bluuebunny/crossref_metadata_2025 huggingface dataset:
Settling and coagulating behaviour of fractal aggregates
Authors: Li X.-y. , Logan B.E.
Published: May 2018

Sedimentation of fractal aggregates (200-1000 μm) and their coagulation with suspended small particles (1.5 μm) were investigated through both theoretical analysis and experimental measurement. The settling velocities of the aggregates were nearly 3 times faster than calculated using Stokes' law. Attachments of small particles on the aggregates were found to be 1 order of magnitude higher than predicted by a curvilinear collision model and 2 orders of magnitude lower than predicted by the rectilinear model. It is suggested that the internal flow through large pores within fractal aggregates likely contributed to the faster settling velocities and enhanced coagulation between the aggregates and suspended particles. The predictions for the interior flow rates and settling velocities of aggregates can be largely improved using a new fractal structure model in which aggregates are built directly from large clusters instead of the primary particles.
Tailoring of highly efficient nitrifying biofilms in fluidized bed for ammonia-rich industrial wastewater treatment
Authors: Tsuneda S. , Miyoshi T. , Aoi Y. , Hirata A.
Published: May 2018

We proposed two tailoring methods for efficient nitrifying biofilms on particles which are expected to be used in fluidized bed in nitrogen removal processes for industrial wastewaters. The first method was examined with gradual reduction of the hydraulic retention time in continuous feeding reactor to form biofilm with high nitrification ability. As a result, nitrification rate was successfully improved mainly due to acclimation of nitrifying bacteria to higher loading. The second tailoring method for nitrifying biofilm started with the biofilm which had been previously constructed in synthetic domestic wastewater containing high concentration of NH4+-N as well as various biodegradable organic compounds. Stepwise reduction of C/N ratio in inlet wastewater was performed during one month simultaneously with observation of microbial population dynamics in the biofilm using fluorescent in situ hybridization (FISH) analysis. As a result, this acclimation process promoted occupation of the biofilm by ammonia-oxidizing bacteria and resulted in making suitable biofilm structure for nitrification of ammonia-rich industrial wastewater. Moreover, it is confirmed that this new tailoring method greatly shortened required time to obtain nitrifying biofilms.
Occurrence and phase distribution of polycyclic aromatic hydrocarbons in urban storm-water runoff
Authors: Smith J.A. , Sievers M. , Huang S. , Yu S.L.
Published: May 2018

A total of 42 storm-water overland-flow samples were collected from four sampling sites (a highway off-ramp, a gas station, and a low- and high-traffic-volume parking lot). For each sample, the suspended-sediment and water phases were separated and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs). The gas station site produced the highest total PAH loading (2.24 g/yr/m2), followed by the high-traffic-volume parking lot (5.56 X 10-2 g/yr/m2), the highway off-ramp (5.20 × 10-2 g/yr/m2), and the low-traffic-volume parking lot (3.23 × 10-2 g/yr/m2). In several samples, one or more PAHs were detected in the aqueous phase at concentrations above its aqueous solubility. This result suggests the presence of colloidal-size particles capable of sorbing PAHs to an appreciable extent, or the presence of an oil-and-grease microemulsion. Based on rainfall and PAH data from seven discrete storm events, PAH concentrations were usually highest during the “first flush” of storm-water runoff and tapered off rapidly as time progressed. It is apparent from these analyses that storm-water runoff from parking lots, highways, and gas stations is a significant source of PAHs to the environment. Because some of the PAHs are carcinogens or suspected carcinogens, best management practices such as oil/grit separators should be implemented at “hot spots” in urban areas to mitigate potential PAH pollution.
Optimal location of artificial aeration in a tidal river for water quality improvement
Authors: Li S. , Chen G.H. , Yen B.C.
Published: May 2018

Artificial aeration is one of the alternatives proposed for the improvement of DO level of the Shing Mun River in Hong Kong. This study employs Saint Venant equations and one-dimensional water quality models to simulate the hydrodynamics and DO distributions in the river, respectively. Processes affecting the river quality, such as biochemical degradation, oxygen production and consumption by algae and sediment oxygen demand are considered in the models. In-situ and laboratory tests were conducted to determine the values of reaction rates of these processes. By comparing the simulated results of DO concentration under different locations of the aeration equipment along the river with the present DO condition during spring and neap tides, the optimal position of artificial aeration is determined based on the effectiveness of water quality improvement. The effect of intermittent aeration and that of continuous aeration are compared and it is found that the increase of DO in the intermittent aerationcase is about 50% of that in the continuous case on the cross-section of aeration. The influence of water temperature on the aeration is also discussed.
Single-disc investigations on nitrogen removal of higher loads in sequencing batch and continuously operated RDR systems
Authors: Lindemann J. , Wiesmann U.
Published: May 2018

