bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of micronucleus in vitro assay to micropollutants in river water
Authors: Chung Youn-Son , Ichikawa Kazuhiro , Utsumi Hideo
Published: May 2018

To determine the genotoxicity of river water towards mammalian cells, we applied Micronucleus in vitro test using mammalian cells to the samples taken from river Tamagawa located between Tokyo and Kanagawa prefecture. Water samples were condensed by Sep-pak cartridges and extracted by dichloromethane and methanol. Positive genotoxicity was observed in methanol extracts from sampling stations of Hinobashi and Marukobashi, while no dichloromethane extracts showed genotoxicity, suggesting that polar genotoxic micropollutants may be contained in the water of Tamagawa, at least in its down-stream. Significantly high mutagenicity also detected from Hinobashi and Marukobashi by Ames mutagenicity test using Salmonella Typhimurium, and some difference was obtained in sensitivity between the two methods. This may arise from the difference in species used, that is, mammalian cells in micronucleus test and bacteria in Ames mutagenicity test.
Respiratory quinone profile as a tool for refractory chemical biodegradation study
Authors: Hu Hong-Ying , Fujie Koichi , Tanaka Hajime , Makabe Tsuyosi , Urano Kohei
Published: May 2018

The respiratory quinone profile was successfully used as a tool for identifying the change of bacterial phase in the microbial film of aerobic submerged biofilter treating refractory chemicals such as dimethylformamide (DMF). It was ascertained that the coexistence of easily biodegradable substances such as glucose and peptone hindered the acclimation of bacteria inhabiting the microbial film in biofilter to DMF. The higher initial microbial concentration and the feeding of DMF as a sole organic substance accelerated the acclimation of microbial film to DMF. Appreciable changes in quinone profile were detected through the acclimation to DMF, and the results showed that DMF degrading bacteria such as Methylobacterium and Mycobacterium had grown in the biofilter.
Estimation of suspended solids concentrations in activated sludge settling tanks
Authors: Kim Youngchul , Pipes Wesley O. , Chung Paul-Gene
Published: May 2018

This is a report of a field study based on data from an activated sludge process in a wastewater treatment plant in Chester, Pennsylvania, USA. The objective was to develop an accurate method for estimation of the average suspended solids concentration (SSB) of the layer of sludge in the settling tanks (the “sludge blanket”). Plant operators estimated SSB by averaging the mixed liquor suspended solids (Sm) and the return sludge suspended solids (Su) concentrations. Measurement of SSB showed that averaging Sm and Su frequently overestimated SSB by a large amount. A different relationship between SSB and parameters which are normally measured for operational purposes was developed. The parameters are Su, the overflow rates and data from the sludge volume index (SVI) measurement. It was found that an increasing overflow rate will result in an exponential decrease in the ratio of SSB to Su. Also, the SVI has a marked effect on the ratio of SSB to Su and thus on the amount of suspended solids which can be stored in the settling tanks. The proposed estimation equation was found to be statistically superior to estimation by averaging the Sm and Su.
Effects of hydraulic shock loads on small on-site sewage treatment unit
Authors: Panswad T. , Komolmethee L.
Published: May 2018

This research was to determine the effects of hydraulic shock loads by intermittent feeding on the removal efficiency of a small prefabricated real-sized septic tank/anaerobic filter unit. Besides the ‘control’ 24-hour continuous runs the other twice a day feeding periods covered 16, 12 and 8 hours per day, with the tank's retention time varying from 22.5 to 90 hours. It was demonstrated that the variation of the hydraulic feeding patterns ranging from 24-hour continuous feed to 8 h per day intermittent feed did not affect the performance of the system much. The percentage of BOD reduction was decreased from 85 to 82 and 81 percent for the feed times of 24, 16 and 8 hours per day, respectively.

The tank capacity played a relatively major role in determining the removal efficiency of the process. The efficiency of BOD and SS reduction dwindled from 82.2 to 68.9 and 56.0% with the corresponding reduction in tank sizes from 90 to 45 and 22.5 hours retention, respectively. In any event, the unit could not satisfactorily remove nutrients. A retention period of not less than 48 hours is recommended if the Thai effluent standards are to be met. Equations for predicting the BOD removal capability were also developed.
Effects of calcium ion on sludge conditioning
Authors: Chang Min-chao , Chuang Shun-hsing , Lin Hui-ling
Published: May 2018

Investigating the sludge conditioning behavior and improving sludge conditionability were the primary objectives of this study. The effects of calcium ion with and without polyelectrolyte conditioning behavior on two industrially activated sludge systems were studied via Capillary Suction Time (CST) tests.

