bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Settling Velocity of Phosphorus in an Aerated Lake
Authors: Sperling E. V.
Published: May 2018

The paper deals with the determination of the settling velocity of phosphorus in lakes and reservoirs. The main approaches to estimate the phosphorus loss in aquatic ecosystems are presented. A case study of a lake situated in Berlin, Germany is discussed. The results show that in aerated lakes the values of the settling velocity of phosphorus can be much higher than currently assumed in the literature.
Simultaneous Removal of BOD and Nitrogen with Anoxic/Oxic Porous Biomass Support Systems
Authors: Kondo M. , Hozo S. , Inamori Y.
Published: May 2018

To protect the public water, there is a growing demand to treat domestic gray water as well as night soil using onsite wastewater treatment systems (OWTS) in Japan. Therefore, to meet this demand, we seek the potential of the technology of the system with porous biomass support particles (BSP) using large number of small, open-cell foam pads to support high concentration of biomass in an aeration tank. From aneconomic point of view, durability of pads is an important factor of this process. Polyurethane foam with certain physical characteristics was chosen for pads. To attain simultaneous removal of BOD and nitrogen in an aeration tank, optimum pore size and pads dimensions were chosen in terms of diffusion. To aim for steady and further removal of nitrogen with biomass both on BSP and in suspension, we applied intermittent anoxic/oxic porous biomass support systems process to a full-scale field test, operated in the manner of 1.5 hours aeration and subsequent 0.5 hours agitation. For 330 days of the experiment, less than 20 mg/L and 15 mg/L of effluent BOD and nitrogen are achieved regardless of water temperature between 13 and 31 degrees centigrade.
Biodegradation of Organic Substances by Biological Activated Carbon – Simulation of Bacterial Activity on Granular Activated Carbon
Authors: Nishijima W. , Tojo M. , Okada M. , Murakami A.
Published: May 2018

Biodegradation of organic substances by attached bacteria on biological activated carbon (BAC) was studied to clarify the advantages of granular activated carbon (GAC) as support media over conventional media without adsorption capacity with regard to biodegradation activity and community structure of attached bacteria. Anthracite (AN) was used as reference support medium without adsorbability. Low molecular organic substances with different biodegradability and adsorbability (phenol, glucose, benzoic acid and m-aminobenzoic acid) were fed into completely mixed BAC and AN reactors. The rate of biodegradation by BAC reactors fed with biodegradable organic substances was approximately 3 times as high as that by AN reactors. The difference in adsorbability of organic substances onto GAC had little effects on the rate of biodegradation. The structure of GAC with micro and macro pores did not provide better habitat for attached bacteria with regard to the size of population in comparison with anthracite without pores. The rates of biodegradation per attached bacteria for biodegradable organic substances in the BAC reactors were from 1.7 to 4.9 times higher than those in the AN reactors. GAC, as a bacterial support media, stimulated the biodegradation activity of each bacteria without increase in their population and probably with little change in their species composition. Although the number of attached bacteria on BAC was not different significantly from that on anthracite, m-aminobenzoic acid with low biodegradability was degraded only by the GAC reactor.
Nitrogen Removal by a Submerged Biofilm Process with Fibrous Carriers
Authors: Wang B. , Li G. , Yang Q. , Liu R.
Published: May 2018

A study on nitrogen removal by submerged biofilm attaching on fibrous carriers in A/0 process was carried out, with the emphasis put on finding out the optimal conditions for nitrification and denitrification with highest nitrogen removal. The influence of return flow ratio of nitrified effluent on the removal capacities of the system for organic substances and nitrogen was studied as well.
Sequential Chemical/Biological Oxidation of 2-Chlorophenol
Authors: Stowell J. P. , Jensen J. N. , Weber A. S.
Published: May 2018

The feasibility of preozonation with subsequent biodegradation as an alternative treatment of 2-chlorophenol was investigated. The major ozonation byproduct of 2-chlorophenol was chlorosuccinic acid which was oxidized to oxalic acid upon further ozonation. Only chlorosuccinic acid sustained substantial growth of Pseudomonas putida during batch biodegradation experiments compared with a blank, 2-chlorophenol, and oxalic acid. Accordingly, based on the results obtained with this model system, preozonation of persistent compounds can result in an increased extent of mineralization. However, care must be exercised in the chemical oxidation process to prevent formation of secondary refractory intermediates.
The Removal of Selenium from Water by Slow Sand Filtration
Authors: Carlo P. L. , Owens L. P. , Hanna G. P. , Longley K. E.
Published: May 2018

The feasibility of selenium removal from drainage water by slow sand filtration (SSF) was investigated. Two anaerobic laboratory-scale slow sand filters, operated in parallel, received synthetic feed solution. Selenate reduction and subsequent selenium removal were monitored during five experimental filtrations. The results suggest that selenium removal occurred by the dissimilatory reduction of selenate to elemental selenium. This reduction was independent of sulfate. Selenium removal efficiencies were governed by the hydraulic loading rate (HLR).
Comparative Rates of Disinfection of Microbial Indicator Organisms in Chlorinated Sewage Effluents
Authors: Rippey S. R. , Watkins W. D.
Published: May 2018

The densities of several microbial indicator organisms, including fecal coliforms, enterococci, Clostridiumperfrinaens, and a male-specific bacteriophage group, were determined in the pre- and post-chlorinated effluents of three wastewater treatment plants during a rainfall event when the plants were operating near maximum flow capacity. These studies were undertaken to determine the effects of elevated flow rates on the relative rates of inactivation of the microbial indicators due to chlorine disinfection.

