bluuebunny/crossref_metadata_2025 huggingface dataset:
Tariff Systems for Industrial Wastewater Discharges
Authors: Sørensen P. E. , Calvo L. G.
Published: May 2018

The paper describes the systems in selected countries as regards the legal, economic and administrative aspects of wastewater treatment and disposal, namely: distribution of costs, financing, wastewater discharge fees, and fees for new connections to the wastewater system.

A tariff system which combines the fully user-paid Danish municipal system and the French system of levying discharge fees is recommended.
Photocatalytic oxidation of dichlorvos in the presence of hydrogen peroxide and ferrous ion
Authors: Lu Ming-Chun , Roam Gwo-Dong , Chen Jong-Nan , Huang Chin-Pao
Published: May 2018

The photocatalytic oxidation of dichlorvos has been investigated with two different reactors. The reactor using 254 nm light is a system with TiO2 suspensions. The 360 nm light is used as the light source of the fixed system which was TiO2 coated on the inner surface of the reactor. In terms of quantum yield, the 254 nm radiation is more effective for dichlorvos oxidation than the 360 nm light. The effect of H2O2 on dichlorvos oxidation shows a negative performance. The influence of H2O2 on the photocatalytic oxidation of dichlorvos is greater in the fixed system than that in the suspension system. The ferrous ions can induce the photo-Fenton-type reaction. However, the photocatalytic oxidation of dichlorvos will be inhibited slightly at the concentration of 1.0 × 10−5 M Fe+2. This result is explained in terms of the net production of hydroxyl radical.
Regulating Specific Organic Substances and Heavy Metals in Industrial Wastewater Discharged to Municipal Wastewater Treatment Plants
Authors: Grüttner H. , Munk L. , Pedersen F. , Tørsløv J.
Published: May 2018

Due to the extension of wastewater treatment plants to nutrient removal and the development towards reuse of sludge in agriculture, new guidelines for regulating industrial discharges in Denmark were needed. The paper describes how a concept for regulating the discharge of specific organic substances and heavy metals has been developed during the past two years. The concept is based on guidelines that are made according to considerations of the environment and the treatment plant system, and that encourage the introduction of a cleaner technology and integrated preventive measures.

For most organic substances, present knowledge of fate and effects in biological treatment plants is too scarce to underpin the setting of general standards. Therefore, it has been decided to base the developed priority system on the data used in the EEC-system for classification of hazardous chemicals. This includes ready degradability, defined by the OECD-test, bio-sorption and bio-accumulation, defined by the octanol/water distribution coefficient and toxic effects on water organisms.

Several potential effects of seven heavy metals have been evaluated, and the most critical effects were found to be the quality criteria for sludge intended for use in agriculture, and the quality criteria for the aquatic environment. Proposals for general guidelines have been calculated using a simple mass balance model combined with water quality criteria and the Danish limit values for use of sludge in agriculture.
Biological Treatment of Photoprocessing Wastewaters
Authors: Pavlostathis Spyros G. , Jungee Shabbir A.
Published: May 2018

The activated sludge and anaerobic digestion processes were used for the biological treatment of photoprocessing wastewaters from two commonly used photoprocesses, namely KODAK Flexicolor Process C-41 and KODAK Ektacolor Process RA-4. Photoprocessing wastewaters were simulated in the laboratory and fed to fill-and-draw activated sludge reactors at loading levels less than or equal to 100% v/v along with a synthetic base feed. Up to 68% photoprocessing wastewater-derived COD removal was achieved by the fill-and-draw activated sludge reactors. Ammonia removal was achieved by all reactors, although some degree of nitrification inhibition -- manifested by the accumulation of nitrite -- was observed in some of the photoprocessing wastewater treating reactors. The performance of digesters fed with activated sludge generated in the presence of photoprocessing wastewaters (up to 50% v/v levels) matched or even surpassed that of the control digester (fed activated sludge without any photoprocessing wastewaters present). Digester failure -- accompanied by a cessation of gas production, increase in volatile fatty acids and lowering of the pH - was observed for only the digestion of activated sludge produced from the aerobic treatment of 100% photoprocessing wastewaters, primarily due to inhibition of methanogenesis. However, with prolonged incubation, digester recovery was observed.
In-Plant Control in Oil and Soap Industry
Authors: Abdelmonem Nabil , Abou-Elela Sohair I.
Published: May 2018

ln-planl control measures in the different manufacturing units in an Oil and Soap Company were carried out. The hot spent lye at 105°C can be saponified again with a predetermined free fatty acid produced in the plant in order to recover soap and to avoid excessive foams. Also, recovery of residual soap resulting from steam blowing during shutdown periods was achieved by using a Jacketed storage tank heated with steam. The techno-economic study for this proposal revealed that the total saving per year is 237,000 L.E. and the percentage return on investment is almost 86%, while the payout period is 0.2 month. Also, the implementation of any possible housekeeping was taken into consideration.
Utilization of Wastewater from Fertilizer Industry – A Case Study
Authors: Abou-Elela Sohair I. , Abdelmonem Nabil
Published: May 2018

In-plant control in a superphosphate fertilizer company in Egypt was implemented. The control measures in the plant included utilization of wastewater produced from the scrubbing towers to produce sodium fluorosilicate (Na2SiF6) which is a preservative for Portland cement. Wastewater recovery reduced the pollution amount by 40%. Moreover, it saves almost 600,000 L.E./year. The remained unwanted residue which is a very concentrated highly acidic wastewater was diluted with wasted cooling water in the plant. The proposed study is already implemented and is presently in operation.
The Temperature-Phased Anaerobic Biofilter Process
Authors: Kaiser Sandra K. , Dague Richard R.
Published: May 2018

The “temperature-phased anaerobic biofilter” or TPAB process (U.S. Patent pending), is a new high-rate anaerobic treatment system that includes a thermophilic (56°C) biofilter connected in series with a mesophilic (35°C) biofilter providing for two-temperature, two-phase treatment.

