bluuebunny/crossref_metadata_2025 huggingface dataset:
Filtration resistance induced by ammonia oxidizers accumulating on the rotating membrane disk
Authors: Kimura Katsuki , Watanabe Yoshimasa , Ohkuma Naoki
Published: May 2018

Membrane filtration and oxidation of ammonia were simultaneously performed by using a rotating membrane disk module. Nitrification performance, composition of the accumulated cakes on the membrane and the filtration resistances were investigated under five different operating conditions. The filtration resistance due to the accumulated cake on the membrane was found to be dominant in this treatment method, compared to the resistance due to the micropore plugging or irreversible adherence. The cake consisted mainly of iron, humic substances and bacteria. The possibility that extracellular polymeric substances were related to the cake resistance was also shown. The composition of the cake depended on the length and the condition of operation. Accumulation of ammonia oxidizers caused by oxidation of low concentrations of ammonia (less than 1 mg/l) did not increase transmembrane pressure significantly. Therefore, the application of this treatment method for drinking water treatment is feasible. Filtration resistance due to the micropore plugging or irreversible adherence to the membrane was caused by organic substances.
Detection of filamentous and nitrifying bacteria in activated sludge with 16S rRNA probes
Authors: van der Waarde Jaap J. , Geurkink Bert , Henssen Maurice , Heijnen Guido
Published: May 2018

Activated sludge samples from wastewater treatment plants from potato starch and starch derivatives factory and from a municipal sewage treatment plant were analyzed with DNA probes specific for several filamentous bacteria. It was found that Haliscomenobacter hydrossis, Sphaerotilus natans, Thiothrix sp. and Eikelboom Type 021N were common in the activated sludges. Fluorescent in situ Hybridization (FISH) analysis could detect more types of sheathed bacteria and yielded a more accurate quantification of bacteria than conventional microscopy.

In a pilot and a full scale wastewater treatment plant (WWTP) clear correlations were found between the SVI and growth of a Sphaerotilus natans and a Thiothrix sp. Addition of chlorine to the bulking sludge resulted in an improved SVI of the sludge but only damaged filamentous cells outside the floc. Nitrification was measured with substrate depletion and FISH analysis. Signal interpretation of FISH analysis was demonstrated both manually and with automated image analysis.
Development and application of 16S rRNA-targeted oligonucleotide probe for detection of the phosphate-accumulating bacterium microlunatus phosphovorus in an enhanced biological phosphorus removal process
Authors: Kawaharasaki Mamoru , Kanagawa Takahiro , Tanaka Hideo , Nakamura Kazunori
Published: May 2018

A 16S rRNA-targeted oligonucletide probe (MP2) specific for the phosphate-accumulating bacterium (PAB) M. phosphovorus was designed and applied to a sludge from an enhanced biological phosphorus removal (EBPR) process. Probes specific for defined phylogenetic groups and the polyphosphate staining dye, DAPI (4′, 6-diamidino-2-phenylindol dihydrochloride) were also used to analyze the activated sludge community. M. phosphovorus was about 3% of the total bacteria in the EBPR sludge used. Proteobacteria belonging to the beta subclass were the most abundant. Many coccoid bacteria similar to M. phosphovorus were stained with DAPI. The percentage of PABs detected by DAPI stain was about 9% of the total bacteria.
Influence of particle size and surface charge on critical flux of crossflow microfiltration
Authors: Kwon D. Y. , Vigneswaran S.
Published: May 2018

The effect of particle size and ionic strength of the feed suspension on critical flux was studied. The critical flux was defined in two different ways (strong and mild definition). The fouling, the increase of resistance (which is the basis of the mild definition of the critical flux) was relatively sensitive to the deposition of particles of 0.46 μm on the membrane of 0.2 μm mean pore. On the other hand, the deposition of large particles of 3.2 μm to a certain value on the membrane surface of 0.2 μm mean pore did not lead to the increase in resistance. In case of 11.9 μm particles, the transmembrane pressure did not increase even with significant amount of deposition of particles. The ionic strength of suspension had significant effect on the critical flux. For an ionic strength less than 1×10−1.5 M, there was a decrease in the critical flux. This could be due to the dense layer of deposit which is the result of less diffuse layer thickness of particles. Above this ionic strength, a significant increase in critical flux was noticed which may be due to the aggregation of particles.
Performance of low pressure reverse osmosis membrane (LPROM) for separating mono- and divalent ions
Authors: Ujang Zaini , Anderson G. K.
Published: May 2018

This paper describes an investigation on the rejection of the divalent anions from ZnSO4 using LPROMs, and to establish the effect of operating pressure, feed concentration and temperature on metal removal, then to compare with the monovalent anions, ZnCl2. A bench-scale spiral wound configuration of sulphonated polysulphone low pressure reverse osmosis membrane (LPROM) was used to remove heavy metals at various operating conditions, i.e. operating conditions, solute concentrations and temperature. The results show that the higher the operating pressure the greater will be the permeate flux for heavy metals from both mono- and divalent anions. At low operating pressure however, metals from the divalent anions give a higher permeate flux than did the monovalent anions. Permeate flux in both mono- and divalent anions is shown to be subsequently increased by a decrease of the concentration of feed solution. Regarding metal removal, metals from divalent anions were rejected more effectively than monovalent anions at all levels of feed concentration.
Autecology of scum producing bacteria
Authors: Lemmer Hilde , Lind George , Schade Margit , Ziegelmayer Birgit
Published: May 2018