Nitrification of ammonium-rich synthetic wastewater was studied in a continuously operated rotating disc reactor (RDR) with additional aeration. For a wastewater with 500 mg L−1 NH4−N a nearly complete oxidation to nitrate could be demonstrated for a hydraulic residence time of 27 h (HRT). The reactor was nearly completely mixed. Nevertheless, the biofilm covering the first discs was remarkably thicker than that of the last discs. In order to study the bioactivity of selected discs, single-disc reactors were used. The determined ammonium oxidation rate was nearly independent of the thickness and location of the disc. In contrast, the nitrite oxidation rate increased from the first to the last discs. Some results from experiments on nitrogen removal in sequencing batch single-disc reactors (SBSDR) are discussed. The SBSDR was operated with 2 phases, a partially submerged phase for nitrification and a completely submerged anoxic phase in which acetate was added for denitrification. It was advantageous to operate without additional aeration and thus produce more nitrite and saving carbon and energy. First results of the treatment of a synthetic wastewater with a C:N ratio of 1 in a 5-phase SBBR process providing 2 nitrification, 2 anoxic and a final aerobic post-treatment phase showed average specific rates.
Experimental comparison between MBBR and activated sludge system for the treatment of municipal wastewater
Authors: Andreottola G. , Foladori P. , Ragazzi M. , Tatàno F.
Published: May 2018

The aim of the described experimentation was the comparison of a low cost MBBR and an activated sludge system (AS). The MBBR applied system consists of the FLOCOR-RMP® plastic media with a specific surface area of about 160 m2/m3 (internal surface only). The comparison with activated sludge (AS) was performed by two parallel treatment lines. Organic substance removal and nitrification were investigated over a 1-year period. Comparing the results obtained with the two lines, it can be observed AS totCOD removal efficiencies were higher than MBBR ones; the average efficiencies for totCOD removal were 76% for MBBR and 84% for AS. On the contrary, the solCOD removals resulted alike (71% for both systems).

In spite of the remarkable variations of wastewater temperature, mainly in winter (range of 5–21°C), the average ammonium removal efficiency resulted 92% for MBBR and 98% for AS. With an ammonium loads up to 1.0 g m2 d−1 (up to 0.12 kg m−3 d−1), nitrification efficiencies in MBBR were more than 98%. At higher loads decrease in the MBBR efficiency was registered; that is related to the increase in the applied COD load.
Recovery and encapsulation of heavy metals on refinery spent hydrotreating catalyst
Authors: Sun D.D. , Tay J.H. , Easton C.
Published: May 2018

The experimental results indicate that spent hydrotreating catalyst (Co/Mo/γAl2O3) contains carbon (C), sulfur (S), molybdenum (Mo), cobalt (CO) and vanadium (V) at levels of 16 wt.%, 7.3 wt.%, 10.9 wt.%, 4.0 wt.% and 4.6 wt.% respectively. Calcination at 500°C is an effective process for the removal of carbon and sulfur and generates oxide form of heavy metals. Optimum removal of these metals was achieved by two stage leaching process. The first stage using concentrated ammonia was successful in removing 83 w/v % Mo. In a second stage with 10% v/v% sulfuric acid, it was found that 77% w/v% Co together with 4 w/v% Mo were removed from the spent Co/Mo/γAl2O3. A TCLP leaching test confirmed that leaching treatment produced residue that was almost stabilised with respect to V but not for Co and Mo. Enhanced binder stabilization treatment generated a commercial value brick, with up to 30 wt.% spent catalyst in marine clay which proved to be an effective means of heavy metals stabilization.
Studies on activated sludge response to variations in the composition of a synthetic surfactant-containing feed effluent
Authors: Carvalho G. , Paul E. , Novais J.M. , Pinheiro H.M.
Published: May 2018