Three TPAB systems of different thermophilic:mesophilic reactor size ratios were operated at system HRTs of 24 hrs, 36 hrs, and 48 hrs to characterize performance and to determine if an optimum size ratio exists between the thermophilic and mesophilic phases. The three TPAB systems achieved SCOD reductions in excess of 97% and TCOD reductions in excess of 90% for a synthetic milk substrate over a range of system COD loadings from 2 g COD/L/day to 16 g COD/L/day. There was little difference in performance between the three TPAB systems based on COD reduction and methane production. The 1:7 ratio of thermophilic:mesophilic phase TPAB system performed as well as the 1:3 and 1:1 size ratio TPAB systems. In applications of the process, a relatively small thermophilic first-phase can be used without sacrificing overall two-phase system performance.

The TPAB process is a promising new anaerobic treatment technology with the ability to achieve higher efficiencies of organic removals than is generally possible for single-stage anaerobic filter systems operated at equivalent HRTs and organic loadings.
Deep-bed filtration of SBR effluent for agricultural reuse: pilot plant screening of advanced secondary and tertiary treatment for domestic wastewater
Authors: Brenner Asher , Shandalov Semen , Oron Gideon , Rebhun Menahem
Published: May 2018

A wastewater reclamation program has been proposed as a means of supplying a major part of agricultural water demand in Israel. This program may solve the two fold problem of a national water shortage combined with continuous contamination of groundwater resources by inadequately treated wastewater. A pilot-scale investigation of an advanced treatment scheme incorporating a sequencing batch activated sludge system, followed by deep-bed granular filtration, has been started. It is aimed at the development of design and operation guidelines for such systems to be applied on a full scale. Preliminary results presented herein indicate that the sequencing batch reactor system is capable of producing high-quality, low-suspended-solids effluent to be further polished by granular filtration. A single medium quartz sand filter operated under a high variety of filtration velocities and inflow turbidities with no chemicals added, demonstrated good performance and supplied basic design information to be applied in further investigation.
Membrane Separation of Wool Scour Effluent
Authors: Bilstad T. , Espedal E. , Madland M.
Published: May 2018

Norway's largest yarn factory, Sandnes Uldvarefabrikk, produces knitting wool from 1,000 tons of raw wool a year. The raw wool is washed in 55°C water with high pH detergents. The resulting wastewater has a chemical oxygen demand, COD, of up to 100,000 mg/l and was previously piped directly to the public sewer. The Norwegian Environmental Protection Agency ordered the factory to reduce the COD loading by 75%, effective at the end of 1989.

The winter and spring of 1989 was used to test membranes and gather design information for a fullscale separation plant for treating the wool washwater. The results from the pilot testing were encouraging and a fullscale membrane plant was designed, manufactured and installed during the fall of 1989. The wool factory gradually increased the wool scouring capacity, however, and two years later the capacity of the full scale membrane plant was doubled simply by doubling the membrane area of the original plant.

The membrane separation plant is tubular ultrafiltration (UF) and the treatment is on a batch basis with a volume reduction of ten. The 31 m2 UF membrane area has an average permeate production capacity of 2 m3/h at 8 kg/cm2 inlet pressure and 3.8 m/s fluid velocity. The feed temperature is never allowed below 40°C due to the high concentration of fat which tends to solidify at lower temperatures and would plug the membranes.

The retentate from UF separation is returned to the feed tank whereas the permeate is routed through a heat exchanger to the public sewer. The start volume of each batch is between 15 m3 and 25 m3 with the UF plant manually started. The shutoff is automatic by a level switch set at 2 m3 batch volume. The retentate or sludge is pumped to a second holding tank and the accumulated sludge is once a week transported and dewatered in a lagoon at the local sanitary landfill.

The UF membrane plant has a 10 kW power consumption and has more than 700 operating days since 1989. The operator spends two hours a day managing the UF plant including cleaning the membranes after each daily batch, pumping the sludge, logging the data and reporting to the plant management. Membrane replacement is performed once a year at a cost of ₤3,800. The COD, fat and solids reductions have consistently been above 80%.
Optimization for Reduction/Precipitation Treatment of Hexavalent Chromium
Authors: Patterson J. W. , Gasca E. , Wang Y.
Published: May 2018

This paper describes wastewater treatment optimization studies performed on an industrial wastewater generated in Boston, Massachusetts, USA. The manufacturing plant generates hexavalent chromium [Cr(VI)] wastewater as a result of chromating brass, bronze and copper parts produced in the manufacturing operations. The facility utilizes a continuous flow treatment train, involving segregated Cr(VI) reduction with sodium metabisulfite (Na2S2O5) under acidic conditions, followed by combined wastestream two-stage pH adjustment, metals precipitation, and clarification before discharge to the municipal sewer.

