bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution of chemical constituents within the sewage settling velocity grading curve
Authors: Becker Fiona A. , Hedges Peter D. , Smission Robert P. M.
Published: May 2018

Over the past decade there has been an increase in legislation relating to the quality of effluent discharges. The legislation, which contains higher standards for metals, nutrients and organic matter has prompted a need for sewage treatment works to upgrade existing processes. For a significant improvement in process efficiency there is a need for a better understanding of the characteristics of sewage, in particular the association of chemical constituents with solids. This research has used a settling column to determine a profile of the chemical constituents associated with solids in crude sewage. The results indicate that the particulate concentration of Chemical Oxygen Demand (COD) and Phosphorous are associated with solids which have settling velocities in the range 0.04-0.90 cm/sec.
Modeling (partly) cohesive sediment transport in sewer systems
Authors: Berlamont Jean E. , Torfs Hilde M.
Published: May 2018

Although the basic mechanisms of sediment transport in sewers are the same as in rivers, it is not necessarily appropriate to use the many models that have been developed for sediment transport in rivers also in sewers. Different reasons are: 1) sewer sediments are often mixtures of cohesive and non cohesive material, and the bed is often stratified; 2) due to consolidation of the (partly cohesive) bed material, the erosion resistance of the bed may vary with time; 3) the flow conditions in sewers are usually unsteady, which is not accounted for in the classical sediment transport models; 4) existing models have been derived from experiments in rectangular flumes: the results are not directly applicable to sewers with circular cross section where the distribution of bed shear stress may be completely different from a rectangular section; 5) the limited availability of erodible material and the varying supply of sediments add additional difficulty to the modelling of sediment transport in sewers.
Development of design methodology for self-cleansing sewers
Authors: May Richard W. P. , Ackers John C. , Butler David , John Siân
Published: May 2018

New guidelines for the design of self-cleansing sewers have been developed in a recently completed CIRIA research project. Laboratory and field studies were reviewed and compared, and appropriate equations were selected for predicting sediment movement in pipes. Self-cleansing performance was defined in terms of three design criteria covering the transport of fine-grained materials in suspension, the transport of coarser sediments as bed load, and the erosion of cohesive deposits. Information on typical sediment characteristics in UK sewers was reviewed and used to produce guidelines on values of minimum flow velocity and pipe gradient for different types and sizes of sewer.
Effectiveness of the membrane bioreactor in the biodegradation of high molecular-weight compounds
Authors: Winnen H. , Suidan M. T. , Scarpino P. V. , Wrenn B. , Cicek N. , Urbain V. , Manem J.
Published: May 2018

The activated sludge process has been used extensively to treat municipal wastewater. The membrane bioreactor (MBR) process is a modification of the conventional activated sludge process where the clarifier is replaced with a membrane system for separation between the mixed liquor and the effluent. This paper presents the biological and physical performance data of a pilot-scale membrane bioreactor system, fed with a synthetic wastewater. At steady state, particularly high effluent quality was obtained and maintained for an extended period of time. Heterotrophic plate counting showed that the membrane retains heterotrophic microorganisms. Bacteriophage MS-2 was used to determine the retention of viruses. The membrane proved to retain the MS-2 virus.
Settleable sewer solids at stormwater tanks with clarifier for combined sewage
Authors: Michelbach Steven , Weiß Gebhard J.
Published: May 2018

A six-year study of CSO problems showed that in most cases the settleable sewer solids are responsible for poor water quality. This is the reason why the settling behaviour of settleable solids should be taken into account at stormwater treatment to a greater degree than it is done up to now. New efficiency measurements at stormwater tanks with clarifier overflows for combined sewage showed two important results:

1) The annual mean surface loading qA of a clarifier-type CSO tank is only about 25 % of the design surface loading of 10 m3/(m·h) recommended by the German guideline A 128.

2) The settling process in stormwater tanks is effective:

- The median settling velocity vs of sewer solids is reduced from about 0,21 cm/s to vs = 0,035 cm/s.

- The concentration of settleable solids is reduced about 80 %, that of total solids about 65% and COD concentration about 50 %.

With this efficiency, well designed stormwater tanks will be a good measure in many cases to reduce significantly CSO impacts on receiving water quality.
Nitrification in a bubbleless oxygen mass transfer membrane bioreactor
Authors: Brindle K. , Stephenson T.
Published: May 2018

Two laboratory scale biological reactors with hollow fibre incorporated to provide bubbleless aeration to a biofilm attached to the membrane wall were investigated during the nitrification of a synthetic wastewater high in ammonia (30-50 mg l−1). Pure oxygen on the lumen side of the fibres was transported through the pores of the membrane wall directly to the biofilm without the formation of bubbles. As a consequence oxygen usage efficiency is significantly increased. During the 51 d investigation the volumetric nitrogen loading rate increased from 0.08 to 0.20 kg NH4-N m−3 d−1. At the highest loading rate nitrification rates approaching 0.20 kg NH4-N m−3 d−1 were achieved. The dissolved oxygen concentration in the bulk liquid phase stayed well above critical. Hollow-fibre bubbleless oxygen mass transfer membrane bioreactors (MBR) show promise in providing a small-footprint alternative to conventional tertiary nitrification processes.
Hazardous waste stabilization with clean-coal technology ash residuals
Authors: Neufeld Ronald D. , Cobb James T. , Pritts J. , Clifford V. , Bender C. , Beeghley J.
Published: May 2018