Three distinctly different responses to chlorine treatment were observed. The vegetative bacterial organisms (fecal coliforms and enterococci) were most sensitive, the male-specific bacteriophage group was considerably more refractory, and c. perfringens, a bacterial spore-former, was highly resistant to inactivation by the disinfecting agent. These findings are significant for two reasons. First, the vegetative bacterial indicators did not reliably index the decay rates of the bacterial virus under the field conditions experienced. This has important public health ramifications to consumers of certain seafood products and to marine recreationists. Second, because of the highly refractory nature of the c. perfrinaens spore, this microbial indicator has practical use in assessing the magnitude of the impacts (source strengths) of sewage contaminated wastewaters on estuarine and marine environments.
Investigation of Reduction in Oxygen Requirements of Biological Phosphorus Removal Systems
Authors: Wable M. W. , Randall C. W.
Published: May 2018

The introduction of an anaerobic zone before the aerobic zone of a conventional activated sludge system was previously found to result in less-than-theoretical oxygen use. The difference between actual and theoretical oxygen use was termed Anaerobic Stabilization (AnS). In this study, an improved method was developed for the determination of AnS, and was applied to a lab-scale Anaerobic/Oxic (A/O) system in which nitrification was chemically inhibited. 15-20 percent of the theoretical oxygen requirement was eliminated by AnS. Oxygen, COD, and sulfate were found to be the major species involved in redox reactions in the system, and therefore major components of AnS. Production of hydrogen, methane, or carbon monoxide, and limitations of the COD test were eliminated as possible explanations for AnS. Aeration-induced stripping of reduced volatile species produced in the anaerobic zone was identified as a possible mechanism requiring further investigation.
Phosphate Precipitation with On-Site Alkali Generation
Authors: Kolbé F. F. , Terblanche J. S.
Published: May 2018

Commercially available membrane electrolysis equipment can be used to produce substantial quantities of caustic soda from salt (NaCl) with chlorine gas being produced as a by-product. This caustic soda may be employed to raise the pH of the final effluent in order to achieve high levels of phosphate precipitation or removal in the form of crystallization. The pH may then be lowered, prior to final discharge, by re-carbonation utilising combusted biogas, which is produced on-site.

At the Kempton Park wastewater treatment works, which achieves biological phosphate removal by means of the Phostrip process, laboratory scale tests proved the commercial viability of this process. It was found that a dosage of 150 mg/l of caustic soda was needed to reach a redox potential of −250 mV, at which point the phosphate content of the stripper overflow was reduced from 30 mg/l to under 1 mg/l. The savings effected in the cost of chlorinating the final effluent, entirely offsets the cost involved.

A number of other possible process configurations are proposed, with treatment costs varying from 0,8 to 5,3c/kl, which compares favourably with biological or other methods of chemical treatment, which typically range from 3 to 6 c/kl (costs given in SA cents = 0,35 US cents).
Effectiveness of a Secondary Impoundment System in Reducing Industrial Wastewater Toxicity
Authors: Khan A. , Kent D. , Barbieri J. , Khan S. , Sweeney F.
Published: May 2018

Aquatic toxicity testing was employed over a three year period to test the effectiveness of a secondary impoundment system in reducing biological toxicity of an industrial wastewater discharge. A two tiered approach was used to determine the effects of the wastewater on two cladoceran species, Daphniamagna and Ceriodaphniadubia, and two sensitive life stages of a vertebrate, Pimephalespromelas. Endpoints measured were both acute (lethality) and chronic (growth and reproduction). Results from the first year of testing, conducted on wastewater collected from the inflow to the secondary impoundment system, indicated both lethal and sublethal effects. Results from the second year of testing, conducted on the outflow of the secondary impoundment system, showed reduced chronic toxicity and complete absence of acute toxicity. Minor modifications were made to the existing treatment system and toxicity testing was conducted for the second consecutive year on the outflow of the secondary impoundment system. Results from the third year of testing showed no acute or chronic toxicity, indicating improved wastewater treatment.
Comparison Between Thermophilic and Mesophilic Anaerobic Digestion of Sewage Sludge Coming from Urban Wastewater Treatment Plants
Authors: Cecchi F. , Pavan P. , Musacco A. , Mata-Alvarez J. , Sans C.
Published: May 2018

Yields of anaerobic digestion (AD) of sewage sludge carried out at mesophilic and thermophilic conditions at the optimum hydraulic retention times (HRT) found for the semi-dry AD of the mechanically selected organic fraction of municipal solid waste (OFMSW) (15 and 12 days, respectively) are compared. Due to the characteristics of the sludge used in thermophilic conditions (partially stabilized) the specific biogas production was lower. However, stability parameters show a secure process. Based on experience gained digesting OFMSW and hypothesizing a similar ratio between yields at mesophilic and thermophilic conditions, an economic analysis has been carried out. It shows that the increased biogas production is large enough to compensate the additional consumption to heat the feed flow rate to 55°C instead to 35°C.
Concepts for Minimizing Emissions at Activated Sludge Plants
Authors: Pincince A. B.
Published: May 2018

In the next few years, the need to decrease emissions of odors and volatile organic compounds will become increasingly important in the design and operation of wastewater treatment plants.