The objectives of the studies were to define and evaluate critical parameters, such as pH and oxidation reduction potential (ORP) for hexavalent and total chromium control and to perform treatability studies to optimize the performance of the wastewater treatment plant (WWTP). The treatability studies included Cr(VI) reduction versus Na2S2O5 dosage evaluations and corresponding chromium reduction kinetic studies, and trivalent chromium hydroxide precipitation. The Cr(VI) reduction experiments and chromic hydroxide precipitation studies were performed for three different wastewaters collected from within the manufacturing process; a high, typical, and dilute strength wastewater.
Preoxidation of Chlorophenolic Wastewaters for their Subsequent Biological Treatment
Authors: Yu Yue-Hwa , Hu Szu-Tsong
Published: May 2018

Industrial wastewaters containing chlorophenolic compounds exhibit various degrees of resistance to biodegradation. Preoxidation of these wastewaters by using ozone as the chemical oxidant has been found previously to be quite effective in promoting their biodegradabilities.

This study was made to further investigate whether or not preozonation taking place under different pH conditions would bring about different effects over the following activated-sludge treatment systems. The results indicate that the pH conditions set for the preozonation step did play significant roles in the subsequent biological treatment processes. To the activated sludge system which had not been exposed to chlorophenolic compounds before, preozonation carried out at low or high pH both greatly improved the biodegradabilities of the influents, with the latter condition showing better improvements. Nevertheless, to the activated sludge system previously acclimated to the individual chlorophenolic compounds, the process of preozonation in some cases would then bring about retarding effects over the biodegradabilities of the influent. The phenomena of retardation were generally more apparently observed in the samples which had been preozonated under alkaline conditions.
Interactions of sediment contaminants in the testing of mutagenicity
Authors: Abe Akemi , Urano Kohei
Published: May 2018

The influence of sediment contaminants on the Salmonella mutagenicity test was investigated to develop a preparation method not subject to interference by coexisting substances. Organic chemicals were extracted from sediment by dichloromethane/ethanol (4:1), acetonitrile or ethanol, and dichloromethane (DCM) extract was refined by washing with alkali, passing through a reduced-Cu column and/or fractionation with a silica cartridge. The strain Salmonella typhimurium TA98 was used. Sediment extracts and their refined preparations were first determined in their own mutagenicity, and then the influence on the mutagenicity of a fixed dose of 2-aminofluorene (2-AF) as a positive standard mutagen was examined. The toxicity to the strain was also tested. It was concluded that the coexisting environmental chemicals in sediment inhibited or promoted the original mutagenicity of the samples.
Correlations of water quality, sediments and benthic invertebrates in Ell-Ren River, Taiwan
Authors: Kuang-Chung Yu , Shien-Tsong Ho , Jiunn-Kae Chang , Sheue-Duan Lai , Chao-Hsiung Wang
Published: May 2018

The correlations of benthic invertebrates, sediments and water quality were investigated at two stations in the Ell-Ren river of Taiwan by means of statistical analysis every two months during a one year period. A total of 8 aquatic insect species and 2 annelid species were collected. Based upon the statistical analyses, several significant correlations for the population of benthic invertebrates and heavy metal contents of sediment were found between Simulium sp. and “adsorptive and exchangeable” lead, Simulium sp. “bound to carbonates” copper as well as Baetis sp. and “bound to carbonates” chromium. Results of stepwise multiple regression indicated that the heavy metal contents of sediment could explain a considerable portion of the variance in the population of benthic invertebrates. “Adsorptive and exchangeable” lead accounted for 86.2% of the variance of the population of Simulium sp. while “Bound to carbonates” chromium retained 81.5% of the variance of the population of Baetis sp.
Relationship between water qualities and treatments in the ultra pure water production system
Authors: Okouchi S. , Yamanaka K. , Ishihara Y. , Yanaka T. , Uedaira H.
Published: May 2018

In an ultra pure water (UPW) production system which can satisfy the water qualities for 4 megabit DRAM, the changes in water qualities from a tap water (58.4 mg/dm3 as CaCO3 hardness) as a raw water to UPW were followed from the view of the micro-structure and microdynamic behavior of water molecules with increasing of the water purity by a complex permittivity and 17O-NMR measurements, as well as measurements of resistivity, density, and so on. The dielectric relaxation time and spin-lattice relaxation time of 17O nuclei related to the microdynamic behavior of water molecules indicated a trace change between the tap water and UPW. However, the dielectric parameter α which characterizes a symmetric distribution of relaxation times was gradually lowered with increasing of the water purity. The relationship between the half-width of 17O magnetic resonance and pH gave the rate constants for the prototropic charge migration in water. The difference of α and density between the tap water and UPW became a measure of water purity.
Study on the performance of an up-flow aerated biofilter (UAB) in municipal wastewater treatments
Authors: Watanabe Yoshimasa , Okabe Satoshi , Arata Tomochika , Haruta Yuji
Published: May 2018

