bluuebunny/crossref_metadata_2025 huggingface dataset:
Upland vegetation management: the impacts of overstocking
Authors: Sansom A. L.
Published: May 2018

During the last century, the numbers of sheep in Britain have increased significantly. Today a large proportion of the total flock is concentrated in the uplands. In terms of wildlife and landscape, Britain's uplands are among the most vulnerable areas. Poor, thin soils, high rainfall, and extremes of climate and slope increase their vulnerability. Damage to land in the uplands is also likely to have adverse effects downstream. In particular fisheries, water resources and flood defences are likely to be put at risk. It is widely recognised that the increased numbers of stock have led to a reduction in biodiversity in the uplands. It is less widely recognised that they may also have caused soil erosion, riverbank erosion, increased run-off, reduced aquifer recharge and low river flows. Ultimately, the process of desertification (severe and catastrophic soil erosion) results in hillsides that have been stripped of their vegetation and soils, a process which is accelerating in Britain's uplands. This paper considers the problem by highlighting the processes involved and by presenting case studies from Britain and the USA.
Development of the heavy metal pollution trends in several European rivers: an analysis of point and diffuse sources
Authors: Vink Rona , Behrendt Horst , Salomons Wim
Published: May 2018

A comparison has been made between the metal pollution in several European rivers in various stages of clean-up and management for the period of 1980-1996. The investigated rivers were Rhine, Meuse, Scheldt, Weser and Elbe. The results from this comparison showed that the simple statement that characterizes the river Elbe as ‘the most polluted river in Europe’ is a simplification. Three independent methods are presented to estimate point and diffuse source contributions in emissions and riverine transports. All methods were applied to the Elbe and Rhine rivers to estimate the contribution of point and diffuse sources for six heavy metals. The results of the source apportionment estimates show that there are temporal differences in source strength and source origin. A dramatic drop in industrial inputs and inputs from waste water treatment plants can be observed. The comparison of all methods shows some differences, which might be caused by retention processes (such as sedimentation) in the river system.
A natural approach to watershed planning, restoration and management
Authors: Petersen Mark M.
Published: May 2018

Each watershed has an overall hydrologic function to capture, store and safely release water. How well a watershed is able to perform this overall function is dependent upon how well each geomorphic component landform is functioning within the watershed. Each geomorphic component landform within a watershed has a specific hydrologic function and ecological potential. Component landforms that commonly occur in a watershed include stream channels, floodplains, stream terraces, alluvial valley bottoms, alluvial fans, mountain slopes, and ridge tops. When a component landform within a watershed becomes ecologically altered or degraded, its ability to perform its natural hydrologic and geomorphic functions becomes impaired and the watershed or ecosystem is unable to function properly. Component landforms within a watershed are interrelated. For example, the condition of a stream channel is closely related to the condition of its floodplain. Water from upland slopes is transported over and through alluvial fans and bottoms. Therefore, each component landform needs to be considered in the planning process and in setting watershed goals. This paper presents a simple field approach to inventory, evaluate and plan watershed restoration based on geomorphic, hydrologic and ecological principles. Examples of successful use of the approach on several watersheds in Utah, USA are given.
Advanced Wastewater Treatment and Reuse: Related Problems and Perspectives in Italy
Authors: Bonomo L. , Nurizzo C. , Rolle E.
Published: May 2018

An overview of water availability and distribution, water consumption, wastewater treatment trends, with particular reference to advanced ones, is briefly presented. Data about the current situation of municipal wastewater treatment and advanced treatment options are presented and regional trends about wastewater reclamation (agricultural and industrial reuse) are summarised. Some considerations about present and possible future standards, both for disposal into surface waters and for wastewater reclamation in agriculture are discussed. A short list of examples in the field of advanced wastewater treatment and reclamation in various Italian regions is presented and some information about environmental crisis areas in Italy is given.
Wastewater Reuse in France: Water Quality Standards and Wastewater Treatment Technologies
Authors: Faby J. A. , Brissaud F. , Bontoux J.
Published: May 2018

Wastewater reuse is not widely applied in France, because water resources match most of the needs. Only 6 projects were in operation in 1989. But more than 15 new projects were found to have been set up 7 years later. In the meantime, the Ministry of Health issued a provisional regulation on the reuse of wastewater for irrigation purposes and the Ministry of Environment a Water Law and application decrees acknowledging wastewater reuse as a means of disposal for treated wastewater, which is recommended to be implemented along the coastline. Actually, most of the projects are located in Atlantic islands and on the Atlantic coast. They were developed not only to face the limitation of water resources but also as a means of protecting bathing waters and shellfish farming areas. Most hinterland projects were driven by the rehabilitation of rivers threatened by eutrophication. The inforcement of the recommendations of the Ministry of Health resulted in a slowing down of the development of wastewater reuse and the implementation of wastewater treatments–long residence time lagooning or chlorination ad ultra violet radiations–providing water quality higher than required by the standards.
Selection and Implementation of Nonpotable Water Recycling in “Silicon Valley” (San Jose Area) California
Authors: Rosenblum Eric
Published: May 2018

