bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematic Model of River Ice Motion During Dynamic Breakup
Authors: Ferrick M.G. , Weyrick P.B. , Nelson D.F.
Published: May 2018

We begin a study of the dynamics of ice motion during river breakup by formulating a kinematic model. Ice continuity equations are applied to relate the speeds of a breaking front, a convergence front, a stoppage front, and a release front with the ice discharge and volume per unit surface area (unit volume) on either side of each front. Ice velocity was measured with time during a dynamic breakup at a pair of sites bounding a reach of the Connecticut River. We simulate the ice and front motion through time for this reach using the kinematic model with the assumptions that accumulation thickness and porosity are uniform, and that changes in the ice conditions and motion occur only at a front. Contrary to the basic assumption of static jam formation, we find that the accumulation developed while the ice was moving, and that jam formation merely represents the arrest of the motion.
A Recession-Forecast Model for the Blue Nile River
Authors: Abdelhadi A. W. , Hata Takeshi , Hamad O. E.
Published: May 2018

An analytical model for the forecasting of the Blue Nile River low flow is developed and compared with the current modified similar year method. The model is based on the general non-linear reservoir equation and the historical flow of the river for the calibration period 1912-1961. The comparison is made after the year 1961 for 6 different years in terms of the temporal 10-day flows and for the period 1962-1996 in terms of the standard error of estimates (SEE). The model and the modified similar year forecasted 10-day flows were also compared with the actual temporal 10-day flows during the driest and the wettest year of the whole record between 1912-1998. Results showed that the model temporal distribution of flows is more close to the actual ones compared with the modified similar year method. The model has less SEE in 31 years out of 38 compared with the modified similar year method.
Relationship between rainfall and beach bacterial concentrations on Santa Monica Bay beaches
Authors: Ackerman Drew , Weisberg Stephen B.
Published: May 2018

Rainfall effects on beach water quality in southern California are large enough that county health departments typically issue warnings for the public to avoid recreational water contact for 3 days following a storm. To enhance the scientific foundation for these preemptive public health warnings, we examined the relationship between rainfall and beach indicator bacteria concentrations using 5 years of fecal coliform data taken daily at 20 sites in southern California. There was a countrywide increase in ocean bacterial concentrations associated with almost all storms larger than 6 mm and with every storm larger than 25 mm. Only for storms less than 2.5 mm was there no observable rainfall effect. Bacterial concentrations remained elevated for 5 days following a storm, although they generally returned to levels below state water quality standards within 3 days. The length of the antecedent dry period had a minimal effect on this relationship, probably reflecting a quickly developed equilibrium between the decay of older fecal material and the introduction of new fecal material to the landscape.
The Interaction Between Water Scarcity and Water Quality Degradation: Israel as a Case Study
Authors: Shuval H I
Published: May 2018

Israel is facing an impending water crisis of potentially major proportions due to severe water scarcity and increasing degradation of water quality. By 1981 all of the country's known replenishable fresh water resources were being utilized with severe over pumping of the ground water. The gradual accumulation of chlorides and nitrates in the coastal aquifer may severely reduce the utility of this major water resource for both agricultural and domestic purposes by the year 2000, unless drastic steps to abate the process are initiated immediately. Lake Kinneret, the country's major surface watersource, is a highly sensitive ecosystem whose stability could be threatened unless organic pollution is strictly controlled. The belief in desalinization of sea water as some sort of technological “Messiah”, providing solutions to both the problems of water quantity and quality is seriously questioned. The need to reorganize the country's water management system to meet the urgent problems of the impending crisis is proposed.
Treatment of Alkaline Wastewater from Lignite-Fired Power Plants
Authors: Dziubek Andrzej M , Kowal Apolinary L
Published: May 2018

Given are characteristics of, and treatment methods for, alkaline wastewaters from the hydrotransport of the fly ash from a lignite-fired power plant. The principal component of the fly ash is CaO. The impact of this type of waste on the aquatic environment is considered.

Two treatment procedures are tested - CO2 recarbonation and aeration. The aeration of alkaline wastewaters yields good treatment efficiencies, bringing about the precipitation of calcium carbonate. Determined is the relationship between the duration of the treatment process and the chemical composition of the wastewater, as well as the aeration time required to achieve the desired decrease of the alkalinity and pH levels.
Odorous Compounds of Different Strains of Anabaena and Nostoc (Cyanobacteria)
Authors: Möhren S , Jüttner F
Published: May 2018

The odorous compounds of different strains of Anabaena and Nostoc were identified by gas chroraatography and mass spectroraetry. The Anabaena and Nostoc strains used produced different patterns of volatile substances including hydrocarbons, alcohols, aldehydes and ketones.