The primary methods for decreasing emissions are adding precipitating chemicals to raw wastewater, using velocity-controlled or vortex-type gritchambers, eliminating or decreasing free falls, covering tanks andchannels, decreasing stripping in aeration tanks, minimizing chlorine use, operating treatment plants properly, and collecting and treating vented air.

The methods cannot all be used simultaneously at a single treatment plant, and some of them might prove to be too costly, except in special circumstances. Nevertheless, they are worth considering.
Initial Studies on the Anaerobic Sequencing Batch Reactor
Authors: Dague R. R. , Habben C. E. , Pidaparti S. R.
Published: May 2018

This research focuses on an evaluation of the performance of a new process being called the “anaerobic sequencing batch reactor” (ASBR). The ASBR operates on an intermittent, fill and draw regimen. This results in alternating high substrate/low substrate (feast/famine) conditions. The high substrate conditions right after feeding results in high rates of substrate conversion to biogas. The low substrate concentration near the end of the react sequence results in efficient bioflocculation and solids separation.
A New Operation of Carbohydrate-Containing Wastewater Treatment in an Anaerobic Fluidized Bed System
Authors: Matsumoto A. , Sakamoto M. , Noike T.
Published: May 2018

The effects of pH on the characteristics of conversion of starch to methane in anaerobic digestion were investigated by using a laboratory-scale anaerobic fluidized bed reactor over the pH range of 5.8-7.0. Furthermore, a new operation method was proposed to treat wastewater containing starch effectively.

At pH 6.2, starch was decomposed well and methane was also formed well. The phenomenon showed methanogenesis in an attached growth system developed more tolerance for lower pH than in suspended growth type systems. After all, pH 6.2 was the optimum pH value for conversion of starch tomethane in our experiment.

From these results, it is proposed that the more effective anaerobic digestion is made possible by the operation at low pH (for example 6.2) which accelerates acidogenesis and doesn't inhibit methanogenesis in attached growth systems.
Fluidization and Sedimentation of Carrier Material in a Pilot-Scale Airlift Internal-Loop Reactor
Authors: Cai J. , Nieuwstad Th. J. , Kop J. H.
Published: May 2018

Balsalt (ρ=2760 kg.m−3, d=0.245 mm) was used as the solid carrier in a pilot-scale airlift internal-loop reactor for wastewater treatment (AILRW), which was filled with tap water in this study, to investigate the regimes of fluidization and sedimentation. Solid sediment was observed even when the liquid velocity in the riser was much higher than the terminal settling velocity of the particles. Circulation cannot be maintained if the superficial liquid velocity in the downcomer ud. is below a definite value (blocking velocity ub) . In a dimensionless model, ub is related to the bulk volume of carrier solids added (Vt), the available space at the bottom (Va) and the gap size at the bottom (a0) according to ub2/(a0.g) = 0.04(Vt/Va) −0.036.
Developing an Appropriate Wastewater Management Strategy for Sydney's Future Urban Development
Authors: Dodds A. A. , Fisher P. J. , Paull A. J. , Sears J. R.
Published: May 2018

Over the next 20 years, Sydney's population is expected to increase by about one million, with most of this growth proposed to be within the already environmentally stressed Hawkesbury-Nepean River catchment. The Water Board is providing infrastructure to the future urban development using a combination of conventional and innovative structural and non-structural solutions within an integrated river basin planning approach. The package of total water resource management initiatives that form the servicing strategy for the first major urban release area is outlined. It is demonstrated that the use of appropriate technologies can be effectively combined with resource management techniques to mitigate the potentially adverse environmental impacts of urban growth.
New Generation Beltpresses and Decanters for Sludge Dewatering
Authors: van der Roest H. F. , Salomé A. A. , Koornneef E.
Published: May 2018

Stimulated by diminishing sludge disposal facilities in agriculture in the Netherlands, an increased interest has developed for improved sludge dewatering techniques. The required changeover to sludge treatment processes like composting, drying and incineration is expensive and costs are considerably influenced by extended mechanical dewatering capabilities. In cooperation with the Dutch Water Authorities and industry, DHV Water BV has been performing full-scale test programmes since 1989. Each test programme involves the treatment of various sludges, simultaneously dewatered using between two and nine different types of full-scale equipment, such as beltpresses, decanters, filterpresses and high pressure equipment. A combination of proper process design and control, together with the latest developments in the design of dewatering equipment, have resulted in dry solids percentages far higher than any reported to date. In this respect, the decanter has been shown to be an attractive alternative in many situations where filterpresses are used for the dewatering of municipal sludges.
Design Methods for the Development of Wastewater Land Disposal Systems
Authors: Thoma K. , Baker P. A. , Allender E. B.
Published: May 2018