Laboratory batch and sequencing-batch reactors and closed respirometry techniques were used to study the response of activated sludge to non-ionic synthetic surfactants. Two laboratory-grade and three commercial surfactant mixtures used in the textile industry (alkyl- and alkylphenol-ethoxylate types) were tested. Respirometric profiles during degradation experiments were complemented with titrimetric surfactant measurements and TOC determinations, representing primary and ultimate biodegradation, respectively. Though non-acclimatized sludge was apparently not inhibited by the surfactant products, total degradation took at least 20 hours with S0/X0 values in the 0.24–0.86 range. Respiration rate profiles (respirograms) showed several peaks, suggesting stepwise primary-ultimate degradation of the surfactant molecules. Acclimatization shortened degradation times and produced repirograms with a single peak. Biomass adaptation, response to load increases and memory loss was faster for primary than for ultimate degradation. Alkyl ethoxylate-adapted biomass was apparently more capable of adaptation to alkylphenol ethoxylate than the inverse.
COD removal of phenolic wastewater by biological activated carbon-sequencing batch reactor in the presence of 2,4-DCP
Authors: Ha S.-R. , Qishan L. , Vinitnantharat S.
Published: May 2018

Treatment performance of COD in the presence of 2,4-dichlorophenol (2,4-DCP) was explored by using a biological activated carbon-sequencing batch reactor (BAC-SBR) system. Two COD levels of basic substrate were synthesized with a mixture of phenol and 2,4-dichlorophenol. Although effluent concentration was increased with reduction of sludge retention time (SRT) from 8-days to 3-days, treatment efficiency was indicated more than 90% of COD in all SRTs applied. Reactors operated with acclimated sludge could be expected to cope with quite high loading of inhibitory substances.
Adaptation of an inoculum to 2,4,6-trichlorophenol biodegradation in an activated-sludge bioreactor
Authors: Olguin Lora P. , Sjölund M. , Tracol C. , Morvan J.
Published: May 2018

The aim of this work is to study the acclimation of an activated sludge inoculum fed at a constant COD volumetric load, to a recalcitrant substrate: 2,4,6-TCP. Phenol was used as an inductive and energy-supplier co-substrate and was progressively replaced by TCP. A loss in TCP removal activity to a value of 40 and then 6% was the result of two events: a shock load due to the first TCP addition that had represented 5% of the COD volumetric load and a second shock achieved with a 100% TCP inlet. This last overload stage was characterized by the reduction of non-TCP halogenated compounds concentration in the reactor effluent. On the other hand, the progressive increase of TCP generated a loss in dehalogenation and mineralization activities while TCP removal rate remained high. A load of 11.3 mgCOD.g-1VSS.h-1 of TCP as sole carbon and energy source was achieved and was accompanied with a net biomass production.
Overview of the application of anaerobic treatment to chemical and petrochemical wastewaters
Authors: Macarie H.
Published: May 2018

During the last 20 years, as a result of its low cost, anaerobic digestion has turned into a popular wastewater treatment technology. Today, with at least 1330 reactors constructed in the world, it is considered to have reached technological maturity. Until recently however, it was used quite exclusively for the treatment of food industry effluents. It is only during the last 10 years that anaerobic digestion has started to be applied massively to the treatment of sewage and effluents from other industrial activities. During the 1970s and 1980s, the chemical and petrochemical industries were almost refractory to the introduction of anaerobic digestion. The situation has reversed since 1990 and at least 80 full-scale anaerobic plants are nowadays treating this type of waste. Nevertheless, a great amount of promotion is still required before anaerobic digestion can be considered as an accepted technology by this industry. The paper presents the actual situation of anaerobic treatment at full-scale inthis industrial sector as well as recent developments at lab-scale and discusses some important concepts to consider before the implementation of an anaerobic treatment. In particular a table is presented with the main characteristics of 65 of the 80 full-scale plants identified to date. The probable reasons for the slow initial development of anaerobic treatment are also discussed and it is shown that anaerobic digestion has been the solution to treatment problems for which aerobic systems were inefficient.
Degradation of azo dye Mordant Yellow 10 in a sequential anaerobic and bioaugmented aerobic bioreactor
Authors: Tan N.C. , Borger A. , Slenders P. , Svitelskaya A. , Lettinga G. , Field J.A.
Published: May 2018