South Bay Water Recycling, a nonpotable water recycling project in the San Jose, California (USA) area, was commissioned in 1998 to supply up to 60,000 m3/day (15 mgd) of high-quality treated effluent to nearly 200 customers for irrigation and industrial use. The project was selected, along with water conservation, as the most effective approach to protecting salt marsh habitat at the south end of San Francisco Bay from degradation due to low-salinity discharge from the San Jose/Santa Clara Water Pollution Control Plant. The project was selected over an outfall discharge based in part on its ability to offset demand for potable water by municipal and industrial customers, including computer-related industries in northern California's “Silicon Valley”. Project development began in 1991 with feasibility and conceptual design studies. Preliminary project design and surveying began in 1994, and construction commenced in 1996. The project was completed in July 1998 at a cost of approximately $140 million (US), and consists of a 90 km (60 mile) pipeline with three pump stations and one reservoir. In addition to transmission and distribution facilities, construction included customer retrofits to segregate the nonpotable system from each site's potable supply.
Particle Characteristics: A Key Factor in Effluent Treatment and Reuse
Authors: Adin A.
Published: May 2018

Particulate matter presents a major problem in advanced wastewater treatment and in water reuse operations. This paper illustrates and analyses the approach that particle characterization may serve as an important tool in understanding treatment process mechanisms for improved design and solving clogging problems in field systems. Particle size distribution and particle surface characteristics are defined, examples of their application to effluent chemical coagulation, to wastewater reservoir effluent characterization and to the prevention of particle deposition in reuse systems are described.
Sonochemical Destruction of Trichloroethylene in Water
Authors: Cyr P. J. , Paraskewich M. R. , Suri R. P. S.
Published: May 2018

Sonolysis is an effective technique of destroying a variety of organic compounds in an aqueous solution. In sonolysis, the organic pollutant is destroyed either by direct pyrolysis in the cavitation bubble or by free radical attacks in the interfacial region and in the bulk solution. The objective of this study is to examine the technical feasibility of the sonochemical process for the destruction of organic contaminants. Trichloroethylene (TCE) was chosen as the model organic compound and batch experiments were conducted employing a microprocessor controlled 20 kHz ultrasound source. This paper presents results on the effect of the following parameters on reaction rate: bicarbonate concentration (1–1000 mM), metal/metal oxide concentration (0.01–100 g/L), metal/metal oxide (0.01–0.1 g/L) in presence of hydrogen peroxide (1mM), and solution pH.
Anoxic Phosphate Uptake in the DEPHANOX Process
Authors: Bortone G. , Libelli S. Marsili , Tilche A. , Wanner J.
Published: May 2018

The innovative nutrient removal process scheme DEPHANOX proved to be very efficient because it maximises the utilisation of organic substrate for phosphorus and nitrogen removal. The process solves the competition for organic substrates among Poly-P organisms and denitrifiers as well as the problem of overgrowing of slow nitrifiers by faster organotrophs, typical of activated sludge. In experiments, DEPHANOX showed better P removal efficiency than a JHB configuration, working with a very low influent COD/TKN ratio. This paper reports the results of a simulation study that has been carried out to better understand the behaviour of the two configurations with a wide variety of influent wastewater characteristics and under dynamic conditions.

The results of the simulation confirmed the high P removal capacity of the DEPHANOX configuration with low influent COD/TKN ratios.
Tie and tre: an abbreviated guide to dealing with toxicity
Authors: Coombe Vyvyan T. , Moore Keith W. , Hutchings Matthew J.
Published: May 2018

The UK environmental regulator, the Environment Agency, is at present in the process of introducing a revision to the effluent discharge consenting system, based on the assessment of whole effluent toxicity - so called Direct Toxicity Assessment (DTA). The concepts of the most ‘sensitive’ species and of risk assessment based on estimation of Predicted Environmental Concentration (PEC) form the basis of the proposed consenting structure. The objective is to control the toxicity of point source discharges to riverine, estuarine and coastal waters and it raises the need for understanding of the nature and expression of toxicity in such discharges.

Internationally recognised toxicity test protocols are well established, enabling the quantitative measurement of toxicity with levels of confidence similar to the more traditional physical and chemical determinands, such as individual organic solvents, COD or metals. However, traditional protocols are seen as resource intensive and as involving high cost. This paper presents some experiences from the Zeneca Brixham Environmental Laboratory in the characterisation of the toxicity expressed to freshwater and marine species by several chemical manufacturing effluents and in the conduct of a number of Toxicity Identification Evaluations (TIE) using both standard and enhanced protocols for toxicity testing.
Zinc biosorption by waste activated and digested sludges
Authors: Bux F. , Atkinson B. , Kasan H. C.
Published: May 2018