Recent changes in legislation governing water quality management of receiving water bodies have led to a reappraisal of wastewater land disposal techniques. However, more stringent regulations have also necessitated the development of a multi-disciplinary planning approach, to ensure that land based wastewater disposal is functionally and environmentally sustainable in the long-term. Of principal concern are the long term impact of nutrients, salt and other potential contaminants on the soils of the receiving site and on downstream water quality. Assessment of hydrological, soil physical and geological characteristics, together with civil construction and service considerations, assist in the determination of receiving-site selection, application area and balance storage volume, irrigation method, environmental monitoring system specification etc. Analysis and interpretation of wastewater and soil chemical characteristics determines the pre-application water treatment required, and aliows long-term monitoring of the effect of wastewater disposal on the receiving-site soils. Two case-studies are presented. One describes the planning and design of a recently commissioned land-disposal system using industrial wastewater from a chemical process plant to irrigate a Eucalypt plantation in western metropolitan Melbourne. The other reports on the on-going assessment and planning of a large-scale land-disposal system proposed to accommodate the treated sewage effluent from a large north-west Victorian regional city.
Parameters Influencing Sludge Thickening by Dissolved Air Flotation
Authors: Sugahara M. , Oku S.
Published: May 2018

The purpose of this study was to investigate factors influencing sludge thickening in the dissolved air flotation process. Attention focused on the alteration of sludge characteristics as a result of coagulation and aeration. Batch thickening experiments showed that both coagulation and aeration enhanced sludge thickening. The most important parameter influencing sludge thickening appeared to be sludge particle size; larger particle sizes produced higher sludge solids concentrations in the float.
Phosphorus Removal in Constructed Wetlands Using Gravel and Industrial Waste Substrata
Authors: Mann R. A. , Bavor H. J.
Published: May 2018

The phosphorus removal efficiency of three gravel based constructed wetland systems (CWSs) has been investigated in a two year study in which secondary sewage effluent was treated. The constructed wetlands systems, 100m × 4m × 0.5m with an impervious liner, comprised an unplanted gravel “control” trench and gravel trenches planted with monoculture stands of either Typhaorientalis or Schoenoplectusvalidus. Inlet and outlet phosphorus concentrations and vertical and linear profiles of phosphorus were determined to characterise immobilisation/translocation through the systems. Laboratory phosphorus adsorption experiments were conducted with regional gravels and alternative adsorptive media including industrial slag and ash by-products.

Phosphorus adsorption in the large scale gravel systems was variable and ranged from −40% to 40%. Laboratory adsorption capacity studies conducted with the gravel substratum indicated that field adsorption potential could be successfully simulated and modelled.

Ion exchange experiments have been used to evaluate gravel and industrial conglomerates, with a view to improving phosphorus immobilisation through substratum selection and effluent flow management. Langmuir and Freundlich isotherms characterised phosphorus adsorption and the maximum adsorption capacity of regional gravels ranged from 25.8 to 47.5 μg P/g compared to blast furnace slag 160 to 420 μg P/g and fly ash 260 μg P/g. These results indicate that further investigations into the inclusion of industrial waste substrata in a CWS are warranted.
A Water Treatment and Recycling System for Intensive Fish Farming
Authors: Chin K. K. , Ong S. L. , Foo S. C.
Published: May 2018

Rain water was collected from storm drains and after filtration was stored at an earth pond. The pond water was the main source of fresh water supply for intensive fish cultivation. To conserve the limited water resources, effluent from fish cultivating ponds was treated and recycled for reuse. With proper blending of water from the storing earth pond and recycling of the water between the fish ponds and the fish lagoon, water quality at the fish ponds and the lagoon was maintained at acceptable levels. Although fresh water replenishing rate was low there was no serious buildup of metals and total solids in the fish ponds.
Influence of Particle Size Distribution on the Dewatering of Organic Sludges
Authors: Olböter L. , Vogelpohl A.
Published: May 2018

The particle size distribution of different sludges from sewage treatment plants was compared. Since the dewaterability of a sludge depends on its particle size distribution, this property can be used to characterize dewaterability. Thus, as shown by an example, the change in the dewaterability by conditioning a sludge with a polymer reflects the change of the particle size distribution. The measurement of the particle size distribution at a defined position in a settling tube during the settling process may also be used to study the settling behaviour of a sludge.

The floc structure of sludges from different treatments varies in a wide range. It is not possible, therefore, to give a full characterization by the particle size distribution only. Furthermore, structural elements of the sludge flocs cannot be neglected. Taking this into consideration, new dewatering parameters have to be defined in order to characterize dewaterability as a function of the particle size distribution.
Household Membrane Bioreactor in Domestic Wastewater Treatment
Authors: Chiemchaisri C. , Yamamoto K. , Vigneswaran S.
Published: May 2018

The activated sludge process coupled with hollow fiber membrane for solid-liquid separation was applied to treat low strength domestic wastewater.