Clean coal technology by-products, collected from commercial operations under steady state conditions, are reacted at bench-scale with metal-laden hazardous wastes. Reaction conditions involve mixing calibrated weight ratios of by-product to hazardous waste with attention to minimizing added moisture. Of the 15 heavy metals monitored, lead appeared to be the element of greatest concern both from a leaching and a regulatory point of view. While leaching information is focused on lead stabilization, similar information exists for other metals as well. Stabilized solid products of reactions are sampled for TCLP evaluations. For samples showing evidence of metal stabilization, further experimentation was conducted evaluating optimum moisture content and development of physical strength (measured as compressive strength) over time of curing. Results show that certain hazardous wastes are highly amenable to chemical stabilization, while others are not; certain by-products provided superior stabilization, but did not allow for strength generation over time.
Bacterial consortia for crude oil spill remediation
Authors: Chhatre Suneel , Purohit Hemant , Shanker Rishi , Khanna Purushottam
Published: May 2018

Oil spills generate enourmous public concern and highlight the need for cost effective and environmentally acceptable mitigation technologies. Physico-chemical methods are not completely effective after a spill. Hence, there is a need for improved and alternative technologies. Bioremediation is the most environmentally sound technology for clean up. This report intends to determine the potential of a bacterial consortium for degradation of Gulf and Bombay High crude oil. A number of bacteria were isolated from an acclimated semicontinuous reactor fed with crude oil. A four membered consortium was designed that could degrade 70% of the crude oil. A member of consortium produced a biosurfactant, rhamnolipid, that emulsified crude oil efficiently for effective degradation by the other members of consortium. The wide range of hydrocarbonoclastic capabilities of the selected members of bacterial consortium leads to the degradation of both aromatic and aliphatic fractions of crude oil in 72 hours.
Institutions and water management efficiency: the art of equilibrium
Authors: Lesouëf A.
Published: May 2018

Various factors explaining centralization or decentralization in water management systems are discussed. Relative interactions between the various bodies sharing responsibilities are identified. Different approaches for water pollution control are presented and discussed. Some accent is put on funding and water pricing. Two examples taken from the French experience are given: one to illustrate a financial incentive system, the French Water Agencies, the other to present a partnership system between municipalities and private water companies.
Design and operations experience with flocculator-clarifiers in large plants
Authors: Parker Denny , Butler Richard , Finger Richard , Fisher Reed , Fox William , Kido Wendell , Merrill Steve , Newman Gary , Pope Rod , Slapper Jeff , Wahlberg Eric
Published: May 2018

Historically, secondary clarifiers have contributed to instability in plant performance. The flocculator-clarifier development has demonstrated in a variety of plant situations that stable secondary process operation is achievable. Consistently low effluent SS levels (average values of 10 mg/l) are realistically achievable. This performance enhancement has been obtained at lower costs than for conventional designs. The clarifier incorporates some special design features including a large flocculator centerwell to incorporate dispersed solids into settleable floc. Other features include rapid sludge removal, inboard weir placement and deeper sidewater depths than conventionally used (5.5 to 6m).
Environmental engineering education in Germany
Authors: Schmitt Theo G. , Wilderer Peter A.
Published: May 2018

The paper describes Environmental Engineering education in Germany. The dual system of engineering education is outlined having scientific-oriented programmes at university level and application-oriented programmes at ‘school of engineers’ level. The historical development of Environmental Engineering and its main topics are described as well as its common integration in the study programme of Civil Engineering. The paper then focusses on the educational programmes for Environmental Engineering itself. The organisation in a preparatory module, a basic subject module and a specialized module is discussed. Topics, special courses and the time frame of the education programmes in Environmental Engineering are presented. The programmes of 3 selected universities, Hannover, Kaiserslautern and Cottbus, are described in greater detail and their specific character is outlined.
UV absorption as control-parameter for biological treatment plants
Authors: Matsché N. , Stumwöhrer K.
Published: May 2018

Dissolved organic compounds with aromatic structures absorb UV-light. Thus, the measurement of UV absorption is an indication for the pollution of water with such substances. In surface and drinking water technology this method has a long tradition. In this paper it will be shown that UV-absorption has a very good correlation with COD in wastewater treatment plants and can be used as a continuous and cheap measuring device without the use of chemicals and avoiding errors that can be made in the withdrawal and preparation of composite samples.
Two examples of thermal drying of sewage sludge
Authors: Hassebrauck Martin , Ermel Gerrit
Published: May 2018