Experimental results indicated that the calcium ion can strongly enhance the conditionability of the industrial biological sludge system. The good conditionability of calcium ion added system could have possibly resulted from the interaction of polysaccaride from activated sludge with calcium ion. Additionally, adding polyelectrolyte solution first would produce more suitable conditioning in a situation in which calcium ion is involved with polyelectrolyte system.
Acidification during anaerobic treatment of brewery wastewater
Authors: Suzuki Hitomi , Yoneyama Yutaka , Tanaka Toshihiro
Published: May 2018

Several experimental tests were performed to study acidification during the anaerobic treatment of brewery wastewater. Batch test results suggested that a pH of 5-6 and a water temperature of 40°C were optimal conditions for acidification. Continuous-flow test results indicated a tendency for the carbohydrate reduction percentage to become higher with longer retention time in the acidification reactor. A high Specific Methanogenic Activity (SMA) of over 1.4 kg COD kg−1 MLVSS d−1 was observed, which the carbohydrate reduction percentage exceeded 75%. However, there was a tendency for the SMA to become lower due to residues of highly concentrated carbohydrates. The carbohydrate reduction percentage dropped to below 60% in the acidification treated water, when the retention time in the acidification reactor was extremely short. For achieving a carbohydrate reduction percentage of more than 75%, the retention time showed a tendency to become longer with higher organic concentration (e.g. COD 2,500-4,000 mg l−1: 3 h, COD 5,000-8,000 mg l−1: 6 h, and COD 10,000-16,000 mg l−1: 12 h).
Evaluation methods for the design of adaptive water supply systems in urban environments
Authors: Jeffrey P. , Seaton R. , Parsons S. , Stephenson T.
Published: May 2018

The issue of sustainable modes of development are not restricted to those concerning environmental protection or pollution control/minimisation. In generic terms, sustainable systems are those which can be adapted to changing circumstances. Given the essential nature of utilities there is a clear need to plan and manage their technologies in a sustainable manner. This paper offers an initial theoretical structure for designing and managing adaptive technological infrastructures for utilities in generic terms and suggests how such a framework may apply to water supply systems. In particular, the development of new water recycling technologies and the emergence of ‘complex system’ modelling techniques provide opportunities for the design of water supply systems which are adaptive to changes in the urban social and physical environment in which they are embedded.
Tracking heavy metals reveals sustainability deficits of urban drainage systems
Authors: Boller Markus
Published: May 2018

Heavy metals such as cadmium, copper, lead and zinc are the critical metals in domestic wastewaters. Based on mass flow studies, the runoff from roofs and streets contribute 50-80% of these metals to the total mass flow in domestic sewage. Depending on the sewerage concept, the metals accumulate in different environmental compartments. Witt the combined sewer system, most commonly applied, the major part of the metals is bound to the sludge during sewage treatment. If the sludge is used in agriculture, the metals are enriched slowly in the top soils. With separate sewer systems, the metal loads to the receiving waters are increased, finally leading to accumulation in the sediments. If the new concept for the infiltration of runoff waters is applied, rapid and concentrated accumulation at the infiltration sites will occur. As a short term measure, new adsorptive elements in infiltration facilities would allow us to control the accumulation. The deposition of heavy metals in the environment cannot be avoided as long as no further efforts are made to reduce metal emission at the source. New partnerships between environmental/sanitary engineers and other professional groups such as architects, plumbers, car engineers, material technologists have to be established in order to minimize diffuse longterm deposition of hazardous substances and to be able to realize sustainable small water cycles without negative side-effects.
Application of waste stabilisation ponds in Bhutan - lessons within a sustainable development context
Authors: Charlton John
Published: May 2018

The Danish International Development Assistance agency has funded a project in Bhutan which includes a water supply component in six urban centres, a sewerage component in the two largest cities plus associated institutional development. The project includes the implementation of an extensive water-borne sewerage system and associated wastewater treatment. The treatment process adopted was waste stabilisation pond technology due to the low associated construction, operations and maintenance costs and low requirements for technical skills hence contributing to financial and O&M sustainability of the project, as well as meeting the water quality requirements for the receiving waters. Since essentially all available land is utilised in the country, the locations of the treatment plants are adjacent to rivers which are fast flowing, leading to a risk of severe erosion conditions during the monsoon season. In order to protect the treatment plant structure, river training was necessary. The high elevation of the country also has consequences for the design and operation of the plants. The wastewater treatment process includes a train of anaerobic, secondary facultative and maturation ponds, lined with a high density polyethylene liner. This paper describes the project as implemented, focusing on the wastewater treatment plants and the hurdles required to be overcome to ensure sustainable operation of the waste stabilisation pond treatment plants, in particular overall design of the system, the re-design required due to the loss of land occasioned by the intense monsoon rains in the south of the country prior to construction of river training works, the training required for the local staff from the operations and maintenance authorities and the financial aspects of the project. The project is discussed within a broader framework of Danish development aid in the country which covers the health, environment and the public health infrastructure sectors. Lessons learnt from the project are discussed.
Improved design and control of industrial and municipal nutrient removal plants using dynamic models
Authors: Coen F. , Vanderhaegen B. , Boonen I. , Vanrolleghem P. A. , Van Meenen P.
Published: May 2018

Dynamic simulation can be used to improve the design and performance of the activated sludge process. This is illustrated by means of two case studies:The simulation of a full scale industrial plant treating nitrogen-rich wastewater by an intensive nitrification-denitrification process. By means of simulation the most important operational cost (dosage of an external carbon source) was optimised and a control strategy was proposed.The simulation of a municipal wastewater treatment plant with the extension of nitrogen removal. Based on simulation the feasibility of the redesign was evaluated.