Pilot-scale experimental unit used in this study consisted of 2 modules of 0.03 μm pore size with 9 m2 surface area each, immersed in the reactor which has a maximum working volume of 1.5 m3. Even when sewage was fed at varying rates following its diurnal flow variation to the bioreactor, good stability of the process was achieved which was shown by the consistency in treated water quality. The effluent turbidity and COD were well within the limits (less than 0.5 NTU and 3-5 mg/L). The transmembrane pressure drop was less than 20 cm Hg even after 2 months of operation. Application of jet aeration could be used to prolong the operational life of the membrane in the bioreactor. This system is an ideal one to be used as household wastewater treatment system.
Microbial Activity and Performance of an Anaerobic Reactor Combining a Filter and a Sludge Bed
Authors: Chung Y. C. , Choi Y. S.
Published: May 2018

Microbial activity and performance of anaerobic upflow sludge bed filter(AUBF) were investigated using two types of AUBF: 1/2 packed (AUBF-1/2) and 1/7 packed (AUBF-1/7) with media, and a fully packed anaerobic filter (AF). Each reactor was loaded with 1 to 3 kg COD/m3-day of distillery wastewater using naked barley as raw material. Adenosine triphosphate and dehydrogenase activity measurements were applied to measure the microbial activity in the reactors. AUBF presented comparable treatment efficiencies, while the microbial activity in AUBF is equal to or higher than in AF. Upper packing and lower sludge bed were very efficient to retain the biomass and reduce the amount of packings needed without sacrificing the performance. However, AUBF resulted in less process stability at shock loading than AF, and operation of AUBF needs more careful control to maintain the stability.
Improved Sludge Dewatering by Enzymatic Treatment
Authors: Thomas Lutz , Jungschaffer Gerald , Sprössler Bruno
Published: May 2018

Nowadays West Germany produces 50 million cubic metres of liquid sludge per year. This tendency is still on the increase, whereas traditional means of utilisation, such as in agriculture, show a sharp decline. For this reason, about 60 - 70 % of the sludge has to be deposited at waste tips with a limited capacity. Therefore it is highly desirable to reduce the sludge volume as much as possible. By enzymatic hydrolsis it is possible to modify the hydrophilic, water-retaining organic compounds of the sludge in order to reduce its water content. Enzymes improve mechanical dewatering in common belt-type filter presses or decanters in combination with flocculation by means of special flocculating aids.
A New Process to Treat Strong Biological Waste
Authors: Henry D. P. , Thomson R. H.
Published: May 2018

Strong brewery waste was trickled through a vertical curtain consisting of two 3mm layers of reticulated Polyurethane foam bonded to a reinforcing nylon cloth core. A filamentous fungus, Geotrichum fragrans adhered to the curtain and provided a matrix for other yeasts and aerobic bacteria which include Kloeckera lindneri and a Candida sp., a Bacillus sp. and a Corynebacterium sp. The organisms grew as a lawn. To avoid anaerobiosis the lawn was harvested periodically by passing the curtain through rollers leaving a viable representative residue of the population. Passage through 6m of curtain reduced a TOD of 55,000 mgL−1 to 3,300 mgL−1 (94%). Probably the length of the curtain could be reduced to 4m with a residence time of 9.6h. One m2 of curtain with a 4m fall can treat 15Ld−1.

A further waste from pigs (2% solids) was acidogenically fermented to produce organic acids. The acids during clarification were used to kill the bacterial pathogens in the waste. The liquor was run through a curtain inoculated with suitable organisms. These removed the unpleasant odour and 88% of the TOD in a 4m passage through the curtain. Treatment time: fermentation 5d, clarification and removal of pathogens 2d, treatment in curtain 0.3d, total 7.3d.
Dewatering of Activated Sludge by an Oxidative Treatment
Authors: Mustranta A. , Viikari L.
Published: May 2018

Different activated sludges from pulp and paper mills were treated with hydrogen peroxide in the presence of ferrous sulphate under different reaction conditions in order to improve the dewatering characteristics of the sludges. The efficiency of the treatment was evaluated on the basis of the specific filtration resistance. Although sludges from different mills varied considerably with respect to their chemical composition and dewatering properties, the specific resistance values of all the sludges could be decreased using rather mild conditions. The filterabilities of the sludges were dependent on reaction temperature, hydrogen peroxide concentration and the reaction time used in the oxidative treatment. Depending on the type of sludge, hydrogen peroxide concentrations of 15 to 30 % mmoles/l sludge were sufficient to decrease the filtration values to a low level at 70°C using a reaction time of 1-2 hours at pH 3.
Thermophilic Anaerobic–Aerobic and Aerobic Treatment of Kraft Bleaching Effluents
Authors: Rintala J. , Lepistö R.
Published: May 2018

Thermophilic anaerobic-aerobic treatment of bleach kraft mill effluent (BKME) at 55°C was studied using reactors partially packed with polyurethane carrier material. The wastewater was a mixture of chlorination stage and alkaline extraction stage effluents from softwood pulping. Both the thermophilic anaerobic and aerobic treatments provided about 40-45% COD and AOX removals at loading rates of about 13-2.5 kg COD m−3 d−1, which corresponded with hydraulic retention times of 17.6-30 h. The aerobic post-treatment removed less than 10% of the COD and AOX present in the anaerobically treated BKME.
Studies of the Refuse Methanogenic Fermentation by Use of Laboratory Systems
Authors: Watson-Craik I. A. , Sinclair K. J. , James A. G. , Sulisti  , Senior E.
Published: May 2018