The increasing amount of sewage sludge, legal requirements and a change in the assessment of common disposal paths lead more and more to thermal drying of sewage sludge. During the last years a lot of sludge drying plants in Germany were planned, built and brought into service. This paper describes two different kinds of sludge drying plants with their determining and operating values, the costs and the reasons for the choice of the drying method. The examples given are the sludge drying plant at Darmstadt (2 lines with a 2 stage dryer) and in the surrounding area of Frankfurt (1 line with a drum dryer).
Biological phosphorus removal processes - effect of pH on anaerobic substrate metabolism
Authors: Wen-Tso Liu , Mino Takashi , Matsuo Tomonori , Nakamura Kazunori
Published: May 2018

Effect of pH on the anaerobic acetate metabolism of biological phosphorus (P) removal processes was determined using anaerobic-aerobic activated sludge cultured with mainly acetate and containing a 12% or an 8% of total biomass as P (Px). The acetate uptake coupling to phosphate (Pi) release was found to be kinetically and thermodynamically influenced by pH. In the pH range 5.0–6.5, the acetate uptake rate (AUR) increased linearly with pH from 0 to about 50 (mg C/g VSS/h), and the Pi release rate (PiRR) from 20 to about 50 (mg P/g VSS/h). In the pH range 6.5–8.0, AUR remained at a constant range but PiRR continuously increased. Above pH 8.0, both AUR and PiRR started to decrease. With regard to the molar ratio of Pi released per acetate taken up (Pi/Ac), it was about 1.0 or 0.70–0.75 in the pH range 5.5–6.5, and proportionally increased to 1.75 or 1.50 in the pH range 6.6–8.5 for sludge containing a 12% Px or an 8% Px, respectively. Apparently, acidic pH inactivated the acetate metabolism, and basic pH stimulated too much Pi release, resulting an increase in energy consumption for acetate uptake (i.e. the Pi/Ac ratio). As a compromise, an optimum pH 6.8±0.7 was proposed for anaerobic acetate metabolism, because that a relatively high AUR with less energy consumption can be maintained by the bacteria that respond for biological P removal.
The impact of phosphorus deficiency on nitrification - case study of a biological pretreatment plant for rendering plant effluent
Authors: Nowak O. , Svardal K. , Kroiss H.
Published: May 2018

The highly concentrated wastewater of a rendering plant (7 g COD/l and 1.1 g TKN/l on average) is biologically pretreated in an activated sludge plant. Due to low loading of this plant, full nitrification and nitrogen removal are generally achieved. In periods of high COD loads, however, the nitrification capacity was substantially reduced. Control analyses revealed extreme phosphorus deficiency and that only nitrite, but no nitrate was formed. An extended model based on the ‘Activated sludge model No. 1’ has been used to investigate the kinetics of nitrification in the case of phosphorus deficiency, the demand for phosphorus under dynamic conditions, as well as the effect of variations in the nitrogen load at low levels of phosphate.
Nitrate removal from groundwater using an anoxic-aerobic rotating biological contactor
Authors: Mohseni-Bandpi A. , Elliott D. J.
Published: May 2018

The removal of nitrate-nitrogen from groundwater was investigated using two rotating biological contactors (RBC) in series. The first pilot plant RBC reactor was operated under anoxic condition to remove nitrate-nitrogen. A fraction of effluent of the anoxic RBC was fed to a bench scale aerobic RBC to study the degradation of residual organic carbon and oxidation of nitrite-nitrogen. The first reactor achieved a nitrate removal efficiency of 90 percent for a loading rate of 76 mg/m2.h. The corresponding effluent nitrate, nitrite and residual carbon sources concentrations amounted to 3.3, 0.34 and 3.9 mg/l, respectively. The optimum ethanol to nitrate-nitrogen (E/N) ratio was found to be 2.35. No residual ethanol and nitrite-nitrogen were observed in the final effluent under optimum conditions. Dissolved oxygen in the final effluent was found to be greater than 7 mg/l. The results of the study suggest that using a continuous anoxic-aerobic RBC is a convenient and reliable process for removal of nitrate, residual organic carbon and nitrite.
Nitrification and denitrification in continuous upflow filters - process modelling and optimization
Authors: Sanz Juan Pablo , Freund Martin , Hother Stefan
Published: May 2018

This paper discusses the simultaneous removal of nitrogen and solids in continuous upflow filters and a computer simulation of the nitrification process. The simulation model is based on the Activated Sludge Model No. 1 of the IAWQ. Data of a semi-scale filtration plant are being reviewed and compared to the results of the computer simulation, showing a high correlation.
Optimizing phosphorus removal at the Ann Arbor Wastewater Treatment Plant
Authors: Shehab Oula , Deininger Rolf , Porta Frank , Wojewski Thomas
Published: May 2018

The Ann Arbor Waste Water Treatment Plant was originally designed as a conventional activated sludge plant. In 1992 it was modified to operate as an A/O plant. Initial operations were difficult and the required phosphorus removal could be obtained only through heavy additions of ferric chloride. Our study focused on the application point of the ferric chloride, and reexamined the major operating parameters of the plant. Paying close attention to parameters such as sludge blanket levels and oxygen concentrations in the aeration tanks lead to an improved phosphorus effluent level of 0.5 mg/l on a continuous basis. Close attention to the oxygen levels in the anaerobic sections also resulted in a better operation. The addition of ferric chloride has been greatly reduced, and thus has lowered the operating costs and the sludge disposal costs.
Estimation for urban runoff quality modeling
Authors: Haiping Zhang , Yamada Kiyoshi
Published: May 2018