Complete biodegradation of azo dyes requires an anaerobic and aerobic step, in the anaerobic step sulfonated azo dyes (SADs) are reduced, yielding (sulfonated) aromatic amines ((S)AAs) which can be degraded aerobically. The complete biodegradation of the SAD Mordant Yellow 10 (MY10) was studied in a sequential anaerobic and aerobic bioreactor. Anaerobically, MY10 was reductively cleaved and the resulting aromatic amines, 5-aminosalicylic acid (5-ASA) and sulfanilic acid (SA), were both recovered in high stoichiometric yields. One of the AAs, 5-ASA, was readily degraded under aerobic conditions. However, SA was not degraded aerobically in the continuous experiment because no SA-degrading bacterial activity was present in the system. Therefore, a SA-degrading enrichment culture derived from Rhine sediment was used as an inoculum source. This enrichment culture was bioaugmented into the aerobic reactor by increasing the hydraulic retention time (HRT), thus enabling SA-degrading activity to develop and maintain in the aerobic reactor. After decreasing the HRT, the SA-degrading activity remained in the bioreactor and the stoichiometric recovery of sulfate (a SA biodegradation product) indicated the mineralization of SA after bioaugmentation. Batch experiments with aerobic reactor sludge confirmed the biodegradation of SA and 5-ASA. The sequential anaerobic and aerobic bioreactor was able to completely remove the sulfonated azo dye MY10 at a maximum loading rate of 210 mg MY10 (lreactor d)-1 after the appropriate microorganisms for aerobic degradation of SA were bioaugmented into the aerobic bioreactor.
Bioremediation of highly energetic compounds: a search for remediation technologies
Authors: Hawari J. , Shen C.F. , Guiot S.R. , Greer C.W. , Rho D. , Sunahara G. , Ampleman G. , Thiboutot S.
Published: May 2018

When TNT (N-source) was treated with anaerobic sludge it biotransformed into triaminotoluene (TAT) in high yield (80%). Results of experiments using 13C-labeling indicate that denitrated or deaminated products such as p-cresol and toluene were not formed. Whereas 14C-labeling showed negligible mineralization (<0.1% 14CO2) despite the complete disappearance of TNT. On the other hand, when TNT (175 μM) was treated with the fungus Phanerochaete chrysosporium it disappeared completely in less than two weeks, but mineralization (liberated 14CO2) did not exceed 1%. Several intermediates, marked with the initial formation of the two monohydroxylamino-dinitrotoluene (HADNT) followed by their transformation to monoamino-dinitrotoluenes (ADNT), diamines (DANT), acetylated TNT products, and azo and hydrazo derivatives were detected. In contrast, high concentrations (ca 20,000 ppm) of RDX and HMX were effectively degraded (ca 70%) in soil slurries using municipal anaerobic sludge. RDX and HMX disappearance was accompanied by the elimination of toxicity associated with RDX and HMX as determined by the Microtox test.
The fate and behaviour of human estrogens in a night soil treatment process
Authors: Takigami H. , Taniguchi N. , Matsuda T. , Yamada M. , Shimizu Y. , Matsui S.
Published: May 2018

A night soil treatment plant which collects a high amount of human urine and excreta, is a very unique system to Japan and the object of this investigation on the fate and behavior of the human estrogens in the water treatment process. Water and sludge samples at different treatment phases were taken at a night soil treatment plant. Their hydrophobic fractions were assayed using an in vitro yeast assay (yeast estrogen screen) and an enzyme immunoassay (ELISA) employed for the detection of overall estrogenic activity and 17β-estradiol (E2), respectively. Estrogenic activity observed by the yeast assay was quantified as E2 concentration equivalent, which was comparable with E2 concentration measured by the ELISA, in order to estimate the contribution of E2 to the total activity. Based on the ELISA results, a sketch of the mass balance of E2 in the treatment system was drawn and treatability of E2 was discussed.
Occurrence of butyltin compounds in mussels from Indonesian coastal waters and some Asian countries
Authors: Sudaryanto A. , Takahashi S. , Tanabe S. , Muchtar M. , Razak H.
Published: May 2018

The green mussel (Perna viridis) samples were collected from Indonesian coastal waters and some other Asian countries in the period of 1997–1998 to elucidate the present status of marine pollution by butyltin compounds (BTs) including mono- (MBT), di- (DBT), and tributyltin (TBT). BTs were detected in all the mussel samples from Indonesian coastal waters in the range of 3.7 to 64 ng/g wet wt as total butyltins (SBTs = MBT+DBT+TBT). The highest concentrations were found in green mussels from Jakarta Bay and Surabaya coastal waters. Relatively higher concentrations of BTs were detected in the mussels from adjacent areas of high maritime activities such as marina, harbour and fishing port. This suggests pollution of BTs arising from TBT usage in antifouling paints. BTs were also detected in mussels from aquaculture areas, implying TBT usage for fisheries activity. The composition of butyltin derivatives in green mussels from Indonesian coastal waters were in the order of TBT>MBT>DBT, suggesting fresh input of TBT in the marine environment. The contamination levels of BTs in green mussels from Indonesia were comparable or lower than those from other Asian developing countries. The elevated concentrations of BTs were found in mussels from some areas of Thailand, Philippines, India and Malaysia where residue levels of BTs were comparable to those in developed nations.
A novel method of analyzing environmental chemical mutagens in human cell systems
Authors: Takahashi S. , Chi X. J. , Nomura J. , Sugaya S. , Kita K. , Suzuki N.
Published: May 2018