Simple closed-culture models and single-stage refuse column studies were used to demonstrate, respectively, responses of the intact association, and the effects of leachate movement on the refuse fermentation. Differential inhibitory effects on each physiological group could not, however, be directly demonstrated. To achieve this requires the spatial isolation of each group in individual vessels of multi-stage models. These were used to investigate the kinetic properties of an association exposed to the electron acceptors NO3, SO4 and CO2, and the differential inhibitory effects of phenol on sulphate-reducing bacteria and methanogens.
Pollution Profile of Leather Industries; Waste Characterization and Pretreatment of Pollutants
Authors: Sengül F. , Gürel O.
Published: May 2018

The leather industry is one of the most widespread industries in the Aegean Region and its pollution loads are very high. In this study, chemicals used in the leather industry with regard to different production technologies utilized and the water consumption and pollution loads are determined. With the help of this data, characterization of the leather industry wastewaters during production are carried out, and the possible pretreatment of the leather industry's wastewaters are examined.
Anaerobic Treatment of the Centrifuged Solid Fraction of Piggery Wastewater in an Inclined Plug Flow Reactor
Authors: Górecki J. , Bortone G. , Tilche A.
Published: May 2018

This paper reports the experimental results of a 6 months run on a bench scale inclined tubular anaerobic reactor treating centrifuged piggery sludge at 12-18% TS. The particular reactor design was demonstrated to be appropriate for handling this very dense feed material. Reactor performances were very satisfactory: with increasing loading rates up to 10 g COD.1−1.d−1 (corresponding to 12 d HRT the organic matter degradation was always constant around 60%. Methane yield was calculated around 321 CH4/l raw feed. The effluent was well dewaterable and showed low phosphorus levels in the liquid phase. A curious phenomenon of granulation is also discussed.
Observations on the Kinetics of Nitrification under Inhibiting Conditions Caused by Industrial Wastewater Compounds
Authors: Nowak O. , Svardal K.
Published: May 2018

Within the next few years nitrogen removal will be obligatory for both municipal and industrial wastewater treatment plants in Austria. During the operation of pilot plants, severe inhibition of the nitrification process has been observed in several cases. Further investigations have been carried out at two biochemical factories at temperatures in the range of 22 to 32 ±C, in one case at two pilot plants, in the other case at a full-scale plant in order to estimate kinetic parameters of nitrifying biomass under the particular inhibiting conditions of these wastewaters. In both cases competitive inhibition occurred during the start-up period for about two months. The ammonia nitrogen half-saturation coefficient for autotrophic biomass was in the range of 10 mg/l. In one case also maximum autotrophic specific growth rate varied in a wide range. It could be proved that the compounds of this wastewater have an inhibiting but no toxic effect on Nitrosomonas. The effluent ammonia concentration can be kept within the limits in case of competitive as well as non-competitive inhibition up to about 60% by increased minimum SRT. In case of severe non-competitive inhibition it is not possible to achieve feasible biological nitrification. In any case the inhibiting compounds should be located and removed from the wastewater.
Upflow Anaerobic Filtration of a Sugar Containing Wastewater
Authors: Boller M. A. , Eugster J.
Published: May 2018

Pretreatment of a sugar containing wastewater from a date processing plant was tested for COD removal in an anaerobic pilot filter over a period of eight months. The filter was operated in the upflow mode and randomly packed with a plastic pipe carrier material. Initial start and restart after a 6-week break, steady state performance on seven different COD load levels ranging from 1.6 to 25 kg COD/m3·d, and filter behavior during reactor acidification were observed. In all examined experimental cases, the anaerobic filter rapidly adapted (5-7 days) to new operating conditions, thus indicating its high process flexibility. Below COD loads of 20 kg COD/m3·d, a COD removal of 90% or more was achieved. The specific CH4 gas production was measured at 0.40 - 0.53 m3 CH4/kg COD removed, and the specific sludge production was quantified at 0.1 kg paniculate COD/kg COD removed throughout the experimental periods. Biomass distribution revealed that 60% was attached to the packing media and 40% was suspended in the pore space. Based on COD profiles along the filter height, conclusions on the reactor flow pattern could be drawn. With the help of a simple reactor model, the experimental results could be used to simulate other process conditions for design considerations.
One- and Two-Step Anaerobic Digestion of Solid Agroindustrial Residues
Authors: Weiland P.
Published: May 2018

Large quantities of solid organic residues are generated during the processing of vegetable matters in agro-industry. In general, these residues are structureless and contain more than 80 % water, so that composting is hindered. A possible alternative for the stabilization of these residues may be the anaerobic methanogenic degradation, which has the additional advantage of biogas formation. For the development of an efficient and reliable anaerobic treatment process, two novel digestion systems with one- and two-step operation have been built in pilot-scale and tested with different agro-industrial residues. The results have shown that for residues with a C:N-ratio above 15 the one-step process should be used preferably, whereas protein-rich residues with a C:N-ratio below 10 can be treated only in the two-step process. For the different agro-industrial residues it was found that about 50 - 70 % of the organic matter can be degraded within retention times of 10 - 20 days. The biogas production was typically 300 -500 m3 per ton of dry organic matter.
Behavior of a Biological Fixed-Film System Treating Toxic and Nontoxic Organic Wastes
Authors: Hamoda M. F.
Published: May 2018

The treatment of industrial wastes containing both toxic and nontoxic organic compounds is often accomplished by biological processes. Despite its success in many instances, the complex nature of the effects of toxic substances on process performance and kinetics is not well understood. This study was conducted to examine the behavior of an aerated submerged fixed-film (ASFF) biological system receiving a mixture of toxic (phenol) and nontoxic (sucrose) bisubstrate and evaluate its kinetic parameters. Laboratory experiments were carried out using a 50-litre ASFF reactor composed of four equal compartments.