Many models have been developed which simulate the quality of runoff from urban impervious areas. Common to these models is the use of exponential accumulation and washoff equations. The two equations have often been calibrated separately by trial and error. However, field data of nonpoint source investigations are usually collected at the watershed outlet or at a few points on impervious surfaces, both of which reflect the combining effects of accumulation in dry weathers and washoff in wet weathers. It is therefore preferable to estimate these parameters simultaneously to obtain the global optimal values. In this study, the accumulation and washoff equations have been formulated into one model. And optimization techniques for estimating the best fit values of the parameters in the model have been developed using adaptive step size random search and Marquardt method. Bounds of these parameters have been set during optimal search to make sure that the calibrated values are physically meaningful. The method is demonstrated in Kyoto catchment in Japan. Results show that the simulated and measured data match quite well and the calibration approach can generate accurate estimates efficiently.
Earthquake resistance of sewerage pipe line facilities
Authors: Chiba Yasuto , Jo Takao , Ito Norio
Published: May 2018

As may be gathered from the fact that Japan is known as an earthquake archipelago, the country has experienced earthquakes in numerous areas in the past and has suffered from great damage as a result of these.

Although the need for earthquake resistance measures in pipe line facilities has increased as a result of this earthquake damage, there is still a shortage of information regarding sewerage pipe materials that are earthquake resistant. In order to rectify this situation, Japan Institute of Wastewater Engineering Technology (JIWET) has brought together sewerage pipe materials that are considered to be both earthquake resistant and suited to open-cut method (which is the main element required in discussing the seismic resistance of sewerage pipe line systems) in a publication known as “Technical Data on Earthquake Resistant Sewerage Pipe Line Materials - Special Edition” (hereinafter referred to as the Technical Data).
Advanced primary treatment: An alternative to biological secondary treatment. The city of Los Angeles hyperion treatment plant experience
Authors: Shao Y. J. , Liu Anmin , Frank Wada , Crosse John , Jenkins David
Published: May 2018

Advanced primary treatment (APT) is a process, in which chemicals are added to raw sewage to enhance total suspended solids (TSS) and biochemical oxygen demand (BOD5) removals by coagulation and flocculation. The City of Los Angeles Hyperion Treatment Plant (HTP) is the largest APT plant in the USA, servicing over 4 million people within an area of 1500 km2 and currently treating an average of 15 m3/s (350 MGD). HTP began using APT in 1986; current chemical doses to the raw sewage are 10 mg/l of FeCl3 and 0.15 mg/l of an extremely high molecular weight anionic polymer. The 1992 annual average influent TSS and BOD5 concentrations were both 330 mg/l and the APT removed an average 83% TSS and 51% BOD5 at an average surface overflow rate of 75 m/day (1900 gals/ft2,day). This paper discusses the overall performance of APT. The process is more cost effective than conventional primary treatment and its use can significantly reduce the size of the following secondary treatment process. APT is especially suitable for developing countries because of its low capital and operating costs.
Characterization and coagulation-flocculation treatability of Mexico City wastewater applying ferric chloride and polymers
Authors: Mijaylova Nacheva Petia , Torres Bustillos Luís , Ramírez Camperos Esperanza , López Armenta Socorro , Cardoso Vigueros Lina
Published: May 2018

Physical, chemical and bacteriological characterization of two principal Mexico City wastewater flows are reported. COD and TSS variations were in the ranges of 290 to 680 mg/l and of 50 to 380 mg/l, respectively. The wastewater was strongly alkaline with marked bacteriological characteristics. High concentrations of chlorides, sulfates, Na, K, Ca, Mg and Si were found. Ascaris counts were between 24 and 84 eggs/l. Zeta Potential was from −20 mV to −40 mV. Conventional bench-scale tests were done to study the treatability of the wastewater by coagulation-flocculation with FeCl3 and polymers. The tests of FeCl3 performance showed that at a dosage of 80 to 100 mg/l, TSS and COD removals of between 60 to 68% can be obtained. Best performing flocculants were the cationic acrylamid copolymers, but good results were obtained with some anionic flocculants, too. The removal rates achieved with 20-30 mg/l of FeCl3 and a series of anionic polymers at doses 0.2 to 1.5 mg/l were 74 to 84% for TSS, 48-55% for COD and up to 77% for turbidity and color. Coliforms were not removed, however helminth eggs could be removed completely with low reagent doses.
Theory of filtration of highly compactable biosolids
Authors: Cleveland Theodore G. , Tiller Frank M. , Jae-Bok Lee
Published: May 2018

Compactability of particulate structures is a key factor in the behavior of thickeners, filters, centrifuges, and presses. Aggregates in slurries are deposited at a cake or sediment surface under null stress. As more deposits cover the surface, developing stresses compact the particulate bed. Principal sources of stress originate from (1) sediment weight in thickening, (2) frictional drag in filters, (3) centrifugal forces in centrifuges, and (4) surface forces in belts or diaphragms. Only frictional forces in filters are considered in the present work.