A.oscillarioides produced high concentrations of compounds with Cg - skeletons with different substituents and unsaturations. The major compounds were oct-2-en-l-ol, oct-l-en-3-ol, octa-1,5-dien-3-ol and octa-1,trans 3, cis 5-triene. Together with numerous substances found in low concentrations, the two Nostoc strains produced acetone and butan-2-one. Anabaena PCC 7120 and A. flos-aquae produced trace amounts of different odorous compounds. Lack of nor-carotenoids such as β-ionone, β-cyclocitral and 6-methylhept-5-en-2-one is pointed out.
Dry Bed Filtration as a Second Biological Stage for the City of Mannheim (1,200,000 PE)
Authors: Seyfried CF
Published: May 2018

Mannheim's large treatment plant (Qtr = 14.000 m3/h) is being expanded on the principle of dry bed filtration. In the first stage of expansion a filtration system of 32 filters covering a total area of 2.784 m2 is being added to the existing sludge plant. 24-h composite samples of the effluent have to meet the following specifications: 80 mg/l COD and 20 mg/l BOD5.

Before the contract was awarded extensive experiments were conducted on the plant grounds in Mannheim. The performance capability of the system was proven (see Prof. Ruffer's paper).

It was shown that at filtration rates of around 5 m3/m2·h, the suspended solids in the effluent could be kept under an average of 8-9 mg/l, the COD under 80 mg/l, and the B0D5 under 20 mg/l.

The advantage of the system lies in its ability to supply the biologically active filter with atmospheric oxygen, resulting in lower operating costs.

This system like other biologically operative ones has its limits in the short contact time; very high loading peaks show up again moderately in the effluent.
Failure to Detect Cytopathic Enteroviruses in Drinking Water
Authors: Morris R. , Sharp D. N.
Published: May 2018

No cytopathic enteroviruses were detected in 284 samples of drinking water. A total volume of 135,000 litres from 265 locations was examined.
Legal and Administrative Aspects of the Treatment and Discharge of Industrial Wastewaters in the Mediterranean
Authors: Saliba L. J.
Published: May 2018

Approximately 80-85% of the total Mediterranean pollution load originates from land-based sources. Industrial wastewater discharges form a significant proportion. National legal and administrative measures vary enormously within the region, and coverage and coordination need improvement, as do waste management and disposal practices. The only legal instrument providing overall regional coverage is the 1980 Protocol for the Protection of the Mediterranean Sea against pollution from Land-based Sources, which only provides the framework for programmes and measures to be progressively developed. In reviewing the situation regarding the treatment and discharge of industrial wastewaters in the Mediterranean, a recent WHO Workshop emphasized the integrated nature of the pollution problem, and stressed that a regional code of practice for industrial waste discharge should form an integral part of an overall pollution control framework. National programmes should be undertaken progressively in ascending order of complexity to ensure cost-effectiveness and capability of enforcement. Treatment and re-use of industrial wastewaters could provide a new water resource. Interim effluent standards should be established until such time as the capability is developed to define local environmental quality criteria, on which firm effluent standards could then be based. The progressive implementation of such measures would help in finally resolving the problem of industrial pollution in the region.
Fixed Activated Sludge Makes Sewage Treatment Simple
Authors: Mesdaghinia A.
Published: May 2018

The objective of this research was to conduct a bench scale study of fixed activated sludge treating domestic sewage.

Two different units employing diffused aeration with plastic and aluminum media were studied in four separate phases.

Data indicated that the system could produce a high quality effluent without any requirements for sludge recycling through the system. Suspended solids concentrations of 3–6 mg/l, BOD5 concentrations of 4 – 12 mg/l and COD concentrations of 35–45 mg/l were found in the effluent with wastewater retentions ranging from 3–15 hours, whereas an indication of nitrification was observed in higher detention periods.

As far as the type of media was concerned, the plastic and aluminum media did not differ significantly once the microbes had grown on the media.
Reducing the Discharges to Water – Technical Objectives
Authors: Norrström Hans A.
Published: May 2018

The main technical objective in reducing the discharges to water is to implement technology to maintain a desired level of priority pollutants. Several investigations indicate that the priority pollutants may be found in the chlorinated material discharged from the bleach plant.

Based on this assumption the state of art of production and abatement technology will be reviewed. Oxygen bleaching is in most cases the most efficient first step to reduce the discharge of chlorinated material. With appropriate process design and control the discharge of chlorinated material will be 3-4 kg/tonne (as TOC1).

If lower discharge levels are aimed at, the chlorination stage can be modified by applying lower chlorine charge alone or in combination with chlorine dioxide addition. The present Swedish environmental requirements of about 2 kg TOC1/tonne necessitate such measures. Careful process optimization is necessary to avoid changes in product quality. Modified cooking can be one way to create the extra flexibility necessary to maintain top quality.

To reduce the discharge levels further, new process technology has to be introduced. The Prenox process, membrane filtration of effluents, partial or complete recycle of bleach effluents, will be discussed and also external treatment methods.
Water Pollution Abatement in Small Paper Mills in India
Authors: Panneerselvam L.
Published: May 2018

In order to reduce the demand for the forest based raw materials by the organised industrial sectors like the large integrated pulp and paper mills, the Government of India started promoting several small-scale pulp and paper mills based on non-wood agricultural residue raw materials. However promotion of these small mills has created another environmental problem i.e. severe water pollution due to non-recovery of chemicals. Because of the typical characteristics like high silica content etc. of the black liquor produced and the subsequent high capital investment needed for a recovery system, it is not economically feasible for the small Indian mills to recover the chemicals.