Biological matter is known for its ability to biosorb solubilised heavy metal ions to its surface. Experiments were therefore conducted to assess the biosorptive capacity of two waste products of the wastewater treatment industry ie., waste activated and waste digested sludge. Surface charge of each was determined in order to relate electronegativity with biosorptive potential. Activated sludge was found to be more effective than digested sludge for removal of zinc from a metal plating effluent, viz., 5.9 mg Zn/(g sludge)−1 as opposed to 4.0 mg/g, respectively, as well as producing a higher net negative charge. It was also noted that as initial zinc concentrations in solution increased there was a concomitant increase in sludge biosorption capacity. Activated and digested sludges were capable of biosorbing zinc from a metal plating effluent although activated sludge showed better potential for industrial application.
Heavy metals removal by chemical coagulation and precipitation
Authors: Charerntanyarak Lertchai
Published: May 2018

Synthetic wastewater of pH 1.9, consisted of Zn, Cd, Mn and Mg at concentrations of 450, 150, 1,085 and 3,154 mg/l respectively. It was found that the optimum pH for chemical coagulation and precipitation by lime treatment was more than 9.5, which could decrease the concentration of heavy metals pertinent to the Wastewater Standard of the Ministry of Industry. Moreover, if 0.5 mg/l of polymer was added, it could decrease the concentration of heavy metals further. In addition when sodium sulphide solution was used in secondary treatment, it was also found that the optimum pH by lime in primary treatent was more than 9.5 and the optimum concentration of sodium sulphide was more than 250 mg/l.
A chemical profile of the mutshindudi river, northern province
Authors: van Ree T.
Published: May 2018

A catchment in a typical underdeveloped region was studied to obtain a detailed picture of the physicochemical characteristics of the river. Chemical criteria of water quality such as suspended and dissolved solids, pH, electrical conductivity, dissolved oxygen and several cations were determined periodically at a number of representative sites. The results were analysed graphically to provide a baseline for regular follow-up studies to monitor the influence of environmental changes on water quality.
The Forest Cluster and Society
Authors: Kettunen J.
Published: May 2018

The forest industry uses renewable raw materials to produce means necessary for the material and non-material well-being of mankind. Societies set different priorities within the framework of their overall structures. Future scenarios have brought up two major alternatives, namely agreement/political control and technology/enlightened consumer, the latter approach probably having better prospects for global success, but also stronger opposition of traditional structures. Mass production obviously remains dominant in fiber production while other parts of processing approach consumption. For improved productivity, the target of availability should replace ‘bottleneck thinking’. Principles of lean resources and simplicity should be emphasized.
Biological Treatment of Paper Pulping Effluents by Using a Fungal Reactor
Authors: Taseli Basak (Kilic) , Gokcay C. F.
Published: May 2018

Pulp and paper plants are amongst the most polluter industries in this country and elsewhere. Most of the organic halides (AOX) and colour from pulp bleaching units are discharged to the receiving basins without being fully treated. A fungus, which is able to affect over 50% AOX and colour removals from soft-wood bleachery effluents within two days contact time, have been isolated in this laboratory. Optimum condition for dechlorination by this fungus in batch tests was determined as pH 5.5 and 25 °C. The low agitation speeds required by the fungus indicated its tendency towards immobilisation on a solid substrate. Glass wool was chosen as a suitable immobilising matrix to be used in the continuous experiments. An up-flow column was packed with glass wool and operated successfully for over one and half years with AOX removals around 70% in 7-8 hours contact time. Fungal dehalogenation required very low supplemental carbon and no DO. The fungal reactor was also effective in dechlorinating polychlorinated aromatics, e.g. PCP, though dehalogenation ability decreased considerably with the chlorinated aliphatics. High PCP concentrations presumably toxified the fungus, even at short exposures, thereby irreversibly damaging the column reactor.
Kraft-Mill Biosolids Treatment by Conventional and Biphasic Fermentation
Authors: Ghosh S. , Taylor D. C.
Published: May 2018

Kraft primary and mixed primary-activated sludges were gasified by thermophilic (50 °C) high-rate and mesophilic two-phase digestion. Kraft sludges were deficient in nitrogen, phosphorus, and other unidentified nutrients. Municipal sludge proved to be a much better nutrient source than inorganic salts. Performance of the mesophilic (35°C), two-phase anaerobic digestion (TPAD) system was about the same as that of thermophilic single-stage, high-rate digestion at a 10-day HRT as judged in terms of methane yield (0.17 SCM/kg VS added) and VS reduction efficiency (43%). The mesophilic TPAD process yielded a higher methane-content (65%) fuel gas; it is capable of exhibiting higher net-energy recovery efficiency than thermophilic single-stage digestion.
Improvement of Sludge Settleability in Activated Sludge Plants Treating Effluent from Pulp and Paper Industries
Authors: Andreasen Kjær , Agertved Jeanette , Petersen Jens-Ove , Skaarup Henrik
Published: May 2018

The main objective of many activated sludge plants treating wastewater from the pulp and paper industry is to remove COD only. These plants are often designed as high-load aerobic systems without any microbial selector system. As a consequence the sludge settling properties are normally poor due to fast growing filamentous microorganisms, which severely reduce the treatment capacity and the effluent quality.