Stress applied to cakes results in a decrease in porosity and an increase in resistance to flow (decrease in permeability). The rate at which the permeability decreases with pressure has a profound effect on cake behavior. For highly compactable beds of biosolids or fragile flocs, doubling of the pressure may result in more than a doubling of the local resistance. Consequently, at applied pressures frequently below one atmosphere, increasing pressure neither increases the flow rate nor decreases the average cake porosity.

For highly compactable biosolids, theoretical equations show that (1) filtrate volume vs. t is independent of pressure drop across the cake, Δpc, (2) the average specific resistance is proportional to Δpc, and (3) the average volume fraction of solids is independent of Δpc.
On-line estimations of settling capacity in secondary clarifier
Authors: Hasselblad S. , Xu S.
Published: May 2018

In a biological nitrogen removal system, efficient performance of the secondary clarifier is essential since the system depends on a high concentration of active biological solids being available in the biological reactor. Estimations of the current capacity of the clarifier can be made from observing maximum feasible solids flux to the clarifier which does not cause escape of sludge. The aim of this work is to demonstrate a method to establish maximum feasible solids flux, the limiting solids flux, from on-line operational data. In this method the solids flux into the clarifier is calculated from on-line measurements of effluent flow and of suspended solids in the biological reactor, and a known value of return sludge flow. From relations between solids flux and sludge blanket height, the value of limiting flux is estimated. This method is based on the assumption that the movement of sludge blanket height is directly related to changes in the solids flux. When the limiting solids flux is estimated from on-line measurements a measurement of the capacity of the clarifier is retrieved. The suggested method also gives an early warning to prevent sludge escape from the clarifier.
Mathematical modelling of downflow floating medium filter (DFF) with in-line flocculation arrangement
Authors: Ngo H. H. , Vigneswaran S. , Jegatheesan V.
Published: May 2018

A laboratory-scale set-up consisting of rapid mixing device and floating medium filter was used to study the use of a downflow floating medium filter (DFF) with an in-line flocculation arrangement as a static flocculator and a prefilter. The semi-empirical mathematical model formulated incorporates flocculation within the filter, particle/floc attachment onto the filter and the detachment of flocs from the medium. The mathematical model for filtration takes into account the expansion of the filter bed. The removal efficiency of DFF and headloss development were successfully simulated for different conditions of filtration velocity, filter depth and influent suspended solids (SS). The values of attachment coefficient apβ and headloss coefficient β′ were found to be independent of filtration velocity, filter depth and influent SS concentration.
The influence of currents on circular secondary clarifier performance and design
Authors: Deininger Andrea , Günthert Frank W. , Wilderer Peter A.
Published: May 2018

Density currents in the deeper zones of clarifiers and currents in the clear water zone have a significant influence on clarifier performance. Measurements of flow velocity profiles were conducted in full-scale horizontally flown circular secondary clarifiers. Relations between the hydraulic load and the development of density currents could be detected. Those patterns are not taken into account in current design procedures. Stationary design approaches are mainly based on the overflow rate. Novel design methods based on the dynamic behavior of flow and density distribution in clarifiers are needed in order to improve the efficacy of wastewater treatment systems.
Sludge management in highly urbanized areas
Authors: Lue-Hing Cecil , Matthews Peter , Nàmer Juraj , Okuno Nagaharu , Spinosa Ludovico
Published: May 2018

The management of sewage sludge is becoming of even greater concern since the generated volumes are increasing as a result of extended sewerage and advanced wastewater treatments. Agricultural use and landfilling face growing difficulties due to sludge increased contamination observed and stricter disposal criteria introduced, while incineration continues to be undesirable by the public, although technology is available today to meet extremely stringent air quality standards and guarantee a safe and convenient operation. Sludge management is particularly problematic in highly urbanized areas because of the large volumes in one location and the lack of suitable sites at convenient distance. In this paper, management options applicable to large urban centers are outlined and several case histories in Western and Eastern Europe, N. America and Asia described.
Basic comparison of structure and functioning of legislative, governmental and non-governmental bodies for water quality management in the USA and CR: a Czech view
Authors: Chour Vladimir
Published: May 2018

Surface and ground waters are one of the basic resources; they are an important constituents of the environment and serve to satisfy economic and other needs of the society. The purpose of the actually prepared modification of the Czech Water Act (Law No. 1381973) discussed in this paper is (1) to protect water in a comprehensive and flexible manner, considering its irreplaceability and society-wide significance, (2) to regulate its withdrawals and other treatment in a planned manner in order to maintain a balance between the demand for water and the capacity of water resources, (3) to care for its purity and economic utilisation, (4) to protect against floods, and at the same time, to respect the conservation of nature and ecosystem protection, and (5) to provide for recreation, shipping and other important water uses which are of interest to the society. The paper is presented to serve as a basis for the planned comparisons of the legislational state-of-the-art in the USA and Czech Republic.
Landuse-based nonpoint source pollution. A threat to water resources in developing countries
Authors: Tonderski Andrzej
Published: May 2018