Estimation of levels of plasminogen activator (PA)-like protease activity in peripheral blood lymphocytes was demonstrated to be a rapid and sensitive method for screening chemicals with mutagenic activity in mammalian cells. The combination of the PA induction test and K-ras codon 12 mutation assay was suitable for screening the mutagenic chemicals at very low concentrations. Using these methods, the mutagenicity of chlorpropham (CIPC) and di(2-ethylhexyl)phthalate (DEHP) was demonstrated in cultured human cells.
Understanding minamata disease and strategies to prevent further environmental contamination by methylmercury
Authors: Takizawa Y.
Published: May 2018

Minamata disease is a neurological disorder caused by methylmercury poisoning which originated from the discharge of wastewater containing methylmercury from chemical plants in Japan. Residents in the area who consumed large amounts of fish and other seafoods suffered from the disease. The main symptoms consist of sensory disturbance, ataxia, restriction of visual field and hearing impairment. Various measures have been taken to deal with Minamata disease, including environmental pollution control, treatment for patients, and promotion of research activities. Through the compensation law, 2,952 persons have been certified as Minamata disease patients, and a total of approximately 144 billion yen had been paid in compensation by the responsible companies as of March, 1999. Meanwhile, people who were not certified as patients have filed suits against the Japanese Government and local government challenging the diagnostic criteria. The Japanese Government, patients and their supporters reached an agreement in 1996, and Minamata disease legal issues were finally resolved, 40 years after the outbreak. The Minamata experience has left us with an invaluable understanding of the importance of taking thoroughgoing measures to prevent health damage from environmental pollution.
Surfactants – standard determination methods in comparison with substance specific mass spectrometric methods and toxicity testing by Daphnia magna and Vibrio fischeri
Authors: Li H.-Q. , Schröder H. F.
Published: May 2018

The recovery of different types of surfactants formerly applied and up-coming new ones from spiked wastewater and ultra-pure water was examined by sum parameter determinations (substance-group-specific Methylene Blue (MBAS), Bismuth Active (BiAS) and Disulfine Blue Active Substances (DSBAS)) and by substance-specific mass spectrometric detection (MS). For MS determination atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) was applied in the flow injection (FIA) and liquid chromatographic separation (LC) mode. Quantitation was performed in the multiple ion detection mode using mass and tandem (MS/MS) mass spectrometric detection. In parallel the ecotoxicological potential of these surfactants was determined by Daphnia magna and Vibrio fischeri toxicity testing. MS was found to provide more reliable data in surfactant analysis than the substance-group-specific methods. The toxicity of the up-coming new surfactants against water organisms should not be neglected.
Performance of a system combining aerated lagoons and waste stabilization ponds in a temperate climate
Authors: Nameche T. , Dufayt O. , El Ouarghi H. , Vasel J.L.
Published: May 2018

AbstractThe Bertrix wastewater treatment plant was designed and built for experimental purposes, especially for comparing aerated lagoons and stabilization ponds in a temperate climate. This plant was designed for a capacity of 7500 inhab. eq, and aerated lagoons were dimensioned to eliminate 50% of the organic load. The remaining load has to be degraded in the series of stabilization ponds.

In this paper we shall present the plant in more detail and the results of a 3-year study, i.e., 79 rounds of samples for each of the five ponds under study, placing emphasis on the performances of aerated lagoons and stabilization ponds. Principal components analysis (of inflow and outflow) of aerated lagoons and stabilization ponds will be presented and commented on. The most important factors are the hydraulic loading and the concentrations. Seasonal variations appear only in the basins' temperatures. The fates of nitrogen compounds are quite different from those of organic compounds, confirming that a high efficiency of nitrogen removal is difficult to achieve, especially for short residence times (less than eight days).

A few other conclusions of our study are given below:

The ponds' hydrodynamics has been studied and a mathematical model is now available If there is no stratification in the ponds, a thermal model can be proposed where the mean absolute difference is 0.7°C±0.2.