Heterogeneous biomass acclimated to a bisubstrate (phenol/sucrose) system demonstrated the preference of microorganisms to utilize sucrose with a slower concomitant utilization of phenol. However, the removal in a bisubstrate system is slightly higher than that in a single substrate system which may be attributed to the extra biomass accumulated from the utilization of the other substrate. A steady-state approach to process kinetics indicates that substrate removal in the first compartment follows the Monod model for both sucrose and phenol where no mhibition (Haldane rate expression) appears over the studied range of phenol concentrations up to 800 mg/l. Meanwhile, substrate removal in the second through fourth compartments is better described by a variable order model which is likely to be a function of the hydraulic loading.
The Acidogenic Digestion of the Organic Fraction of Municipal Solid Waste for the Production of Liquid Fuels
Authors: D'Addario E. , Pappa R. , Pietrangeli B. , Valdiserri M.
Published: May 2018

Several reactors were tested for the anaerobic conversion of the organic fraction of municipal solid waste into volatile fatty acids. The reactors examined included Batch, Semi-Continuous Stirred Tank Reactor and Multistage-Counter Flow Reactor.

After reasonable retention times (12 days), Batch systems operating at 15% w/v of dry matter and under pH controlled at 6.5, gave better performances both in terms of total Volatile Fatty Acids (VFA) concentration (23-24 g/l) and conversion yield (215 g VFA/kg volatile solids). However, these conditions of reaction caused a high level of liquefaction of the feedstock which resulted in a difficult down-stream processing. On the contrary, the acidogenesis under uncontrolled pH, allowed the production of leachates directly processable for acids recovery. Based on this reason, the Multistage-Counter Flow Reactor, operating under uncontrolled pH, appeared to be the most promising system.

The leachate obtained from such a system was processed to obtain mixtures of C2-C7 methyl esters, potentially usable as octane enhancers. The digested solid was intended to be dried and refined to obtain soil amendment. A process for the treatment of municipal solid waste based on the previous steps and including conventional sorting facilities and units for the incineration of all residual solids, was evaluated to be economically comparable with landfilling. The revenues from the sales of esters and fertilizers were highly sensitive to the yield of the acidogenic step and to the value and the amount of the derived fertilizer. Further research is still in progress to improve the economics of the process. The activities are addressed to study proper procedures for the improvement of the down-stream processing of the mixtures originating from acidogenesis under almost neutral pH.
Modeling of Pretreatment and Acidogenic Fermentation of the Organic Fraction of Municipal Solid Wastes
Authors: Beccari M. , Longo G. , Majone M. , Rolle E. , Scarinci A.
Published: May 2018

The organic fraction of municipal solid waste represents a potential feedstock to be treated through biorefining. However, the process feasibility strongly depends on the effectiveness of a chemical pretreatment. Consequently, experimentation aimed at choosing the optimal type of reagent (alkali or acids) and optimal operating conditions was carried out. The best results were obtained using NaOH at room temperature. Solubilization data are in good agreement with a kinetics based on two competing reactions. Simulation of the overall process (pretreatment and acidogenic fermentation) taking place in two CFSTR reactors shows that an optimum ratio exists between the hydraulic residence times of the two stages of the process.
Codisposal of Disposable Diapers with Shredded Municipal Refuse in Simulated Landfills
Authors: Pohland F. G. , Cross W. H. , King L. W.
Published: May 2018

Pilot-scale investigations on the fate and potential effects of disposable diapers codisposed with shredded municipal refuse were conducted using simulated landfills operated under leachate containment and recycle conditions. Carbon fourteen(14C)-labelled absorbent gelling material (AGM) was used to detect the possible loss of the diaper polymer to the gases and liquids generated during the various stages of landfill stabilization. Only a small quantity (<3%) of the total 14C appeared in either the leachate or gas phases. This indicated only minor degradation of the 14C-labelled AGM to either leachate soluble products or methane (CH4) or carbon dioxide (CO2). Retrieval of the diapers and waste after the completion of the landfill stabilization is scheduled to confirm this finding and complete a 14C mass balance. Moreover, the overall results indicated the effectiveness of landfill simulations for determining the fate and effects of codisposed post-consumer products throughout the sequential phases of landfill stabilization.
Process Constraints in Source-Collected Vegetable Waste Composting
Authors: Vallini G. , Pera A. , Valdrighi M. , Cecchi F.
Published: May 2018

A pilot plant for compost stabilization of the vegetable waste (green waste or residues) which daily accumulates at the garden-produce markets in Florence (Italy) is described here. The green residues are source-collected. After shredding they are mixed with a ligno-cellulosic bulking agent in order to reduce their high moisture content and to promote porosity of the vegetable biomass. Composting is carried out in a special kind of open reactor (Aerated Dynamic Composting Trench) with forced ventilation and turning machinery. Retention time for composting in the biooxidation trench is 35 days. Following this the compost is placed in a post-maturation yard. This paper gives information about the main aspects to be taken into account for the management of the composting process applied to vegetable waste in order to obtain a high-quality organic soil amendant.
Prediction Rules for Biogas Valorisation in Municipal Solid Waste Landfills
Authors: Marticorena B. , Attal A. , Camacho P. , Manem J. , Hesnault D. , Salmon P.
Published: May 2018

The objective of this study was to develop a tool to predict the quantity of biogas produced by a municipal solid waste (MSW) landfill site to allow the energy it represents to be exploited.

