bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishing procedures for design, operation and maintenance of sewage sludge anaerobic treatment plants
Authors: Killilea J.E. , Colleran E. , Scahill C.
Published: May 2018

In 1993 the Irish Government commissioned a strategy study to address the difficulties encountered with sludge management and disposal in this country. Many Local Authorities have complied with the recommendations of this strategy study by incorporating Anaerobic Digestion (AD) of sewage solids in the design of new and retrofitted sewage treatment plants. Irish Local Authorities have little experience in anaerobic technologies compared to the more traditional mechanical and aerobic processes. The United States Environmental Protection Agency (US EPA) developed procedures for evaluating sewage treatment plants. These Comprehensive Performance Evaluations (CPE) are described in such publications as “Retrofitting Publicly Owned Treatment Works (1989)”. The emphasis in such documentation was on aerobic secondary treatment processes. The present study developed an evaluation procedure for AD plants similar to the CPEs produced by the US EPA for secondary processes. This procedure was applied to existing and newly commissioned AD plants in Ireland in order to deduce process performance. Based on these studies, recommendation for the design, operation and maintenance of AD plants is presented. All plant operators agreed that frequent and accurate monitoring of pH and temperature was essential for adequate process control. The five existing sites were surveyed. Apart from the usual difficulties at start-up, plant operators expressed satisfaction with the anaerobic process at four of the sites. The fifth plant is currently being upgraded.
Biological odour control by diffusion into activated sludge basins
Authors: Bowker R. P.
Published: May 2018

Diffusion of odourous air into activated sludge basins is an effective and economical approach for odour control at wastewater treatment plants. Over 30 facilities in North America practice this technique. Most of these applications are for dilute or moderate strength air streams with relatively low hydrogen sulfide (H2S) levels. Unfortunately, the lack of data documenting the effectiveness of the process and concerns for blower corrosion have limited its acceptance as a method for controlling odour emissions.

This paper presents a compilation and review of wastewater treatment facilities that are currently using activated sludge diffusion. Performance data are tabulated, and information on operation and maintenance of the blower/diffuser systems are summarized. New data are presented that compare the effectiveness of coarse vs. fine bubble diffusers for treatment of a high strength, high-H2S air stream from sludge holding tanks at Concord, NH.

Designand performance information is presented on a dedicated odour control system installed at Phoenixville, Pennsylvania in 1996 that collects high-H2S air streams from an influent chamber and primary clarifiers and diffuses it into a mechanically-aerated activated sludge basin. A cost-effectiveness analysis is presented for a blower/diffuser system installed exclusively for odour control. Methods used to overcome initial operational problems are discussed.
Bromate formation under ozonation conditions to inactivate Cryptosporidium
Authors: Amy G. , Douville C. , Daw B. , Sohn J. , Galey C. , Gatel D. , Cavard J.
Published: May 2018

Ozonation has emerged as the most effective disinfectant for inactivation of Cryptosporidium, the controlling microorganism in drinking water treatment. However, ozonation of waters containing bromide also produces bromate ion, a regulated DBP, leading to possible tradeoffs between microbial and chemical risk. Since higher O3 doses will be necessary, even relatively low-bromide waters may become problematical. Whileeffective disinfection cannot be compromised, there are methods for controlling bromate, providing a means of reducing overall risk.
Cryptosporidium contamination hazard assessment and risk management for British groundwater sources
Authors: Morris B. L. , Foster S. D.
Published: May 2018

Contamination of aquifers by Cryptosporidium oocysts has only recently been recognised as a risk to the security of important groundwater-based drinking water supplies in the UK. The predominance of dual porosity aquifers with complex flow systems, the fact that UK water utilities hardly ever own or control the catchments overlying the aquifer supplying their abstractions and the diverse designs of the wells/springs themselves renders hazard assessment necessary but not simple. A tripartite approach is proposed which is a modification of standard contaminant transport source→pathway→receptor principles. The complex interaction of factors and uncertainty of underpinning data greatly limit the applicability of a strictly numerical approach to risk assessment. Instead the importance is emphasised of understanding the blend of hydrogeological and operational factors which makes each site and its setting unique.
UKWIR initiatives for implementing expert group recommendations to minimise Cryptosporidium risk in water treatment—a summary review
Authors: Hall T. , Head R. , Holt D.
Published: May 2018

The UK Expert Group on Cryptosporidium in Water Supplies provided recommendations to the Water Industry on optimising water treatment for the removal of oocysts. UK Water Industry Research Ltd (UKWIR), on behalf of the UK Water Utilities, commissioned research to facilitate the implementation of these recommendations. This involved extensive pilot plant trials, the results of which were disseminated through research reports and workshops. The findings of the research were also included in a water treatment manual which provided more detailed operational guidance to supplement the Expert Group recommendations. A brief overview of this research is provided, with examples of the findings to illustrate thenature of the operational guidance in the manual.
Influence of US EPA 1622 method successive steps on the viability of Cryptosporidium oocysts
Authors: Guyot K. , Gireaudot-Liepmann M. F. , Cabon A. , Riveau-Ricard I. , Lange M. , Delattre J. M. , Dei-Cas E.
Published: May 2018