This article intends to raise some reflections on the increasing pollution from landuse-based nonpoint sources in developing countries. It is focused on historical development of agro-environmental factors such as deforestation, wetland transformation, monocultural crop production, agro-chemical inputs, concentrated animal production, and irrigation. It is shown that reduction of natural ecosystems in favour of agricultural land and intensification of the agricultural practices in developing countries continue on a larger scale and speed than in the industrialized countries. Some practices (e.g. the use of commercial fertilizers) show dramatic increases over last decades, others (e.g. deforestation) have increased at a steady rate over time. The major conclusion of this analysis is the necessity for urgent action of national and international communities on scientific and political level. If we do not focus our activities on controling pollution originating from landuse-based sources, developing countries will, in the near future, face dangerous deterioration of water resources with limited financial means to tackle the problem.
Diffuse nutrient losses in Denmark
Authors: Kronvang B. , Græsbøll P. , Larsen S. E. , Svendsen L. M , Andersen H. E.
Published: May 2018

Since 1989, nutrient loading of the Danish aquatic environment has been monitored in 270 Danish streams draining catchment areas differing in climate, physico-geographic and land usage. Diffuse nutrient loading from non-point sources (mainly agricultural) is now the main cause of eutrophication of the Danish aquatic environment; thus in 1993, diffuse sources accounted for 94% of riverine nitrogen loading and 52% of riverine phosphorus loading. Annual riverine total nitrogen (total-N) loading from diffuse sources during the period 1989-93 was on average 10 times greater in 66 small agricultural catchments (median 23.4 kg N ha−1) than in 9 natural catchments (median 2.2 kg N ha−1). Correspondingly, annual riverine total phosphorus (total-P) loading from diffuse sources was on average 3.5 times greater in the agricultural catchments (0.29 kg P ha−1) than in the natural catchments (0.07 kg P ha−1). The annual total-N and total-P load was found to increase with the proportion of agricultural land in the catchments. In 1993, intensive measurements of phosphorus load in 8 agricultural catchments showed that normal point sampling (fortnightly) underestimates annual total-P loading by a median of 37% as compared to that estimated by frequent sampling. Moreover, estimates of monthly total-P loading are even more biased, especially in late summer and early autumn (−50% to −65%).
Nutrient emissions from agriculture in the Netherlands, causes and remedies
Authors: Boers Paul C. M.
Published: May 2018

Agriculture causes 60% of the total nitrogen emissions and 40-50% of the total P emissions to the surface waters in the Netherlands. These high emissions are mainly caused by the large amounts of fertilizers used on Dutch farms. On average, 39 kg P ha−1 and 340 kg N ha−1 are given in excess to the uptake by the crop.

The Netherlands follows a strategy of gradual reduction of the nutrient applications to crops. The first two phases were aimedat stabilisation and a gradual reduction of the use of organic manure. The goal of the third phase is to accomplish equilibrium fertilization in the year 2000. This means that the amount of fertilizer given may not exceed the crop uptake, considering an acceptable loss to the environment. The losses are based upon acceptable emissions, mainly to surface waters. With the average excess rainfall in the Netherlands, the water quality standards are met with a loss of 0.4 kg P ha−1 and 6 kg N ha−1, much lower than the present excesses of minerals. The challenge for the future is to close the gap between environmentally acceptable and present losses. Equilibrium fertilization will not solve all problems at short notice. Therefore, additional techniques to reduce nutrient losses are in development. Examples are restoration of buffer strips and wetlands, lowering of groundwater levels, dosing of ferric and aluminum compounds in the soils and several additional measures in eutrophied lakes.
Watershed-scale response to agricultural diffuse pollution control programs in Vermont, USA
Authors: Meals Donald W.
Published: May 2018

From 1979 to 1990, the LaPlatte River Watershed and the St. Albans Bay Watershed Rural Clean Water Program projects in Vermont (USA) sought to reduce sediment, nutrient, and bacteria loads to parts of Lake Champlain impaired by eutrophication. Best Management Practices (BMPs) to control diffuse sources of pollution from dairy agriculture were widely implemented through a voluntary program of technical assistance and cost-sharing by agencies of the U.S. Department of Agriculture. Intensive water quality monitoring was undertaken to document water quality changes resulting from the land treatment programs, including studies of BMP effectiveness and long-term watershed-scale trend monitoring. Some BMPs significantly reduced edge-of-field pollutant delivery to surface waters. Phosphorus export from corn fields was up to 1500% higher where manure was winter spread and up to 15% of the phosphorus applied in winter-spread manure was lost in runoff. A vegetated filter strip retained more than 90% of sediment and nutrients in milking center waste and functioned effectively year-round. Watershed-level response, however, was not simply the sum of edge-of-field changes. Sediment concentration and export decreased in both project areas, but anticipated decreases in nutrient concentrations and loads did not occur. The most significant water quality trends observed were 50–75% reductions in indicator bacteria counts in all study watersheds. Factors contributing to the lack of general response in nutrient levels, recommendations for future agricultural pollution control projects, and implications for planning of diffuse source pollution control programs are discussed.
Integration of GIS and a dynamic spatially distributed model for non-point source pollution management
Authors: Meiner Andrus
Published: May 2018

