levels of education and experience to determine the effectiveness of the training materials. Studies conducted on the performance of operators who had participated in the training program and those who had not received the training revealed that trained operators produced a better quality effluent at the same treatment plant over a one-year period. Effective training materials and programs can help operators safely and efficiently operate and maintain small wastewater treatment plants.
Dewatering of Drying Beds–Combined Biological-Chemical Sludge Behaviour
Authors: Marklund S.
Published: May 2018

Aerobically digested sludge from a small wastewater treatment plant was dewatered on five sand drying pilot beds and four small drainage beds. The experiment was conducted in a controlled environment with constant air humidity and temperature. A total of between 147 and 263 kg of a combined biological-chemical sludge was used on each of the sand drying beds. Initial sludge total solids (TS) content was 4.6 - 5.5%.

Sludge drainage was completed within 28 days, and the thinner sludge layers were drained within 16 days. The sludge evaporation phase, prior to equilibrium with air moisture, lasted a maximum of 84 days and resulted in a final TS content of 88 - 92%. The drying time to achieve 30% TS was 35-50 days, depending on initial sludge thickness. Sludge cracking behaviour or rate did not control the drying rate at less than 30% TS.
Design of On-Site Treatment Systems in Caliche Soils
Authors: Liljestrand H. M. , Parten S. M.
Published: May 2018

Caliche soils, weathered limestone soils of high calcium carbonate content and and low organic content, are common in regions with limestone sedimentary geology and arid to semi-arid climate. Currently, there are no standards other than hydraulic soil properties for the design and construction of on-site wastewater treatment systems in caliche soils. Experimental studies were performed to investigate biological transformation rates for organic carbon to inorganic carbon and organic nitrogen to nitrate, using four different caliche soils and the range of recommended hydraulic loading rates. The experimental results indicate that oxygen demanding materials readily decay over short distances in caliche soils. Efficiency of removal for TOC was >97%. However in three of the four caliche soils, nitrate concentrations were significantly higher than the background and the control cases. The high calcium carbonate content of the caliche soils leads to solutions well buffered with respect to pH and alkalinity. Nitrification rates are very rapid in these soils which are buffered at the optimum pH range for Nitrosomonas growth. The low organic carbon content of caliche soils results in low denitrification rates. Nitrate in the effluent is the limiting pollutant in the determination of appropriate loading rates, drain field area, and land requirements. Phosphate and metal aqueous concentrations are acceptably low and are limited by solubility control in the open system equilibrium model.
Using Diurnal Variations in a High Rate Algal Pond for Management Pattern
Authors: Picot B. , Moersidik S. , Casellas C. , Bontoux J.
Published: May 2018

The high rate algal pond (HRAP) is an efficient low cost wastewater system. It is well adapted to small communities with high summer loads.

Many studies have been carried out on HRAP in order to adapt them to the seasonal variations of climate but very few have been devoted to the diurnal behavior of the system which could be an important design parameter.

The work for this investigation was carried out at the ‘Centre de Lagunage de Recherche Pluridisciplinaire‘ in Mèze, France, community located on the Mediterranean

The results show that all variables, except COD, do have diurnal variations. During daylight, photosynthetic activity is at its peak between 13:00 GMT and 15:00 GMT with oxygen saturation rates of 350 %, high pH's (pH>9) and low total alkalinity. The highest removal rates of NH4-N and PO4-P are 94 % and 89 % respectively. During the night, photosynthesis stops and the dissolved oxygen concentrations drop to very low levels or even to zero. pH decreases (8.6) and total alkalinity increases as a consequence of the intense respiration of the algae and other organisms of the system.The various efficiencies decrease. Nutrient removal is linked to the variations of solar radiation and temperature which are considered as the main characteristics controlling algal activity. Algae contribute to the elimination of nutrients through two mechanisms: biological uptake and pH increase causing a volatilization of NH3 and a chemical precipitation of calcium phosphates. The decrease of the performances of a HRAP during the night is caused on the one hand by the interruption of photosynthesis combined with respiration, causing a decrease in pH and, on the other hand, to the continued inflow of sewage in the pond. The knowledge of the diurnal behavior of HRAP leads to a new concept of pond management. When HRAP pond effluent was withheld according to photosynthetic activity, this resulted in a more efficient removal of nutrients. Automatic systems tied to time or pH could control the release of effluent and easily implement such a management.
Use of Water Hyacinth (Eichhornia crassipes) in Upgrading Small Agroindustrial Wastewater Treatment Plants
Authors: Yeoh B. G.
Published: May 2018