While the quantity of wastewater generated per tonne of paper produced by a small mill is same as from a large integrated pulp and paper mill with a chemical recovery system, their BOD load is four times higher, due to non recovery of chemicals. However the existing wastewater disposal standards are uniform for large and small mills for e.g. 30 mg BOD/l. To meet these standards, the small mills have to install a capital intensive wastewater treatment plant with heavy recurring operating costs. Therefore the feasible alternative is to implement various pollution abatement measures, with the objective of not only reducing the fibre/chemical loss but also to reduce the investment and operating costs of the final wastewater treatment system. To illustrate this approach, a case study on water pollution abatement and control in a 10 TPD mill, will be discussed.
3-D Model and Field Studies of Silt Transport in the Dutch Coastal Zone of the North Sea with Emphasis on Dump Sites
Authors: Spanhoff R. , de Kok J. M.
Published: May 2018

A proper management of coastal zones and adjacent estuaries with respect to man-made contaminants requires tools to describe and predict transports of suspended sediments. In a complicated area such as the outflow region of the river Rhine a coherent program of combined field studies and numerical modelling is required to arrive at such tools. Elements of an on-going program are described.
Development of Excess Phosphorus Removal Characteristics in a Sequencing Batch Reactor
Authors: Shin H.-S. , Jun H.-B.
Published: May 2018

Biological phosphorus removal mechanisms become popular in activated sludge wastewater treatment systems due to their economy and efficiency. The objectives of this paper are to develop the excess phosphorus removal system in a short start-up period and to find the optimal operating conditions. In this experiment, excess phosphorus removal was achieved in a week on the proposed operating method which is to keep substrate zero before the start of aerobic react. The removal raters of both TOC and phosphorus were above 98 % in one week operation. Phosphorus removal bacteria can utilize glucose as well as acetate and also use nitrate as a single electron acceptor. The developed excess phosphorus removal system had good Stability against the impact load.
Movement of Nitrogen through an Agricultural Riparian Zone: 2. Distributed Modeling
Authors: Nikolaidis N. P. , Shen H. , Heng H. , Hu H.-L. , Clausen J. C.
Published: May 2018

The Nutrient Transport and Transformation model (NTT) is a generalized fate, speciation and transport model capable of simulating the movement of nutrients in the environment. The hydrologie model is an energy-driven, distributed parameter model that couples surface and ground waters. The vertical discretization consists of overland flow, perched saturated layer, root zone, percolation zone, and groundwater. The chemical model is based on the mass balances of nitrate, ammonium ion, organic nitrogen, humus material, organic phosphorus, phosphate, litter and biomass in the unsaturated zone and the groundwater. Geochemical processes affecting the nitrogen species mass balance that are included are nitrification, denitrification, plant uptake, mineralization, litter partition, humidification, decomposition, and biomass growth (uptake) and respiration. The NTT model was used to simulate the fate, transport and speciation of nitrogen through a corn riparian zone using data collected during the summer months of 1992. The NTT model was shown to be capable of simulating the hydrologic and biogeochemical processes occurring in riparian zones. The root mean square error between the simulated and observed nitrate concentration is 1 mg/l. The model can be used in the design of riparian buffers for nonpoint source pollution control.
Biofilms and Environmental Protection
Authors: Flemming Hans-Curt
Published: May 2018

Biofilms are the result of adhesion and growth of microorganisms at interfaces. They consist mainly of water (70-95 % wet weight), held by the highly hydrated extracellular polymers (EPS, 70-95 % dry weight) in which the microorganisms are embedded. Adhering cells differ from their suspended counterparts in both activity and resistance to toxic substances. The cells are immobilized next to each other and form well organized consortia, capable of performing sequential degradation processes. Biofilms are ubiquitous and the majority of microorganisms on earth is living in biofilms.

The particular properties of biofilms are utilized for environmental protection in bioreactor technology, applied to sewage water and waste air purification, soil remediation and solid waste decomposition. Biofilms can have detrimental effects, inducing metal corrosion and microbially induced weathering of mineral materials such as stone or cement. Resulting damage, e.g., to oil tanks and pipelines and to concrete sewers, has lead to substantial pollution of soil, groundwater and surface water. Biofilm development on heat exchangers, filter materials and separation membranes leads to the application of large amounts of biocides. These cause waste water problems after use.

