bluuebunny/crossref_metadata_2025 huggingface dataset:
Acidogenesis of dairy wastewater at various pH levels
Authors: Yu H.-Q. , Fang H.H.P.
Published: May 2018

Continuous experiments were conducted to study the influence of pH in the range 4.0–6.5 on the acidification of dairy wastewater at 37°C with 12 hours of hydraulic retention in an upflow reactor. Results showed that degradation of dairy pollutants increased with pH from pH 4.0 to 5.5. At pH 5.5, 95% of carbohydrate, 82% of protein and 41% of lipid were degraded. Based on chemical oxygen demand (COD), 48.4% of dairy pollutants were converted into volatile fatty acids and alcohols in the mixed liquor, 6.1% into hydrogen and methane in biogas, and the remaining 4.9% into biomass. The biomass yield at pH 5.5 was estimated as 0.32 mg-VSS/mg-COD. Further increase of pH, up to 6.5, increased degradation of carbohydrate, protein and lipid only slightly, but resulted in the lowering of overall acid and alcohol production due to their increased conversion into methane. Acetate, propionate, butyrate and ethanol are the main products of acidogenesis. Productions of propionate and ethanol were favored at pH 4.0−4.5, whereas productions of acetate and butyrate were favored at pH 6.0−6.5.
Treatment of fish processing wastewater in a one- or two-step upflow anaerobic sludge blanket (UASB) reactor
Authors: Palenzuela-Rollon A. , Zeeman G. , Lubberding H.J. , Lettinga G. , Alaerts G.J.
Published: May 2018

The performance of one-step UASB reactors treating fish processing wastewater of different lipid levels was determined using artificially generated influent simulating that of the canning of sardines and tuna. The organic loading rates (OLR) and the hydraulic retention times (HRT) were 5–8 g COD.L−1.d−1 and 11–12 hours, respectively. In treating a wastewater that contains 3–4 g.L−1 total COD of which 5–9% was lipids, the COD removal and conversion to methane were ca.78% and 61%, respectively. In treating a wastewater with a higher lipid content (ca. 47% of the total COD), the total COD removed and converted to methane were 92% and 47%, respectively. A considerable part of the influent total COD was removed via adsorption on reactor surfaces and sludge particles. The adsorption of lipids on sludge particles threatens the stability of the UASB operation. Thus, the performance of a first-step UASB reactor in removing suspended solids (SS) from a “high-lipid” wastewater was also determined in this study.
Mesophilic and thermophilic anaerobic digestion of sulphate-containing wastewaters
Authors: Colleran S. , Pender S.
Published: May 2018

The effect of sulphate at an influent chemical oxygen demand (COD):sulphate ratio of 4 on the operational performance of anaerobic hybrid reactors treating molasses wastewater was investigated under mesophilic and thermophilic conditions in a long-term laboratory-scale study over a 1,081 day period. The presence of sulphate reduced the COD removal efficiency under both mesophilic and thermophilic conditions. At 55°C, effluent acetate levels were consistently greater than 4000 mg L−1, indicating that thermophilic acetate-utilising methane-producing bacteria (MPB) or sulphate-reducing bacteria (SRB) had not developed in the reactor under the conditions applied. At 37°C, acetate was exclusively utilised by acetoclastic methanogens, whereas H2-utilising SRB predominated over H2-utilising MPB in the competition for hydrogen. By contrast, hydrogenotrophic MPB were shown to outcompete H2-utilising SRB during long-term thermophilic operation. 16SrDNA analysis of the seed sludge and reactor biomass on conclusion of the 37°C and 55°C trials illustrated that the dominant methanogen present on conclusion of the thermophilic trial in the absence of influent sulphate was related to Methanocorpusculum parvuum, and was capable of growth on both acetate and hydrogen. By contrast, an organism closely related to Methanobacterium thermoautotrophicum was the dominant methanogen present in the sulphate-fed reactor on completion of the thermophilic trial.
A comparative analysis of a balance between the rates of polymer hydrolysis and acetoclastic methanogenesis during anaerobic digestion of solid waste
Authors: Vavilin V.A. , Schelkanov M. Yu. , Lokshina L. Ya. , Rytov S.V. , Jokela J. , Salminen E. , Rintala J.
Published: May 2018

A distributed model of anaerobic digestion of solid waste was developed. Waste, volatile fatty acids (VFA), methanogenic biomass and methane concentrations were the model variables. A system of parabolic partial differential equations in the one space variable and time with slab, cylindrical or spherical symmetry of the problem was solved numerically. Diffusion of VFA inhibiting both polymer hydrolysis and acetoclastic methanogenesis was taken into account. The model showed that concentration waves of methanogenic biomass and VFA propagated over reaction space. Diffusion-based “acceleration” of methane production in the reactor was possible when intensity of VFA utilisation in the methanogenic area was sufficient for complete digestion of incoming VFA. Otherwise, methanogenic area propagation would be suppressed. Optimum conditions for the solid waste digestion can be reached at low mass transfer at the beginning and at high mass transfer when methanogenic population increases. If the initial methanogenic biomass was localised at the centre of the reactor, the total reaction time was shorter as compared to the case when the initial biomass was uniformly distributed over the reactor volume. In the last case, there was no concentration wave propagation.
Early warning of disturbances in a laboratory-scale MSW biogas process
Authors: Hannsson M. , Nordberg Å , Sundh I. , Mathisen B.
Published: May 2018