Water hyacinth (Eichhornia crassipes) was found to be useful in enhancing the final discharge quality of some agroindustrial wastewaters treated in lagoon systems. With a hydraulic retention time (HRT) of 5 days, the macrophyte was able to further reduce the biochemical oxygen demand (BOD) of anaerobically and aerobically treated palm oil mill effluent by 40% to 50 mgl-1, accompanied by remarkable removal of ammoniacal nitrogen (AN) and total kjeldahl nitrogen (TKN) by 53.7% and 68.8% respectively. It also assisted in the settling of suspended solids (SS) to below 20 mgl-1. In the secondary treatment of small-scale piggery effluent, the aquatic weed was found in a pilot field investigation to be 17-112% more efficient than algae in removing BOD and COD loads from a reconstituted effluent. A study at an institutional farm confirmed that >97% reduction of the major pollutional parameters was achieved. Introduction of hyacinth to a pilot plant treating sugar refinery wastewater resulted in the removal of BOD, COD and SS by 43.5%, 35.8% and 21.9% respectively with a HRT of 7 days. However, a chloride content exceeding 100 mgl-1 would inhibit its healthy growth. In the tertiary treatment of natural rubber processing effluent, removals of 85% BOD, 80% COD, 88% SS, 50% AN and 53% TKN were achieved with a HRT of 10 days. Increasing the HRT to 15 days resulted in higher removal efficiencies. Harvesting data indicated that the average biomass produced was 6-10% per day. The average growth rate of the aquatic plant could be as high as 505kg ha-1day-1 on dry weight basis.
Observations of Particle Detachment during Filter Backwashing
Authors: Fitzpatrick C. S. B.
Published: May 2018

The behaviour of filter grains and detaching deposits during backwashing was investigated at University College London using a High Speed Video and endoscope technique.

A detailed understanding of the backwashing process was required after decades of backwashing on a trial and error basis. This investigation provided detailed visual information on detaching deposits and bed behaviour.

Experiments were performed using standard filter sand and synthetic suspensions. The endoscope viewed inside the sand bed and a high speed video camera recorded what happened, during the backwashing process, on a pore/grain scale with a video screen magnification of about 100X. The video material was analysed and grain velocities obtained.

Results showed that combined air and water wash at collapse-pulsing gives best cleaning, due to the high degree of bed agitation resulting in high fluid shear stresses and maximising grain collisions. It has been observed that fluid shear forces dominate detachment, whether the bed is cleaned by water fluidisation or collapse-pulsing. During collapse-pulsing grains exhibit velocities as high as those measured for a fully fluidised bed. Since this degree of agitation is obtained for flow rates of around 40% of the water fluidising rate this represents a saving in the use of clean water for backwashing purposes.
The Effects of Chemical Precipitation by Slaked Lime on Suspended Particle Dynamics in Wastewater Ponds
Authors: Cripps S. J. , Hanæus J.
Published: May 2018