Non-filamentous hydrophobic scum bacteria were isolated from scumming wastewater treatment plants (WWTP) by means of adhesion to hydrocarbons. They were characterized with respect to taxonomy, substrate preferences, cell surface hydrophobicity, and emulsification capability. Their role during flotation events is discussed. Rhodococci are selected by hydrolysable substrates and contribute to flotation both by cell surface hydrophobicity and emulsifying activity at long mean cell residence times (MCRT). Saprophytic Acinetobacter strains are able to promote flotation by hydrophobicity and producing emulsifying agents under conditions when hydrophobic substrates are predominant. Hydrogenophaga and Acidovorax species as well as members of the Cytophaga/Flavobacterium group are prone to proliferate under low loading conditions and contribute to flotation mainly by emulsification.
Low temperature effects on phosphorus release and uptake by microorganisms in EBPR plants
Authors: Helmer Christine , Kunst Sabine
Published: May 2018

A continuous flow pilot plant with a mixed population of activated sludge was used to investigate the influence of temperatures between 5°C and 20°C on the efficiency of enhanced biological phosphorus removal (EBPR) and on the phosphorus release and uptake mechanisms. Bacterial strains, isolated at different temperatures, were tested for their ability to store polyphosphate. At temperatures of between 15°C and 20°C the uptake of phosphate in the aerobic reactor was correlated directly with the quantity of phosphate released in the anaerobic zone. Mainly aerobic microorganisms were isolated. In batch tests they showed comparatively high polyphosphate storing capacities. There was no indication that Acinetobacter sp. played a dominant role in the processes of EBPR. A drop in temperature to 10°C and then to 5°C had no significant influence on the efficiency of EBPR. In spite of a clearly reduced release of phosphate in the anaerobic zone, the bacterial uptake of phosphate reached unchanged high levels. Because of reduced nitrification at low temperatures, making the anoxic zone into an additional anaerobic zone, facultative anaerobic microorganisms accumulated in the microbial population. They showed the best abilities to store polyphosphate under these conditions, whereas aerobic bacteria lost their polyphosphate storing capacities.
Operation with biological nutrient removal with stable nitrification and control of filamentous growth
Authors: Rothman Maria
Published: May 2018

Bromma WWTP is the second largest wastewater treatment plant in Stockholm, Sweden. To meet new regulations regarding nitrogen removal the plant needs to be operated with nitrogen removal all year round. In previous years, severe bulking problems during the winter have made it impossible to maintain nitrification during colder temperatures. Microscopic examination of the activated sludge has increased the understanding of bulking. The bulking is mainly due to excessive growth of filamentous organisms, mainly Microthrix parvicella. By operating the plant with a high F/M ratio and decreasing the F/M ratio when filamentous growth occurs, excessive growth of these organisms can be avoided. The nitrification rate is optimized by adjusting the concentration of mixed liquid suspended solids in the tanks so that the nitrification is complete and by operating the tanks at a DO concentration of 4 mg/l. By this process strategy it is now possible to operate the plant with nitrification all year round.
Assessment of sediment contamination from pollutant discharge in surface waters
Authors: Kern Ulrich , Li Chen-Chien , Westrich Bernhard
Published: May 2018

Based on theoretical considerations, the pollutant trapping efficiency (PTE) of a river section was introduced to assess sediment contamination from pollutant discharge. Under simplified assumptions, PTE can be calculated by the sedimentation of suspended particulate matter (SPM), the inflowing concentration of SPM and the solid-water partition coefficient Kd. Regarding a more complex field case, a one-dimensional flow and transport model was applied to a lock-regulated section of the Neckar River, Germany. Long-term simulations (1950–1994) were carried out (a) to analyse the temporal development of sediment contamination and (b) to quantify the dependence of the PTE of cadmium on Kd and the Damkoehler number, characterizing the time scale of the adsorption process with respect to the water residence time in the regarded river section. Sediment contamination by Cd shows a strong response to the decrease of Cd emission in the past. In the case of rapid adsorption, sediment contamination increases non-linearly with rising partition coefficient. This agrees qualitatively with the formula derived from theoretical considerations. At the measured kinetic adsorption rates, chemical equilibrium of solid-water partitioning is reached at low to moderate discharge, and sediment contamination in the river reservoir is determined by the hydraulic trapping of the polluted SPM.
The influence of nitrilotriacetic acid (NTA) on metal mobilization from a contaminated river sediment
Authors: Chen Shen-Yi , Liou Chiou-Nan , Lin Jih-Gaw
Published: May 2018