The use of near-infrared spectroscopy (NIR) to monitor the dynamics of a biogas process was evaluated using multivariate data analysis. The digester was a completely stirred 8 l tank reactor fed with the organic fraction of source-sorted MSW. Intermittently the digester was overloaded with feed. Before and after overload on-line monitoring of NIR spectra and off-line analysis in the liquid and the gas phase of traditional chemical variables and microbial biomass, determined as total concentration of phospholipid fatty acids (PLFA and PLEL), were done. The dynamics that occurred due to overloading could be followed using principal component analysis of the obtained NIR-spectra. In addition, the response to changes in the digester fluid was reproducible and could be detected within five minutes, which can be considered as real-time monitoring. Selected wavelengths in the region 800–2,000 nm were used to make a PLS1-regression with propionate. The regression resulted in a good correlation for propionate (R = 0.94 and RMSEP of 0.21 g/l in the range of 0.3–3 g/l). The results indicate the possibility to develop an early warning biogas control system based on near-infrared spectroscopy monitoring of propionate.
Sustainability of thermal oxidation processes: strengths for the new millennium
Authors: Guibelin E.
Published: May 2018

Incineration of sludge is occasionally accused of pollution. This paper shows that if it is correctly designed and implemented, it can be environmentally friendly. For this purpose, sludge incineration is compared to agricultural spreading of limed sludge with respect to toxicity criteria, greenhouse effect gases (GEG) release, energy wasting and other environmental parameters. Landfilling is also considered but as a standby route. Since present regulations on agricultural use and gas emission release from incinerators are stringent, incineration cannot be suspected to release more noxious substances in the environment than agriculture. A distinction is made between biogenic CO2 and fossil CO2. Nevertheless case studies show that incineration produces more GEG and wastes more energy than agricultural spreading if no energy is recovered from hot flue gas. In the case of thermal power or electrical power generation, the environmental balance becomes dramatically more favorable for incineration.
A novel in-situ sampling and VFA sensor technique for anaerobic systems
Authors: Pind P.F. , Angelidaki I. , Ahring B.K.
Published: May 2018

A key information for understanding and controlling the anaerobic biogas process is the concentration of Volatile Fatty Acids (VFA). However, access to this information has so far been limited to off-line measurements by manual time and labour consuming methods. We have developed a new technique that has made it possible to monitor VFA on-line in one of the most difficult media: animal slurry or manure. A novel in-situ filtration technique has made it possible to perform microfiltration inside the reactor system. This filter enables sampling from closed reactor systems without large scale pumping and filtering. Using this filtration technique together with commercially available membrane filters we have constructed a VFA sensor system that can perform automatic analysis on animal slurry at a frequency as high as every 15 minutes. The VFA sensor has been tested for a period of more than 60 days with more than 1000 samples on both a full-scale biogas plant and lab-scale reactors. The measuring range covers specific measurements of acetate, propionate, iso-/n-butyrate and iso-/n-valerate from 0.1 to 50 mM (6–3,000 mg).
Autotrophic denitrification for combined hydrogen sulfide removal from biogas and post-denitrification
Authors: Kleerebezem R. , Mendezà R.
Published: May 2018

In this paper we describe an alternative flow-chart for full treatment of wastewaters rich in organic substrates, ammonia (or organic nitrogen), and sulfate, such as those generated in fish cannery industries. Biogas generated during anaerobic pretreatment of these wastewaters is rich in hydrogen sulfide that needs to be removed to enable application of the biogas. Nitrogen elimination is traditionally achieved by subsequent nitrification and denitrification of the effluent of the anaerobic reactor. Alternatively, the hydrogen sulfide in the biogas can be applied as an electron donor in an autotrophic post-denitrification step. In order to study whether sufficient hydrogen sulfide containing biogas for denitrification was produced in the anaerobic reactor, the biogas composition as a function of the anaerobic reactor-pH was estimated based on a typical wastewater composition and chemical equilibrium equations. It is demonstrated that typical sulfate and nitrogen concentrations in fish cannery wastewater are highly appropriate for application of autotrophic post-denitrification. A literature review furthermore suggested that the kinetic parameters for autotrophic denitrification by Thiobacillus denitrificans represent no bottleneck for its application. Initial experimental studies in fixed-film reactors were conducted with sodium sulfide and nitrate as an electron donor-acceptor couple. The results revealed that only moderate volumetric treatment capacities (< 1 g-NO3-N L−1 day−1) could be achieved. Mass balances suggested that incomplete sulfide oxidation to elemental sulfur occurred, limiting biomass retention and the treatment capacity of the reactor. Future research should clarify the questions concerning product formation from sulfide oxidation.
Institutionalising community-based watershed management in India: elements of institutional sustainability
Authors: Saravanan V.S.
Published: May 2018