A deeper understanding of the particular properties and dynamics of biofilm development and processes could help to optimize the application of desired biofilms and to minimize the detrimental effects of undesired biofilms and of countermeasures.
Evidence for Use of Methylated Sulfur Compounds by Anoxygenic Phototrophic Bacteria Isolated from a Salt Marsh
Authors: Bergstein-Ben Dan Talya
Published: May 2018

Anoxygenic phototrophs were isolated from salt marsh sediments and creek waters. Several of the isolates obtained were able to consume dimethyl sulfide (DMS) and dimethyl disulf ide (DMDS) during growth in the light. Rhodopseudomonassulfidophila was the most abundant phototroph in the marsh and also displayed the greatest ability to metabolize DMS. DMS stimulated CO2 fixation in R. sulfidophila. DMSO was the most likely product of DMS metabolism.
Some thoughts on the implementation of water quality management strategies for Central and Eastern Europe
Authors: Kindler Janusz
Published: May 2018

The countries of Central and Eastern Europe (CEE) continue their efforts to address environmental problems, including water quality management, in the context of a transition from the centrally planned to market economies. Their economic recovery and further development is the most pressing and central goal since water quality deterioration is nothing but one of the many consequences of the lack of economic progress. Since international assistance to the CEE countries is limited, an early action should be taken to support the establishment of national financial mechanisms and incentives. To improve water quality, the efficiency of water, energy and material use must be increased in the CEE countries; reducing water use is an imperative. Industrial wastewater management strategy shall distinguish between the old and new enterprises. The non-point pollution sources of agricultural character should largely be controlled by preventive measures, applied jointly by land, water and agricultural specialists and managers. Transformation of industry and agriculture and water quality improvements must be undertaken together.
Improved Method of Activated Sludge Biomass Determination
Authors: Liebeskind M. , Dohmann M.
Published: May 2018

With the development of kinetic models and new design criteria for activated sludge systems, biomass determination becomes important. Various methods can be used to estimate the amount of biomass. Most of these methods are only applicable to pure culture studies. The activated sludge of wastewater treatment plants contains not only biomass, but also a high content of dead organic and inorganic material of unknown composition. Distinguishing between these sludge constituents is difficult. The best and most reproducible method for biomass estimation is often described as the determination of DNA content. This method includes the acid extraction of DNA, the quantitative determination of deoxyribose sugar by a colour reaction with diphenylamine, the calibration with standard DNA and the mathematical conversion into biomass. This study shows that the conventional method is strongly affected by unknown activated sludge constituents and in particular iron. The interference can be overcome by EDTA treatment. Inconsistencies in published calibration data are overcome.
Mass and Viability Estimations of Nocardia in Activated Sludge and Anaerobic Digesters Using Conventional Stains and Immunofluorescent Methods
Authors: Hernandez Mark , Jenkins David , Beaman Blaine L.
Published: May 2018

An immunofluorescent method was developed to estimate the quantity and viability of Nocardia filaments in activated sludge and anaerobically digested sludge on both a mass and volume basis. The Gram stain counting technique of Vega-Rodriguez (1983) and Pitt (1988) was modified to estimate the mass of Nocardia in activated sludge and compared to the immunofluorescent method. Both methods were calibrated on a pure culture of chemostat grown Nocardia amarae. Using the immunofluorescence technique, Nocardia were estimated to comprise an average of 18% by weight of the VSS in a foaming activated sludge plant. Nocardia were found to be, on average, 79% viable as judged by INT reduction staining. Nocardia were found to comprise 13% of the VSS in a foaming anaerobic digester sludge and had an average viability of 63%. These organisms were estimated to be 30 to 50% viable in a mixed anaerobic digester with a hydraulic detention time of 14 days.
The dan region sewerage wastewater treatment and reclamation scheme
Authors: Shelef G. , Azov Y. , Kanarek A. , Zac G. , Shaw A.
Published: May 2018

The Greater Tel-Aviv (Dan Region) urban area is composed of seven municipalities producing close to 100 million cubic meters per year (mcmy) of wastewaters, serving a population equivalent of over 1.7 millions. The Dan Region Association of Towns for Sewerage serves the largest population, commercial and tourism center of Israel as well as an important part of its industry. The flow of wastewater in the region is expected to reach some 150 mcmy by the end of this decade due to its intensive growth. Due to the perennial and severe shortage of water, Israel has adopted a national policy of maximizing wastewater reuse, aimed principally at agricultural irrigation of crops without any restrictions (including fruits and vegetables eaten uncooked). The quality requirements for the reclaimed wastewater are quite stringent, due to the fact that a large proportion of the agricultural produce is intended for export to foreign countries. The Dan Region - Third Line scheme is an example of a holistic approach to urban sewerage system integrated with reclamation and agricultural reuse, within an overall policy-making, engineering design, operation, monitoring, surveillance, management, administration and legal framework. It has a combined health, environmental and economical benefit to the urban communities and critical economic and livelihood benefit to the rural community.
Rehabilitation Concept for the Emscher System
Authors: Londong D. , Becker M.
Published: May 2018

The densely populated Emscher basin (~ 800 km2) is embedded between the Ruhr and Lippe rivers in the North-West Germany. The sewerage from 2.5 million inhabitants, from a diversity of industrial plants and storm water is conveyed by a combined open sewer system to a central sewage treatment plant located at the mouth of the Emscher. The use of the natural drainage system as an open sewer was due to severe land subsidence caused by underground hard coal mining, which had a most deteriorating influence on flow conditions. After closing down most mines, land subsidence has been greatly reduced: consequently the open sewer concept can be abandoned and a general rehabilitation of the Emscher system is now in progress.