Sediment samples and river water used in this study were collected from a contaminated river, namely, the Lau-Che river located in northern Taiwan, in order to investigate the mobilization of heavy metals from river sediment influenced by NTA in a simulated continuous-flow channel reactor. Concurrently, the kinetic model was applied to describe the mobilization of heavy metals from sediments. When the NTA was first discharged into the reactor, the initial adsorption of NTA by the sediment decreased the mobilization of heavy metals and changed the released behavior of heavy metals. It made bad agreement between models and experimental data. Due to the bacteria were completely acclimated to degrade NTA in the former experiment, the release of heavy metals was significant at the initial addition of NTA and the concentrations of heavy metals in the liquid phase decreased after that the NTA was degraded by bacteria. The maximum mobilization of heavy metals increased with the increase of concentration of NTA. According to the experimental data, the mobilization of heavy metals by NTA appeared to follow multiple first-order reaction model, two constant model, or diffusion model.
Characterisation of PAH-contaminated sediments in a remediation perspective
Authors: Cuypers M. P. , Grotenhuis J. T. C. , Rulkens W. H.
Published: May 2018

To support the choice of a remediation technique for the decontamination of PAH contaminated dredged sediments a characterisation test is needed, that takes into account the physical state in which PAHs occur. Here, solvent extraction is proposed as such a characterisation test. Solvent extraction experiments were performed with a 1/1 acetone-water mixture on (particle size fractions of) PAH-contaminated harbour sludge. The PAHs were more easily dissolved from fine than from coarse fractions, which indicates that the PAHs in the fine fractions are better (bio)available. The results further suggest that PAHs were present in particulate form, absorbed in organic matter and dissolved in oil. The performed extraction experiments provide a basis for further development of existing models.
Characterization of sediments from Copenhagen Harbour by use of biotests
Authors: Pedersen Finn , Bjørnestad Estelle , Andersen Helle Vang , Kjølholt Jesper , Poll Christian
Published: May 2018

The potential environmental hazard of sediment samples from Copenhagen Harbour was investigated by a combination of chemical analyses and biological tests. The chemical analyses comprised determination of the content of heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and the biological tests comprised whole sediment bioassays with the amphipod Corophium volutator, testing of a sediment suspension with the Microtox Solid Phase test, and testing of sediment pore water by the copepod Acartia tonsa and the alga Skeletonema costatum. For all sediment samples, the concentrations of contaminants exceeded the Probable Effect Levels and toxic effects should therefore be expected. However, various degrees of toxicity were determined by the biotests with the Microtox Solid Phase test system being the most sensitive, the amphipod and the copepod being intermediately sensitive, and no toxicity of the pore water was registered to the algae. Moreover, no direct correlation between the content of the contaminants in the sediment samples and the registered toxicity could be established. It is therefore concluded that the combination of biotesting and chemical analysis is a valuable tool for evaluating the environmental risks of sediments.
Sequential risk mitigation and the role of natural recovery in contaminated sediment projects
Authors: Garbaciak Stephen , Spadaro Philip , Thornburg Todd , Fox Richard
Published: May 2018

Sequential risk mitigation approaches the remediation of contaminated sediments in three phases designed to: (1) immediately reduce the ecological and human health risks associated with high levels of contamination, using methods such as the confinement or capping of high-risk materials; (2) reduce the risks associated with moderate levels of pollution to a minimum, on a less urgent schedule and at a lower cost; and (3) address areas of limited contamination through a combination of natural recovery and enhanced natural recovery (to aid or speed those natural processes). Natural recovery, the reduction of contaminant concentrations through natural processes, is based on the practical observation that overall ecosystem recovery appears to be largely a function of time. Sediment decomposition and the mixing of new and old sediments by bottom-dwelling organisms can both contribute to reduced contaminant concentrations. Knowledge of these processes--sediment decomposition, sediment mixing by bottom-dwelling organisms, and chemical residence time is critical in the development of appropriate ecosystem recovery and waste management strategies. Evaluations to support natural recovery predictions are designed to collect and evaluate information necessary to determine whether surface sediment chemical concentrations, with adequate source control, will reach the cleanup standards within a ten-year period.
New technology of mechanical treatment of dredged material from Hamburg Harbour
Authors: Detzner Heinz D. , Schramm Wolfgang , Döring Ulrich , Bode Wolfgang
Published: May 2018

Harbours and water ways can only fulfil their commercial task if there is always sufficient water depth for navigation. Environmental problems have started to influence dredging methods in recent decades. As a logical consequence of a policy giving high priority to environmental protection, Hamburg built the METHA plant (Mechanical Treatment of Harbour Sediments). METHA produces a clean sand product (grain size > 63 μm) which is reused and a contaminated silt fraction (grain size < 150 μm) which is disposed presently. Previous investigations showed that the content of heavy metals and organic contaminants are primarily governed by the grain size. In 1995 Strom- und Hafenbau started a new investigation to produce a further fraction from the METHA silt which can be reused.