In both cases the wastewater composition was characterised and the biological model (the activated sludge IAWQ-model No. 1) calibrated. By means of respirometry and standard laboratory analyses it was possible to estimate the COD fractions of the wastewater and the parameters for heterotrophic and autotrophic growth of biomass.
Nitrogen removal from wastewater with high ammonia nitrogen concentration via shorter nitrification and denitrification
Authors: Surmacz-Górska Joanna , Cichon Andrzej , Miksch Korneliusz
Published: May 2018

Shorter nitrification is reached through Nitrobacter bacteria activity inhibition. Nitrobacter bacteria responsible for nitrite nitrogen oxidation are sensitive to free ammonium. The presence of free ammonium depended on a high ammonia nitrogen concentration in wastewater and its pH. It was the pH of the wastewater that was the decisive parameter in Nitrobacter bacteria activity inhibition in stable temperatures and at stable ammonia nitrogen concentrations. Reaction control in the aeration phase of the treatment process guaranteed the concentration of free ammonium within the 1 to 6 mg NH3/l range and at the same time concentration of free nitrous acid did not exceed 0.04 mg HNO2/l. It allowed nitrification to be significantly shortened and to receive build-up of nitrite nitrogen up to 300 mg NO2-N/l. Nitrification rate was about 0.06 g N/g MLSS·d.

Measured oxidation rates of particular groups of nitrifying bacteria as oxygen uptake rates by Nitrosomonas and Nitrobacter bacteria respectively made control of shorter nitrification easier and gave insight into the activity of both nitrifier groups.
A technique in confocal laser microscopy for establishing biofilm coverage and thickness
Authors: Silyn-Roberts G. , Lewis G.
Published: May 2018

This study uses confocal laser scanning microscopy to determine the coverage and thickness of biofilms on rock types commonly used in wetland sewage treatment systems in New Zealand. Samples of scoria, greywacke and slag - with glass used as a comparison - were submerged in subsurface flow wetlands and examined after six weeks.

An image analysis technique was used to quantitatively determine the coverage and thickness of each biofilm. The technique consisted of the biofilm quantification of each individual image obtained from the confocal optical sectioning. The results indicated that the biofilm coverage for the substrata types did not exceed 25%. However, there was a marked difference between the biofilm structures grown on the different substrata; that on glass formed thin spindly structures, and slag and scoria showed similar dense patches interspersed with open channel structures that followed the contours of the pocketed rock surface.
Sludge activity under the conditions of crossflow microfiltration
Authors: Brockmann Martin , Seyfried Carl F.
Published: May 2018

For the past year a semi-scale pilot plant for the anaerobic pretreatment of potato starch wastewater has been in operation. A reactor of 4 m3 was equiped with a settler and a so called membrane thickener to reduce the amount of sludge which has to pass the membrane. According to other publications about membrane supported anaerobic digesters, organic loadings of more than 6 kg COD/m3d rarely have been achieved by this reactor. A loss of 50% of activity was observed after circulating the sludge 20 times and a 90% loss within 100 cycles. It can be shown that the symbiosis between acedogenic and methanogenic bacteria is the most sensitive part. These observations imply that a ‘gentle’ transport of sludge through the membrane module must be developed, if membrane filtration at anaerobic reactors is to be further utilized. The results for an aerobic batch reactor implied that parallel to the destruction of sludge flocs due to the unsuitable pumps or to high transmembrane pressure, a significant decrease of the specific activity will take place.
Effects on anaerobic digestion of sewage sludge pretreatment
Authors: Choi H. B. , Hwang K. Y. , Shin E. B.
Published: May 2018

This research investigates the effect of sludge pretreatment on the anaerobic digestion of waste-activated sludge (WAS). In the key of this sludge pretreatment process, bacteria in the WAS were ruptured by mechanical jet and smashed under pressurized conditions. The protein concentrations in the sludge varied significantly after pretreatment. Protein concentration increased according to jet times and pressure. In batch experiments, volatile solids (VS) removal efficiencies were 13∼50% when the WAS pretreated once under 30 bar was fed into an anaerobic digester with 2∼26 day retention time. In the same operating conditions, when intact WAS was fed into the digester, VS removal efficiencies were 2∼35%. Therefore, it is recognized that higher digestion efficiencies of the WAS were obtained through a mechanical pretreatment of sludge.
Comparison of phosphorus removal characteristics between various biological nutrient removal processes
Authors: Sang Eun Lee , Kwang Soo Kim , Jae Hwan Ahn , Chang Whoe Kim
Published: May 2018

Bench scale experiments were carried out with four biological nutrient removal(BNR) units, A/O, A2/O, Phostrip and P/L units, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in four experimental BNR units. The influent COD/T-P ratio was varied from 22 to 64 by changing COD concentration while maintaining phosphorus concentration constant. In general sidestream BNR units such as Phostrip and P/L units outperformed mainstream BNR units such as A/O and A2/O units in terms of phosphorus removal. While phosphorus release and uptake in A/O and A2/O units became less significant at low influent COD/T-P, the phosphorus release in A2/O unit was further influenced by nitrate in return sludge and thus A2/O unit required even higher influent COD/T-P ratio for luxury uptake of phosphorus. The luxury uptake of phosphorus in Phostrip and P/L units were not affected by influent COD/T-P ratio and the adverse effect of nitrate in return sludge on anaerobic phosphorus release in P/L process was not significant due to the sludge blanket in P-stripper.
UASB performance in presence of algae and synthetic media
Authors: Park Jae Eun , Kim Jong O , Lee Woo Bum , Lee Sung Taik , Lee Jung Jun
Published: May 2018