A comprehensive wastewater treatment system that accomplishes oxidation of organic matter, nitrification, and denitrification was developed, and its characteristics and performance were investigated. A municipal wastewater was treated by an up-flow aerated biofilter (UAB), in which biofilms were developed on stainless meshes installed horizontally. This UAB exhibited a great potential ability of oxidation of organic matter, SS stabilization, and nitrification due to a unique aeration mechanism giving high DO concentrations with relatively low aeration rates. Another unique feature of the UAB was that attached biofilms on stainless meshes physically filtered out and/or adsorbed suspended solids in the wastewater in addition to the biological oxidation of organic matter. A stable nitrification could be achieved at HRT=10 hours corresponding to a hydraulic loading of 86 L m−2 d−1 and at a ratio of aeration rate to wastewater flow rate (A/W) of 2, which is considerably low as compared to aeration rates of typical activated sludge systems. This UAB system also could handle relatively high hydraulic loading rates. The UAB used in this study still have enough space to install more stainless meshes so as to reduce hydraulic loading rates resulting in the reduction of HRT and aeration rate, which leads to improvement of the system performance as well as reduction of the running cost.
Metals removal by algal biofilms
Authors: Liehr Sarah K. , Chen Hui-Jung , Lin Shun-Hung
Published: May 2018

The objective of this research is to evaluate the possibility of enhanced metal precipitation inside algal biofilms. The pH environment surrounding microorganisms growing in biofilms is frequently different than the environment of the bulk liquid because products of metabolic reactions are limited in their ability to diffuse out of the biofilm. This occurs with algal biofilms, in which CO2 utilization during photosynthesis results in an increase in the pH. The pH inside algal biofilms can be several units higher than the pH of the surrounding liquid. This higher pH favors removal of metals by precipitation and possibly adsorption. Laboratory studies were conducted in which biofilms of Cladophora glomerata were grown in buffered nutrient media. Copper or nickel was added to the media to study short term metal removals. Experimental results were compared to predictions of solubility based on a theoretical model of pH inside algal biofilms. Results provide evidence to support the theory that higher internal pH can result in greater metal removal by the biofilms.
Effect of turbulent structure on filament-type biofilm reaction
Authors: Nagaoka Hiroshi , Sugio Katsuyuki
Published: May 2018

Effect of turbulent diffusion on substrate uptake rate by biofilms was studied. A new turbulent diffusion biofilm model was developed considering profiles of turbulent diffusivity in and over biofilms. A numerical simulation was conducted using a proposed model to show that substrate flux changes with turbulent diffusivity obeying a power law with the coefficient value between 0 and 1. Biofilm was grown in open channels and the effect of short-term changes in turbulence of the overlying flow on substrate flux into the biofilm was measured. Profiles of velocity and turbulent intensity in the overlying flow were measured using a Laser Doppler Velocimeter. It was concluded that the substrate uptake rate by biofilms was dependent on the turbulence near biofilms, the mechanism of which can be explained by the proposed turbulent diffusion model.
Activated sludge population dynamics
Authors: Wanner Jiri
Published: May 2018

The paper briefly surveys topics covered by the IAWQ Specialist Group on Activated Sludge Population Dynamics. The activated sludge population dynamics has been formulated as a branch of water science and technology concerned with phenomena governing the relationships between activated sludge microorganisms and their functions. The characterization of organic pollution fractions in wastewaters according to their rate of biodegradation has been discussed and the role of wastewater as an inoculum stressed. The characterization of activated sludge biomass has been evaluated from two viewpoints: grouping according to metabolic abilities and identification and classification of activated sludge microorganisms. The basic selection mechanisms influencing the microbial composition of activated sludge have been described. The problems with activated sludge settling and thickening properties have been mentioned as a typical example of applied population dynamics research.
Hydrophobicity of activated sludge flocs and laboratory-grown bacteria
Authors: Jorand F. , Guicherd P. , Urbain V. , Manem J. , Block J. C.
Published: May 2018

The cohesion of activated sludge biological flocs is controlled by the ratio between hydrophilic exopolymers in which bacteria are embedded and hydrophobic interactions. As shown in this study highly hydrophobic bacteria coexist in the flocs with highly hydrophilic bacteria which seem to release large quantities of exopolymers (polysaccharides, DNA, proteins…). Addition to the activated sludge of easily assimilable nutrients such as glucose does not change the hydrophobicity of bacteria but increases both exopolymer production and the sludge volume index. The environmental conditions and the bioavailability of nutrients may considerably shift the hydrophilic/hydrophobic balance. Moreover experiments carried out with four different strains to fourteen isolated from activated sludges have shown that a few strains (variable types) have quite considerable possibilities of hydrophobic property variations in the course of growth.
Comparative studies on differently arranged activated sludge systems
Authors: Jobbágy A. , Grady C. P. L. , Morsányi G. , Nyeste L. , Simon J.
Published: May 2018

Rearrangement of existing treatment facilities for optimum bioreactor configuration offers a cost-effective upgrading possibility. Model experiments were performed to determine how the configuration of bioreactors of a given total volume can influence system performance, with the goal of influencing planned modifications of activated sludge plants in Hungary. In the first experiment, two bioreactors arranged in series were compared to two in parallel. In the second experiment, a two-stage system with sludge recycle around each stage was compared to a single-sludge selector system. In the last experiment, three types of selectors (two anoxic and one aerobic) were evaluated for addition to a conventional, flow-through activated sludge system. The experiments were performed with dairy-type synthetic wastewater and with effluent from the primary clarifier of an existing municipal treatment plant.