The result of laboratory- and pilot-scale research showed the possibility of a further separation at 20 μm grain size. The best result was reached through a two-step separation made by hydrocyclons and spirals. The produced fraction (20–150 μm) is mainly quartz material with a low level of contamination. In February 1996 Strom- und Hafenbau decided to built a test plant in a technical scale. The capacity of the test-plant is 50 t/h based on dry substance The technical concept is integrated into the METHA concept. All aspects of technical feasibility, economy, environment and product reuse will be investigated in the test plant. The results of the early test phase will be presented.
Chances for biological techniques in sediment remediation
Authors: Ferdinandy-van Vlerken Marijke M. A.
Published: May 2018

Biological techniques can be applied in remediation of sediments contaminated with organic pollutants, such as mineral oil, PAH, PCB and chlorobenzenes. Within the period of 1989-1997 several techniques were developed from laboratory to full-scale. The chances for bioremediation lay in the relatively small environmental impact and the low costs of the techniques. Little energy is required, no emissions to soil or air occur and the natural structure of the sediments is not destroyed. The costs vary between 45 (landfarming) and 70 (reactors) Dutch Guilders per ton dry weight. The quality of the product to meet the legal standards for re-use was achieved for some, but not all, of the sediments. However, bioassays and leaching tests showed that bioremediation strongly reduces the ecotoxicity and dispersion risks of the material. Further research of the actual risks, accompanied by policy development of the standards for re-use, might increase the number of different types of sediments which can be successfully remediated by biotechnology.
Field monitoring of ripening of dredged material at three sites in the Netherlands (preliminary results)
Authors: de Haan W. , Otten K. J. , Heynen J. J. M. , Folkerts H. , Elsman M.
Published: May 2018

Ripening of dredged material in a deposit is a natural ‘drying’ process by which raw dredged material transforms into soil. The aim of ripening is to obtain soil which complies with environmental legislations and geotechnical specifications for application in earthworks (e.g. dikes, noise reduction banks, landfill covers).

The paper deals with the background and contents of a monitoring programme on the ripening behaviour of clayey, peaty, and sandy dredged material, and changes in chemical composition, especially of organic compouds, and leaching characteristics during ripening. The main objectives of the monitoring programme are (1) to develop a management system for the ripening process, (2) to quantify the input and output volumes of dredged material, and (3) to develop guidelines for the design of (transit) deposits. The results of the monitoring programme will also be used for calibration and validation of a computer model on ripening. Prelimanary results on ripening of clayey material and biodegration of PAH and mineral oil are presented. On the basis of these results it is expected that large volumes of slightly to moderately contaminated dredged material are suitable for beneficial use after ripening.
Immobilization of heavy metals in sediment dredged from a seaport by iron bearing materials
Authors: Müller I. , Pluquet E.
Published: May 2018

Pot and field trials were carried out using sediment dredged from the port of Bremen (Germany) and deposited in a settling basin near Bremen; the sediment is polluted with Cd and Zn. Five iron-bearing materials were added to the soil (1% pure Fe in soil dry matter) to immobilize the heavy metals: ‘Red mud’ from the aluminium industry, sludge from drinking-water treatment, bog iron ore, unused steel shot and steel shot waste. The pH and CEC were little influenced by any of these treatments, but the NH4NO3 and DTPA extractable amounts of Cd and Zn, and particularly the uptake of Cd and Zn by plants, were markedly reduced. It was demonstrated that red mud and precipitated Fe-bearing sludge were the most effective materials. They caused an increase in the adsorption capacity of the dredged sediment with respect to Cd of about 50%. In the pot trials, NH4NO3 soluble amounts of Cd and Zn in samples of soil treated with these materials were reduced by 50% (DTPA: −20%), while the uptake by plants was reduced by 20–50%. In the field trial, Cd and Zn were immobilized in the soil to a certain extent, but less effect was observed on the concentrations in plants and soil extracts compared with the pot trials. In practice, red mud is unsuitable as it contains large amounts of Cr and Al3+ ions. Therefore, only sludge from drinking-water treatment, as long as the As concentration in it is low, remains as a useful material for immobilizing heavy metals in polluted sediment dredged from a seaport.
Control of filamentous bulking and interactions among sulfur oxidation-reduction and iron oxidation-reduction in activated sludge using an iron coagulant
Authors: Yamamoto-Ikemoto Ryoko , Matsui Saburo , Komori Tomoaki , Bosque-Hamilton Edja Kofi
Published: May 2018

The effect of iron coagulant on control of filamentous bulking and phosphate removal was investigated using a laboratory scale activated sludge process. Sulfate reduction was correlated to activated sludge bulking. When FeCl2 was added to the aeration tank, most of the phosphate was removed. Sulfate reduction and filamentous bulking were also suppressed. The addition of FeCl2 was also effective in suppressing phosphate release and sulfide production from wasted sludge. Interactions among sulfur oxidation-reduction and iron oxidation-reduction were examined in the batch experiments. When FeCl2 was added, iron reducing bacteria outcompeted sulfate reducing bacteria and iron oxidizing bacteria grew predominantly.
Estimation of the competent biomass concentration for the degradation of synthetic organic compounds in an activated sludge culture receiving a multicomponent feed
Authors: Magbanua B. S. , Poole L. J. , Grady C. P. L.
Published: May 2018