Implementation of selectors, in which the substrate concentration and the metabolic pathways can be manipulated, has in many cases reduced the bulking sludge problems in activated sludge systems. An example of a successful upgrading of a Danish pulp industry wastewater treatment plant with an anoxic selector is presented. the use of a novel technique to investigate the in situ physiology of filamentous microorganisms is discussed. It is concluded that a successful application of selectors relies on detailed knowledge about: a) physiology and substrate requirement of the filamentous microorganisms, b) wastewater composition and c) substrate removal kinetics in the selector system.
Enhancement of Capacity and Efficiency of a Biological Waste Water Treatment Plant
Authors: Kaindl Nikolaus , Tillman Ulf , Möbius Christian H.
Published: May 2018

The capacity and efficiency of the existing activated sludge waste water treatment plant at SCA Graphic Laakirchen AG needs to be enhanced due to an expected future increase in waste water flow and COD-load. For the case of an existing upper limit of COD discharges into the river, the COD reduction rate of the waste water treatment has to be increased to a degree which is unobtainable by biodegradation only.

Laboratory and pilot plant trials using a moving bed biofilm technique and an activated sludge treatment combined with ozone treatment and subsequent biofiltration have been performed with the aim to increase the COD reduction capacity and efficiency of the plant.

The results show that the COD reduction capacity of the existing activated sludge plant can be increased by more than 100% by integrating a moving bed biofilm pre-treatment stage into the plant. In addition, improved sludge separation in the secondary clarifier was established. A special benefit of the ozonation plus biofilter treatment is a controllable COD reduction between 20 - 90% related to the outflow of the activated sludge plant.

It is concluded that by integrating the investigated treatment techniques in the existing activated sludge plant the future increases in waste water flow and COD-Load can be handled satisfactorily without increasing bioreactor volume.
Limitations for Biological Removal of Resin Acids from Pulp Mill Effluent
Authors: Werker A. G. , Hall Eric R.
Published: May 2018

This paper highlights results from a fundamental study into the fate of resin acids during biological treatment. Pulp mills in Canada rely on biological treatment systems for the removal of resin acids that are released from wood during pulping and bleaching. These are priority contaminants for the pulping industry since they have been associated with events of toxicity breakthrough. Although tighter mill control has helped to minimise the frequency of these events, it would be useful to have an understanding of the basic limitations of biological systems as the last line of defence for limiting resin acid discharges. The dependence of physico-chemical and biological phenomena on pH will influence the chances for successful biological removal of resin acids. Changes in pH within the typical range used for biological treatment significantly alter the bioavailability of resin acids and the ecology of the microorganisms responsible for their degradation. Changes in resin acid loading during continuous treatment also affect the microbial ecology. Further, the capacity of a treatment system to degrade resin acids is a function of the contaminant loading. Time delays for microbial community acclimation in response to a shift-up in loading are significantly long and are also a function of pH. The capacity to remove resin acids is readily gained and lost in a biological system. Hence the bioreactor operating conditions in conjunction with the period and amplitude of loading fluctuations can impact on the extent of biological removal for resin acids. Consequently, biological systems can be severely compromised by influent transient loading when it comes to the removal of specific contaminants like resin acids.
Sources and Fate of TRS Compounds in a Pulp Mill ASB
Authors: Mahmood Talat , Banerjee Sujit , Sackellares Robert W.
Published: May 2018

The source and treatability of TRS emissions at a mill in the Southeastern USA was studied in connection with potential capital upgrades in response to recently promulgated regulations. The front-end of the lagoon is anoxic, and is associated with odor, which drops markedly beyond the onset of the aerated zone. Laboratory work with wastewater from two mills showed that the rate of H2S degradation corresponded to that of oxygen consumption, confirming that the two processes were related. The rates were biphasic; the initial decrease was rapid, and then a slower process took over. The rate of the slower process equaled the degradation rate of H2S in distilled water, suggesting that it originated from the uncatalyzed oxidation of H2S. Hence, H2S oxidation appears to be initially catalyzed by a wastewater component that is inactivated before the process goes to completion. Subsequent degradation of H2S then occurs through the uncatalyzed step. Wastewater taken from the lagoon showed the presence of the transition metals necessary for sulfide catalysis. A dissolved oxygen level of 1 ppm was sufficient to suppress H2S generation.
Investigation of Substrate Degradation and Nonbiodegradable Portion in Several Pulp Bleaching Wastes
Authors: Çeçen Ferhan
Published: May 2018