An upflow anaerobic sludge blanket (UASB) technology has showed an excellent performance compared to other biological treatment methods when a high organic loading rate of domestic and industrial wastewaters was applied. The objective of this study was to investigate the effect algae from lake-sediments and synthetic activated ceramic as media on UASB performance. The algae and synthetic media were introduced to the UASB reactor in order to obtain the enhanced granulation, which resulted in the increase in the UASB performance. 1–3% higher methane content and 3–10% higher COD removal efficiency were obtained in the reactors with the media than in the reactor without the media. The respective gas production rates in reactors 1,2, and 3 were 0.15–0.36 m3/kg COD-day, 0.24–0.54 m3/kg COD-day, and 0.24–0.56 m3/kg COD-day. As organic loading rate increased, gas production rates increased.
Development of a rapid quantification method for nitrosomonas and nitrobacter using elisa for wastewater treatment facilities
Authors: Inamori Yuhei , Takai Tomotake , Noda Naohiro , Hirata Akira , Niioka Hiroshi , YueHua Gao , Matsumura Masatoshi
Published: May 2018

Enzyme-linked immunosorbent assay (ELISA) by use of monoclonal antibodies (MAbs) is very useful and helpful for the detection and quantification of the specific bacteria like nitrifiers in a mixed bacterial habitat. In this study, seven monoclonal antibodies were raised from splenocytes of mice(BALB/c) that are specific for the surface antigen of the two kinds of nitrifying bacteria. Three were directed against Nitrosomonas europaea (IFO 14298) and four were directed against Nitrobacter winogradskyi (IFO 14297). Cross-reactivities of MAbs against other strains of nitrifying bacteria as well as some kinds of representative heterotrophic bacteria in activated sludge and biofilm were checked to determine the usefulness of MAbs. It was found that there were some strain specificities between the same genera of IFO and ATCC strain. By means of a competitive ELISA, correlation curves for quantifying nitrifying bacteria were developed in a pure culture. It was found that this monoclonal antibody method could be used as a quick and powerful tool for estimating and controlling the population of nitrifying bacteria.
Environmental assessment of LAS on the aquatic ecosystem using a scale-up system
Authors: Takamatsu Yoshie , Inamori Yuhei , Nishimae Hironao , Ebisuno Toichi , Sudo Ryuichi , Matsumura Masatoshi
Published: May 2018

Scale-up microcosm system consisting of producer, decomposer and predator was employed to assess effect of LAS on aquatic ecosystem. Effect of LAS was determined with not only population density but also chemical data such as ATP, nutrients, pH and DO, etc. Microorganisms such as bacteria, algae, protozoa and micrometazoa in the microcosm system proliferated and reached to stationary phase on day 16. In the stationary phase, values of biological and chemical factors were constant, supporting the dynamic equilibrium of scale-up microcosm. No observed effect concentration (NOEC) of LAS on population density was less than 1.5 mg·l−1. NOECs of LAS on ATP, DO and P/R (net photosynthesis/respiration) ratio were less than 2.5 mg·l−1. It was suggested that scale-up microcosm system was useful for environmental assessment because it could provide precise assessment of chemical substances based on biological and chemical condition of ecosystem.
Effect of C/N ratio on the bioregeneration of biological activated carbon
Authors: Kim Duk-Jin , Miyahara Takashi , Noike Tatsuya
Published: May 2018

To obtain insight into the role of biological activated carbon (BAC) in the operation of the denitrification process using external carbon source, the effect of C/N ratio on bioregeneration of BAC was investigated using a fluidized bed reactor. The C/N ratio was controlled by the semi-continuous mode in which NO3-N was continuously supplied to each column. The supply of sucrose as a sole organic carbon was controlled during the experimental period. The BAC under steady state of the continuous experiments was supplied to the semi-continuous experiment. The organic carbon was supplied to each column for 20 minutes in all semi-batch experiments, but the intervals were varied from 8 to 24 hours. The influent organic carbon concentrations were controlled to maintain the average C/N ratio at 7.06 for all semi-batch experiments. In the semi-continuous experiment, the five columns have achieved an average denitrification efficiency ranging from 71% to 99%, though the influent C/N ratios were varied from 0 to 508. This is due to the adsorption and desorption capacities of BAC. BAC plays a role as a storage tank for the residual sucrose using its micropore during the time when sucrose was supplied, and BAC supplied the sucrose to the denitrifying bacteria as a carbon source so as to keep high nitrogen removal rate when sucrose was not fed to the columns. These results suggest that bioregeneration may be influenced by the C/N ratio in the environment around BAC.
An enhancement of critical flux in crossflow microfiltration with a pretreatment of floating medium flocculator/prefilter
Authors: Kwon D. Y. , Vigneswaran S. , Ngo H. H. , Shin H. S.
Published: May 2018