Biomass samples from two completely mixed activated sludge (CMAS) systems fed an array of biogenic and synthetic organic chemicals (SOCs) were subjected to microbial enumeration using substrate-specific most probable number techniques to quantify the biomass fractions degrading isophorone, phenol, 4-chlorophenol, 4-nitrophenol, m-toluate, and m-xylene, which individually constituted 1.88–4.30% of the total chemical oxygen demand (COD) in the CMAS feed. The competent biomass fractions ranged from 3.1–6.4%, showing that only a small fraction of the total biomass was responsible for degrading the test SOCs. The efficacy of the influent COD fraction as a predictor of the competent biomass fraction was evaluated. Generally, the influent COD fraction underestimated the competent biomass fraction by a factor of about two. The convergence of degradation pathways for different SOCs could contribute to the discrepancy between the influent COD fraction and the competent biomass fraction for each SOC. An accurate estimate of the competent biomass fraction is essential for correctly predicting system response to transient SOC loads. Using the influent COD fraction to approximate the competent biomass fraction, despite the twofold difference, is still more realistic than assuming that the total biomass is responsible for SOC removal.
New combined system of biological process and intermittent ozonation for advanced wastewater treatment
Authors: Kamiya T. , Hirotsuji J.
Published: May 2018

A new system combining both biological treatment and intermittent ozonation has been developed to reduce excess sludge production with a small amount of ozone. In this system, activated sludge in the aeration tank was circulated via intermittent ozonation. Experimental results have shown that 50% of the sludge generation was cut down with only 30% of the ozone dose required for continuous ozonation. Furthermore, the process had a remarkable effect on maintaining the sludge settling characteristics. The sludge ozonation was almost of little influence on the effluent quality though the slight degradation of effluent quality was observed in few cases. These facts suggested the effectiveness of the newly proposed system for saving costs and stabilizing treatment performance of biological waste water treatment processes.
Treatment of simulated aquaculture water using biofilters subjected to aeration/non-aeration cycles
Authors: Shanableh A. , Hijazi A.
Published: May 2018

The overall objective of this research activity is the development of a fixed-film biological nutrient removal (BNR) biofilter system for the reuse and discharge of a selected aquaculture water. The three stage biofilter system used in the study provided alternating aeration/non-aeration cycles for phosphorus removal in two of the three biofilters. The removal of TOC and ammonia improved as the cycle duration (CD) increased as a result of the reduction in the frequency of the transition periods between the cycles. The system achieved limited net phosphorus removal due to the limited sludge wasting and lack of external organic carbon supplies during phosphorus uptake. However, the phosphorus activity in the system was significant and was modified by the CD. The denitrification activity was coupled with phosphorus uptake and both activities appeared to have been supplied by an internal organic carbon source.

The major challenges of achieving phosphorus removal in the system include: (1) overcoming the deterioration in the performance of the system during the transition period following the start of each new cycle; and (2) wasting the excess biomass following the aeration cycle. Without active sludge wasting, the system behaves as a phosphorus reservoir with a limited storage capacity. On the other hand, frequent sludge wasting may disrupt the performance of the system.
Nitrogen loss in a nitrifying rotating contactor treating ammonium-rich wastewater without organic carbon
Authors: Siegrist H. , Reithaar S. , Koch G. , Lais P.
Published: May 2018

Extensive loss of nitrogen (up to 70% of ammonium oxidized) is observed in a nitrifying rotating biological contactor (RBC) treating ammonium-rich leachate from a hazardous-waste landfill site. Due to pretreatment (precipitation, flocculation, sedimentation, BOD removal, activated carbon adsorption), the DOC is less than 20 mg/l. Heterotrophic denitrification can therefore be excluded. The nitrification rate reaches 3-4 g NH4-N m−2 d−1 at a pH of 7-7.3 in the first two compartments of the three-stage RBC. An increasing partial pressure of oxygen and ammonium concentration favor nitrogen removal over ammonium oxidation. The reduction of nitrite might therefore be strongly coupled with ammonium oxidation. The degradation mechanism is not yet known. Two possibilities are suggested: (i) nitrite produced in the aerobic biofilm layer close to the surface diffuses into deeper anoxic layers of the biofilm and is reduced in parallel with ammonium oxidation similarly to the Anammox process, or (ii) nitrite produced by Nitrosomonas is reduced by NADH2+ generated during hydroxylamine oxidation.
Anaerobic degradation kinetics of acetic acid in the presence of 2,4-dichlorophenol (2,4-DCP)
Authors: Ning Z. , Fernandes L. , Kennedy K. J.
Published: May 2018

Anaerobic degradation kinetics of acetic acid (HAc) in the presence of 2,4-DCP were investigated, using 2,4-DCP acclimated anaerobic granules. The effect of HAc on 2,4-DCP dechlorination was minimal. On the basis of model discrimination, the degradation kinetics of HAc were found to follow uncompetitive inhibition with 2,4-DCP as an inhibitor.
The periodic anaerobic baffled reactor
Authors: Skiadas I. V. , Lyberatos G.
Published: May 2018