Biological treatment studies were carried out with several Kraft pulp bleaching wastewaters both in continuous-flow and batch activated sludge reactors and substrate degradation was examined. The results of different studies indicated comparable findings. In the first study, bleaching effluents from the chlorination and extraction stages of the last pulp bleaching (Process: D/C-E/D-D-E-D, prebleaching with oxygen) were taken. Substrate removal has been evaluated using the parameters TOC, DOC, COD, AOX, BOD5 and Color (A436) and UV254. In the second study, spent bleaching effluents from a Kraft pulp mill using a conventional C/E-H-D/E-D bleaching were used. COD and Color (A436) was used for substrate determination. In the third study, the bleaching effluent from the same process was used at another time interval and substrate removal was followed by the measurement of COD and BOD5 and the spectrophotometric changes in the visible and UV regions. In all wastewaters a high amount of nonbiodegradable substrate was left over as expressed by residual TOC, DOC, COD. In general, the nonbiodegradable fraction of these wastes was about 30-60 % of the initial substrate. The dehalogenation of chlorinated compounds was either negligible or occurred not at all. Additionally, the specific absorption ratios A436/CODs, A346/CODs, UV272/CODs, UV254/CODs and the relative UV absorption ratio UV254/UV272 were measured in biotreated wastes and compared to the raw waste. These measurements proved to be a very useful tool since they provided information on specific pollutant groups. It was seen that UV absorbing substances were removed to a lesser extent than the total of organics measured by either TOC or COD.
Cost-efficiency and performance of individual and small-scale treatment plants
Authors: Geenens D. , Thoeye C.
Published: May 2018

The problem of diffuse pollution by individual housing can be tackled by installation of individual wastewater treatment systems. At the moment there are initiatives towards standardisation and certification of these systems to ensure efficient installations. Treatment results of recently installed individual plants prove to be very good towards BOD, COD and SS removal. Factors such as frequency of maintenance, control and mechanical breakdown may however affect these promising results. Investment and operation costs per PE are discussed and compared with a more centralised approach, emphasising the highly variable nature of these costs for individual wastewater treatment. Additional long-term experience is needed to evaluate the potential weak points and achieve improved cost-benefit analysis.
Southern Water faces the small works challenge
Authors: Rowland I. , Strongman R.
Published: May 2018

Southern Water (a ScottishPower company) has 392 wastewater treatment works, 242 of which serve small communities with populations of less than 2000. Continuing pressures to improve effluent quality coupled with expectations of improved efficiency, and increased demand for resources for major capital schemes prompted Southern Water to take a more holistic approach to improvements and operation of its small treatment works. Operational costs (OPEX) were analysed for individual works enabling identification of target costs of operation (£/pe), opportunities for efficiency savings and investment priorities. A Company approach to investment in small works was produced which included development of a model to identify whether rationalisation (diverting the flows to an adjacent WTW and closing the site) was an economic option, and a Design Standard to simplify decision-making and process engineering for works refurbishment or replacement. The Design Standard focused on delivering low “whole-life-cost” solutions using simple and robust processes that require minimal operator involvement and ensure compliance with discharge consent standards. Southern Water is steadily reaping the benefits from its structured approach to ensuring compliance and cost-effective operation of its small works.
Operational and control practices to improve the performance of small wastewater treatment plants in Catalonia
Authors: Camos C. , Martorell S. , Rey A. , Güell D. , Robusté J. , Colprim J.
Published: May 2018

Observations during routine wastewater treatment plants (WWTP) controls in Catalonia suggest that in small Activated Sludge (AS) plants suspended solids separation problems could reach a special intensity. In order to evaluate their incidence, filamentous scums, clarifier floating solids, rising sludge, deflocculation and bulking incidences occurring in 34 small WWTP were controlled for a year. To improve the efficiency of these plants, analyses of mainly suspended solids separation problems were systematically performed.
Small wastewater treatment plants in Flanders (Belgium): standard approach and experiences with constructed reed beds
Authors: Vandaele S. , Thoeye C. , Van Eygen B. , De Gueldre G.
Published: May 2018

In Flanders (Belgium) an estimated 15% of the population will never be connected to a central wastewater treatment plant (WWTP). Small WWTPs can be a valuable option. Aquafin bases the decision to build SWWTPs on a drainage area study. To realise an accelerated construction the process choice is made accordingly to a standard matrix, which represents the different technologies in function of the size and the effluent consents. A pilot scale constructed two-stage reed bed is used to optimise the concept of the reed beds. The concept consists of a primary clarifier, two parallel vertical flow reed beds followed by a sub-surface flow reed bed. The removal efficiency of organic pollutants is high (COD: 89%, BOD: 98%). Phosphorus removal is high at the start-up but diminishes throughout the testing period (from 100% to 71% retention after 7 months). Nitrogen removal amounts to 53% on average. Nitrification is complete in summer. Denitrification appears to be the limiting factor. In autumn leakage of nitrogen is assumed. Removal efficiency of pathogens amounts to almost 99%. Clogging forms a substantial constraint of the vertical flow reed bed. Problems appear to be related with presettlement, feed interval and geotextile.
Wastewater treatment by infiltration percolation: a case study
Authors: Mottier V. , Brissaud F. , Nieto P. , Alamy Z.
Published: May 2018

A 1700 p.e. pilot infiltration percolation plant treating the sewage of Mazagon, a seaside resort in the South of Spain, is investigated. Primary effluents, intermittently applied over twin 200 m2 infiltration basins, percolate down to the aquifer through unsaturated dune sands. Each application sequence delivers a volume of 0.25 m3 per m2 of infiltration basin. Analyses of the water sampled at five depths ranging from 0.3 to 2.0 m below the infiltration surface show that the oxidation performance of the plant is highly dependent on the applied load. Monitoring the oxygen content in the air phase of the vadose zone allows to determine the kinetics of the oxygen stock recovery and the oxidation capacity of the plant. Disappointing removal of faecal coliforms and streptococci is attributed to high pore water velocities due to infiltration heterogeneity and the high water height applied during each feeding sequence.
Capacity of small wastewater treatment plants and their effects on the groundwater
Authors: Kunst S. , Kayser K. , Lenz H.-M.
Published: May 2018