In this study, use of a combined system of flocculation-microfiltration was assessed for its capability in removing solids and organics. The improvement of flux by the preflocculation was also investigated. The experimental set-up consisted of (i) Millipore flat plate microfiltration module with constant permeate withdrawal arrangement and (ii) a floating medium flocculator/filter consisting of polypropylene beads as a pretreatment. Commercial ferric chloride(FeCl3) was used for flocculation. The purpose of floating medium filter was primarily to produce filterable flocs and also to achieve partial solids and organics removal. The critical flux of kaolin clay suspension of 10–100mg/L was measured for membrane of pore size of 0.2μm in the presence of 0–4mg/L of fulvic acid in the suspension without any pretreatment. The critical flux was found to decrease with the increase in kaolin clay concentration. The results also indicated that there was no significant effect of organic (fulvic acid) concentration on critical flux. The pretreatment of floating medium filter alone without flocculant addition removed 30–40% of solids and resulted in a significant improvement of critical flux in crossflow microfiltration. Degree of solids and organic removal and the variation in critical flux were then studied in detail for the preflocculated/filtered kaolin clay suspension in the presence of organics. The pretreatment of flocculation/prefiltration removed approximately 50% of organics while producing uniform microflocs of 13–16 μm size. In addition, it enhanced the critical flux by 70% and resulted in 30–70% of the remaining organic removal in the crossflow microfiltration.
Performance improvement of an unstable anaerobic leachate treatment system in an industrial waste landfill
Authors: Moon Sung Sung , Duk Chang , Hwa Young Lee
Published: May 2018

Investigation on effects of temperature and HRT on the anaerobic biodegradation of an industrial waste leachate was carried out to improve the performance of an unstable field anaerobic process operated at the ambient temperatures. Maximum biodegradable COD fraction of the leachate was 36% at the mesophilic temperature. Stable COD removal at 35°C was at least 1.2 to 1.4 times higher than those at the ambient temperatures, depending upon HRT. Temperature increase of the field anaerobic process to the mesophilic range was believed to be a competitive and practical option for the performance improvement.
Study of the reactor with down-flow injection on the characteristics of ozonation
Authors: Morioka Takayuki , Kato Yasuhiro , Hoshikawa Hiroshi , Okada Mitsumasa , Moniwa Takeo
Published: May 2018

The ozone transfer from the gas-phase to the liquid phase in the down-flow tube of the reactor showed high efficiency because of its large value of gas-liquid interface area. The estimated gas-liquid interface area of the down-flow tube was approximately in the range from 60 to 600 (1/m).

The ozone transfer efficiency (O.T.E.) of the down-flow tube was increased with the increase in ozone gas concentration. Therefore, it was clear that a high concentration of ozone gas should be applied when a higher ozone dose was needed for ozonation.

The estimated dissolved ozone concentration and O.T.E. by a mathematical model which was developed in this investigation showed good agreement with experimentally obtained data. As a result, it was shown that the model was able to describe the ozone absorption in the reactor with down-flow injection (DFI) in the wide range of operational variables.

In the case study that was carried out to compare the Cryptosporidium removal of DFI with that of a conventional fine bubble diffusion reactor by numerical simulation, DFI showed a higher performance. This higher performance is contributed to the advantage of DFI which includes the usage of high concentration ozone, greater gas-liquid interface area in the down-flow tube, and the preferable dissolved ozone profile in DFI.
Determination of the impact of toxic inflows on the performance of activated sludge by wastewater characterization
Authors: Andreadakis A. D. , Kalergis C. M. , Kartsonas N. , Anagnostopoulos D.
Published: May 2018

A rational approach for the design of the activated sludge process based on wastewater and biomass characterization techniques as applied to the upgrading of the treatment plant of Volos, a city in the central part of Greece, is presented. The study investigates possible nitrification inhibition and carbon inadequacy, due to high salinity, industrial inflows and pre-precipitation by iron salts. The experimentation was carried out by means of batch Ammonium Uptake Rate (AUR) and Nitrates Uptake Rate (NUR) tests. The results show that within the studied range, 900-4000 mg l−1, chlorides did not inhibit nitrification. Contrary to this, the industrial wastewater entering the plant was found to be toxic. With the existing 1:15 ratio of industrial to total wastewater flow a 50% inhibition to the nitrification process was observed, which is higher than the 25 - 30% inhibition caused by typical domestic sewage. Industrial contributions exceeding 20% resulted in complete inhibition of nitrification. With respect to denitrification it was found that the industrial wastewater provided a suitable source of carbon, without any adverse effects on denitrification. Pre-precipitation removed about 25% of the filtered COD, thus reducing the amount of nitrates which could be rapidly denitrified. Design of the biological reactors on the basis of the findings indicate that a significant under-design may result if typical nitrification and denitrification rates obtained from the literature and practice concerning typical domestic sewage are adopted.
Pretreatment of pesticide wastewater by photocatalytic oxidation
Authors: Lu Ming-Chun , Chen Jong-Nan
Published: May 2018

The toxic chemicals, 2,4-D (a herbicide) and propoxur (an insecticide), were used as the model compounds in these experiments. Total organic carbon analyzer was used to assess the efficiency of photocatalytic mineralization. Microtox bioassay was employed in evaluating the toxicity of solutions treated by photocatalysis. Ultraviolet absorption spectra were also used for showing the different characteristics of the compounds undergoing photocatalytic oxidation. Results show that propoxur is less degradable than 2,4-D, and the photomineralization of these pesticides follows a behavior of first-order reaction. Products of 2,4-D and propoxur are more toxic than the parent compound after partial photodegradation. This shows that complete mineralization is necessary for total detoxification of these pesticides. In other words, toxicity is an important criteria in assessing the pretreatment process.
Ultrafiltration and reverse osmosis treatment of an acid stage wastewater
Authors: Sierka R. A. , Cooper S. P. , Pagoria P. S.
Published: May 2018