Viable Cryptosporidium parvum oocysts were processed by the US EPA 1622 method to determine if the procedure that requires successive filtration, elutionand centrifugation alters their integrity and viability (determined by in vitro excystation). Oocyst seeded in tap water samples were also used to evaluate recovery efficiencies and impact of the whole procedure on oocyst viability. Filtration through Envirochek Gelman cartridge was found not to damage oocysts. The use of Laureth-12 buffer during the elution step was shown to lead to greater spontaneous oocysts excystation than other phosphate buffers containing between 80 and/or SDS (like the Gelman buffer). However, this drawback was widely balanced against the best efficiency of this buffer to elute oocysts captured by the cartridge filter and therefore against its high recovery efficiency. Thus, in water samples in which the oocyst concentration is expected to be low, it is more advantageous to employ the Laureth-12 buffer for the elution through it can influence viability. Centrifugation speeds (1,000–5,000 g) did not alter oocysts.
The characterisation of slurry dewatering
Authors: Aziz A. A. , de Kretser R. G. , Dixon D. R. , Scales P. J.
Published: May 2018

The dewatering of flocculated suspensions presents a significant challenge to water and waste water processing operations world-wide. Traditionally the dewatering process is enhanced through the use of flocculants or a surface chemical modifier to draw together fine particles and increase settling rates and sediment permeabilities, however, present methods of gauging chemical performance are somewhat empirical. Recently, Landman and White developed a theory of suspension filtration which incorporates the compressibility and permeability of a sediment into a filtration diffusivity, D(φ). D(φ) is a material property used to calculate the time scale of a dewatering process from first principles for a given set of process conditions i.e. final desired solids concentration, applied pressure, initial sediment height. A model alumina system and an alum water treatment sludge have been used to show the effect of flocculation conditions on compressibility, permeability (determined from filtration experiments) and the diffusivity, D(φ).
Disintegration as a key-step in sewage sludge treatment
Authors: Müller J.
Published: May 2018

Fields of application of the mechanical sewage sludge disintegration are presented. Various methods of mechanical cell disintegration are described and the obtained results are compared. All methods are able to break up the flocs, but only some of them provide enough energy for the disruption of micro-organisms. The possible improvement of the anaerobic degradation process using raw sludge, excess sludge and digested sludge is shown. Excesssludge proves to be the most suitable. The use of disintegrated sludge as a carbon source for the denitrification is explained as a second field of application. External carbon sources can be substituted and the amount of sewage sludge to be disposed of is reduced at the same time. Foamingin digesters caused by filamentous micro-organisms can be reduced by disintegration of these sludges. Adsorbed gas bubbles are released and the settling properties of the sludge are improved. Another field of application is the solution of organic components of the sludge solids. The increased concentration of nitrogen and phosphorous in the supernatant causes recovery processes to be operated at a higher cost efficiency. A comparison of effort and advantages shows that disintegration is especially useful if there are problems in the sludge treatment process of the WTP.
Assessment of sludge reuse options: a life-cycle approach
Authors: Bridle T. , Skrypski-Mantele S.
Published: May 2018

This analysis suggests that a holistic or life-cycle approach be taken when assessing the long-term sustainability of sludge reuse options. Issues such as compliance with world best practice environmental/health standards, energyusage, greenhouse gas emissions, odour control and volume reduction must now be taken into account when assessing the long-term sustainability and public acceptability of the various management options. Four major criteria for the assessment of sludge reuse options are proposed and five management options are assessed using these criteria. The results indicate that traditional land application reuse options must be evaluated in more detail to confirm whether they offer a long-term sustainable management option. Newer thermal based management options may however provide long-term sustainable management options.
Enhancing the removal of ammonia in nitrifying biofilters by the use of a zeolite containing expanded clay aggregate filtermedia
Authors: Gisvold B. , Ödegaard H. , Föllesdal M.
Published: May 2018

Pilot plant experiments were carried out on a nitrifying biofilter with a zeolite containing expanded clay aggregate filtermedia (Filtralite ZL). The filter removed ammonium from domestic wastewater by a combination of nitrification and ion exchange. An identical filter material, but without sorptive capacity with respect to ammonium, was used as a reference (Filtralite). The experiments demonstrated that Filtralite ZL removed more ammonium at high ammonium loading rates than Filtralite. This was caused by ion exchange of ammonium in addition to nitrification. Under low ammonium loading rates, nitrification of already sorbed ammonium took place. This combined effect of ion exchange and nitrification of ammonium in Filtralite ZL was demonstrated in experiments with constant ammonium loading for periods up to 10 days and as well as in experiments with daily variations in ammonium loading rate. No chemical regeneration was necessary in addition to the biological regeneration during the experimental period of four months.
Effect of sludge cell disruption on compactibility of biological sludges
Authors: Erdincler A. , Vesilind P. A.
Published: May 2018