Chemical precipitation can be used to treat wastewater in ponds when environmental conditions are unsuitable for biological treatment, such as during periods of low temperature or reduced solar radiation. The main purpose of this precipitation is to separate phosphorus and particulate matter from the effluent. Previous investigations have shown that most of the phosphorus leaving ponds, in which chemical precipitation by slaked lime is used, is in the particulate form. It is therefore important to identify processes that regulate the particulate content of the wastewater. An investigation was conducted to determine the particle size distribution within wastewater taken from a slaked lime settlement pond. Experiments were conducted in the second pond at the Tänndalen wastewater treatment plant in central west Sweden. Wastewater flowed into the first, volume buffering pond, then to an automatic lime feeding unit immediately prior to the second settlement pond. Water quality measurements and samples were taken at various depths and locations within the settlement pond. Changes in the particle size distribution, within a range of 1.39 to 43.30 µm diameter, using a Coulter Multisizer particle analyser, were determined. Statistics summarising these changes were related to the pH, temperature and total phosphorus concentration of the samples. The majority of particles at the effluent to the pond were so small that they were unable to settle. Improvements to the pond detention time were therefore considered unnecessary, but the initial precipitation environment at the pond influent required attention.
Organic Carbon and Nitrogen Removal from Wastewaters of Single Houses and Small Separate Establishments Using a Simple Sequencing Batch Reactor
Authors: Vuoriranta P. , Haile Mariam D. , Kautia E.
Published: May 2018

Purification capacity of a low-loaded sequencing batch activated sludge process pilot-plant, operated in a way to simulate the flow profile in small point sources, was studied. Oxidation capacity of organic matter and ammonium nitrogen, capacity to denitrify the oxidised nitrogen by alternating aerobic and anoxic operation, suspended solids removal and sludge settling characteristics were determined. Best results were obtained in a 24 h total cycle with three anoxic hours in addition to a three hours settling period. BOD7 removal was 94 %, residual concentration being less than 20 mg/l. Suspended solids were removed with equal efficiency. Hydrolysis of solid organic waste in a low loaded plant was efficient, and no excess sludge had to be removed. Almost complete nitrification could be maintained at 13°C, and 60 % of the oxidised nitrogen was denitrified without supplementary carbon source.
Batch Operated Activated Sludge Plant for Production of High Effluent Quality at Small Works
Authors: Chambers B.
Published: May 2018

In the UK there are about 7500 sewage treatment works of which 85% serve populations of less than 5000. Many of the smaller works do not comply with effluent quality standards and options for improving treatment are being pursued by many water companies. WRc have developed designs for packaged activated sludge systems to serve populations in the range 100 - 1000 persons. A detailed design has been completed for a population equivalent of about 600. Target effluent quality is 15:20:5 mg/l of BOD, SS and ammonia nitrogen respectively on a 95 percentile basis. The activated sludge system is designed to operate as a batch process with aeration and sludge settlement both occurring in the same tank. Batch operated activated sludge plants are known to produce sludges with good settling properties providing the influent wastewater is admitted into the aeration tank in controlled manner. Therefore a specially designed holding tank has been included as the first stage in the treatment sequence.

All process tanks are specified as glass-coated steel installed on a flat concrete base. Target construction cost for 600 population is ₤350 per capita.
Influence of Algal Species and Cultivation Conditions on Algal Removal in Direct Filtration
Authors: Petruševski B. , Vlaški A. , van Breeman A. N. , Alaerts G. J.
Published: May 2018

The influence of growth media on the behaviour of cultured algae in direct filtration was examined. Cultured Chlorella vulgaris and Selenastrum capricornutum on Jaworski and Z-8 media are used for model water preparation. It was found that the same algal species in the same growth phase had different responses under identical treatment conditions. Also, difference in growth phase influenced their behaviour. Therefore, assuming similarity between cultured algae and algae from natural waters is highly questionable.

The efficiency of the direct filtration treatment process for the removal of dominant algal species present in Biesbosch Water Storage Reservoirs was investigated. Different removal patterns were found for various algal species. The most difficult to be removed were Rhodomonas minuta and µ-algae. High removal efficiency was found for Stephanodiscus hantzschii and other cylindrical diatoms. An overall algal biomass removal of 90 % was achieved. Algal penetration through filters is a consequence of algal size and inefficient agglomeration during coagulation. It was found that the application of oxidants (ozone and potassium permanganate) prior to coagulant addition improves the efficiency of direct filtration. The use of H2O2 did not enhance algal removal under the conditions investigated.
Urban Drainage Systems: Design and Operation
Authors: Marsalek J. , Barnwell T. O. , Geiger W. , Grottker M. , Huber W. C. , Saul A. J. , Schilling W. , Torno H. C.
Published: May 2018