In order to gain an updated evaluation of the purification capacity of small wastewater treatment plants (SWTPs), several districts in Lower Saxony were questioned on this matter. The incoming results were then compared to and completed by existing results published in reference literature. A simulation program was run to estimate the COD loads which leach out into the groundwater at the effluents of SWTPs. The results gained from the questionnaire and the literature are indicating that vertical filters, wastewater lagoons and rotating biological discs are especially suitable types of SWTPs. The results of the simulation show that a percolation of the effluent of efficient plants can be regarded as harmless given a percolating distance of 60 or better yet 120 cm. This is different with the subsoil irrigation where the passage through the soil is virtually the biological purification stage. Then, even after having passed through the soil for 250 cm, considerably high COD loads are still emitted into the groundwater. As this kind of SWTP is very frequently used in Lower Saxony, it would be worthwhile to increase the efficiency of the pre-treatment of wastewater before the percolation by adding simple aggregates to the plants. This should be examined in future analyses.
A case study on the performance of trickling filter plants in Alpine regions: influence of seasonal variations
Authors: Schreff D. , Echterbruch A. , Wilderer P.A.
Published: May 2018

The increasing number of people who come to enjoy the beauty of the Alps makes it necessary to provide proper disposal of the wastewater produced in the touristic resorts including huts and cabins. Advanced wastewater treatment is not easy to achieve because of the difficult conditions prevailing in this region. Highly variable wastewater flows, low temperature in winter, poor availability of input data for design, energy problems, and the demand for keeping costs for building and maintenance at a minimum level are the key obstacles in the process of implementing wastewater treatment facilities. In the past, trickling filter plants have been commonly applied, since this technology has been assumed to provide fairly high reliability despite the aforementioned conditions. The results of a survey focusing on the efficiency of such systems showed that to take into account only peak loads is insufficient when designing a plant. In addition, it is necessary to provide measures to handle discontinuous load conditions by managing water distribution to the trickling filter, and by a recirculation strategy adapted to each condition scenario. Based on the results obtained a number of process modifications are suggested. The overall performance could be enhanced considerably with only a few process modifications.
Performance of a combined biofilm-suspended growth system for wastewater treatment
Authors: Hamoda Mohamed F. , Al-Sharekh Hamed A.
Published: May 2018

This paper summarizes the results obtained using the hybrid aerated submerged fixed-film (HASFF) reactor which utilizes suspended as well as attached biomass for the treatment of wastewater. The HASFF reactor consists of four compartments with an array of fixed ceramic plates maintained under diffused aeration to support attached biomass with suspended biomass recycle to promote suspended growth in the reactor. Wastewater from a municipal treatment plant was fed to the reactor and its activated sludge was used for recycling in the hybrid system. Four pilot units were operated in the plant at various HRTs (2, 4, 6 and 8 hrs) with flow rates in the range of 0.32 to 1.2 m3/d, using primary-settled wastewater under organic loading rates up to 0.7 g BOD/g BVS.d.

The data obtained showed that the overall BOD removal efficiencies were consistently above 94.0% at all HRTs, while the COD removal efficiencies ranged between 65.7–76%. The effluents' mean filtered BOD concentrations were between 4.5–7.5 mg/l whereas the mean filtered COD concentrations ranged between 70.0–89.6 mg/l. Increasing the hydraulic loading rate four-fold from 0.08 to 0.32 m3/m2.d had minor effect on the reactor's BOD and COD removal efficiencies indicating a robust biological process that is resilient to flow variation, thereby offering a viable treatment option for small plants. The HASFF process achieved organic removal and nitrification in a single reactor, with minimal sludge production. The organic removal rate was equally high at all HRTs whereas nitrification was directly proportional to the HRT, being higher at longer HRTs. The suspended biomass activity exceeded that of the attached biomass at shorter HRTs while the opposite was true at longer HRTs.
Environmental engineering education in conjunction with or as Part of social sciences curricula
Authors: Hahn H.H.
Published: May 2018

Traditionally in Germany environmental engineering education took place within the context of a civil engineering programme. There were reasons for this: the beginning of much of what we understand today to be environmental works fell within the parameters of city engineering. There were and are advantages mostly in view of the necessary planning, construction and operation of environmental infrastructure. There are also disadvantages which become more and more pronounced as the field of environmental protection expands: the civil engineer frequently lacks basic training in disciplines such as biology and chemistry and carries a large and sometimes burdensome knowledge of other less relevant subjects. Thus, educators begin to look for alternatives.

This paper deals with an alternative that was developed some ten years ago and therefore has proven viable and successful: at the University of Karlsruhe students may choose to major in environmental engineering within the context or on the basis of an economics and business administration curriculum. The basic question here is as to what extent the student masters the field of environmental engineering if he or she has predominantly a solid background in social sciences and very little in natural sciences.