Community-based watershed management (CBWM) has gained prominence in developing world towards integrated resource management for livelihood enhancement of the poor, due to failure of large-scale river valley projects. This paradigm shift has enabled to narrow the divide between the state and community, and marks a beginning for the State towards a “learning organisation” that is adaptive to the changing social and environmental condition. The paper examines the role of State in institutionalising CBWM in three Indian states. It calls for the State to create an enabling institutional environment for coordination among institutions to emerge by devolving adequate responsibilities. This would offer opportunities for institutions to negotiate their concerns and build credibility for a long lasting institutional solution towards integrating resource management.
Neighbourhood catchments: a new approach for achieving ownership and change in catchment and stream management
Authors: Carroll C. , Rohde K. , Millar G. , Dougall C. , Stevens S. , Ritchie R. , Lewis S.
Published: May 2018

The Neighbourhood Catchment approach integrates land and stream management practices at a property and through to a local catchment scale, links production and environmental goals, and is a building block to achieve ownership and change at a sub-catchment scale and larger.

Research conducted in two 'focus' Neighbourhood Catchments has shown that land management practices that retain >30% soil cover reduce sediment movement to streams. The Neighbourhood Catchment approach engages both early and cautious adopters, and enables continuous improvement of resource management to take place, and be recorded at an individual property and local catchment scale.
Vietnam and the sustainable development of the Mekong river basis
Authors: Quang Nguyen Nhan
Published: May 2018

Vietnam is a riparian country located in most downstream area of the Mekong river basin which is also shared by other states namely China, Myanmar, Laos, Thailand and Cambodia. While the Central Highlands of Vietnam has a great potential for hydropower development in tributaries of Mekong river, the Mekong delta in Vietnam territory is rich in natural resources which are favorable for agricultural development. However, besides local constraints which have being gradually remedied by Vietnam, the development of the Mekong delta is subject to, in both terms of quantity and quality, availability of water resources which relates to the water use of or discharge into the river of upper riparians. With a view to co-developing these resources in a sustainable and mutual benefit manner, Vietnam has cooperated with other states through framework of the Mekong River Commission set up by the 1995 Mekong Agreement. This paper describes the strategy and action plan applied by Viet Nam National Mekong Committee to reach the sustainable development of the Mekong river basin in general and of Vietnam parts located in the Mekong basin in particular.
Development of a biological process for livestock wastewater treatment using a technique for predominant outgrowth of Bacillus species
Authors: Choi Y.S. , Hong S.W. , Kim S.J. , Chung I.H.
Published: May 2018

The investigation has been carried out by treating 1 m3/day of livestock wastewater for 9 months. The biological process is composed of two reactors connected in series. Each reactor has been designed to stimulate the growth of Bacillus sp., spore-forming aerobic or facultatively anaerobic bacteria. As a consequence, the population of Bacillus sp. is aptly increased via the cycle of sporulation, germination and proliferation. With a predominant growth of Bacillus sp., the microbial activity has been increased comparing to activated sludge based on the result of measuring specific oxygen uptake rate (SOUR). This process was able to remove nitrogen and phosphorus as well as organic matter efficiently. More than 98% of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were removed. In term of removing the total nitrogen (T-N), about 98% of this was reduced. On average, the T-N concentration in the feed was 3,270 mg/l but 74 mg/l in the effluent including 30 mg/l of nitrite and nitrate nitrogen. The total phosphorus (T-P) reduction averaged 87.5%. As a result, it would be advantageous to load this process in order to deal with high-strength wastewater.
Decolorization of textile wastewater by ozonation and Fenton's process
Authors: Sevimli M.F. , Kinaci C.
Published: May 2018

The aim of this study is to investigate the effect of some operational parameters on the efficiency of ozonation and Fenton's process for decolorization and COD removal. Acid Red 337 and Reactive Orange 16 dye solutions and the effluents of acid and reactive dye-bath effluents were used in the experiments. The influence of ozone dose and pH for color and COD removal from the wastewater were studied. Increasing the ozone dose increased the rate constants, and color and COD removal efficiencies. Ozone consumption ratio per unit color and COD removal at any time was found to be almost the same while the applied ozone dose was different. pH did not significantly affect color and COD removal from the wastewater by ozonation. In spite of having high color removal efficiencies (60–91%), limited COD removal efficiencies between 9–17% at 30 minutes ozonation time were obtained. In the Fenton oxidation experiments, the effects of pH, temperature, dosage of ferrous sulfate and hydrogen peroxide, and the proper ratio of Fe(II)/H2O2 were studied. The result indicates that up to 99% color removal and 82% COD removal can be obtained by Fenton's oxidation. While Fenton's oxidation was greatly affected by the pH value, temperature of wastewater did not significantly affect the Fenton process for color removal. Increasing the dose of both hydrogen peroxide and ferrous sulfate enhanced the removal efficiencies of color and COD. Suitable ratios of Fe(II)/H2O2 were found to be between 0.5 and 0.83.
Ozonation application in activated sludge systems for a textile mill effluent
Authors: Orhon D. , Dulkadiroğlu H. , Doğruel S. , Kabdaşli I. , Sozen S. , Germirli Babuna F.
Published: May 2018