The Weyerhaeuser Grande Prairie pulp mill produces 300,000 tons per year of bleached kraft for the tissue and specialty grade paper markets. Alberta Environmental Protection has given the mill stringent limits for Color (90 kilograms/admt) BOD (3 kg/admt), TSS (5 kg/admt), and AOX (1.5 kg/admt). Several technologies and combinations are being studied to ensure that the mill meets future requirements to minimize environmental impact including: oxygen delignification, ozone treatment, chemical coagulation, and membrane separation. The specific research objectives were to: (1) employ ultrafiltration techniques to separate the Do wastewater into various molecular size fractions and to characterize each in terms of total organic carbon (TOC) and color, (2) to quantify the ability of a UF membrane with a molecular weight cut-off of 8,000 Daltons (D) to reject TOC and color at three temperatures (20°, 30° and 40°C) and three wastewater pH levels (2.4, 5.3 and 7.0), and (3) to quantify the effect of 5 μm cartridge filtration and UF pretreatment on the flux and rejection characteristics of a reverse osmosis (RO) membrane. The following summarizes the results of this research. 1) Chemical characterization after separation showed that 59% of the TOC is comprised of molecules with a molecular size of less than 1,000 D but, only 20% of the color is due to these molecules. 2) Increasing the processing temperature in the range 20 to 40°C positively impacted permeate flux rate, however, water quality was not significantly affected. 3) UF processing at pH 7.0 above the pKa (5.3), increased the permeation rate but at a wastewater pH below (2.4), the converse was true. 4) Pretreatment by either 5 μm filtration or UF followed by RO yielded a permeate equal in quality, however, permeate flux rates were higher with UF treatment.
Effect of H2O2 and DTPA on the characteristics and treatment of TCF (totally chlorine-free) and ECF (elementally chlorine-free) kraft pulping effluents
Authors: Larisch B. C. , Duff S. J. B.
Published: May 2018

Perceived negative environmental effects associated with chlorine bleaching have led to the development and implementation of pulp bleaching technologies which eliminate the use of elemental chlorine (ECF) or any chlorine containing compounds (TCF). Commercial implementation of these technologies has moved forward; however, the research necessary to fully understand the impact of effluents from these new bleaching technologies on the environment and on existing biological treatment processes has lagged behind, and is for many novel bleaching sequences, non-existent. This study examined the impact of hydrogen peroxide (H2O2) and chelating agents on the characteristics and treatment of TCF and ECF kraft effluents.

Effluent BOD was reduced approximately 25% by addition of H2O2 concentrations from 20-640 mg/L, however, effluent toxicity was not affected by hydrogen peroxide concentrations of up to 640 mg/L. Unacclimated activated sludge was inhibited by sudden exposure to shock doses of hydrogen peroxide. While the viability of the sludge (as measured by the rate of substrate metabolism) was profoundly affected, the effect was reversible, with full recovery of metabolic activity restored within approximately 10 hours of the shock. In continuous trials, as the activated sludge reactor became acclimated to H2O2, the kinetics of degradation of hydrogen peroxide increased.

Chelating agents, particularly diethylene triamine pentaacetic acid (DTPA), were also found to have a dramatic impact on sludge viability and reactor performance. Batch tests indicated a DTPA dose-dependent decrease in oxygen uptake rate. Introduction of DTPA at levels commonly found in TCF effluents to continuous reactors resulted in a disruption of floc structure and a 39% decrease in BOD removal efficiency. Removal of acute toxicity as measured by Microtox was maintained despite the poor BOD removal efficiency.
The use of aerobic selectors in activated sludge systems for treatment of wastewater from the pulp and paper industry
Authors: Dalentoft Eva , Thulin Peter
Published: May 2018

Lab-scale have been made with an aerobic selector followed by an aerated reactor. Sulphate mill effluent and waste paper mill effluent were used during the tests. It was verified that the treatment system could produce a sludge with an SVI below 140 ml/g and a high COD-reduction. It was also found that a high fraction of the COD was reduced as uptake and storage in the selector. The COD was thereafter oxidized in the aerated reactor. Full scale plants have been studied where aerobic selectors are used. The plants produce a sludge with a stable SVI below 150 ml/g. This enables a stable function regarding COD-reduction at varying loading conditions and at frequent product quality changes.
Utilization of a small soda pulp and paper mill effluent for rice field irrigation
Authors: Adisesha H. T. , Purwati S. , Panggabean P. R. , Sarief S. E.
Published: May 2018

Padalarang pulp and paper mill, a soda pulp and paper mill without chemical recovery, located near Bandung, Indonesia, discharges untreated effluent mixed with domestic waste water into surrounding rice fields. For more than 60 years, paddy has been harvested 3 times a year. An in-depth study to characterize the effluent, the soil and the biomass production was conducted to define the evidence. A field study using four experimental plots indicated that soil irrigated with effluent had a higher concentration of potassium, calcium, sodium ions and greater cation exchange capacity than near-by soil. Analysis of well water showed that the effluent had no effect on the ground water. A reduction of suspended solids and BOD occurred in the effluent while flowing through rice fields. The yields of paddy demonstrated significant positive effect of effluent either in dry or in rainy season, while zeolites as soil amendment did not give significant effect to the already high paddy crop yield.
The pretreatment of acrylonitrile and styrene with the ozonation process
Authors: Chang Cheng-Nan , Lin Jih-Gaw , Chao Allen C. , Cho Bo-Chuan , Yu Ruey-Fang
Published: May 2018