The most common bioreactor type used for anaerobic digestion is the Continuously Stirred Tank Reactor (CSTR). The main problem of this reactor type, i.e. the fact that the active biomass is continuously removed from the system leading to long retention times, has been overcome in a number of systems based on immobilization of the active biomass. Two represenstative types are the Upflow Anaerobic Sludge Blanket Reactor (UASBR) and the Anaerobic Baffled Reactor (ABR). The success of these reactor systems rests on the highly flocculated, well settling, compact methanogenic sludge granules which develop in these reactors. A novel reactor type named Periodic Anaerobic Baffled Reactor (PABR) has been designed, offering the following major advantage: it may be operated as an ABR, a UASBR or at an intermediate mode. The PABR hydraulic behavior has been characterized using residence time distribution experiments at different retention times. Simulating the PABR behavior, the dependence of the reactor performance on the switching frequency is determined as a function of the retention time. In particular, it is found that for high retention times the ABR mode is superior, whereas for low retention times, the UASBR mode should be preferred. In order to establish the accuracy of the predictions of the simulation study, the PABR behavior was experimentally verified using three different stable periodic states.
Effect of autothermal treatment on anaerobic digestion in the dual digestion process
Authors: Ward Amanda , Stensel H. David , Ferguson John F. , Ma Gregory , Hummel Stan
Published: May 2018

The performance of two laboratory mesophilic anaerobic digesters was studied to determine if the claims for improved mesophilic anaerobic digestion following autothermal pre-treatment are valid and if the benefits claimed are affected by the mesophilic digester SRT. One digester was fed sludge taken after a full-scale autothermal reactor and the other was fed sludge from the same plant just before the autothermal treatment unit. Autothermal treatment did not significantly increase volatile solids destruction kinetics during subsequent anaerobic digestion. The VS destruction rate was 2.7 to 2.8% per day with or without autothermal treatment. Autothermal pre-treatment did not affect methane production per unit VS destroyed at anaerobic digester SRTs ranging from 6 to 12 days. In the digester fed autothermal sludge, higher alkalinity and lower VFA concentration produced a lower VFA to alkalinity ratio, indicating the autothermal pretreatment has the potential to make anaerobic digester operation more stable compared to anaerobic digestion only. Autothermal pretreatment consistently reduced fecal coliform to below detection limits and fecal coliform remained below detection limits during anaerobic digestion.
Characterization and treatment of effluent from opium alkaloid processing wastewater
Authors: Sevimli M. F. , Aydın A. F. , Sarikaya H. Z. , Öztürk İ
Published: May 2018

Opium is a traditional produce of Turkey planted and harvested under the control of the Government. This study was undertaken to characterize the wastewater from opium alkaloid processing. Thus, the laboratory records of the two stage aerobic biological treatment plant of the Opium Alkaloid factory were evaluated. Following the statistical analysis of the results for the last three years, it was found that the median values of influent COD and BOD5 concentrations were 29,300 mg/l and 15,000 mg/l respectively. Two stage aerobic biological treatment could reduce these values down to 1,132 mg/l and 100 mg/l. Specific wastewater generation was 6.7 m3 per ton of the opium capsule processed.

Experiments conducted at an upflow anaerobic sludge blanket reactor type pilot plant have demonstrated that 70 percent of the incoming COD can be removed anaerobically, and can be considered as a cost effective substitute for the 1st stage of the aerobic treatment.

Post treatment of the effluents of the existing two stage aerobic treatment with ozone resulted in significant color removal and COD reduction.
Removal of heavy metals from sewage sludge by extraction with organic acids
Authors: Veeken A. H. M. , Hamelers H. V. M.
Published: May 2018

Waste water treatment in activated sludge plants results in the production of large amounts of surplus sludge. After composting the sludge can be reused as fertiliser and soil conditioner in agriculture. Compared to landfilling and incineration, utilisation of sludge-compost is a more sustainable treatment because it recycles both nutrients and organic matter. However the high levels of heavy metals in sludge frequently prevent the reuse of sludge compost in agriculture. The extraction of heavy metals from the sludge before composting is therefore a necessary step to achieve a more sustainable sludge treatment. Extraction of heavy metals by inorganic acids and complexing agents has severe drawbacks. Organic acids could be an attractive extracting agent because the extraction can be performed at mildly acidic conditions (pH 3-5) and they are biologically degradable. The extraction was studied for heavy metals Cu and Zn and for competing metals Ca and Fe. The rate of extraction increases for increasing temperature and citric acid concentration. Cu can be extracted for 60-70% and Zn for 90-100% by citric acid at pH 3-4. A first economic valuation of the extraction and subsequent composting process showed that the total costs of the treatment process are below the costs of incineration.
Evaluation of treatability for two textile mill effluents
Authors: Babuna F. Germirli , Soyhan B. , Eremektar G. , Orhon D.
Published: May 2018