The study investigates the effect of partial ozonation of textile wastewater, both at the inlet (pre-ozonation) and the outlet (post-ozonation) of biological treatment, for the optimization of COD and color removals, both typical polluting parameters associated with the textile industry. Pre-ozonation provides at optimum contact time of 15 minutes 85% color removal, but only 19% COD reduction. Removal of the soluble inert COD fraction remains at 7%, indicating selective preference of ozone for simpler compounds. Post-ozonation is much more effective on the breakdown of refractory organic compounds and on color removal efficiency. Ozonation after biological treatment results in almost complete color removal and a 14% soluble inert COD reduction. The polishing effect of post-ozonation also proves quite attractive from an economical standpoint, involving approximately 50% of the ozone utilization at the same ozone flux rate and contact time, yet providing a lower soluble residual COD level.
Sustainable development of wastewater treatment strategies for the food industries
Authors: Sekoulov I.
Published: May 2018

The sustainable development of environmental protection is a newly created philosophy. It means continuous development of better protection of the air, soil, water and resources, used from the industry, to be saved also for future generations. The globalization of the economy is another process, which interferes with environmental ideas, and an equilibrium with the socio-eco-sustainable development is wanted. The industry is subjected to big changes depending on economic development. Thus the treatment plants at the end of the pipe must be constructed with maximum flexibility. A removal of constructed devices, if not necessary, must be considered from the beginning as a possibility. Priority is given to integrated production processes solving wastewater problems directly by production devices. The treatment of the process wastewater streams separately will become more important. The end of the pipe solutions will be less complicated and more reliable. The reuse of valuable waste substances and treated water will reduce the total cost of the treatment plants substantially.
The effect of reactor configuration and operational mode on Microthrix parvicella bulking and foaming in nutrient removal activated sludge systems
Authors: Noutsopoulos C. , Mamais D. , Andreadakis A.D.
Published: May 2018

Three bench-scale nutrient removal activated sludge units were used to examine the effect of the reactor configuration and the intermittent aeration mode on the growth of Microthrix parvicella. According to the results, the plug flow configuration seems to achieve satisfactory Microthrix parvicella control. The imposed concentration gradient for both RBCOD and SBCOD creates a selective advantage for the floc forming bacteria throughout the system (both the anoxic and oxic zones) and limits Microthrix parvicella growth. In terms of the operational mode, the intermittent aeration CSTR nutrient removal system promotes the growth of M.parvicella and deteriorates the settling characteristics of the activated sludge.
“Microthrix parvicella”: a new approach for kinetic and physiological characterization
Authors: Rossetti S. , Tomei M.C. , Levantesi C. , Ramadori R. , Tandoi V.
Published: May 2018

Two strains of “Microthrix parvicella” (RN1 and 4B strains) have been physiologically and kinetically characterized by utilizing a new technique particularly suitable for slow growing bacteria. The proposed method is based on the Total Extended Filament Length (TEFL) measure on filaments grown on agar surfaces. This allows us to study more easily and rapidly slow growing bacteria under many different conditions without altering the growth environment during the test. “Microthrix parvicella” appears to have versatile physiological capabilities allowing effective competition against other bacteria in the complex biocenosis of activated sludge. Main peculiarities of this organism are its storage capabilities under an aerobic/anoxic/anaerobic reaction environment, the resistance to long periods of anoxic/anaerobic conditions, the possibility of growing with appreciable kinetics at very low temperatures. In the kinetic characterization low Ks values have been observed; this finding supports the assumption that “Microthrix parvicella” is a “Ks- strategist” with high substrate affinity. Kinetics tests performed in a mixed population of activated sludge bacteria and on pure culture of filaments isolated from the same sludge sample showed that no beneficial effect on the growth rates of “Microthrix parvicella” seems attributable to the presence of activated sludge. This last result confirms the validity of pure culture studies for this microorganism and the reliability of physiological and kinetic data so evaluated in describing real systems.
Dispelling the “Nocardia amarae” myth: a phylogenetic and phenotypic study of mycolic acid-containing actinomycetes isolated from activated sludge foam
Authors: Stainsby F.M. , Soddell J. , Seviour R. , Upton J. , Goodfellow M.
Published: May 2018

Right-angle branched filaments and rods micromanipulated from activated sludge foam and mixed liquor were identified as putatively novel members of the genera Gordonia, Mycobacterium and Rhodococcus using a combination of chemical, molecular and morphological data. Pyrolysis mass spectrometric analyses of gordoniae isolated in both the present and a previous study revealed pyro-groups, distinct from validly described Gordonia species, which could be equated with those based on morphological properties and 16S rDNA data. Putative gordoniae assigned to one of these groups were found to be closely related to strains currently identified as “Rhodococcus australis”. These strains were also found to have properties consistent with their classification in the genus Gordonia. The results of this study highlight the limitations of the microscopic approach to filament identification and cast further doubt on the view that foaming can be attributed to members of one or a few Nocardia species.
Flow cytometric sorting and RFLP analysis of phosphate accumulating bacteria in an enhanced biological phosphorus removal system
Authors: Kawaharasaki M. , Manome A. , Kanagawa T. , Nakamura K.
Published: May 2018