The rehabilitation concept is based on the separation of natural river flow and sewage, which will be conveyed via modified combined systems to decentralized treatment plants. A step-wise programme is necessary to complete the basic system rehabilitation through “learning by doing”. The realization period is expected to be 25-30 years. For the construction of sewer systems and plants, including stormwater treatment facilities, and for the reconstruction of the surface drainage system in a natural form, including flood retention measures, the expected investment cost amounts to about 8 billion DM (~ 4.7 billion US $).
Determination of oxygen transfer rate to a rotating biological contactor by microelectrode measurement
Authors: Nishidome K. , Kusuda T. , Watanabe Y. , Yamauchi M. , Mihara M.
Published: May 2018

With an oxygen microelectrode developed by the authors for the measurement of dissolved oxygen (DO) concentration profiles of biofilms in a rotating biological contactor (RBC), DO concentration profiles in the inside and outside of rotating biofilms were measured continuously in the air and water phases. Thicknesses of attached-water film (Lw) and the diffusion layer (Ld) formed on the biofilms were estimated from DO concentration profiles. The oxygen transfer rate to the biofilm was determined with measured DO concentration profiles and a steady state biofilm kinetic model by use of the thicknesses of attached-water film and the diffusion layer. The oxygen transfer rates obtained by two independent methods agreed well, so that the method of the measurement of DO concentration profilesis considered highly reliable. The conclusions in this study are summarized as follows: (1) Lw and Ld on a biofilm attached on a partially submerged rotating biological contactor were 50 and 70 μm thick, respectively; (2) The measured oxygen fluxes were about 10 g-O2/m2/day, and reasonably agreed with those calculated from removing rates of ammonia nitrogen.
Activated carbon membrane biofilm reactor for the degradation of volatile organic pollutants
Authors: Kolb F. R. , Wilderer P. A.
Published: May 2018

For the treatment of inhibitory wastewaters, biofilm reactors are distinguished by high process stability and flexibility. The activated carbon membrane biofilm reactor described in this paper combines the advantages of membrane technology and activated carbon adsorption in order to biologically degrade volatile organic pollutants in wastewater. Membranes provide oxygen, and activated carbon ensures a rapid reduction of organic concentration below the toxicity limit of the microorganisms. Two different reactor types are compared in this investigation.
Constructed reed beds: appropriate technology for small communities
Authors: Green M. B. , Upton J.
Published: May 2018

Reed bed treatment is put in the context of a major water company’s need to provide reliable, high quality, effluents from small sewage treatment works whilst seeking to minimise running costs. Design and operational information is given for reed bed applications in Severn Trent Water. Performance details are provided for application to secondary, tertiary and storm overflow treatment. The results give particular confidence in the system’s ability to deliver very high quality effluents when used for tertiary treatment, the company’s biggest application. Reed beds work well against less demanding criteria for secondary treatment at small sites and show great promise for storm overflow treatment.
The occurrence, distribution, and remediation of transient pollution events in agricultural and silvicultural environments
Authors: Schreiber J. D. , Smith S. , Cooper C. M.
Published: May 2018

Transient pollution events occur in runoff from both agricultural and silvicultural environments. In agricultural runoff, transient pollution events may be associated with sediment, nutrients, and pesticides. Depending upon hydrological conditions, these events may be responsible for most of the yearly yield of sediment, nutrients, and pesticides, and may have a profound effect on the ecological health of streams and reservoirs, limiting seasonal primary productivity, changing the balance of functional groups, and altering reproductive cycles. Transient pollution events are most noticeable in surface runoff, but are also observable in shallow ground water. Such occurrences in both runoff and shallow ground water may be associated with natural seasonal events including the fall leaching of crop residues, or with cultural activities including the application of fertilizers and pesticides. In either case, rainfall distribution and intensity become important factors in the magnitude of the transient pollution event. Best management practices (BMPs) must be designed to remediate transient pollution in agricultural storm events. Not only must total storm agrichemical loading to aquatic ecosystems be reduced, but also the transient agrichemical concentration peaks occurring within the storm hydrograph.
Assessing oxidation pond design criteria in a tropical town with low water availability
Authors: Teixeira Pinto Marcelo A. , Neder Klaus D. , Luduvice Maurício L.
Published: May 2018