The integrated system described in the paper combines GIS software based on a vector data structure with a simulation model for non-point source pollution management. Territory is disaggregated to spatial modelling units through a series of map overlays. The two major software components are linked through a set of the GIS package's macro language routines and operating system script files. The level of integration can be described as “running the model as a GIS subsystem.” It contains the following steps: invoking the GIS software; calling the model for a simulation run (with possible input editing); import of the model output to a GIS compatible database file; establishing a file relation between the model output and the georeferenced attribute file; and displaying and analysing model results. The user interface is menu driven, and options are provided for defining the temporal and spatial extent of the modelling session. After a simulation run, results are available for further analysis in the form of a classification map and a network loaded with the simulated variable.
The rouge river watershed pollution by trace elements: atmospheric depositions and emission sources
Authors: Pirrone Nicola , Keeler Gerald J.
Published: May 2018

Atmospheric inputs of trace elements to the Rouge River watershed by particle dry deposition and aerosol scavenging by precipitation were presented along with the annual emission of trace elements to the atmosphere by emission source category. A dynamic physical-based model was used to evaluate the dry and wet deposition flux of particle-segregated trace elements and its temporal and spatial variation in the Rouge River watershed from 1982 to 1992. Annual emissions of trace elements to the atmosphere were estimated assuming a controlled status for all the emission sources which include coal and oil combustion utilities, iron-steel manufacturing plants, metal production from primary and secondary pyrometallurgical processes, cement manufacturing, solid waste and sewage sludge incinerators. In general, there is a good agreement between the trend in the atmospheric input (dry + wet deposition fluxes) to the Rouge River watershed and that in the annual emission of trace elements to the atmosphere with r2 in the range of 0.84 to 0.98. Atmospheric inputs and emissions are following downward trends for Pb, whereas for Cd, Cr, Ni and Hg show a steady increase since 1987/1988. The modeled long-term average of the total (dry + wet) deposition flux of trace elements to the Rouge River watershed is 3167 ± 2548 g km−2 yr−1 for Pb, 397 ± 132 g km−2 yr−1 for Ni, 350 ± 160 g km−2 yr−1 for Cr, 130 ± 39 g km−2 yr−1 for Cd, and 8.6 ± 3.7 g km−2 yr−1 for Hg.
Field studies on controlled drainage and recycling irrigation drainage for reduction of nutrient loading from Arable land
Authors: Paasonen-Kivekäs Maija , Karvonen Tuomo , Vakkilainen Pertti , Sepahi Noor , Kleemola Jouko , Teittinen Matti
Published: May 2018

Three on-farm trials were established to evaluate the suitability of water table management for Finnish growing conditions. The sites differed in soil texture, topography and cultivation. Drainage control was managed through specific wells in collector pipes. In recycling, a reservoir stored drainage water discharging from the fields. This water was used for subirrigation through conventional drainage or a dual level irrigation-drainage system. Hydro-meteorological variables were monitored continuously and real time transfer of the data was carried out via radiolink and microcomputers. Quality of surface and subsurface waters was surveyed by manual sampling from the weirs, piezometers and reservoirs. Physical soil properties and mineral nitrogen (N) from several soil profiles were determined. Furthermore, above ground biomass, and N content and yield of crop were observed. In fine sand/loamy sand, subirrigation and controlled drainage raised groundwater table on average 80 cm compared to the reference areas. N concentration in the reservoirs declined significantly during May-August. Nitrogen in the piezometers and soil showed considerable spatial and temporal variation within a single field. Evidence of the relationship between groundwater level and N concentration was observed. However, no unique correlation from the existing data could be detected. N yield of cereals was 10–50% higher in the controlled drainage and subirrigation areas compared to the reference areas. Most of this extra N was allocated to grains and removed from the fields reducing N load into the environment.
On the modelling of the dynamic propagation of biological components in the secondary clarifier
Authors: Jeppsson Ulf , Diehl Stefan
Published: May 2018

When coupling a model of the biological reactor to a model of the settler, difficulties appear because of the different representations used for the particulate material. A combined model of the entire activated sludge process needs to include an algorithm for the dynamic propagation of the biological components of the particulate material through the secondary clarifier. In particular, this is of importance for an accurate description of the sludge that is recycled to the biological reactor. Two one-dimensional algorithms have been evaluated by means of numerical simulations. The first algorithm investigated is the one by Otterpohl and Freund in 1992 and some inherent problems of this method are discussed. For example, it will produce oscillating solutions as the number of layers in the settler model increases. Therefore, an alternative algorithm is proposed. It is based on a percentage vector that describes the different particulate biological components as fractions of the total suspended solids concentration. The vector is updated for every layer in the settler model by a robust numerical method. The algorithm is derived analytically, is computationally efficient and does not exhibit any oscillatory behaviour.
Diffusional limitation and process kinetics in suspended growth systems
Authors: Eliosov Boris , Rubin David , Papkov Gregory , Argaman Yerachmiel
Published: May 2018