Phosphate accumulating organisms (PAOs) stained with 4′,6-diamidino-2-phenylindol dihydrochloride (DAPI) at polyphosphate probing concentration were sorted from enhanced biological phosphorus removal (EBPR) sludge by flow cytometric sorting. All the genome DNA was extracted from the sorted bacteria and the 16S rDNA genes were cloned. Cloned 16S rDNA was PCR-amplified and analyzed by restriction fragment length polymorphism (RFLP) analysis. Eighty eight clones were analyzed and the RFLP patterns which appeared more than twice were classified into seven groups. The most dominant group (Group 1) contained four clones and accounted for 4.5% of the total clones. Four groups (from Group 2 to Group 5) contained three clones. Group 6 and 7 consisted of two clones. Sixty-eight clones gave unique RFLP patterns. By sequencing 16S rDNA in seven groups, Group 1, 2 and 5 were Rhodocyclus relatives (11%, 10/88). Rhodocyclus relatives were suggested to be one of the bacteria responsible for EBPR in this sludge. Groups 6 and 7 were related to b- or g-Proteobacteria. Group 4 belonged to e-Proteobacteria. Group 3 was related to green nonsulfur bacteria. Considering the complex RFLP pattern and the existence of the groups not related to Rhodocyclus by sequence analysis, in this EBPR system, together with Rhodocyclus relatives, some other bacteria might also play a role as PAOs.
Competition between polyphosphate- and glycogen-accumulating organisms in biological phosphorus removal systems – effect of temperature
Authors: Whang L.-M. , Park J.K.
Published: May 2018

This study demonstrated that temperature is an important factor in determining the outcome of competition between polyphosphate-accumulating organisms (PAOs) and glycogen-accumulating non-poly-P organisms (GAOs) and the resultant stability of enhanced biological phosphorus removal (EBPR) systems. At 20°C and a 10-day sludge age, PAOs were dominant in the anaerobic/aerobic (A/O) SBR, however, at 30°C and a 10-day sludge age, GAOs were dominant in the A/O SBR. For kinetic batch studies, the anaerobic specific acetate uptake rate of GAO-dominated sludge (1.34 × 10−3 mg C/mg VSS·minute) was higher than the rate of PAO-dominated sludge (0.89 × 10−3 mg C/mg VSS·minute) at 30°C, leading to the eventual failure of EBPR processes at high temperatures.
Change in metabolism of PHA accumulation by activated sludge modifying operating conditions
Authors: Serafim L.S. , Lemos P.C. , Reis M.A.M.
Published: May 2018

In the present work, sludge from a stable and efficient phosphorus removal process was used to evaluate the change in the metabolism when the reactor operation was modified from anaerobic/aerobic to aerobic dynamic substrate feeding. The change in operational conditions allowed the population to modify the metabolism of phosphorus and polyhydroxyalkanoates (PHA) accumulation. Under aerobic dynamic feeding, phosphorus accumulation was almost hindered while the amount of PHA accumulation increased significantly. After ten days of operation under dynamic substrate feeding, the reactor operation turned back to anaerobic/aerobic cycles and the metabolism of phosphorus was progressively recovered
Community structure of micro- and macroflocs in pin-point sludge and the influence of sludge age and potassium addition on microfloc formation
Authors: Müller E. , Kriebitzsch K. , Wilderer P.A. , Wuertz S.
Published: May 2018

Settling problems caused by pin-point sludge constitute a serious problem in biological wastewater treatment, particularly in many industrial plants. Until now, most studies focused on the relationship between pin-point sludge formation and either shearing forces or the impact of toxicants. This study deals with the community structure in both the micro- and macrofloc fraction which was analyzed by fluorescent in situ hybridization (FISH) and BIOLOG substrate utilization patterns. It was shown that each fraction consisted of different microbial communities with unique metabolic profiles suggesting that pin-point sludge formation is not due to dispersal of intact flocs but to microcolonies growing separately. Alternatively, macroflocs may have an architecture leading to segregation of microbial communities after floc dispersal. Further it could be shown that the formation of microflocs was influenced by sludge age. The best sludge sedimentation was obtained for a sludge age of 5 and 10 days. Additional analysis of extracellular polymeric substances (EPS) suggested that the lower protein to carbohydrate ratio of 10-day-old sludge led to better flocculation compared to 20-day-old sludge containing similar total amounts of EPS. From a practical point of view, addition of potassium (0.1 g/l) effected a noticeable improvement of sludge settleability.
Are filamentous mycolata important in foaming?
Authors: Davenport R.J. , Curtis T.P.
Published: May 2018

In a previous study, we showed that there was a significant increase in mycolata numbers associated with foaming events at a wastewater treatment site possessing three activated sludge plants. In this paper, we demonstrate that branched filamentous mycolata were a minor proportion of the mycolata morphotypes present in those activated sludge plants, accounting for less than 21% of the mycolata population in the mixed liquor and foam samples examined. In most samples examined, the number of filamentous mycolata was negligible compared to the number of other mycolata morphotypes present. Furthermore, filamentous mycolata did not contribute to any of the significant differences in mycolata concentration observed between foaming and non-foaming situations (P<0.01). These findings suggest that conventional microscopic examination for monitoring mycolata populations in foaming plants may be misleading and should be used with caution.
Filamentous micro-organisms observed in industrial activated sludge plants
Authors: Eikelboom D.H. , Geurkink B.
Published: May 2018