Design and operation of urban drainage systems are addressed in the context of the urban water system comprising drainage, sewage treatment plants and receiving waters. The planning and design of storm sewers are reviewed with reference to planning objectives, design objectives, flows and pollutant loads, sewer system structures and urban runoff control and treatment. The discussion of combined sewers focuses on hydraulic design of combined sewer systems, including combined sewer overflow (CSO) structures, and the use of CSO structures and storage in control of CSOs. The section on operation of sewer systems focuses on real time control, its feasibility, planning, design, operation and applications. Sewer system planning and design are generally conducted using computer modelling tools and procedures which are reviewed in the last section. A brief listing of selected models focuses on internationally used models. Finally, it was concluded that further improvements in environmental and ecological protection of urban waters is feasible only by consideration of urban drainage systems in conjunctions with sewage treatment and water quality in the receiving waters.
Comparison and Evaluation of Different Microbiological Quality Criteria for Shellfish and Shellfish-Growing Waters
Authors: Martinez-Manzanares E. , Moriñigo M. A. , Castro D. , Balebona M. C. , Borrego J. J.
Published: May 2018

The objective of this study is to compare different microbiological criteria based on the control of shellfish-growing waters and shellfish flesh, to assess the microbiological quality of the shellfish harvested in a marine zone affected by discharges of a moderately polluted river.

Two species of shellfish grown in Mediterranean countries, cockles (Cardium edule) and striped venus (Chamelea gallina) were chosen to carry out this study. A total of 55 samples of diellfish and sea water were collected over the four seasons of the year.

According to the results obtained, the US, EEC and Spanish criteria, based on the level of faecal coliforms in shellfish flesh, guaranteed appropriately their safety for human consumption, but among the criteria based on the level of Escherichia coli, only the Australian criterion has been shown to be totally safe, this microorganism being the best indicator of the presence of Vibrio parahaemolyticus and Salmonella.

For the criteria based on the analysis of indicators in seawater, the indicators which relate to the age of faecal pollution, such as spores of clostridium sulfite reducer and faecal streptococci are the best indexes of the presence of pathogens in shellfish. Furthermore, criteria that establish the percentage of water samples that fulfill the microbiological level specified, or log-normal distributions of indicators such as total coliforms, faecal coliforms and E. coli, are better than mean counts.
Infective Dose Size Studies on Cryptosporidium parvum Using Gnotobiotic Lambs
Authors: Blewett D. A. , Wright S. E. , Casemore D. P. , Booth N. E. , Jones C. E.
Published: May 2018

Natural waterbourne transmission of cryptosporidiosis was studied by a simulation using low-level accxamulative dosing. Gnotobiotic lambs were fed on a diet artificially contaminated to a predetermined level with Cryptosporidium parvum oocysts and the faecal output of cysts was measured. Results indicate a minimum infectious dose as low as one oocysts.
Occurrence and Removal of Cryptosporidium spp. Oocysts and Giardia spp. Cysts in Kenyan Waste Stabilisation Ponds
Authors: Grimason A. M. , Smith H. V. , Thitai W. N. , Smith P. G. , Jackson M. H. , Girdwood R. W. A.
Published: May 2018