The waste stabilization pond system of Brazlandia consists of two series of anaerobic and facultative ponds running in parallel. Due to the low water availability in the region and the growth of the population, the design conditions of hydraulic retention time and organic loading were strongly modified during the operational period. Assessing of nine years of operational data in comparison with the current design approaches showed that this situation has affected the anaerobic pond efficiency. However, despite what is found in the literature, the increase of anaerobic pond water temperature beyond 20°C was accompanied by decrease in COD removal efficiency. The longer retention times observed in the facultative ponds have favored the increase of algae concentration in the pond, which reduced the overall COD removal efficiency. However, when the filtered sample is taken into consideration, the values easily fit the empirical models proposed in the literature. No significant correlation was obtained between the complete mixing flow model and operational data, which suggests that the reaction constant K is not so constant. In addition to dependence on temperature, Kfilt. values showed a statistically significant correlation with applied COD load.
Steps towards the upgrading of a municipal WWTP affected by nitrification inhibiting compounds - a case study
Authors: Schweighofer P. , Nowak O. , Svardal K. , Kroiss H.
Published: May 2018

The influent to the municipal WWTP of Linz consists of typical domestic sewage and of the discharges of two major industries which results in a severe basic inhibition of nitrification. In the course of a 3-year investigation program, intensive studies were carried out. Pilot investigations showed the nitrification inhibiting properties of this wastewater. On the basis of the operational data, the variation in the inhibition of the maximum specific growth rate was evaluated. In addition, testing procedures which revealed the sources of inhibition - firstly within the catchment area and subsequently inside the industries concerned - were developed. With the results of these tests, risk assessment and a priority schedule became feasible. Based on the information gathered this way and on future steps which will be taken by the industries, major decisions concerning the upgrading of the existing activated sludge plant could be made.
Simulation of a high recirculation airlift reactor for steady-state operation
Authors: Hudson Adam D. , Sanders David A. , Tewkesbury Giles E. , Cawte Howard , Hinks John W.
Published: May 2018

This paper describes a new mathematical model of the fluid dynamic processes in a high recirculation airlift reactor. The model was created to provide information to assist in the design of a reactor, in particular considering the selection of parameters to adjust in order to achieve a steady state solution. The modelling of two phase-flow of air and water in small scale airlift bio-reactors is considered. This modelling was applied to the high recirculation airlift reactor process. A new computer simulation was created and a test program performed to evaluate the models used. The results of this evaluation are presented. The evaluation showed that variation of the superficial gas velocity or the simultaneous variation of the downcomer and riser diameters could be used to produce a steady-state design solution.
Biodegradation of recalcitrant organic matter under sulfate reducing and methanogenic conditions in the landfill column reactors
Authors: Kim Seog Ku , Matsui Saburo , Pareek Sandeep , Shimizu Yoshihisa , Matsuda Tomonari
Published: May 2018

The degradation of cellulose and lignocellulosic material was investigated in simulated landfill column reactors under sulfate reducing and methanogenic conditions. In the sulfate reducing reactors, methane gas production was effectively suppressed. The carbon dioxide produced during the sulfate reduction was dissolved in leachate as IC, leading to low carbon dioxide emission from sulfate reducing reactors. Higher COD in the leachate from the sulfate reducing reactors was probably due to higher solubilization rate of cellulose and lignocellulosic material. In a batch experiment, the hydrolysis of Avicel-cellulose, filter paper and newspaper was faster under sulfate reducing conditions. The percentage of organic carbon biodegradation in sulfate reducing conditions was higher than that in methanogenic conditions.
Ammonia removal and discharges during storm events: integrated approach for a small WWTP and associated CSOs
Authors: Bertrand-Krajewski Jean-Luc , Lefebvre Myriam , Barker Jacqueline
Published: May 2018

An experimental research has been carried out in a small WWTP in order to study the impact of storm events, with a global approach including all CSOs. Special attention has been devoted to the ammonia removal and discharges into the receiving water during storm events. More than 100 rainfalls have been measured between September 1993 and December 1994. The main results are:

- the mass of ammonia discharged by overflows without any treatment ranges from 50 to 90% of the total mass transferred in the sewer system during rainfall periods.

- the mass of ammonia treated in the WWTP ranges from 70 to 140% of the dry weather mass during the same duration, but with a mean concentration ranging from 24 to 76% of the dry weather concentration due to the dilution effect.

- the ammonia removal efficiency remains above 90% even for strong or long rainfall periods, thanks to the overdesign of the WWTP.
The kinetics of metal uptake by microbial biomass: implications for the design of a biosorption reactor
Authors: Butter T.J. , Evison L.M. , Hancock I.C. , Holland F.S.
Published: May 2018