As part of the EU-sponsored MACOBS (Monitoring and Control of Bulking Sludge through Molecular Probe Assays) project, the size and the composition of the filamentous population in 73 industrial activated sludge plants, were investigated. The inventory included plants in Denmark, Germany, Italy and The Netherlands. Large filamentous populations were present in about 60% of the plants, which means that bulking of activated sludge, which is no longer a serious problem in modern domestic nutrient removal plants, still occurs frequently in industrial treatment plants. The filamentous micro-organisms present were identified/described by “traditional” methods, based on their morphological features and several staining techniques, and by the application of molecular probes (FISH: Fluorescent In Situ Hybridisation). Nine species specific probes were available when the project started, nine new probes have been developed during the project. Fifty nine different filamentous species were observed in the samples, including ca. 40 species that have not been described so far. The unknown species are denoted as Type Ind-1, 2, 3, etc. Probes are now available for the identification of about 17 species. Further research aimed at developing additional probes will be necessary in order to establish which species distinguished provisionally are identical, viz. morphotypes of the same filamentous organism.
Lessons learnt at ICA2001
Authors: Olsson G.
Published: May 2018

This paper gives an introduction as well as some general experiences and conclusions from the 1st IWA Conference on Instrumentation, Control and Automation (ICA2001), June 3–7, 2001, Malmö, Sweden. The highlights from the different sessions of the conference are summarised and some challenges for the coming years, with regard to ICA within the field of wastewater treatment, are also discussed.
Respirometry techniques and activated sludge models
Authors: Benes O. , Spanjers H. , Holba M.
Published: May 2018

This paper aims to explain results of respirometry experiments using Activated Sludge Model No. 1. In cases of insufficient fit of ASM No. 1, further modifications to the model were carried out and the so-called “Enzymatic model” was developed. The best-fit method was used to determine the effect of the proposed modifications. Increased agreement was found between simulated data and respirometry results, particularly for repeated respirometric tests with acetate as the sole substrate. Additionally, the influence of different biomass pre-conditioning methods was examined. Results from repeated respirometric tests suggest that presence of residual products in an activated sludge sample before respiration testing may decrease the sample's activity and significantly affect results from respirometric tests. An innovative approach to recover original activity is suggested by washing activated sludge samples with tap water or “mineral medium”. As allylthiourea (ATU) was used in most experiments to suppress endogenous nitrification, its influence on kinetic parameters was reviewed. Respirometric tests confirmed that ATU addition has a significant effect on activity and respiration rate of activated sludge samples and could affect results of respirometric analyses.
Model-based advanced process control of coagulation
Authors: Baxter C.W. , Shariff R. , Stanley S.J. , Smith D.W. , Zhang Q. , Saumer E.D.
Published: May 2018

The drinking water treatment industry has seen a recent increase in the use of artificial neural networks (ANNs) for process modelling and offline process control tools and applications. While conceptual frameworks for integrating the ANN technology into the real-time control of complex treatment processes have been proposed, actual working systems have yet to be developed. This paper presents development and application of an ANN model-based advanced process control system for the coagulation process at a pilot-scale water treatment facility in Edmonton, Alberta, Canada. The system was successfully used to maintain a user-defined set point for effluent quality, by automatically varying operating conditions in response to changes in influent water quality. This new technology has the potential to realize significant operational cost saving for utilities when applied in full-scale applications.
Adsorption of reactive dyes to granulated iron hydroxide and its oxidative regeneration
Authors: Kornmüller A. , Karcher S. , Jekel M.
Published: May 2018

Granulated iron hydroxide (b-FeOOH) is used as a regenerable sorbent and catalyst for reactive dye removal in textile wastewater treatment. In oxidative regeneration the previously sorbed reactive dye is catalytically oxidized after activation of hydrogen peroxide to hydroxyl radicals on the FeOOH surfaces to regain adsorption capacity and reuse the sorbents. A high initial H2O2 concentration is needed for an efficient mass transfer water/solid but its consumption per oxidized dye results only in 7-25 mg mg−1. At room temperature a regeneration time of 3.5 h is necessary for decolorization and 6 h for further decomposition of the formed oxidation products to enable a reloading without any loss in adsorption capacity. Compared to Fenton's reagent, this oxidation process takes advantage of pH-independence between 4 and 8 and additionally no sludge is produced. Salts are commonly used in textile dying processes. While chloride improves the dye sorption, the presence of sulfate results in deteriorating sorption. Carbonate reacts as a scavenger of hydroxyl radicals resulting in a higher hydrogen peroxide consumption, but the efficiency of dye oxidation is only slightly affected. Nearly 20% of DOC of the sorbed dye can be attributed to short chain organic acids (formate, acetate, oxalate) indicating the far-reaching catalytic oxidation and enabling biological post-treatment.
On-line titration of non-ionic surfactants in wastewater treatment plants using a specific electrode
Authors: Feitkenhauer H. , Meyer U.
Published: May 2018