The study emphasizes wastewater characteristics of two different textile plants as they apply to biological treatment. Although conventional characterization reveals no major differences, the effluents from the acrylic fiber and yarn dyeing plant exhibit all the properties of a non-biodegradable wastewater. Appropriate pretreatment consisting of partial chemical oxidation with H2O2 reduces its COD content to 700 mg l−1, almost entirely biodegradable whereas COD fractionation indicates that the effluents of the cotton knit dyeing plant contain 9% residual fractions. Experimental investigation shows that most kinetic and stoichiometric properties of both wastewaters are compatible with that of domestic sewage with the exception of a much slower hydrolysis rate.
Treatability study of organic and colour removal in desizing/dyeing wastewater by UV/US system combined with hydrogen peroxide
Authors: Fung P. C. , Huang Q. , Tsui S. M. , Poon C. S.
Published: May 2018

Treatability of a model dye, cuprophenyl yellow RL, in wastewater by the UV/H2O2/Ultrasonication (US) process was studied on a bench-scale UV/US combined reactor. The effects of pH, hydrogen peroxide dosage and US on the oxidation process were investigated, and the performance of the process on colour removal were evaluated. It was found that degradation of the dye followed a pseudo-first-order kinetic model at different pH and hydrogen peroxide dosages. The relationships between the rate constants and pH as well as hydrogen peroxide dosages were established.
Anaerobic manure treatment under extreme temperature conditions
Authors: Nozhevnikova A. N. , Kotsyurbenko O. R. , Parshina S. N.
Published: May 2018

Usually anaerobic treatment of manure is performed as one stage fermentation under mesophilic (30-35°C) or moderate thermophilic (50-55°C) conditions, with the aim to stabilize organic material for the use of digested manure as a fertilizer. The present study was conducted to develop a new approach for manure treatment, which concerned the sanitation of manure and saving energy for its treatment. Laboratory scale experiments were performed on the digestion of cattle and pig manure under psychrophilic conditions (5-20°C) and extreme thermophilic (55-82°C) conditions. Specifically, we were interested in the digestive activities of microbial populations under low and high temperature conditions. Long-term adaptation (or selection) of active psychrophilic microbial communities is essential to perform sufficient manure treatment at low temperatures. Results of this investigation indicated the development and accumulation of a specific microbial populations at high and at low temperatures in both cattle and pig manure. An acclimated methanogenic microbial community active at 5°C was obtained after 1.5-years incubation of cattle manure at low temperatures, prior to digestion under mesophilic conditions. Fermentation under high temperature conditions resulted in the development of a thermophilic acidogenic microbial populations, with the observed accumulation of volatile fatty acids in the liquid fraction of manure. Thus, a two-step anaerobic manure treatment is proposed in which the sanitation of manure and saving energy present: i) acidogenic fermentation at high temperature, ii) separation for solid and liquid fractions, iii) treatment of liquid manure fraction under low temperature conditions.
Thermophilic and mesophilic operation of an anaerobic treatment of chicken slurry together with organic residual substances
Authors: Maibaum C. , Kuehn V.
Published: May 2018

Lab-scale investigations on mesophilic (35°C) and thermophilic (55°C) degradation of a mixed substrate consisting of chicken slurry, organic fraction of municial solid wastes and other co-substrates were carried out. Both the degradation of VSS (volatile suspended solids) and the formation of methane were determined for different raw substrates at several hydraulic retention times between 4 and 20 d. It could be shown that thermophilic operation was advantageous at fermentation times below 20 d regarding methane formation and degradation of VSS. However, the dewatering of the resulting residues of digestion was more difficult than the dewatering process of the mesophilically digested sludge. Due to the shifting of the NH4-NH3-equilibrium under thermophilic conditions the water recycling was complicated. With regard to peak loads the mesophilic system was more susceptible to disturbances than the thermophilic one. Stable mesophilic operation prooved to be possible at hydraulic retention time beyond 8 d.
Use and minimization of water in leather tanning processes
Authors: Tünay O. , Kabdaşlı I. , Orhon D. , Cansever G.
Published: May 2018

Minimization of water use and reuse applications within industry has recently gained importance within the context of water conservation efforts. The leather tanning industry is one of the subject industries due to large amount of water to be disposed of together with a high pollution load. The leather tanning industry has a complex structure in terms of materials, processes and manufacturing practices. Therefore a systematic approach is required to assess water use practice. In this study, bovine leather processing was taken as an example. An extensive study was conducted as on-site evaluations and questionnaires in the İstanbul Organized Leather Tanning District to assess water use practices, patterns and minimization trends. Results of the study were discussed and important aspects of water minimization practices have been pointed out.
Treatment of tannery wastewater in a sequencing batch reactor
Authors: Carucci A. , Chiavola A. , Majone M. , Rolle E.
Published: May 2018

The aim of the research was to study the treatability of tannery wastewater by a sequencing batch reactor (SBR) compared with a continuous flow full scale reactor. The experimental work presented in this paper was carried out on a laboratory scale anoxic-aerobic SBR fed with tannery wastewater coming from a full scale continuous flow treatment plant located in S. Miniato (Pisa, Italy). After a long acclimation period, a complete and stable nitrification has been developed. The denitrification was always performed without any additional carbon source with good results when influent COD/TKN ratio was higher than 8 and with a higher rate compared to that obtained in the continuous plant. When high effluent nitrate occurred, it was due only to stoichiometric (not kinetic) limitations. The organic substrate removal occurred mainly during the anoxic period and a high effluent COD (refractory) was often present at the end of the process. This research has shown the suitability of the industrial wastewater (particularly tannery wastewater) treatment by SBR because of its several advantages compared to the continuous reactors: i.e. a higher versatility and the possibility to work with higher loads (smaller volumes), by selecting, through the cyclic concentration gradients, a biomass resistant to the presence of inhibiting substances (often encountered in industrial wastewaters).
On the performance of a centralised digestion facility receiving seasonal agroindustrial wastewaters
Authors: Gavala H. N. , Skiadas I. V. , Lyberatos G.
Published: May 2018