Biological sludge contains various fractions of water associated with sludge solids which are mostly microorganisms. These water fractions affect the liquid-solid separation of sludge. A considerable amount of sludge water is trapped either inside the sludge microorganisms or within the floc structure and this is labeled interstitial water. Release of interstitial water held inside the cell structure involves disruption of sludge cells and this does not occur during conventional dewatering. In this study, sludge cell disruption is introduced as a new method to improve the compactibility of sludge. Biological sludge cells are disrupted by different methods including alkali treatment, NaCl treatment, heat treatment, and sonication. The effect of cell disruption on compactibility of biological sludge is investigated. The results of the study indicate that the disruption of the sludge cells changes the water distribution in sludge and improves the compactibility of sludge. Disruption apparently releases from 60% to 80% of interstitial water, depending on the disruption method used. On the other hand, it causes creation of extra surfaces for water binding and leads to an increase in the unfreezable water content (vicinal water, water of hydration and a fraction of interstitial water) of sludge. The cell disruption increases the solid content of compacted sludge up to 87% depending on the cell disruption method used.
Basic investigation on the chemical forms of heavy metals in a sewage treatment plant
Authors: Morita H. , Tsuboi H.
Published: May 2018

Sewage sludge mainly consists of organic matter, and it is rich in nutrients. Therefore, sewage sludge is beneficial as an energy resource and as a raw material for fertilizer. However, heavy metals in it are the obstacle to utilization of sludge. This study was conducted in order to know the chemical forms of heavy metals and their behavior in a sewage treatment plant as a basic study for development of technology to reduce heavy metals in sludge.

Chemical methods and biological methods, such as extraction using acid, bacteria leaching, are applied to reduce heavy metals. In using these methods, the efficiency depends on the chemical forms of heavy metals. From this point of view, factors, which affect the chemical forms of heavy metals, were investigated through the survey at some plants of different conditions. Besides, experiments on the anaerobic digestion process, in which the chemical forms of heavy metals were expected to change, were conducted.

As the results of these studies, it was found that the chemical forms of heavy metals and their behavior vary according to the species of heavy metals. In comparison of zinc (Zn), copper (Cu) and nickel (Ni), Cu was found to be changed most easily into a stable chemical form such as carbonate and sulfide. Zn was the second to Cu in its tendency to be stabilized. As for Ni, the tendency was further less than Zn.
Agricultural utilisation of lime treated sewage sludge
Authors: Akrivos J. , Mamais D. , Katsara K. , Andreadakis A.
Published: May 2018

Over one growing season, lime treated dewatered sludge was applied to pot and field cotton cultivation at rates of 0, 10, 20 and 30 t/ha to determine the effects of sludge agricultural reuse on physical and chemical soil properties, on soil and plant heavy metal content and on plant production. In most cases total N and total and soluble P content of the soil increased with addition of sludge. Maximum pH increase caused by addition of lime treated sludge to alkaline soils did not exceed 0.2. Heavy metal content in all plant tissues and soil samples did not increase significantly as a result of sludge amendment. Plant yields increased significantly with sludge addition for the three alkaline soils used in this study. A low plant productivity observed with one of the soil types studied, was attributed to the high concentration of Ni in the soil and the low nutrient content of the soil.
Biological treatment of potato-starch wastewater – design and application of an aerobic selector
Authors: Nikolavcic B. , Svardal K.
Published: May 2018

The effluent of a potato-starch factory is separately treated in a two-stage activated sludge plant. The occurrence of bulking sludge in the second biological stage due to excessive growth of type 021N was repeatedly observed. The installation of an aerobic selector, consisting of three cascades, prior to the aeration tank of the second stage, where the return sludge and all the influents flow together, has been effective in improving the SVI to values below 150 ml/g. The design procedure was carried out in accordance with Prendl's work, with a simple calculation method based on findings derived from aerobic treatment of sugar mill wastewater.
Co-incineration of dried sewage sludge in coal-fired power plants: a case study
Authors: Luts D. , Devoldere K. , Laethem B. , Bartholomeeusen W. , Ockier P.
Published: May 2018

With the ongoing investment in sewage treatment capacity in Flanders (Belgium), a new challenge is the management of the rising amount of sludge. Since sludge disposal to agriculture and landfill is regularly becoming very difficult, alternative thermal disposal routes become more important. This paper presents the results of the various co-incineration tests with dried sludge in coal-fired power plants. The aim of this project was to investigate whether adding dried sludge to the combustion process is technically possible, whether the emissions remain below the permitted levels, and whether the quality of residual products remains acceptable. It is concluded that the co-incineration of dried sludge is a valuable and responsible sludge disposal option because it can be carried out in the existing units with a high electrical efficiency. Also, sludge disposal is achieved with a limited influence on emissions and residual ashes, without creating additional waste streams. The main points of attentionare a limitation of the co-incineration rate and the total input of sulphur, chloride and (earth) alkali elements to avoid corrosion and fouling problems.
Biodegradation of di-(2-ethylhexyl) phthalate in sewage sludge
Authors: Cheng H. F. , Chen S. Y. , Lin J. G.
Published: May 2018