The paper will describe the curriculum in structure and intensity and evaluate the accumulated knowledge and suitability of these students in terms of actual environmental problems. This will be done in terms of examination performance parallel and/or relative to traditionally trained civil environmental engineers as well as in terms of topics successfully treated in Masters' theses. In conclusion, it is argued that such combination of curricula should not be confined to economic sciences and environmental engineering but also be planned for legal sciences and environmental engineering.
Project-based learning in sanitary engineering - preliminary conclusions after three years' experience
Authors: Schilling W. , Hagen E.
Published: May 2018

The paper describes an ongoing study based on the mandatory “Sanitary Engineering Basic Course” that was taught for third year environmental engineering students at the University of Science and Technology in Trondheim, Norway (NTNU) in the spring semesters of 1997, 1998 and 1999. The focus is on teaching and learning methodology (i.e. traditional individual frontal lecture-based versus project-based in groups). Experience shows that project-based learning (PBL) is a suitable teaching method. PBL challenges the students to stay active throughout the semester and thus results in higher learning efficiency. Simultaneously, both students and teachers need to use more time. Technical skills (“design calculations”) were not improved, but students clearly developed project management skills (communication, organisation, group work, etc.).
Monitoring of a biogas process using electronic gas sensors and near-infrared spectroscopy (NIR)
Authors: Nordberg Å. , Hansson M. , Sundh I. , Nordkvist E. , Carlsson H. , Mathisen B.
Published: May 2018

The use of electronic gas sensors and near-infrared spectroscopy (NIR) to monitor the dynamics in a biogas process was evaluated using multivariate data analysis. The digester, a completely stirred 8 l tank reactor fed with a mixture of cellulose, albumin and minerals, was exposed to an overload of glucose after which monitoring of electronic gas sensor responses, NIR spectra as well as traditional chemical variables and analysis of microbial community structure were done. The responses from an array of electronic gas sensors consisting of MOS and MOSFET-sensors were correlated against volatile compounds in the headspace using partial least square (PLS) regressions. The root mean square error of prediction (RMSEP) was 0.15 g/l for acetate in the range of 0.14–1.72 g/l and the RMSEP for methane was 2.3% in the range of 27–73%. Selected wavelengths from the second derivative of the original NIR spectra (400–2500 nm) resulted in a PLS-model for predicting microbial biomass, measured as total phospholipid fatty acids, with a RMSEP of 9 nmol/ml in the range of 163–293 nmol/ml. The NIR model developed for acetate had a RMSEP of 0.20 g/l within the range of 0.14–1.72 g/l. The results clearly show that both NIR and an array of electronic gas sensors can provide simultaneous non-invasive in situ monitoring of important process variables in anaerobic digesters.
Anaerobic batch degradation of solid poultry slaughterhouse waste
Authors: Salminen E. , Rintala J. , Lokshina L.Ya. , Vavilin V.A.
Published: May 2018

We studied anaerobic batch degradation of solid poultry slaughterhouse wastes with different initial waste and inoculum concentrations and waste-to-inoculum ratios and simulated the dynamics of the process with a new generation  model. Our modelling results suggest that inhibited propionate degradation by long-chain fatty acids (LCFA) and inhibited hydrolysis by a high propionate concentration constituted the rate-limiting step in the waste degradation. Palmitate was the most abundant LCFA in the assays. Within 27 days of incubation, up to 0.55 to 0.67 m3 of methane (STP)/kg VS added was produced under the studied conditions. Lower waste-to-inoculum ratios exhibited a faster onset and rate of specific methane production. In all the assays, ammonification occurred within 3 to 6 days and accounted for 50 to 60% of total nitrogen.
Mathematical modeling of the hydrolysis of anaerobic processes
Authors: Christ O. , Wilderer P.A. , Angerhöfer R. , Faulstich M.
Published: May 2018

In the recently published dynamic simulation model for mesophilic digestion of sewage sludge the hydrolysis constant refers to the total dry solid content without regarding their composition. To apply these models to the digestion of municipal solid waste, the hydrolysis constants of the various fractions must be considered. The major constituents of organic waste were identified as carbohydrates, proteins and lipids. For these three constituents the hydrolysis constants for thermophilic digestion were determined. The implementation of these constants into the existing dynamic models allowed a reasonable characterization of the digestion of municipal organic waste.
Two-phase anaerobic digestion of source sorted OFMSW (organic fraction of municipal solid waste): performance and kinetic study
Authors: Pavan P. , Battistoni P. , Cecchi F. , Mata-Alvarez J.
Published: May 2018

The results of a two-phase system operated in different conditions, treating the source-sorted organic fraction of municipal solid waste (SS-OFMSW), coming mainly from fruit and vegetable markets, are presented. Hydraulic retention time (HRT) in the hydrolytic reactor and in the methanogenic reactor and also the temperature in the hydrolytic reactor (mesophilic and thermophilic conditions) are varied in order to evaluate the effect of these factors. The methanogenic reactor is always operated within the thermophilic range. Optimum operating conditions are found to be around 12 days (total system) using the mesophilic range of temperature in the first reactor. Specific gas production (SGP) in these conditions is around 0.6 m3/kgTVS.