Textile finishing industry wastewater often contains high concentrations of surfactants. Non-ionic surfactants like alcohol ethoxylates are among the most used surfactants and are discharged from batch-processes in widely varying concentrations. The anaerobic biomass and especially methanogenic microorganisms have been shown to be inhibited by surfactants. To protect these microorganisms from irreversible inhibition a measurement of the surfactant concentration is useful for the process control, but most analytical methods are too complicated and expensive for an on-line process control. It was shown that the titration of non-ionic surfactants is possible in the presence of biomass and in wastewater from textile wet processes using the Metrohm NIO-electrode. Titration and sampling were successfully performed with standard equipment. The software used for the process control of a lab-scale anaerobic treatment plant was also used to evaluate the obtained titration curves. This allowed performing the titrations without using a more expensive titrator.
Pollution control of industrial wastewater from soap and oil industries: a case study
Authors: Abdel-Gawad S. , Abdel-Shafy M.
Published: May 2018

Industrial wastewater from soap and oil industries represents a heavy pollution source on their receiving water body. This paper studies a case of pollution control at Tanta Soap and Oil Company, Banha Factory, Egypt. The factory production includes soap, edible oil, and animal fodder. About 4,347 m3/day of industrial wastewater effluent was discharged via gravity sewers to the public sewerage system. Most of the effluent was cooling water because the cooling process in the factory was open circle. In spite of the huge quantity of cooling water being disposed of, disposal of wastewater was violating pertinent legislation.

Three procedures were used for controlling the pollution at the Banha Factory. Firstly, all open circuit cooling systems were converted to closed circuit thus reducing the quantity of the discharged wastewater down to 767 m3/day. Secondly, the heavily polluted oil and grease (O&G) wastewater from the refinery unit is treated via two gravity oil separator (GOS) units, dissolved air floatation (DAF), and biological units in order to reduce the high levels of O&G, BOD, COD, and SS to the allowable limits. Thirdly, the heavily polluted waste effluent from the ‘red water’ saponification unit is treated separately by acidification to convert the emulsified fatty acid to free form in order to be separated through an oil separation unit.

The effluent is then passed to liming stage to neutralize excess acidity and precipitate some of the dissolved matters. The mixture is finally clarified and the pH is adjusted to the allowable limits. The effluent wastewater from the three processes is collected and mixed in a final equalization tank for discharging effluent to the public sewerage system. The characteristics of the effluent water are very good with respect to the allowable Egyptian limits for discharging effluent to the public sewerage system.
Use of thermophilic biological aerobic technology for industrial waste treatment
Authors: Rozich A.F. , Bordacs K.
Published: May 2018

Thermophilic aerobic treatment systems offer unique advantages for treatment of high strength organic waste streams and slurries/sludges. These systems combine the best features of conventional aerobic and anaerobic processes that include rapid biodegradation kinetics and low biological solids production, respectively. Application of these processes can result in substantial economic benefit by reducing residuals processing and disposal costs. These systems have not been widely applied for industrial waste treatment, therefore the goal of this paper to show the advantages of applying thermophilic aerobic treatment to these streams. Also included in the paper is a discussion of the process benefits along with design/application considerations and industrial case histories.
A model to control intermittent aeration phases
Authors: Carucci A. , De Mola M. , Rolle E. , Smurra P.
Published: May 2018

Dealing with intermittent aeration as a useful practice to improve nitrogen removal efficiency of activated sludge plants, the possibility to plan optimal temporisation during daytime was investigated. A mathematical model (NIDEN) that allows us to manage different situations, with respect to influent load, environmental conditions and operating strategy, was then developed. The model represents a useful tool especially to plan the aeration cycles in small and medium sized plants, where high costs of automatic control through on-line instrumentation might not be justified. Once the input variables have been defined and the set-point values for tank nutrient concentration have been fixed, NIDEN gives an optimal phase temporisation, to obtain either the maximum energy saving or the best total nitrogen removal.
On the use of fluorescence measurements to characterize wastewater
Authors: Vasel J.-L. , Praet E.
Published: May 2018

This paper examines the correlations between some water quality parameters and fluorescence intensities and spectra in filtered wastewater using a 280 nm excitation wavelength. We did not obtain satisfying linear relationships between fluorescence and COD or TOC (r2 ≅ 0.4) for any of the emission wavelengths used between 320 and 400 nm (especially at 355 nm, the average emission λmax.). The relationships with NK were better (r2 ≅ 0.7); leading us to suggest that one evaluates mainly the organic nitrogen content at λex. = 280 nm. Whole spectra processing did not improve the correlations. Gel permeation chromatography yielded markedly different TOC and fluorescence chromatograms, which explains the difficulty of correlating organic content and fluorescence. Other investigations are necessary before spectrofluorimetry can be used as a reliable technique for on-line wastewater pollution estimation.
Robustness and economic measures as control benchmark performance criteria
Authors: Vanrolleghem P.A. , Gillot S.
Published: May 2018