Di-(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in the production of polyvinyl chloride to impart flexibility to the product. Because of its mutagenicity and carcinogenicity, the presence of DEHP in sludge limits the application of sludge as a soil fertilizer. In this study, sludges were collected from three sewage treatment plants and thirteen wastewater treatment plants of different industries in Taiwan. A supercritical fluid extraction (SFE) was first established as an effective method for determining the concentration of DEHP in sludge. Laboratory-scale land-simulated experiments were performed to investigate the biodegradation of DEHP in sludge under various conditions (moisture, temperature, sunlight and ventilation). DEHP was found in aerobically and anaerobically digested sludges and their values significantly exceeded the restricted concentration of DEHP for sludge land application. DEHP was found to degrade in sludge under the conditions of good ventilation, sufficient sunlight and proper moisture. The indigenous microorganisms in the sludge appeared to dominate the biodegradation of DEHP in sludge. However about 70% of DEHP remained in sludge after 189 d indicating that DEHP is persistent in the environment.
Design and performance of powdered activated carbon/ultrafiltration systems
Authors: Snoeyink V.L. , Campos C. , Mariñas B.J.
Published: May 2018

The use of powdered activated carbon in combination with ultrafiltration membranes is attracting increasing interest for the removal of organic micropollutants in drinking water treatment. The overall adsorption efficiency of this hybrid treatment process strongly depends on the reactor configuration and its operating conditions. Identification of the operating conditions yielding optimum carbon performance can be facilitated by the use of mathematical models describing the adsorption process. In this study, the effect of various design and operating parameters on the efficiency of the adsorption process is discussed using an adsorption model previously developed and verified by the authors. This discussion includes the effect of filtration time, membrane reactor volume, carbon dosing procedure, and the effect of dosing the carbon in reactors installed in series upstream of the membrane reactor.
Reduction of azo dyes by desulfovibrio desulfuricans
Authors: Yoo E. S. , Libra J. , Wiesmann U.
Published: May 2018

Azo dyes are widely used in textile finishing, and have become of concern in wastewater treatment because of their color, bio-recalcitrance, and potential toxicity to animals and humans. Thus, wastewater with azo dyes must be decolorized and furthermore mineralized in appropriate systems combining biological and chemical processes. In this study, the potential for sulfate reducing bacteria (SRB) to decolorize azo dyes was studied, employing the pure culture of Desulfovibrio desulfuricans (D. desulfuricans) with varying sulfate levels. Under sulfate-rich conditions, the sulfide produced from sulfate respiration with pyruvate (electron donor) by D. desulfuricans chemically decolorized the azo dyes C. I. Reactive Orange 96 (RO 96) and C. I. Reactive Red 120 (RR 120). Under sulfate-depleted conditions (≤0.1 mmol/L), the decolorization of RO 96 and RR 120 occurred in correlation with the fermentation of pyruvate by D. desulfuricans. It is suggested that the electrons liberated from the pyruvate oxidation were transferred via enzymes and/or coenzymes (electron carriers) to the dyes as alternative terminal electron acceptors, giving rise to decolorization, instead of to the protons (H+), resulting in the production of H2. Both decolorization pathways were compared in light of bioenergetics and engineering aspects.
Structure and function of nitrifying biofilms as determined by in situ hybridization and the use of microelectrodes
Authors: Okabe S. , Watanabe Y.
Published: May 2018

Time dependent development of the spatial organization of NH4+- and NO2−-oxidizing bacterial populations in a domestic wastewater biofilm and in an autotrophic nitrifying biofilm were investigated by fluorescent in situ hybridization (FISH) with a set of 16S rRNA-targeted oligonucleotide probes. Population dynamics of nitrifying bacteria in the biofilms were correlated with the biofilm performance. In situ hybridization indicated that Nitrosomonas spp. (excluding probe NEU stained NH4+-oxidizing bacteria: i.e., N. marina-lineage, N. europaea-lineage, N. eutropha, and N. halophila) and Nitrospira-like bacteria were the numerically dominant nitrifying species in the domestic wastewater biofilm. However, probe NEU stained NH4+-inoxidizing bacteria became dominant populations in the autotrophic nitrifying biofilm (which were initially cultured with the primary settling tank effluent) after switching to the synthetic media. This population shift might be attributed to the effect of NO2−-–N accumulation and higher growth rates of N. europaea-lineage and N. eutropha, outcompeting other Nitrosomonas spp. in the synthetic medium. This evidence indirectly supports that N. europhaea has been most commonly isolated and studied in most of the previous researches.

For the spatial organization of NH4+- and NO2−-oxidizing bacterial populations, bacteria of the genus Nitrobacter could not be detected, instead Nitrospira-like bacteria were found as the main nitrite-oxidizing bacteria in both biofilms. Whereas most of the ammonia-oxidizing bacteria were found throughout the biofilms, the location of nitrite-oxidizing bacteria was restricted to the active nitrite-oxidizing zone, which was detected in the inner part of the biofilms.