A kinetic study is also carried out, using the first and the step diffusional models. The latter gives much better results, with fitted constants comparable to other studies. Finally, a comparison with a one-phase system is carried out, showing that a two-phase system is much more appropriate for the digestion of this kind of highly biodegradable substrate in thermophilic conditions.
Effect of moisture content on anaerobic digestion of dewatered sludge: ammonia inhibition to carbohydrate removal and methane production
Authors: Fujishima S. , Miyahara T. , Noike T.
Published: May 2018

The purpose of this study is to investigate the effect of moisture content on anaerobic digestion of dewatered sewage sludge under mesophilic condition. The moisture contents of sludge fed to reactors were 97.0%, 94.6%, 92.9%, 91.1% and 89.0%. The VS removal efficiency changed from 45.6% to 33.8%, as the moisture content of sludge fed to digester decreased from 97.0% to 89.0%. The carbohydrate removal efficiency also decreased from 71.1% to 27.8%. Methane production decreased when the moisture content of sludge was lower than 91.1%. The number of glucose consuming acidogenic bacteria was decreased from 3.1×106 to 3.1×108(MPN/mL) as the moisture content decreased from 91.1% to 89.0%. The numbers of hydrogenotrophic and acetoclastic methanogenic bacteria decreased by one order of magnitude when the moisture content was lower than 91.1%. The decrease in numbers of glucose consuming acidogenic bacteria and methanogenic bacteria was found to correspond to the decrease in the carbohydrate removal efficiency and the accumulation of propionic acid. Batch experiments showed that acetoclastic methanogenic bacteria were acclimated to high ammonia concentration, on the other hand, glucose consuming acidogenic bacteria were inhibited.
Investigations on the changes in anaerobic biodegradability and biotoxicity of an industrial microbial biomass induced by a thermochemical pretreatment
Authors: Delgèns J.P. , Penaud V. , Torrijos M. , Moletta R.
Published: May 2018

In the anaerobic digestion of solid wastes, hydrolysis is the rate limiting step and physico-chemical pretreatment is often required to promote solubilization of organic matter. As an illustration, anaerobic digestion was limited by the substrate solubilization step during continuous cultures performed with an industrial microbial biomass. In optimal operating conditions determined for the hydrolysis-acidogenesis step (T=35°C; pH=8.5; OLR=5.4 g COD/l.d) 50.6% COD solubilization was achieved. A thermochemical pretreatment based on sodium hydroxide addition, was used in order to enhance COD solubilization. Optimal conditions for COD solubilization were pH=12, T=140°C for 30 minutes. In these conditions, 70% COD solubilization was achieved. However, anaerobic biodegradability of the pretreated substrate was not improved and remained near 40%. The poor anaerobic biodegradability performances were attributed to the soluble molecules generated during the thermochemical pretreatment that were refractory and/or inhibitory to anaerobic microorganisms. Fractionation of the soluble pretreated microbial biomass by two methods (treatment with adsorbent resins and precipitation by pH adjustment) demonstrated that high molecular weight compounds (>100 kDa) are involved in the poor biodegradability and in the biotoxicity observed. Partial decolorization through resin use and acid precipitation remove these compounds. The consequence of their removal was an increase of the production of biogas.
Ecological, energetic and economic comparison of anaerobic digestion with different competing technologies to treat biogenic wastes
Authors: Edelmann W. , Schleiss K. , Joss A.
Published: May 2018

In order to get more detailed information for better decision making in future biogenic waste treatment, different processes to treat biogenic wastes in plants with a treating capacity of 10,000 tons of organic household wastes per year were compared. The comparison included life cycle assessments as well as economic considerations for different treating methods. Measurements on compost plants showed that methane emissions are higher than estimated so far. With the tools ECOINDICATOR and UBP anaerobic digestion shows to be advantageous as compared to composting, incineration or combination of digestion and composting, mainly because of a better energy balance. In fully enclosed, professional treatment plants, the specific biotechnological treatment costs are in the range of about 150.-sFr/ton for aerobic, anaerobic and combined technologies. It can be concluded, that anaerobic processes will become considerably more important in the future mainly for ecological reasons.
Emission of greenhouse gases from anaerobic digestion processes: comparison with other municipal solid waste treatments
Authors: Baldasano J.M. , Soriano C.
Published: May 2018

This contribution analyzes the anaerobic digestion process and compares GHG emissions estimated for four different management processes for MSW (Municipal Solid Waste): biogasification, landfilling, composting and incineration. The comparison has been undertaken by considering in the estimation of the emissions the full cycle of MSW treatment, and not only the emissions derived from the fraction of MSW treated by each particular system. For instance, the fraction of MSW not submitted to biological treatment has to be incinerated or deposited in a landfill. The corresponding emissions of these processes have to be considered in the calculations of the final emissions.