This study was designed to determine tlie occurrence and removal of Cryptosporidium spp. oocysts and Giardia spp. cysts, in municipal waste-water by waste stabilisation ponds in tlie Republic of Kenya. Eleven waste stabilisation pond systems located in towns across Kenya were included. A total of 66 waste-water samples were examined for the presence of oocysts and cysts, comprising 11 raw waste-water and 55 pond effluent samples over a two month period. Cryptosporidium spp. oocysts were detected in 6 and Giardia spp. cysts in 9 of the designated pond systems analysed demonstrating their ubiquitous nature throughout Kenya. Oocyst levels detected in raw waste-water samples ranged from 12.5 - 72.97 oocysts/l and various pond effluents between 2.25 - 50 oocysts/l. Cyst levels detected in raw waste-water samples ranged from 212.5 to 6212.5 cysts/l and in various pond effluents from 3.125 to 230.7 cysts/l. No Cryptosporidium spp. oocysts were detected in the final effluent from any pond systems studied (11/11). Whereas no Giardia spp. cysts were detected in the final effluent from 10 of 11 waste stabilisation pond systems studied, one pond system was found to be consistently discharging cysts in the final effluent at concentrations ranging from 40 to 50 cysts/l. The minimum retention period for the removal of Cryptosporidium spp. oocysts and Giardia spp. cysts was 37.3 days. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to express relationships between pond performance and protozoa removal.
Improved Specificity in Detecting F-Specific Coliphages in Environmental Samples by Suppression of Somatic Phages
Authors: Handzel T. R. , Green R. M. , Sanchez C. , Chung H. , Sobsey M. D.
Published: May 2018

Analysis of environmental waters for F-specific coliphages on the genetically constructed host Salmonella tvphimurium strain WG49 is hampered by the detection of Bomatic Salmonella phages. To improve the specificity of F-specific coliphage detection, two agents were tested for selective inhibition of Salmonella phage infectivity: heat-killed cells of female (F) S. tvphimurium WG45 and chemically extracted S. tvphimurium lipopolysaccharide (LPS). When both treatments were tested on pools of environmental isolates of Salmonella phages and the FRNA coliphage MS2, Salmonella phage infectivity was reduced by >90% with no change in MS2 detection. When environmental waters were tested by single agar layer or membrane filter methods, LPS increased the selectivity of F-specific coliphage detection from 28% to >90%, with no loss of sensitivity. The results of this study indicate that LPS effectively inhibits Bomatic Salmonella phage infectivity when added directly to a water sample or to molten agar medium or when used to treat filters on which phages have been concentrated.
Microbial Quality of Drinking Water in Some Finnish Distribution Systems
Authors: Lahti Kirsti
Published: May 2018

The occurrence of heterotrophic bacteria, Pseudomonas aeruginosa, Aeromonas, total coliforms, faecal streptococci, molds and yeasts in distribution systems of two surface water, two artificial groundwater and two groundwater supplies was examined three times during one year. All water samples studied were free of Pseudomonas aeruginosa and faecal streptococci in 100 ml. Total coliforms were detected in water distributed from one groundwater supply. Aeromonas hydrophila/caviae in the concentration range <1 - 32 cfu/100 ml also occurred in distributed water from the same supply. Molds and yeasts were frequently found in piped water from all watenvorks. The concentration of molds exceeded 100 cfu/100 ml in two sampling points. The differences in heterotrophic plate counts were greater between different sampling points of the same surface water supplies than between waterworks with different raw water origins. Over 80 % of the isolated strains of heterotrophic bacteria from different sampling locations were gram-negative and 57 % were oxidase-negative. The identified gram-negative strains belonged to the genera Pseudomonas, Moraxella, Alcaiigenes and Flavobacterium. The majority of strains (64 %) remained unidentified with the biochemical tests used.
Application of the Polymerase Chain Reaction Technique to the Detection of Pathogens in Water
Authors: Toranzos Gary A. , Alvarez Abdiel J. , Dvorsky Elizabeth A.
Published: May 2018

Enteric pathogens may be present in fecally contaminated waters at extremely low concentrations. In addition, these pathogens may be injured when exposed to the environment and may not be able to grow in laboratory culture media or such media may simply not exist for their progagation in the laboratory. It is paramount thus to use techniques which do not depend on culture techniques for the detection of these pathogens and that allow for the detection of single-cell concentrations. The polymerase chain reaction (PCR) technique has been shown to be an excellent and sensitive means of detecting pathogens in waters. Membrane filtration has been combined with PCR and DNA hybridization techniques to be able to detect the DNA equivalent of one single cell in large volumes of water. In addition, this combination of methods allows for the amplification of different target genes fiat may be present in the sample, since the membrane can be subjected to repeated amplification reactions under different conditions. A Most Probable Number PGR was developed which allows for the quantification of gene copy number and thus permits extrapolation to estimate the number of bacterial cells in the original sample.
The Effect of UV Transmission, Suspended Solids and Photoreactivation on Microorganisms in Wastewater Treated with UV Light
Authors: Whitby G. E. , Palmateer G.
Published: May 2018