Microelectrode measurements showed that the active ammonia-oxidizing zone was located in the outer part of a biofilm, whereas the active nitrite-oxidizing zone was located just below the ammonia-oxidizing zone and overlapped the location of NO2−-oxidizing bacteria, as determined with FISH. These observations have considerable significance to our understanding of microbial nitrification occurring in wastewater treatment processes and in the natural environment.
Anaerobic production and degradation of volatile fatty acids in low temperature environments
Authors: Nozhevnikova A. N. , Rebak S. , Kotsyurbenko O. R. , Parshina S. N. , Holliger C. , Lettinga G.
Published: May 2018

Anaerobic conversion of organic matter leads to the intermediate formation of volatile fatty acids (VFA), primarily butyrate, propionate and acetate. The present investigation examined methanogenesis from the VFA by microbial populations associated with natural and man-made cold habitats. Sites that were investigated included lake sediments, tundra wetland soil, sludge lagoons, manure store and anaerobic reactors operated at 3–9°C. Sharp increases in methanogenesis from VFA were observed as incubation temperatures were increased to 30°C. Low temperatures resulted in significant methane production, and butyrate was identified as an important VFA intermediate formed and degraded during sample incubations. The addition of butyrate and propionate to samples indicated that butyrate is degraded preferentially over propionate. Dilution of samples and, hence, microbial populations led to the accumulation of acetate and hydrogen when butyrate and propionate were degraded. Thus, at low temperatures, a highdensity of hydrogen- and acetate-utilizing methanogens is needed for methanogenesis from VFA to occur. An aggregation of proton-reducing acetogenic bacteria and methanogens accelerates this process.
Organic and nitrogen removal with minimal COD requirement by integration of sequestered denitrification and separate nitrification in a low-loaded activated sludge process
Authors: Shin H.-S. , Nam S.-Y.
Published: May 2018

A separate sludge system incorporating sequencing batch reactor (SBR) for sequestered denitrification and an immobilized fixed-film reactor for nitrification was investigated in this study. Emphases were placed on the preservation of organic matter as an electron donor for denitrification and the improvement of nitrification efficiency by using an immobilization technique with alginate coating. To preserve organic materials in the sludge required for denitrification, a study was made with a contact process. The contactor, when operated with a short detention time, gave incomplete metabolism of organic matter. With 64% of the influent soluble chemical oxygen demand (SCOD) was adsorbed to activated sludge within 30 min. The specific mass of organic matter uptaken was 55 mg SCOD/g mixed liquor suspended solids (MLSS), which enhanced the denitrification efficiency up to 63% in the following denitrification step. Thus, the required COD in the proposed system can be saved up to 63% as an available electron donor for the conventional aerobic process. The immobilized nitrification unit showed over 90% of nitrate production rate up to 50 mg/l of influent ammonia load.
Measuring wastewater quality using a sensor array: prospects for real-time monitoring
Authors: Bourgeois W. , Stuetz R. M.
Published: May 2018

The application of using a chemical sensor array to analyse the headspace gas generated from a sparged sample was evaluated. Wastewater samples were sparged with N2 gas in a temperature controlled flow-cell, the headspace gas was then supplied (using a temperature controlled transfer line) to the sensor array for analysis by 12 polypyrrole sensors. Multivariate analysis of the sensor array data (using principal component and multiple discriminant analysis) showed that the different sample types (RO water, raw sewage and final effluent) were separated into distinct clusters. These results demonstrate that the sensor array analysis of an externally generated headspace gas can be used to monitor for changes in wastewater quality and could provide a simple non-invasive technique for real-time wastewater monitoring.
Appropriate process and technology for wastewater treatment and reclamation in China
Authors: Qian Y.
Published: May 2018

China faces a significant challenge resulting from its rapid industrial development, and population and urban growth. Increasing water pollution is compounded by below average per capita freshwater resources. This article examines examples of appropriate processes and technologies that are being applied: natural purification systems (including land application and pond systems), anaerobic biological treatment, biofilms and membrane bioreactors.
Knowledge-based supervision and control of wastewater treatment plant: a real-time implementation
Authors: Baeza J. A. , Ferreira E. C. , Lafuente J.
Published: May 2018

The hardware architecture and the software development of a real-time knowledge-based distributed control system for the supervision of a wastewater treatment pilot plant are presented. The operation scheme is based on an A2/O system (anaerobic, anoxic, oxic) and includes organic matter removal, nitrification/denitrification, and Enhanced Biological Phosphorous Removal (EBPR). The hardware architecture involves different supervision levels, including two autonomous process computers (plant control and analysers control) and a PLC. The software architecture includes a Knowledge-Based Expert System (KBES) as the top control system. The KBES has been developed in G2, an expert system development environment based on object-oriented structural design. This system is fed with data obtained from the plant monitoring (in-line, on-line and off-line data) and with actuation data of the lower control levels. Using this information, the KBES supervises the pilot plant in order to help with fault detection and plant maintenance, but also modifies setpoints and other variables of the local control level to adapt the system to the different influent conditions. The overall system has been implemented and validated at pilot scale.
Hydrogen fermentation of organic municipal wastes
Authors: Noike T. , Mizuno O.
Published: May 2018