This work focuses on the anaerobic co-digestion as a method for treating seasonally generated, strong agroindustrial wastewaters. The co-treatment of such wastewaters secures the stable year-round operation of a treatment plant and is economically favorable (smaller capital costs) due to the use of a centrally located facility. Additionally, co-digestion has the benefit of the avoidance of nutrients (N, P) addition when a codigested wastewater contains nutrients in excess. Batch kinetic experiments codigesting piggery, olive-mill and dairy wastewaters have been carried out with piggery, olive-mill and dairy acclimated cultures. The microbial growth kinetics of each culture were calculated and used for comparison purposes. A unified mathematical model describing the co-digestion process has been developed and is capable of predicting the short-term response of a digester subjected to seasonal feed changes.
Emission predictions with a multi-linear reservoir model
Authors: Vaes G. , Berlamont J.
Published: May 2018

For the assessment of combined sewer overflows detailed models are not necessary. Physically based conceptual models give an optimal balance between model uncertainty and uncertainty in the input data. Besides, it is important that continuous long term simulations are performed. To prove this, in this paper the calibration of a reservoir model is discussed. The emission results of the reservoir model are compared with those of a hydrodynamic model. This research shows that a well-calibrated reservoir model can predict overflow emissions as well as a detailed model, taking into account the uncertainties in the input data. Moreover, when a reservoir model is used the calculation times are 104 to 106 times smaller. Such simplified models are an ideal tool to perform quickly various scenario analyses.
Water quality management for the Talkatora Lake, Jaipur – a case study
Authors: Gupta Akhilendra B. , Jain Renu , Gupta Kapil
Published: May 2018

This paper describes the field-based research study undertaken to quantify the pollution, identify the sources of pollution and draw up a plan of action to restore the water quality of the Talkatora Lake located in Jaipur City, capital of Rajasthan State. Laboratory analysis of water samples at different time periods and a mass balance of the lake waters showed that the first flush of stormwater from the adjoining residential and commercial areas was a major cause of pollution in the lake. An integrated waste management strategy to limit the pollution discharged to this lake to enable self-purification was recommended. The mitigation measures were partially implemented and the results of a rapid assessment of the subsequent lake water quality are also reported.
Case study on water quality modelling of Dianchi Lake, Yunnan province, South West China
Authors: Gray A.V. , Li Wang
Published: May 2018

The main aim of this work was to construct and validate a mathematical water quality model of the Dianchi lake, so that by altering input total phosphate (TP) loads the projected changes in the lake water TP concentrations could be estimated. Historical information had indicated deteriorating lake water quality with increasing TP concentrations. The model was based on a simple annual mass balance, relying on 3 years (wet, average and dry) data with all TP loads quantified, 7 years of lake water quality, and 36 years of flow data. All lake processes were considered within a single variable, R. Planning TP removal at STWs and within fertilizer plants, coupled with interventions to reduce non-point TP loads from all land run-off by 50%, suggested future lake water TP concentrations could be stabilised at about 0.3 mg TP/l, i.e. the estimated limit for producing algal concentrations that would cause major problems in water treatment plants. The TP load reductions envisaged as realistic would only stabilise the lake water quality by about the year 2008; interventions, unfortunately, could not return the lake to its former pristine condition. The accuracy of the predictions was ± 0.1 mg TP/1, so collection of better data was needed.
Arsenic in drinking water-problems and solutions
Authors: Viraraghavan T. , Subramanian K. S. , Aruldoss J. A.
Published: May 2018

The current United States maximum contaminant level for arsenic in drinking water is set at 50 μg/l. Because of the cancer risks involved, Canada has already lowered the maximum contaminant level to 25 μg/l; the United States Environmental Protection Agency is reviewing the current allowable level for arsenic with a view of lowering it significantly. Various treatment methods have been adopted to remove arsenic from drinking water. These methods include 1) adsorption-coprecipitation using iron and aluminum salts, 2) adsorption on activated alumina, activated carbon, and activated bauxite, 3) reverse osmosis, 4) ion exchange and 5) oxidation followed by filtration. Because of the promise of oxidation-filtration systems, column studies were conducted at the University of Regina to examine oxidation with KMnO4 followed by filtration using manganese greensand and iron-oxide coated sand to examine the removal of arsenic from drinking water; these results were compared with the data from ion exchange studies. These studies demonstrated that As (III) could be reduced from 200 μg/l to below 25 μg/l by the manganese greensand system. In the case of manganese greensand filtration, addition of iron in the ratio of 20:1 was found necessary to achieve this removal.