Acrylonitrile and styrene are used as the raw materials for manufacturing acrylic fiber, thus they are often found as pollutants in the petrochemical wastewater. This study utilizes ozone to decompose the organic nitrogen contained in acrylonitrile and styrene, and the oxidation process was monitored using on-line measurements of oxidation-reduction potential (ORP) and pH. The efficiency of organic nitrogen decomposition was also estimated based on the COD, organic nitrogen, TOC, ammonia-N, nitrite, and nitrate measurements. Both the initial pH and alkalinity are observed to affect the degradation rate of organic nitrogen. The acrylonitrile sample with the lowest initial pH value (i.e., 4.0) has a shorter t1/2 of 18.9 min and that for samples of the highest initial pH (i.e., 11) was 34 min. The alkalinity of one acrylonitrile sample was boosted by adding 500 mg/l CaCO3, to simulate the field ABS (Acrylonitrile-Butadiene-Styrene) wastewater effluent. It was observed that within a short ozone contact time, the acrylonitrile sample spiked with 500 mg/l CaCO3 had the highest COD decomposition rate of 0.411 min−1, or 1.3 times more than that for samples without addition of CaCO3. Results of the ozonation process can be fitted with a modified Nernst equation for the various pH conditions. Additionally, the ozone treated synthetic ABS sample shows a faster COD removal rate in the subsequent biological process than those samples without ozone treatment.
Anaerobic treatment of olive mill effluents
Authors: Ubay G. , Öztürk I.
Published: May 2018

The anaerobic treatability of olive mill effluent was investigated using a laboratory scale upflow anaerobic sludge blanket reactor (UASBR) operated for about six months. The effects of various operating conditions including pH, feed strength and hydraulic retention time on the performance of the anaerobic treatment process were determined. In the first part of this study, the reactor was operated with feed COD concentrations from 5000 to 19,000 mg/l and a retention time of 1 day, giving organic loading rates from 5 to 18 kg COD/m3d. Soluble COD removal was around 75% under these conditions. In the second part of the study, feed CODs were varied from 15,000 to 22,600 mg/l while retention times ranged from 0.83 to 2 days; soluble COD removal was around 70%. A methane conversion rate of 0.35 m3 per kg COD removed was achieved during the study. The average volatile solids (VS) concentration in the reactor had increased from 12.75 g l−1 to 60 g l−1 by the end of the study. Sludge volume index (SVI) determinations performed to evaluate the settling characteristics of the anaerobic sludge in the reactor indicated excellent settleability with SVI values of generally less than 20 ml g−1. Sludge granules ranging from 3 to 8 mm in diameter were produced in the reactor. The second order substrate removal kinetics was applied by assuming that hydraulic conditions in the UASBR are approximately completely mixed and the model fitted well to the steady state operating results.
Integrated long-term receiving water study methodology development
Authors: Hall T.J. , Miner R.A.
Published: May 2018

A variety of methods have been used to assess the effects of pulp and paper mill wastewater discharges on receiving waters. Because individual methods have both strengths and weaknesses, aquatic ecosystem health is best characterized by an approach which integrates several methods. In order to better understand the significance of its effluents in the aquatic environment, the forest products industry is interested in developing a methodology for integrated aquatic health assessments. Discussions in NCASI's membership suggest that it would be desirable for an integrated aquatic assessment methodology to be capable of the following: (i) determine the environmental compatibility of mill effluents, and where compatibility is established, the margins of safety against adverse impacts; (ii) document improvements in environmental quality as contaminant or waste loads are reduced; (iii) provide an early indication of any important adverse impacts related to mill effluents; (iv) extend the framework for interpreting new and subtle measures of aquatic organism and ecosystem health; and (v) provide a framework for integrating, as appropriate, point and non-point source studies conducted by the forest products industry. Soon, NCASI will be assembling a team of experts to assist in creating an integrated assessment methodology consistent with these objectives. This paper provides an overview of integrated monitoring study elements and their strengths and weakness. Also provided is the process by which industry information needs were assessed and the results of that assessment.
Anaerobic degradation of benzoate and cresol isomers in sulfate-rich wastewater
Authors: Fang Herbert H. P. , Zhou Gong-Ming
Published: May 2018

Results of a continuous wastewater experiment conducted in an upflow anaerobic sludge blanket (UASB) reactor at 37°C showed that m- and o-cresols (225 mg·1−1 each) could be partially degraded, and their presence did not adversely affect methanogenesis of benzoate (1000 mg·1−1) and sulfidogenesis of sulfate (1800-5600 mg·1−1). With 12 hours of hydraulic retention, the reactor on average was able to remove over 99.5% of benzoate, 11.0% of m- cresol, 8.3% of o-cresol and reduce up to 48% of sulfate. Sulfate was reduced at a constant rate of 1630 mg·(1·d)−1, independent of sulfate concentration. Results of batch tests showed that biogranules were able to remove 46.2% of m-cresol and 37.4% of o-cresol in 100 hours. Furthermore, biogranules treating solutions containing 1250 mg·1−1 of sulfate degraded benzoate at an average rate 125% faster than those treating sulfate-free solutions; 74.4% of the electron flow was used for methanogenesis and only 25.6% for sulfidogenesis. Results suggest that most sulfidogens in the biogranule were acetogenic, producing acetate, most of which was subsequently converted by methanogens into methane.
Inactivation of pathogenic bacteria under mesophilic and thermophilic conditions
Authors: Watanabe Haruki , Kitamura Tomokazu , Ochi Shuichi , Ozaki Masaaki
Published: May 2018