Hydrogen gas is recognized as a promising energy resource in the future. Microbial hydrogen fermentation would be an attractive process for hydrogen recovery. In particular, hydrogen production using fermentative bacteria has some advantages such as a high rate of hydrogen production without light. In this study, the hydrogen production from organic wastes was investigated using batch experiments. Bean curd manufacturing waste, rice bran and wheat bran were used as the organic wastes. The effects of solid concentration on the hydrogen production potential and the characteristics of substrate decomposition were investigated. The percentages of hydrogen in the produced gas were between 54–78%, 43–68% and 42–72% for bean curd manufacturing waste, ricebran and wheat bran, respectively. The hydrogen production potentials of bean curd manufacturing waste, rice bran and wheat bran were 14–21, 31–61 and 10–43 ml.g VS−1, respectively. The hydrogen yields from carbohydrate degradation were 2.54, 1.29 and 1.73 mol of H2 mol−1 of hexose for bean curd manufacturing waste, rice bran and wheat bran, respectively. The carbohydrate was rapidly consumed just after inoculation. On the other hand, soluble protein was hardly degraded for each substrate, indicating that carbohydrate was the main source of the hydrogen production.
Minimization of activated sludge production by chemically stimulated energy spilling
Authors: Chen G.-H. , Mo H.-K. , Saby S. , Yip W.-k. , Liu Y.
Published: May 2018

Minimization of excess sludge production in activated sludge processes has been pursued around the world in order to meet stringent environmental regulations on sludge treatment and disposal. To achieve this goal, physical, chemical, and biological approaches have been proposed. In this paper, a chemical compound, 3,3′,4′,5-tetrachlorosalicylanilide (TCS) was tested for enhancing microbial energy spilling of the sludgeso as to minimize its growth. In order to examine this, an exploratory study was conducted using both batch and continuous activated sludge cultures. Batch experiments with these two cultures were carried out at different initial concentrations of TCS. It has been confirmed that an addition of TCS is effective in reducing the production of both the sludge cultures, particularly the continuous culture where the observed growth yield was reduced by around 70%, when the initial TCS concentration was 0.8 ppm. Meanwhile, the substrate removal activity of this culture was found not to be affected at this TCS concentration. To further evaluate the TCS effect, a pure microbial culture of E. coli was employed. Batch experiment results with this culture implied that TCS might be able to reduce the cell density of E. coli drastically when an initial TCS concentration was greater than 0.12 ppm. It was also found that TCS was not toxic to this type of bacteria. Microscopic examinations with a 4′, 6-diamidino-2-phenylindole (DAPI) staining technique revealed that TCS neither affected the cell division nor altered the cell size of E. coli. However, both the cell ATP content and the cell dry weight were reduced significantly with the addition of TCS.
Removal and recovery of heavy metals by bacteria isolated from activated sludge treating industrial effluents and municipal wastewater
Authors: Leung W. C. , Wong M.-F. , Chua H. , Lo W. , Yu P. H. F. , Leung C. K.
Published: May 2018

A total of nineteen metal-resistant and non-resistant bacteria from activated sludge treating both metal-contaminated industrial effluents and municipal wastewater were isolated and identified. These included both Gram-positive (e.g. Micrococcus) and Gram-negative (e.g. Pseudomonas) bacteria. The biosorption capacity of these strains for five different heavy metals (copper, nickel, zinc, lead and chromium) was determined at pH 5 and initial metal concentration 100 mg/L. Pseudomonas pseudoalcaligenes and Micrococcus luteus were found to be capable of removing significant amounts of copper and lead. Hence, they were selected for further investigations. Langmuir adsorption isotherms adequately represented the distribution of copper and lead for both species. The study of pH effect on metal removal for both species indicated that the metal biosorption increased with increasing pH from 2 to 6. The effect of competing cations on biosorption of P. pseudoalcaligenes was studied. Sulphuric acid (0.05 M) was the most efficient desorption medium among the eleven reagents tested. Over 90% of copper sorbed on the cells of M. luteus could be recovered by washing with 0.05 M sulphuric acid within five minutes. The biosorbent was used for at least five biosorption and desorption cycles without loss of copper removal capacity. Immobilization of M. luteus in 2% calcium alginate and 10% polyacrylamide gel beads increased copper uptake by 61%.
Factors affecting bioleaching of metal contaminated sediment with sulfur-oxidizing bacteria
Authors: Chen S. Y. , Lin J. G.
Published: May 2018

Bioleaching is one of the feasible methods for the treatment of sediments contaminated with heavy metals. Effects of solid content, substrate (sulfur) concentration and pH on the performance of bioleaching process were investigated in this study. It was found that rates of sediment acidification and metal solubilization decreased with increasing solid content. Besides, sulfur concentration greater than 5 g/l was found to be inhibitory to bacterial activity and metal solubilization from sediment. It was concluded that a substrate concentration of 5 g/l in reactor was the optimum concentration for bioleaching process. It was also observed that solubilization of heavy metal from the sediment was highly pH-dependent. For all values of solid content and sulfur concentration tested, the efficiency of metal solubilization from sediment followed the order Cu>Zn>Pb>Cr.
The Hula project: N and P dynamics in Lake Agmon and pollutants removal from the Kinneret inputs
Authors: Gophen M.
Published: May 2018