Reactor arrangement had a great influence on the effectiveness of the treatment, primarily by inducing significantly different sludge structures. The in-series reactor arrangement proved to be, in every respect (effluent COD, residual detergent, and sludge characteristics), more efficient than the parallel arrangement. The two-stage system produced more sludge than the selector system, and the SVI values of the second stage of the two-stage system were extremely unfavorable. However, the effluent from the second stage was significantly clearer. Separating the selector from the flow-through reactor improved the sludge settling considerably. This facilitated an increased hydraulic load in the secondary clarifier and thereby in the whole treatment system.
Tentative guidelines for waste selection, process design, operation and control of upflow anaerobic sludge bed reactors
Authors: Wentzel M. C. , Moosbrugger R. E. , Sam-Soon P. A. L. N. S. , Ekama G. A. , Marais G. v. R.
Published: May 2018

Successful application of upflow anaerobic sludge bed (UASB) technology hinges on the generation of sludge aggregating into bio-conglomerates, to facilitate retention of the sludge in the reactor. In this paper an hypothesis for formation of one type of bio-conglomerate, the biopellet, is presented. From the hypothesis, characteristics that a waste must possess to induce pelletization, and process design and operational procedures to optimize system performance, are identified.
Upgrading of wastewater treatment plants to achieve advanced standards concerning nutrient removal
Authors: Buß S. , Einfeldt J. , Günter H. , Werner T.
Published: May 2018

According to the general wastewater administration rule, it is allowed for the single state authorities of Germany to make the minimal requirements on quality of wastewater discharge more restrictive then those given by the federal government. Schleswig-Holstein particularly has made extensive use of this rule in the past years. On addition of fluctuations due to tourism, industry or combined sewer system, the general criteria for the layout of wastewater treatment plants (WWTP) are presently unsatisfactory in order to meet these requirements. More detailed and comprehensive studies need to be carried out to fulfill these stricter demands.

By illustrating four case studies of WWTP designs of size between 43,000 and 640,000 total number of inhabitants and population equivalents (PT), possible solutions will be presented. With the aid of land-registers, intensive measurement series and semi-technical and full scale experiments, design concepts including multi-stage and split flow treatment could be established.
Conventional and unconventional integration of trickling filters in a process for biological nutrient removal
Authors: Dichtl N. , Engelhardt N. , Firk W. , Koppetsch J.
Published: May 2018

Stricter waste quality standards necessitated the upgrading of a large wastewater treatment plant. Taken with constraints on cost and physical space this led to the investigation of a wide range of conventional and unconventional plant configurations that integrate the existing trickling filters to achieve the nutrient removal target.
The individual and combined influence of temperature, time, pH and COD concentration on the biodegradation activities of selected bacterial strains grown on raw Baker's yeast effluent
Authors: Van Der Merwe M. , Britz T.J.
Published: May 2018

Five bacterial strains (Chryseomonas luteola, Fusobacterium mortiferum, Enterobacter agglomerans,Klebsiella oxytoca and an unidentified Gram-negative rod) were grown on raw baker's yeast effluent to assess the influence of environmental factors on biodegradation processes. A 3×4×3 factorial design was used to determine the effects of time, pH and COD concentration, at four different temperatures. Total volatile fatty acid production was chosen as the most representative indicator of biodegradation. Results showed that the strains differed greatly in their ability to produce anaerobic digester intermediary metabolites, under defined environmental conditions. The study showed that the degradation of the complex compounds in baker's yeast effluent could be enhanced by changing environmental factors. The most positive responses were obtained at the higher COD concentrations (30 g l−1), the higher pH values (6.0), after 24 to 48h incubation time and at the higher temperatures (35°C). The most positive effect (+355.00) was found forChryseomonas luteola at a 48h incubation time, COD concentration of 30 g l−1, pH of 6.0 and temperature of 35°C. The volatile fatty acid yields obtained by the strains differ from the statistical indications, but provide a valuable reference of the actual concentrations obtained during the experimental study. The factorial design represented the effects of environmental changes, while the quantitative TVFA data set gave experimental data. This study showed that the manipulation of various environmental factors in biologically controlled systems, such as anaerobic digesters, could further enhance the biodegradation efficiency of the microbial population in the raw effluent.
A seven year plan for upgrading the 200.000 p.e. treatment plant of Uppsala, Sweden
Authors: Lind Jan Erik , Swedling Ernst Olof
Published: May 2018