The objective of this paper was to investigate the usefulness of new multi-criteria measures to evaluate a control strategy through the Benchmark protocol. Using a case study in which respirometry-based control strategies are evaluated, the proposed measures were calculated. An economic index including weighted investment and operating costs (termed Total Cost Index – TCI) appears more powerful than a grey-scale presentation approach. Using the latter approach, it is hard to reflect the relative importance of the criteria investigated, which makes practical decisions rather difficult. In addition, a Robustness Index (RI) is proposed that allows us to evaluate the transferability of control strategies to situations different from the ones defined in the benchmark protocol. Finally, the case study shows that it may be advisable to replace the currently used open loop benchmark reference by a plant in which dissolved oxygen is controlled in all aerated reactors. This quite simple strategy also turned out to be the best one among all evaluated strategies.
A neural network approach to burst detection
Authors: Mounce S.R. , Day A.J. , Wood A.S. , Khan A. , Widdop P.D. , Machell J.
Published: May 2018

This paper describes how hydraulic and water quality data from a distribution network may be used to provide a more efficient leakage management capability for the water industry. The research presented concerns the application of artificial neural networks to the issue of detection and location of leakage in treated water distribution systems. An architecture for an Artificial Neural Network (ANN) based system is outlined. The neural network uses time series data produced by sensors to directly construct an empirical model for predication and classification of leaks. Results are presented using data from an experimental site in Yorkshire Water's Keighley distribution system.
Dinitrogen oxide detection for process failure early warning systems
Authors: Burgess J.E. , Stuetz R.M. , Morton S. , Stephenson T.
Published: May 2018

A number of experiments were conducted in order to establish whether the concentration of N2O in the off-gas from an activated sludge pilot plant could be used as a indicator for monitoring the nitrification process and as an early indication of ammonia appearing in the plant effluent. A strong correlation was found between ammonia shock loads and the concentration of N2O in the off-gas from the aeration tank for ammonia shock loads and dissolved oxygen depletion. When subjecting the experimental setup to doses of a nitrification inhibitor (allylthiourea) a similar pattern was seen with a correlation between nitrite build up in the aeration tank and concentration increase of N2O in the off-gas from the aeration tank. The results from this work suggest the concentration and the changes in the concentration of N2O in the exhaust gas from a nitrifying process may be a useful parameter for monitoring nitrifying activated sludge processes.
MBR-technology in municipal wastewater treatment: challenging the traditional treatment technologies
Authors: van der Roest H.F. , van Bentem A.G.N. , Lawrence D.P.
Published: May 2018

In the Netherlands a development programme for the application of the MBR technology in municipal wastewater treatment has started. This paper briefly describes this development programme and goes into detail for the first step: a large pilot plant study at the Beverwijk WWTP. Under the supervision of DHV Water four different membrane systems from Kubota, Mitsubishi, X-Flow and Zenon were extensively tested. The objectives set for the study were more than achieved. The available world knowledge regarding municipal MBR was extremely limited and often very specific for a particular country’s wastewater and wastewater flow characteristic. The conditions set by the Dutch situation were the first of its kind and lead to new methods of MBR optimisation. After almost two years of intensive research and further development of the technological feasibility of the MBR for the Netherlands, it has been decided to extend it to demonstration scale.
Enhanced biological phosphorus removal in membrane bioreactors
Authors: Adam C. , Gnirss R. , Lesjean B. , Buisson H. , Kraume M.
Published: May 2018

Enhanced biological phosphorus removal (Bio-P) in a membrane bioreactor (MBR) promises several advantages but was never attempted as not compatible with high sludge ages. This article includes description and results of bench-scale investigations on Bio-P removal in an MBR. An MBR bench-scale plant (210 L) was operated in parallel to a conventional WWTP under comparable process conditions. The results show that Bio-P removal is possible in MBR. The effluent qualities of the plants were comparable. The effluent P-concentration was always lower than 0.2 mg PT/L. In the MBR bench-scale plant P-uptake occurred mainly in the anoxic zone. Investigations with P-spiking showed higher Bio-P potential as P-removal increased up to 20-25 mg/L while P/TS rose up to >6%.
A quantitative risk analysis tool for design/simulation of wastewater treatment plants
Authors: Bixio D. , Parmentier G. , Rousseau D. , Verdonck F. , Meirlaen J. , Vanrolleghem P.A. , Thoeye C.
Published: May 2018

Uncertainty is a central concept in the decision-making process, especially when dealing with biological systems subject to large natural variations. In the design of activated sludge systems, a conventional approach in dealing with uncertainty is implicitly translating it into above-normal safety factors, which in some cases may even increase the capital investments by an order of magnitude. To obviate this problem, an alternative design approach explicitly incorporating uncertainty is herein proposed. A probabilistic Monte Carlo engine is coupled to deterministic wastewater treatment plant (WWTP) models. The paper provides a description of the approach and a demonstration of the general adequacy of the method. The procedure is examined in an upgrade of a conventional WWTP towards stricter effluent standards on nutrients. The results suggest that the procedure can support the decision-making process under uncertainty conditions and that it can enhance the likelihood of meeting effluent standards without entailing above-normal capital investments. The analysis led to reducing the capital investment by 43%, producing savings of more than 1.2 million euro.