During the 1950s the natural Lake Hula and swamps were dried and more than 65×106 m2 of wetland area with a unique natural composition of fauna and flora was turned over to agricultural use. Forty five years later 5.5×106 m2 of this area went through processes causing soil deterioration and a reclamation project was proposed for these soils. The proposal was implemented aimed at ensuring income resource to the land owners and to remove pollutants from the Lake Kinneret inputs. It was found that the newly created (1994) Lake Agmon is acting as a nitrogen sink and the phosphorus is recycled by submerged macrophytes. Long term records of nutrient influx from the catchment (with Hula Valley being major contributor) into Lake Kinneret indicates a decline of organic nitrogen and an increase of SRP. The potential effect of nutrient loads reduction by the Hula Project is presented.
Nutrient pollution at the lower reaches of Mediterranean coastal rivers in Israel
Authors: Herut B. , Kress N. , Hornung H.
Published: May 2018

This study represents the first attempt to evaluate the nutrient load introduced into the coastal waters by the rivers along the Mediterranean coast of Israel. Measurements of nutrient concentrations (phosphate, ammonium, nitrate, nitrite, silicic acid) at two or three stations along the lower river reaches (11 rivers) were carried out annually from 1990 up to 1998. Combining the nutrient concentrations with the monthly riverine discharges we assessed the nutrient load. In general, most of the coastal rivers contain high nutrient contamination level, compared to the criteria adopted by NOAA (USA) for coastal river estuaries. The high degree of contamination is attributed to extreme low natural flow combined with the discharge of domestic and industrial wastes, and with agriculture runoff. In terms of nutrient concentrations, the Kishon River is the most polluted, followed by the Soreq, Poleg and Alexander Rivers. The preliminary estimate is that the coastal rivers transport between ~2000 to 6000 tons of dissolved inorganic nitrogen (DIN) and between ~250–800 tons of dissolved inorganic phosphorus (DIP) to the sea. An additional 3500 and 3000 tons of DIN and DIP, respectively, are supplied through the Kishon River. The load of the Poleg River is unknown (no discharge data) but expected to be significant based on nutrient concentration measured. The total load of the coastal rivers constitutes a major component among the other land-base point sources such as the Gush Dan outfall. Our estimate probably represents minimal values, as it does not include diffused input of agricultural runoff nor the riverine particulate and dissolved organic nutrient loads (which are unknown).
Ammonium removal from primary and secondary effluents using a bioregenerated ion-exchange process
Authors: Lahav O. , Green M.
Published: May 2018

A new process for ammonia removal from sewage effluents is presented. The process uses an ion exchange material, zeolite, both as the separator of NH4+ from the wastewater and also as the carrier for a nitrifying biomass. The process is carried out in a single reactor operating in two modes: an adsorption mode in which the zeolite column acts as a typical ion exchanger and a bioregeneration mode in which the bacteria attached to the zeolite oxidizes the NH4+ to NO3–. The separation between carbonaceous removal and NH4+ removal enables the exclusive selection of nitrifiers at high concentrations attached to the zeolite, thus achieving high bioregeneration rates. This paper summarizes three years of research on the process and focuses on the operation with actual secondary and primary effluents. Process operation showed: (1) no bed clogging occurred due to suspended solids accumulation; (2) residual BOD from the adsorption phase resulted in only minimal heterotroph competition and thus, no fall in the rate of bioregeneration; (3) only a small deterioration in exchange efficiency due to zeolite biofilm coverage as compared to the ion exchange efficiency of “virgin” zeolite. Results show that both secondary and primary effluents can be successfully treated by the process.
Comparison of advanced disinfecting methods for municipal wastewater reuse in agriculture
Authors: Liberti L. , Lopez A. , Notarnicola M. , Barnea N. , Pedahzur R. , Fattal B.
Published: May 2018

The experimental investigation carried out jointly by Italian and Israeli teams within a 3-year research project funded by the European Commission on alternative disinfection methods for reusing municipal wastewater in agriculture is described. Disinfection effectiveness of UV rays, ozone (O3) and peracetic acid (PAA) at pilot scale and hydrogen peroxide (H2O2) plus silver (Ag+) or copper (Cu+2) at laboratory scale was compared for tertiary municipal effluents. Pilot plant results indicated that the well known California limit (2 CFU/100ml of Total Coliforms) was effectively met with reasonable UV doses of 100–160 mWs/cm2 or with exceedingly high PAA dosage (400 PPM); the related WHO microbial guideline (1,000 CFU/100 ml of Fecal Coliforms) was easily met with all three disinfectants (UV, PAA, O3); maximum log-inactivation values were ≥5 for UV and PAA and ≤4 for O3. Laboratory results with tertiary effluents demonstrated that Ag+ was able to inactivate target bacteria (E. coli-B, E. coli-K12), while H2O2 was more effective than Ag+ against MS-2 phages. Copper (250 μg/l) had no bactericidal effect but possessed an appreciable virucidal effect. When hydrogen peroxide and copper were combined, a pronounced increase in both bactericidal and virucidal effects was obtained.
Denitrification of groundwater: pilot-plant testing of cotton-packed bioreactor and post-microfiltration
Authors: Soares M. I. , Brenner A. , Yevzori A. , Messalem R. , Leroux Y. , Abeliovich A.
Published: May 2018