The kinetics of copper ion biosorption by free cell suspensions of inactivated Penicillium biomass was investigated. During the first 15 seconds of the metal uptake reaction copper biosorption was extremely rapid, becoming progressively slower until equilibrium was achieved. At a biomass concentration of 5.48 g dry weight/l, the copper biosorption reaction reached approximately 90% of the equilibrium position in one minute. This is in contrast with biosorption onto immobilised biomass which is known to take up to 24 hours or longer to reach equilibrium. However, the conventional reactor design for free cell suspensions, the stirred tank, may make inefficient use of the equipment and process due to the extended retention time. A plug-flow biosorption reactor with a limited retention time has been developed and demonstrated in the laboratory. The biomass and metal solution were mixed together using static in-line mixers and pumped along a length of pipe before discharging the mixed liquor into a settling tank to achieve phase separation. Desorption of the bound copper ions was achieved by drawing an eluant solution through metal-loaded biomass immobilised as a filter cake. The combination of metal uptake using free cells, and desorption using immobilised cells, optimises the kinetic and mass transfer effects for both processes and minimises the equipment requirements.
Industrial surface water pollution in the region of Devnya, bulgaria
Authors: Dimitrova Ivanka , Kosturkov Jordan , Vatralova Albena
Published: May 2018

The main purpose of this study is to establish the degree of contamination of the rivers and sources of pollution in the great industrial region of Devnya, situated near the Black Sea, so that appropriate technical means for water quality protection and restoration can be developed. A significant problem arises when untreated or partially treated alkaline industrial wastewater is discharged into the water bodies causing sediment formation in the system of the Devnya and Provadiiska rivers, Beloslavsko lake and Varna-West port. All that leads to serious damages to water environment and enormous losses of human, material and financial resources because of the necessity to dredge the sediments that accumulate in the harbour. A lot of available information about the river water quality and flowrates as well as the industrial wastewater for the period 1948–1996 is gathered. Typical physico-chemical parameters for this industrial wastewater namely, suspended solids, dissolved solids, pH, calcium, chlorides, etc., and some biological and radiological characteristics are determined. The sources of pollution are identified and the degree of contamination is determined. An evaluation of the river water quality according to the standards is made and the trends of the rivers water pollution are shown.
Anomalies in the transformation of 3-chlorobenzoate in percolation columns with Pseudomonas sp. strain b13
Authors: Tros Marijke E. , Schraa Gosse , Zehnder Alexander J.B. , Bosma Tom N.P.
Published: May 2018

The biotransformation of 3-chlorobenzoate (3CB) by attached cells of Pseudomonas sp. strain B13 was studied in percolation columns operated at various flow rates and biomass contents. Steady-state residual effluent concentrations were compared with predictions from spreadsheet models describing the combined action of microbial and mass transfer kinetics. The effluent concentrations were successfully predicted above a critical ratio of flow rate and biomass. Below this critical point the steady-state residual effluent concentrations were higher than predicted and this deviation increased with decreasing flow rate:biomass ratios. The results are discussed in the light of convection-diffusion processes limiting the transport of both substrate and oxygen to the attached cells.
Establishing a network of on-line monitors at the purification works and in the distribution network of rand water
Authors: Du Preez L. A. , Husselmann A. J. , Acton N. R. , Lange L.
Published: May 2018

More than 120 on-line instruments were installed in specially designed instrumentation kiosks throughout the Rand Water purification works during the past three years. This forms part of an ongoing expansion programme in which instrumentation is increasingly used for: (i) process monitoring, (ii) process automation and (iii) monitoring of final water quality. This programme is planned to cover the whole distribution network within the next ten years.

Output signals from all instrumentation are relayed via PLCs to run time servers and through the Ethernet to Hewlett Packard Unix systems in the control rooms where continuous monitoring and corrective action will be taken. The real time data will also be directly available via viewer nodes to Scientific and Engineering personnel in the near future for quality monitoring, trend analyses and feedback to consumers.
Evaluation of the impact of disinfection processes on the formation of biofilms in potable surface water distribution systems
Authors: Momba Maggy N. B. , Cloete T. E. , Venter S. N. , Kfir R.
Published: May 2018

In this study, surface water was used to evaluate the impact of disinfection processes (chlorination, chloramination, ozonation, UV irradiation and hydrogen peroxide) on biofilm formation in potable water distribution systems. Biofilm formation was obvious, even in the presence of residual disinfectant concentrations (16.5 mgl−1 hydrogen peroxide, 1 mg−1 monochloramine, 0.2 mgl−1 free chlorine) within the first day after disinfection in the laboratory scale unit. The yield in viable count was higher on stainless steel coupons than on cement coupons within the first 8 days. Viable bacteria numbers on cement coupons were similar (±2 log cfu.cm−2) in chlorinated, ozonated and in the control. Biofilm formation was related to the depletion of residual disinfectant concentration. Monochloramine and hydrogen peroxide had a longer residual effect controlling growth of biofilm cells in the system for a longer period before regrowth occurred. Once no residual concentrations could be detected there was no significant difference between the viable bacterial counts on any of the coupons in the various systems.
Morphological characteristics of microbial sludge performing enhanced biological phosphorus removal in a sequencing batch reactor fed with glucose as sole carbon source
Authors: Jeon C. O. , Lee D. S. , Park J. M.
Published: May 2018