The sewage treatment plant of Uppsala was originally built in 1946 and has since then been extended and upgraded several times up to 1972 when the last major upgrading was completed. In 1987 it was decided to renew the treatment plant for at least another 20-30 years of operation and to upgrade the biological process to include nitrogen reduction. A 7 year plan covering some 18 items with a total investment cost of approximately 120 MSEK was set in action during 1987. The aim was to raise the cost efficiency by introducing modern techniques, new machinery, a better working environment and a better understanding of the processes used. The need to keep the plant in operation during reconstruction work has caused difficulties, delays and unforseen costs but a close cooperation between all parties concerned (operators, contractors, engineers and the regional environment administration) has solved most of the problems. Experiences so far include an improved effluent quality, a better cost efficiency, a healthier and more engaged operating staff. A research team has been engaged to develop and introduce a nitrogen reduction scheme in the activated sludge process. This has been a challenging and fruitful experience.
A novel high rate method for the nitrification of sludge liquors containing high levels of ammonia
Authors: Pickin S. R. , Saunders F. J.
Published: May 2018

A high rate nitrification system is proposed for the nitrification of digested sludge liquors with N-NH3 levels of between 500 and 1,000 mg/l.

Bench and pilot scale studies have established that loading rates of between 1.0 and 2.0 kg N-NH3/m3 of reactor volume/day are achievable by maintaining a constant 30° C reactor temperature. The effluent standard was set at 40 mg/l of N-NH3.

Loading rates in excess of 1.0 kg N-NH3/m3 of reactor volume/day required supplementing conventional fine bubble diffusion with pure oxygen.

pH and alkalinity control were utilised to maintain the pH in the range 7.2 – 7.6 and total alkalinity in excess of 250 mg/l (as CaCO3) by the use of a feed mixture of NaOH and NaCO3 (20 and 40 g/l respectively).

The nitrifying population was fixed and stabilised within the reactor by using reticulated foam blocks (25 mm × 25 mm s× 25 mm) occupying approximately 30% of the reactor volume.

Settlement was achieved by conventional clarification with a nominal up flow velocity of 1.0 m/hour.
Status on science and application of thermophilic anaerobic digestion
Authors: Ahring B. K.
Published: May 2018

Thermophilic anaerobic processes are often regarded as less stable than mesophilic processes. In the paper this postulate is examined and disproved based on real operational data from of full-scale mesophilic and thermophilic biogas plants. The start-up procedure for the thermophilic plants was, however, found to be crucial for determining the period needed before full capacity of the thermophilic plant could be achieved. The importance of balanced loading, determined by the concentration of active biomass, is discussed. Finally, data will be shown on the optimal and maximal temperature for thermophilic digestion along with the implications for the methanogenic bacteria active at these temperatures.
Combined organic carbon and complete nitrogen removal using anaerobic and aerobic upflow filters
Authors: Akunna Joseph , Bizeau Claude , Moletta René , Bernet Nicolas , Héduit Alain
Published: May 2018

Two laboratory upflow aerobic and anaerobic filters fed with synthetic wastewaters were used to study firstly the effects of aeration rate on the nitrification of anaerobically pre-treated effluents and secondly the effects of recycle-to-influent ratios on methane production rate, denitrification and nitrification performances of a combined aerobic and anaerobic wastewater treatment process. Nitrification of anaerobically pre-treated effluent was accompanied by aerobic post-treatment for residual COD removal. A comparison of nitrification performances using autotrophic medium and anaerobically pre-treated effluents (containing 1203 mg COD 1−1) with the same ammonia nitrogen concentration of about 300 mg NH4-N 1−1 showed that 3% of added ammonia nitrogen was assimilated by autotrophic nitrifiers during nitrification of the autotrophic medium while up to 30% was assimilated by both nitrifiers and heterotrophs during organic carbon removal and nitrification of anaerobically pre-treated effluent. Furthermore, it was suspected that significant nitrogen loss through denitrification occured in the aerobic filter especially at low aeration rates. In the study of the combined aerobic-anaerobic system, maximum ammonia nitrogen removal of 70% through denitrification was obtained at recycle-to-influent ratios of 4 and 5. COD removal efficiency in the anaerobic filter decreased from 77 to 60% for recycle-to-influent ratios of zero to 5. Overall COD removal efficiency of the entire system was constant at about 99% due to heterotrophic COD removal in the aerobic filter.
Flood and CSO Control Tanks: The Experience in the City of Nagoya
Authors: Ochi Toshihiko
Published: May 2018

Topographical features of the City of Nagoya, characterized by flat land and hills in the eastern part, make storm drainage and flood control particularly important in this urban region. In the provision of land drainage, small and medium rivers in the City play an important role, but they generally lack adequate hydraulic capacity. Furthermore, there are sewered areas in the city where the local topography, characterized by depressions or sudden breaks in surface slopes between flat and inclining planes cause local flooding and water ponding. Consequently, the city has adopted a flood control program comprising construction of storage tanks in the areas susceptible to flooding, or where the hydraulic capacity of rivers is unreliable. The main concepts of this program include the construction of a variety of storage tanks designed to suit the local flood protection requirements. Scarcity of construction sites makes effective land utilization mandatory, so storage tanks are designed as facilities with dual functions serving as both flood and combined sewer overflow (CSO) controls, and, whenever feasible, the storage tanks are designed and implemented in conjunction with the existing facilities.
Stabilization of Activated Sludge Processes During Wet Weather Flow through Microscreening
Authors: Kummer K.-D. , Geiger W. F.
Published: May 2018