To predict the performance of UV systems for disinfecting wastewater a full scale UV system was subjected to changes in wastewater quality. The effect of changes in the UV transmission and suspended solids on fecal coliforms was measured. The level of UV transmission and suspended solids which can be treated is dependent upon the disinfection limit. There was no relationship between the UV transmission and the suspended solids and the degree of photoreactivation. An antibiotic labeled Escherichia coli was irradiated with the UV system and then observed in glass bottles and in the receiving stream for photoreactivation. Photoreactivation was observed in the glass bottles but not in the receiving stream. In the natural environment photoreactivation may not be important
Reliability of Several Microorganisms to Indicate the Presence of Salmonella in Natural Waters
Authors: Moriñigo M. A. , Martinez-Manzanares E. , Muñoz M. A. , Balebona M. C. , Borrego J. J.
Published: May 2018

A new index of microbiological quality of natural waters based on the coliphage test is proposed. Levels of coliphages corresponding to the concentrationgs of coliphages (Phgs) lower than 300 pfu/100 ml warrant a good microbial quality of waters affected with fecal pollution. In waters with industrial and domestic pollution Salmonella percentages higher than 5 % were detected even when this proposed index (Ph95) was applied. Thus the direct detection of the pathogen could be more useful in this case.
Influence of Diffuse Pollution on the Eutrophication and Water Quality of Reservoirs in the Morava River Basin
Authors: Žáková Z. , Beránková D. , Kocková E. , Kríž P.
Published: May 2018

Diffuse (nonpoint) pollution from the river basin is responsible for a substantial part of Czech reservoirs' deterioration caused by eutrophication and water pollution. The research results of two model drinking water supply reservoirs (different area and depth) in the Morava river basin showed that the main nutrient sources in the period 1960-1991 were: agricultural land use (overland and subsurface transport of nutrients, effects of drainage and erosion), point sources (urban activities, agricultural farms) and atmospheric depositions of N and P compounds. The accelerated eutrophication was manifested by the increasing development of phytoplankton. The main problems entail occurrence of toxic species of Cyanophyta/Cyanobacteria (blue-green algae) Aphanizomenon flos-aquae, Microcystis aeruginosa and some other species (e.g. Pseudanabaena limnetica). In the small and shallow drinking water reservoir of Ludkovice the living algae penetrated drinking water. In the deep reservoir of Vír the situation was more favourable. The increase of nutrient input (N,P) during the period 1969-1992 was highly significant Various measures have been proposed to slow the reservoir eutrophication (sustainable use of land, best management practices - soil retention, buffer strips, constructed wetlands etc.).
The Monthly Impact of Nonpoint Sources to Hoedong Lake, Korea
Authors: Choi Ji-Yong , Koo Ja-Kong
Published: May 2018

Lake Hoedong, located in the south of Korea peninsula, is a small, shallow, eutrophic lake, which is an important water supply source for the city of Pusan. Although point sources are discharged after secondary treatment, there has beena steady deterioration of lake water quality. Removal of point sources alone mayproduce no measurable improvement in the lake condition because of nonpoint sources. So the objectives of this paper are to quantify the nonpoint sources and to assess theimpact to the lake. Nutrient inputs from point sources are unlikely to have been alteredsignificantly, but nonpoint nutrient inputs have great monthly variation. Contributionof nonpoint sources to the external input of total phosphorus is almost 67% in the wet season and 19% in the dry season. Assuming that a substantial nonpoint source reductionis made by the Hoedong Lake basin, we attempt to estimate the effect of the lake waterquality by mass balance equation. The nonpoint source impact to Hoedong Lake waterquality is more than 60% in the wet season.