Active biomass in suspended growth systems exists as porous flocs. Since the rate of biodegradation is directly proportional to the substrate concentration at the microbial cell surface, the intrafloc substrate concentration profile will affect process kinetics. Data from previous experiments have indicated an improved effluent quality at increased SVI. Since the SVI parameter reflects biomass settleability rather than biodegradation kinetics, the experimental work was aimed at the relationship between SVI and mass transfer related properties. Four bench-scale units and one pilot plant were operated in parallel at nearly the same SRT with different anoxic:aerobic volume ratio, or mixed liquor recycle rate. Biomass samples at various SVI values were analyzed for specific surface area, effective diffusivity, and average floc size. The results have shown a direct linear relationship between the SVI and both the specific surface area and the effective diffusivity. These results suggested that changes in effective diffusivity were attributed to floc porosity. Using an existing model, effluent BOD under varying SVI were calculated, and the trend was similar to the results of previous study.
Dyeing wastewater treatment by activated sludge process with a polyurethane fluidized bed biofilm
Authors: Park Yung-Kyu , Lee Chul-Hee
Published: May 2018

In case of the porous polyurethane fluidized bed biofilm-activated sludge process followed by a coagulation process(the FBAS-C process), 75% CODMn was removed by treating with the biological FBAS process in the loading range of 0.16∼0.32 kgCODMn/kgVSS·day. The biomass yield and microbial decay coefficients were 0.42 kg MLSS/kgBOD and 0.11 day−1, respectively. The optimum coagulation conditions for the effluent of the FBAS process were at pH 6 and 600mg/L alum dosage. Consequently, 92% of total CODMn removal efficiency was observed in the FBAS-C process. Meanwhile, in case of a coagulation process followed by the porous polyurethane fluidized bed biofilm-activated sludge process(C-FBAS process). the raw dyeing wastewater was treated at pH 6 in the presence of 1,000 mg/L alum and, continuously, the effluent coagulated wastewater was treated by the FBAS process in the loading range of 0.09∼0.19 kg CODMn/kgVSS·day. Removal efficiency of CODMn in the biological process, FBAS, was 82%. The biomass yield and microbial decay coefficient in the C-FBAS process were similar to those in the FBAS-C process.

The final effluent CODMn was about 65 mg/L in both tested processes, the FBAS-C and C-FBAS. However, the FBAS-C process illustrated better treatibility than C-FBAS in terms of the total sludge production, since the former produced about 20% less sludge than the latter.
Microbial activity in biological activated carbon bed by pulse responses
Authors: Sakoda Akiyoshi , Wang Jianzhong , Suzuki Motoyuki
Published: May 2018

The moment analysis of pulse responses was applied to the biological activated carbon (BAC) in order to elucidate its microbial activity and adsorption capacity separately. The microbial activity derived from this approach was focussed on and the following was found in this work. First, the activity of micro-organisms attached on activated carbon was higher than those on other carriers. Second, the microbial activities of bench-scale BACs treating pond water varied with the pretreatments by ozone and chlorine, but did not change considerably during the operation for about one year. Also, an the empirical relationship was found between the microbial degradation rates of pulse-injected glucose and background dissolved organics. It was concluded that this approach is useful for evaluating the microbial activity in BAC in a relatively easy manner.
Enhanced heavy metal uptake by activated sludge cultures grown in the presence of biopolymer stimulators
Authors: Fukushi Ken , Chang Duk , Ghosh Sam
Published: May 2018

The objective of this research was to investigate the feasibility of developing improved activated sludge cultures capable of removing heavy metals. Cystine, peptone, and β-glycerophosphate (BGP) stimulated metal uptake without the significant reduction of culture viability otherwise experienced in the absence of these chemicals. The cystine-peptone-BGP-grown culture exhibited the highest removal of copper and cadmium of 5.67 and 2.53 mM/g protein, respectively.
Fate and toxic effects of nitrophenols on anaerobic treatment systems
Authors: Haghighi-Podeh Mohammad R. , Bhattacharya Sanjoy K.
Published: May 2018

Modern industrial societies discharge vast quantities of chemicals into the environment. Removal of priority pollutants is a vital task of increasing importance. A literature search shows that more quantitative information about the effects and fates of these pollutants during anaerobic treatment is needed. The objective of this research was to study the fate and toxic effects of nitrophenols (2-nitrophenol, 3-nitrophenol, 4-nitrophenol and 2,4-dinitrophenol) on methanogenic bacteria.

Both batch and continuous flow experiments were performed. Batch anaerobic toxicity assay (ATA) were performed in methanogenic enrichment cultures. The effects of 4-nitrophenol were also studied using chemostats at 15-day solids retention time. Stock acetate enrichment cultures were developed and used in this research.

An inhibition coefficient model was used to quantify the effects of 4-nitrophenol. The competitive inhibition coefficient model can adequately describe the fate of the systems exposed to 4-nitrophenol. The results of this research showed that about 81% of 4-nitrophenol can be removed by biodegradation. Among the nitrophenols studied, 4-nitrophenol and 2,4-dinitrophenol were most toxic.