In the activated sludge process, between the aeration tank and the final clarifier, offline microscreening is introduced to separate activated sludge and purified water. The intention is to reduce the drifting of activated sludge from the aeration tank into the final clarifier. Sludge drifting usually occurs during wet weather flow loading of the treatment facility and can cause higher concentrations of ammonia and suspended solids in the effluent. Laboratory and half-technical scale experiments demonstrate that microscreening is suitable for this application. It is expected that the operational stability of activated sludge processes could be improved significantly by this process modification.
Urban Drainage Modelling Intelligent Assistant
Authors: Griffin S. , Bauwens W. , Ahmad K.
Published: May 2018

The work reported here focuses on research being conducted within the Artificial Intelligence Group at the University of Surrey and the Laboratory of Hydrology at Vrije Universiteit Brussel under the COMETT programme. The paper describes the “Urban Drainage Modelling Intelligent Assistant,” a computer-based tool kit which provides guidance, instruction and support for training on aspects of network modelling in urban drainage design and simulation models commonly used in Europe. The tool kit comprises four interrelated, interactive components: an expert system, a data preparation and model execution tool, a document browsing facility, and a term bank. The results of the work are illustrated with the aid of snapshots of the system in use. The specific emphasis here is on the role played by each component in a) the transfer of knowledge within both an inter-disciplinary field such as urban drainage modelling (hydrology, hydraulics, mathematics, computing), and a multilingual community (of particular importance in Europe at present) and b) the training of novices in urban drainage, enabling them to grasp the domain primitives, their interrelationships and meanings.
Urban Drainage Control Demonstration Program of Canada's Great Lakes Cleanup Fund
Authors: Weatherbe Donald G. , Griff Sherbin I.
Published: May 2018

The Great Lakes Cleanup Fund (CuF) is a component of Canada's Great Lakes Action Plan. Since 1990, the Cleanup Fund has been supporting the development and implementation of cleanup technologies to control municipal pollution sources, to clean up contaminated sediments, and to rehabilitate fish and wildlife habitats. These efforts are focused on Canada's 17 Areas of Concern (AOCs) identified by the International Joint Commission for priority cleanup action and development of remedial action plans (RAPs). The urban drainage program of the CuF is demonstrating new and innovative technologies for controlling urban sources of pollution, and is assisting RAP study teams in developing control options. For combined sewer overflow (CSO) control, demonstrations include high-rate treatment using a vortex separator, and real time operation of a CSO control system. Storm water management demonstrations include development of best management practices, evaluation of control ponds for an industrial catchment, and evaluation of a sewer exfiltration system retrofitted into an existing urban area. Estimates of pollutant loadings to the Great Lakes were made, and overall costs for CSO cleanup were developed for various levels of control. Comprehensive pollution control plans are under development at several AOCs.
A Novel Method for Biological Treatment of Bleached Kraft Mill Wastewaters
Authors: Strehler Andrew , Welander Thomas
Published: May 2018

Removal of adsorbable organic halogen (AOX) and chemical oxygen demand (COD) from bleached kraft mill effluent was investigated in laboratory and pilot scale aerobic suspended carrier reactors and abiotic thermo-alkaline reactors.

Laboratory treatment focused on determination of loading capacity of the suspended carrier process and operation of the process at elevated temperature and pH values in order to combine abiotic thermo-alkaline dechlorination and biological treatment in one reactor. At pH 7, 37°C and hydraulic retention times (HRTs) longer than 3.5 hours, a maximum COD removal of 55% was achieved in the suspended carrier process. The COD conversion rate at the minimum HRT was 2.6 kg COD/(m3*d). The suspended carrier treatment was operated successfully at pH 9.0 and 45°C and at pH 7.0 and 50°C with over 50 percent COD removal with a HRT of four hours. The AOX removal achieved at pH 9 and 45°C (50%) was significantly higher than the removal at pH 7 and 37°C (39%), most certainly because of an increased abiotic dechlorination at the higher pH and temperature levels.

Sequential thermo-alkaline and biological treatment were studied on a pilot scale. Tbermo-alkaline treatment at pH 10, 54°C and a HRT of two hours followed by biological treatment at pH 8, 35°C and a HRT of four hours, removed almost 80% of AOX and 50% of COD from the kraft mill effluent.
Biological Removal of Chlorate from Bleaching Plant Effluent
Authors: Malmqvist Åsa , Welander Thomas
Published: May 2018

Biological chlorate removal was studied on a laboratory and a pilot scale with the aim of optimizing process design and operating conditions with respect to process efficiency, stability and economy.

The results showed a suspended-carrier biofilm process design to be suitable for biological chlorate removal. In the laboratory tests, at pH 7 and 37°C, a complete removal of chlorate could be maintained at hydraulic retention times (HRTs) as short as 24 min. A longer HRT (1.5 h) was required for complete chlorate removal in the pilot test, due to a lower degree of filling with carrier material (25% versus 50% of the reactor volume), higher process temperature, and leakage of oxygen into the process. However, it is assumed that the loading capacity of a large-scale process would approach that of the laboratory system if the operating conditions were the same.

Laboratory tests showed chlorate reduction to be possible within a wide range of pH values and temperatures, although the process stability and loading capacity were strongly affected by changes in these parameters.