The use of raw cotton as carbon source in the denitrification of drinking water was tested in a field pilot-plant. The reactor treated water from a well in which the concentration of nitrate varied from 22 mg N l–1 in summer to a minimum of 9 mg l–1 in winter. The experimental reactor had a capacity of approximately 9 m3 and could be packed with up to 1500 kg of unprocessed cotton. The highest rate of denitrification observed was 0.36 kg N m–3 d–1, at a feed rate of 6 m3 h–1. However, this performance could be sustained only temporarily as the relatively high water pressure caused serious compression of the bed. The long-term (six months) performance of the system was studied at feed rates of 0.8 and 1.5 m3 h–1. The process was stable and 80–100% of the influent nitrogen was removed. The increase in DOC at the outlet was usually less than 7 mg l–1, and the number of bacteria was in the order of 105–106 CFU ml–1. Crossflow microfiltration was an effective post-treatment for the removal of bacteria and elimination of turbidity.
BNP test to evaluate the influence of C/N ratio on N2O production in biological denitrification
Authors: Chung Y.-C. , Chung M.-S.
Published: May 2018

With sufficient carbon sources in the influence to the anoxic stage, the total gas production rate in the BNP (Biolofical Nitrogen potential) system is rapid with a specific gas production of 3.83 mL/g-VSS-hr. The conversion of nitrate to nitrogen gas is accomplished through three steps: nitrate (NO3-) to nitrite (NO2-) to nitrous oxide (N2O), and nitrogen gas (N2). The BNP test results indicate that the optimal C/N ratios are 4.5±0.2, 3.1±0.4, and 2.0±0.2 for these three steps with carbon consumptions being 30%, 24%, and 46% of the total denitrification carbon consumption. With different concentrations of the influent nitrate, the optimal C/N ratios are 5.3∼5.6, 4.3∼4.7, 3.9∼4.0, and 2.5∼2.7 for 25, 50, 100, and 200 mg/L NO3--N, respectively. The conversion rate of N2O under conditions of sufficient carbon source is 0.005%. If the carbon source becomes insufficient, the N2O conversion rate may increase 100 times to 0.5%.
Effect of variations in flow rate and concentrations of influent on the nitrogen removal performance of the aerobic-anoxic-aerobic process
Authors: Funamizu N. , Miyake T. , Takakuwa T.
Published: May 2018

During a rain event municipal wastewater treatment plants experience a rapid change in the inflow conditions. The effect of the rapid change in a flow rate and/or concentrations on the nitrogen removal performance was studied by using results from the lab-scale experiment and simulation analysis. The mathematical model was developed for simulating the dynamic behavior of a biological nutrient removal system, and the validity of the model was confirmed with data from the experiment. Computed results and the experimental data showed that the net inflow of nitrogen compound through the reaction basin was controlled mainly by the flow rate and the reaction rate was subject to the loading rate in the transient state. The pulse-shaped perturbation with the low organic and nitrogen load resulted in the lesser performance of nitrogen removal than the perturbation with the increased load.
Quantification of methanogen cell density in anaerobic granular sludge consortia by fluorescence in-situ hybridization
Authors: Tagawa T. , Syutsubo K. , Sekiguchil Y. , Ohashi A. , Harada H.
Published: May 2018

Whole cell fluorescence in-situ hybridization (FISH) with 16S rRNA targeted oligonucleotides was applied to reveal the microbial ecological structure of UASB-grown granular sludge. The FISH analysis indicated that the members of the domain Archaea accounted for 28 to 53% of the total cells in various granular sludge sources, while Methanosaeta and Methanobacteriaceae cells accounted for 13 to 38%, and 4 to 27%, respectively. Methanosaeta cell density and Methanobacteriaceae cell density were strongly correlated, respectively, with acetate-utilizing methane production activity and with hydrogen-utilizing methane production activity.
Improvment of nitrogen and phosphorus removal in the anaerobic-oxic-anoxic-OXIC (AOAO) process by stepwise feeding
Authors: Chang H.Y. , Ouyang C.F.
Published: May 2018

This investigation incorporated a stepwise feeding strategy into the biological process containing anaerobic/oxide/anoxic/oxide (AOAO) stages to enhance nitrogen and phosphorus removal efficiencies. Synthetic wastewater was fed into the experimental reactors during the anaerobic and anoxic stages and the substrates/nutrients were successfully consumed without recycling either nitrified effluent or external carbon source. An intrinsic sufficient carbon source developed during the anoxic stage and caused the NOx (NO2-N+NO3-N) concentration to be reduced from 11.85mg/l to 5.65mg/l. The total Kjeldahl nitrogen (TKN) removal rate was between 81.81%∼93.96% and the PO4-P removal ratio ranged from 93%∼100%. The substrate fed into the anaerobic with a Q1 flow rate and a Q2 into the anoxic reactor. The three difference experiments contained within this study produced Q1/Q2 that varied from 7/3, 8/2, and 9/1. The AOAO process saved nearly one-third of the energy compared with typical biological nutrient removal (BNR) system A2O processes.