This paper concerns field survey and laboratory experiment on the inactivation of pathogenic bacteria during sludge treatment processes with particular emphasis on anaerobic digestion process. We surveyed the inactivation of pathogenic bacteria processes by sampling various types of sludges from 17 wastewater treatment plants located in Japan and counting the number of bacteria in the sampled sludges. The bacteria we counted included fecal coliform groups, enterococcus and salmonella. The median number of fecal coliform groups in primary sludge was found to be 105 MPN/g, while the number of fecal coliform groups in digested sludge decreased to 103 MPN/g. We also confirmed that the treatments of dewatering using inorganic coagulant, drying and composting are also effective in inactivating pathogenic bacteria. In addition, we studied the performance conditions of anaerobic digestion and the degree of inactivation of pathogenic bacteria in the experiment of anaerobic treatment of the primary sludge. This study showed that the number of fecal coliform groups in mesophilic digestion sludge was in the range of 102 to 104 MPN/g regardless of the HRT, whereas the number of bacteria in thermophilic digestion sludge was of the order of 100 MPN/g, clearly indicating that the number of bacteria substantially decreases when the sludge is digested at thermophilic temperature. The number of enterococcus in digested sludge was in the range of 102 to 105 MPN/g after the sludge was subjected to mesophilic digestion while the number decreased to 100 MPN/g after the sludge was digested at thermophilic temperature. The number of salmonella in digested sludge was in the range of 1.8 to 30 MPN/4g after the sludge was digested at mesophilic temperature, but the number decreased to less than 1.8 MPN/4g after the sludge went through thermophilic digestion process. The thermophilic digestion is thus effective in inactivating pathogenic bacteria.
Microbial consortia selection in anaerobic filters operated in different reactor configurations
Authors: Harper Stephen R. , Pohland Frederick G.
Published: May 2018

The selection and morphology of anaerobic cultures grown in anaerobic packed-bed reactors, with soft-drink wastewater serving as the primary substrate, are compared for four types of laboratory-scale reactors/flow regimes: upflow, downflow, and a pair of two-stage systems. Results were obtained from scanning electron micrographs of cultures withdrawn from sampling ports located in the top, middle, and bottom of each reactor. Samples were compared with respect to the distribution of rod-like, coccoid, and filamentous microbes.
Inhibition of anaerobic digestion by terephthalic acid and its aromatic by products
Authors: Fajardo C. , Guyot J. P. , Macarie H. , Monroy O.
Published: May 2018

With 14.4 million tons produced in 1993, purified terephthalic acid (PTA) and dimethylterephthalate (DMT) are the main monomers used in the world polyester production. Even though there are ten industrial digestors treating the effluents of both products, little is known about the influence of their organic components, terephthalic (TA), p-toluic (p-tol), benzoic (BA) and phthalic (PA) acids as well as 4-carboxybenzaldehyde (4-CBA) on methanogenesis. This study shows that the concentrations of 4-CBA, p-tol and TA required to inhibit by 50% the hydrogenotrophic methanogenic activity are respectively 5.4, 34 and more than 100 mM. At the maximum concentration tested (10 mM), the inhibition of the acetoclastic methanogenic activity by the same compounds was less than 12%. The results indicate that at the concentration of TA, p-tol and 4-CBA found in PTA and DMT wastewater, no significant inhibition of the methanogenic activity should be observed for PTA but that the hydrogenotrophic activity could be reduced by as much as 30% in the case of DMT. The degradation of TA was completely inhibited by the presence of BA and glucose while the presence of phthalate had no effect. According to these results, it is concluded that it is at least possible to anaerobically treat the easily biodegradable compounds of these effluents (acetic, benzoic and formic acid) as they would not be significantly inhibited by TA, p-tol or 4-CBA.
Metal and phosphate speciation during anaerobic digestion of phosphorus rich sludge
Authors: Carliell C. M. , Wheatley A. D.
Published: May 2018

Chemical extraction methods are used to investigate metal and phosphate speciation during anaerobic digestion of phosphorus-rich sludge. Tests were performed using model compounds to evaluate the efficacy of the reagents in the extraction sequences and these results compared with similar work by other researchers. The metal speciation method was found to be suitable for identifying shifts in metal distribution but was unrepresentative of actual metal species. The phosphate speciation method did give adequate separation of the phosphate compounds tested. Full-scale digesters treating chemical and biological phosphate removal (CPR and BPR) sludge were analysed according to the methods developed. Results show that digestion of CPR sludge did not increase the soluble P concentration in the digester and that most of the precipitated phosphorus appeared to be retained in the sludge as inorganic P. The digester treating BPR sludge showed increased soluble and water-extractable P, in comparison to the control digester. Trace metal speciation profiles were found to be affected by addition of CPR sludge.