The results of the laboratory and pilot scale studies, using a suspended-carrier process design, show biological treatment to be an economically viable and efficient process for the removal of chlorate from bleaching plant effluents.
The Removal of Chlorinated Phenolic Compounds from Chlorine Bleaching Effluents Using Thermophilic Anaerobic Processes
Authors: Lepistö Raghida , Rintala Jukka
Published: May 2018

Thermophilic (55°C) anaerobic removal of chlorinated phenolic compounds (CPC) from softwood bleaching effluents was studied using four different types of anaerobic processes: an upflow anaerobic sludge blanket (UASB) reactor (R1); a UASB reactor enriched with sulfate (R2); a UASB reactor with recirculation (R3); and a fixed bed reactor with recirculation (R4). The concentrations of 16 CPCs were analyzed by gas Chromatography. In all processes most of the chlorinated phenols, catechols, guaiacols, and hydroquinons detected in the bleached kraft mill effluent (BKME) were either eliminated or reduced by as much as 80-95%. However, 2,4-DCP, 2,6-DCP, 4,5-DCG, 3,4,5-TCC, and TeCC were accumulated or only partially removed in all reactors, except in R4 where at high concentrations they were significantly reduced. All the reactors removed 30-70% of the COD and 25-67% of the adsorbable organic halides (AOX). The reactors with recirculation had slightly higher removal efficiencies than the other reactors, while the addition of sulfate had no apparent effect. High concentrations of BKME reduced the COD removal efficiency but not the CPC removal.
Feasibility of Anaerobic Pre-Treatment for the Effluents from Hardboard and Laminated Board Industry
Authors: Eroglu V. , Oztürk I. , Ubay G. , Demir I. , Korkurt E. N.
Published: May 2018

This paper presents results of a comparative evaluation of the feasibility of anaerobic pre-treatment for the effluents from a hardboard and laminated board industry.

The problems associated with the treatment of hardboard mill wastewaters using activated sludge process have been observed as relatively low COD removal, high energy cost and high amounts of excess biological sludge production. The purpose of the study is to evaluate the effectiveness and feasibility of the anaerobic pre-treatment to reduce the excess biological sludge production and energy consumption in the aerobic stage. Anaerobic treatability studies were carried out by a lab-scale upflow anaerobic sludge blanket reactor (UASBR) with an effective volume of 10 litres. The UASBR was operated for a wide range of organic and hydraulic loadings during the experimental studies of more than 4 months. Anaerobic treatability studies have shown that a COD removal of 60% is possible at organic loading rates of 5-11 kg COD/m3.d. Anaerobic treatability study results have shown that 70 percent reduction both in the excess sludge production and in energy for aeration are possible by applying anaerobic pre-treatment. Considering these findings, it was demonstrated that anaerobic pre-treatment is a feasible option for waste management of the hardboard mill effluents.
Parameters affecting nitrifying biofilm reactors
Authors: Boller M. , Gujer W. , Tschui M.
Published: May 2018

The variables affecting nitrification in biofilms are identified on a theoretical basis. The influence of various design and operational parameters which affect the resulting substance fluxes into and out of the biofilm and the biomass activity regarding nitrification are illustrated with the help of experimental investigations with plastic media trickling filters, rotating biological contactors and different aerated biofilters. The results of experiments with these systems in tertiary nitrification applications reveal process limitations and technical measures to enhance nitrification performance in each system. In a case study, a comparison between the different biofilm processes and activated sludge alternatives showed that biofilm systems may lead to remarkably smaller reactor volumes, but high energy consumption due to unfavorable oxygen utilization.
The treatment trilogy of floating filters: from pilot to prototype to plant
Authors: Toettrup H. , Rogalla F. , Vidal A. , Harremoes P.
Published: May 2018

The basic kinetic expressions developed in non-aerated biofilms (denitrification and RBCs) were verified on granular floating media in aerated filters. The limiting parameters of biofilms were verified on a small scale lab unit, using wastewater and media from full scale. It could be shown that the observed relationships corresponded to theoretical expectations and half-order kinetics as well as the significant constants were established. Maximum surface removal rates were measured as 1.7 g N-NH4/m2 d for nitrification, and the most limiting parameter was a half-order oxygen concentration close to saturation.

Similar kinetics as on small scale were observed on a full-scale prototype of a new floating aerated biofilter, which can be used for both nitrification and denitrification, as well as complete nitrogen removal from settled wastewater in one reactor. The mixed biofilm nitrified 15 % less than pure tertiary treatment, and 20 % performance was lost between lab and full scale, due mainly to aeration limitations. Also, 35 % lower denitrification rates were observed between ethanol and sewage as carbon source, but addition of ethanol raised the full-scale performance to nitrate removal rates of 1,4 g N-NO3/m2 d.

After pilot testing and full-scale demonstration, the process was implemented on several treatment plants, one of which was located in Denmark, to achieve nitrogen residuals below 8 mg TN/1. This plant uses 8 filters of 63 m2 to treat 12 000 m3/d, and the biological reactor occupies a surface similar to the existing conventional primary settler. The results of the first few months of operation are given: as long as the ratio between biodegradable COD and total nitrogen at the filter inlet is above 5, nitrogen removal of 80 % is achieved.