The model proposed is based on a first-order kinetic equation which describes the production of methane during in-situ decomposition of MSW. This equation was applied to a landfill site considering the MSW mass as a series of layers of waste of differing ages. The equation includes three parameters: MPo, the methane potential of fresh waste which is specific to MSW, d, the in-situ life duration of the waste which depends on the landfilling conditions and Ti, the filling rate, i.e. the rate at which waste is placed in the landfill site. This simple model, usable for all types of landfill and, by virtue of the parameters it uses, closely represents the site operating conditions. The approach was applied to the Villeparisis site and predicted a methane production rate of between 270 and 410 m3h−1, quite close to the measured value of 300 m3.h−1. In addition, the possibility of simulating variable landfill rates and waste life durations can be used to guide site management techniques to optimize the valorisation of the biogas and provide a global approach to the problem by incorporating leachate collection into the biogas exploitation calculations.
Effect of Ion Adsorption with Various Hydrolysis Characteristics on the Dewaterability of Fe2O3 Sludge
Authors: Hsieh Yung-Hsu
Published: May 2018

In the presence of ions with various hydrolysis characteristics, the water-molecule structure and surface charge on iron sludge colloids can be changed and the dewaterability of iron sludge will also be affected. Such effects were studied in the laboratory through determinations of zeta potentials and specific the resistance of Fe2O3 sludge particles. It was found from experiments in the presence of ions with various hydrolysis characteristics in the iron sludge solutions, that the dewaterabilities of iron sludges showed the orders Cl− > Br− > I− and IO3− > BrO3− > C1O3− for anions, and Li+ > Na+ > K+ > Rb+ > Cs+ and Mg2+ > Ca2+ > Sr2+ ∼ Ba2+ for cations. In the presence of ions of different concentrations, the change in zeta potentials and the improvement of dewaterabilities of iron sludge particles followed the order lO−2M > 10−3M > lO−M for both IO3− and Li+; although the change in zeta potentials increased with the ion concentration for I− and Cs+, the dewaterabilities of iron sludges were depressed with increasing ion concentrations.
Fundamental Studies on Hydrogen Production in the Acid-Forming Phase and Its Bacteria in Anaerobic Treatment Processes – The Effects of Solids Retention Time
Authors: Nakamura Michimasa , Kanbe Hiroshi , Matsumoto Jun'ichiro
Published: May 2018

Effects of solids retention time (SRT) on hydrogen gas production, glucose degradation and anaerobic bacteria in anaerobic treatment processes were investigated with use of 11,700 mg/l glucose solution as a substrate. Five series of experiments were conducted at 36 ± 1°C. Volatile fatty acids were produced in the order: acetic, n-butyric, propionic and n-valeric with concentration of effluent. Counts of general anaerobic bacteria and acid-forming bacteria in each reactor increased with increasing SRT, and counts of genus Clostridium and sulphate reducing bacteria in the reactor decreased with increasing SRT of the reactor. Gas production rates and gas composition were investigated to obtain information on energy production. Solids retention time increased from 2 to 10 h, hydrogen gas content decreased from 12 to 9%. The kinetic constants such as the microbial decay coefficient (Kd), the maintenance coefficient (m) and the growth yield for microorganisms (YG) were 4.04,41.7 and 0.097 day−1, respectively.
Effects of Photolytic Pretreatment on Biodegradation and Detoxification of Surfactants in Anaerobic Digestion
Authors: Tanaka Shuzo , Ichikawa Tsutomu
Published: May 2018

The effects of photolytic pretreatment on the biodegradation and detoxification of surfactants in anaerobic digestion were investigated by batch experiments with anaerobic digester sludges. Experimental results revealed that the surfactants were lowly biodegradable and highly toxic to methanogenic bacteria but a photolytic pretreatment with UV irradiation using a TiO2 catalyst was very effective at enhancing the biodegradability and reducing the toxicity of the surfactants. Both anionic sodium dodecyl sulphate (SDS) and sodium dodecyl benzene sulphonate (ABS), and nonionic p-nonylphenyl poly (oxyethylene) ether (NPE) brought about 50-60% reduction and cationic tetradecyldimethylbenzyl ammonium chloride (TBC) caused 100% reduction at a 100 mg/l concentration in the production of methane from glucose. With photolytic pretreatment of the surfactants under 4 h of UV irradiation, however, methanogenic activity was greatly enhanced in TBC and 30-50% increased in methane production in the other three surfactants as compared with unpretreated systems. The results imply that a combined system of photolytic and biological processes will be applicable to the treatment of wastewater containing toxic organics such as surfactants. It is also indicated that the photolysis of such aromatic surfactants as ABS, TBC and NPE is primarily a cleavage of the benzene ring and the degradation rate is expressed as a first order reaction.