Electron microscopic analysis was used to analyse the morphological characteristics of microbial sludge performing enhanced biological phosphorus removal (EBPR) in an anaerobic/aerobic sequencing batch reactor (SBR) fed with glucose as the sole carbon source. The amounts of phosphate release and uptake during the SBR cycle gradually increased with operation time and complete EBPR was achieved after about 90 days. Scanning electron microscopy (SEM) showed that the initial sludge inoculated into the SBR consisted of various microorganisms such as coccus-, rod- and bacillus-shaped bacteria, but after extended operation (more than 650 days) perpendicular cuboidal bacteria of eight coccus-shaped cells dominated the microbial sludge in the SBR reactor. The cell size of the cuboidal bacteria was about 0.7 μm in diameter. In the sludge, coccus- and rod-shaped bacteria also existed but at much lower frequency. Transmission electron microscopy (TEM) also revealed that the cuboidal bacteria dominated the sludge, but they did not contain polyphosphate granules or glycogen inclusions. The rod-shaped bacteria did not contain polyphosphate granules or glycogen inclusions either. Only coccus-shaped bacteria with a diameter of about 1.2 μm contained small black polyphosphate granules and a large white inclusion. Based on previously proposed metabolic pathways and electron microscopic results, it was inferred that the dominating cuboidal bacteria were lactic acid producing organisms (LPO) and the coccus-shaped bacteria were lactate-using phosphorus accumulating organisms (PAO).
Removal of chromate from industrial effluent by a new isolate of Staphylococcus cohnii
Authors: Saxena D. , Levin R. , Firer M.A.
Published: May 2018

We have isolated and identified of a new isolate of Staphylococcus cohnii from a tannery effluent and have studied the capacity of the organism to bioaccumulate chromium. The Staph.cohnii isolate is resistant to Cr, growing well in standard medium supplemented with 1000ppm Cr(VI). Over a treatment period of 96 hrs, the isolate removed about 90% Cr(VI) from medium containing 100ppm Cr(VI) and from contaminated tannery wastewater. Bioaccumulation of Cr from the wastewater was confirmed by atomic absorption. Results further indicate that the organism reduces Cr(VI) to Cr(III).
Immobilization strategies for bioaugmentation of anaerobic reactors treating phenolic compounds
Authors: Guiot S.R. , Tawfiki-Hájji K. , Lépine F.
Published: May 2018

Degradation of phenol, ortho- and para-cresol was investigated in upflow anaerobic sludge bed (UASB) reactors bioaugmented with a methanogenic enrichment consortium able to degrade a mixture of phenolic compounds, in comparison to a reactor, which was inoculated only with anaerobic granules: 1) natural attachment of free cells to the granules, and 2) encapsulation within alginate beads. The increase of the percentage of enrichment from 2 to 5% improved considerably the startup of the reactors. Going from 5 to 10% had no effect on the removal of the phenolic compounds. Following a period of continuous operation at a hydraulic retention time of 3 days, the bioaugmented reactors showed specific activities on phenol, ortho- and para-cresol, at least twofold higher than those of the control reactor. This increase was attributed to the immobilization of phenol, ortho- and para-cresol-degrading bacteria on the granules.
Evaluation of reproductivity of medaka (Oryzias latipes) exposed to chemicals using a 2-week reproduction test
Authors: Shioda T. , Wakabayashi M.
Published: May 2018

Effects of endocrine disrupting chemicals on reproductive ability of medaka (Oryzias latipes) were investigated. Exposure of male medaka to estrogenic chemicals such as 17β-estradiol (E2), p-nonylphenol (NP), 4-t-butylphenol (BP) and bisphenol-A (BPA) caused a decrease in the numbers of eggs hatched rather than those of eggs spawned, which seemed to be affected by estrogen-like effects of these chemicals. Exposure of female medaka to E2 and NP reduced the numbers of eggs spawned rather than those of eggs hatched. The concentrations at which reproductivity of female decreased (E2:0.1 nmol/L, NP:0.03 μmu;mol/L) were lower than those of male (E2:3 nmol/L, NP:μ>0.3 μmu;mol/L). Diethylhexyl phthalate, benzophenone and tributyltin chloride did not affect reproductivity. In this study, adverse effects of estrogenic chemicals on reproductivity of medaka could be detected, so the materials and methods used in this study were considered to be able to be applied for a screening test method.
An example of an integrated approach for health and environmental risk assessment: the case of organotin compounds
Authors: Sekizawa J. , Suter G. , Vermeire T. , Munns W.
Published: May 2018

Because environmental decision making based solely on simple compilation of toxicological data on either wildlife or humans in isolation can not give effective answers about the nature and levels of risk, an integrated approach for risk assessment of adverse effects of chemicals is required. Integration of available information on health and environmental effects, from in vitro to the level of humans, across various species, across different endpoints, and in combination with integrated exposure data, permits enhanced estimation of the potential risks posed by various agents. Mechanistic and quantitative consideration are the keys in this process. A framework for integrated risk assessment has been proposed by an international workgroup. The value and utility of the integrated approach is shown using the example of organotin compounds.