In the system under study, the contribution of algal biomass to the system is very small.
The effect of environmental conditions on faecal coliform decay in post-treatment of UASB reactor effluent
Authors: van der Steen P. , Brenner A. , Shabtai Y. , Oron G.
Published: May 2018

The removal of faecal coliforms (FC) in waste stabilization ponds is partly caused by natural decay processes. This work distinguishes between light mediated and light independent processes, since only the upper layer of a stabilization pond receives solar radiation. Light attenuation by algae matter or other particles causes darkness in the rest of the pond. The purpose of this work was to investigate the decay processes in stabilization ponds in order to yield improved design of pond systems.

Experiments were carried out with buffered effluents from an Upflow Anaerobic Sludge Blanket (UASB) reactor, treating domestic wastewater. The FC decay rate was determined and compared for light and dark conditions, in aerated bottles and beakers, respectively. The effective environmental factors were also investigated and mathematical expressions were derived for their effect on the FC decay rate. Special attention was given to the effect of light attenuation by algae matter.

It was found that light independent FC decay in aerated UASB effluent is caused by a shortage in carbon sources, since glucose addition prevented decay for over ten days. The nutrient content of UASB effluent was satisfactory for a long-term survival. The FC decay in the dark parts of stabilization ponds is therefore under conditions of carbon and nutrient sufficiency expected to be negligible. Under conditions of carbon shortage, the light independent FC decay was found to be temperature dependent, but not pH dependent (in the range 7.2 - 9.1).

The FC decay in beakers exposed to solar radiation was much faster then under dark conditions. The light mediated decay was affected by the pH, DO concentration and the solar radiation intensity, but not by the temperature. The addition of autoclaved algae matter strongly reduced the FC decay in the beakers, due to light attenuation. It is therefore expected that the light attenuation by algae matter in stabilization ponds also reduces the FC decay. This could partly offset the stimulating effects of algae photosynthesis (i.e. increased pH and DO concentrations) on FC decay. It seems therefore that there is an optimum algae concentration for maximum FC decay. This can lead to a new design approach, based on regulation of algae growth in stabilization pond systems.
Towards a mechanistic understanding of pond disinfection
Authors: Davis-Colley R. J. , Donnison A. M. , Speed D. J.
Published: May 2018

A broad overview of mechanisms of disinfection of waste stabilization ponds (WSPs) is based on a review of the literature on indicator micro-organisms in ponds, including our own recent experiments. There is appreciable evidence that sunlight is the single most important factor in WSP disinfection. Much of the uncertainty in the literature regarding pond disinfection may reflect the interaction of sunlight with other factors, including dissolved oxygen (DO) and pH, which fluctuate diurnally within WSPs owing to algal metabolism. Our experiments with WSP effluent (conducted in small, stirred reactors with well-controlled physico-chemical conditions) showed that different faecal indicators are inactivated by different components of the solar spectrum, and the rates of sunlight inactivation have differing dependencies on physico-chemical conditions. For example, F-specific DNA phage was inactivated only by solar UV-B (300–320 nm) at a rate unaffected by other factors, whereas enterococci and F-specific RNA phage were inactivated by a wide range of wavelengths (300–550 nm) by (DO-dependent) photo-oxidation. Sunlight inactivation of faecal coliforms was particularly complicated: at pHs < 8.5 only solar UV-B (300–320 nm) caused (slow) inactivation, but at higher pHs, the inactivation rate increased and a wider range of wavelengths (300–550 nm) contributed – suggesting photo-oxidative damage to membranes which sensitises faecal coliforms to high external pH. Our findings on the different influences of physico-chemical conditions for different indicators suggest difficulties in interpreting microbiological quality of WSP effluent in terms of a single indicator micro-organism. However, clearly disinfection in WSPs may be enhanced by increasing sunlight exposure, for example with shallower ponds or increased residence times.
Waste water reuse, the South African experience
Authors: Buckley C.A. , Brouckaert C.J. , Rencken G.E.
Published: May 2018

Membrane processes have recently been applied much more extensively by South African industry. A number of the older plants have suffered from fouling problems, sometimes brought on by changes in the feed stream. Newer installations are tending to apply the techniques of Cleaner Production to more closely integrate the membrane process into the manufacturing process and to reduce the size of the installation. There has been a trend to investigate methods of using the brine in place of discharging it to the environment. Membrane related research is still very active and a range of current initiatives is provided.
Gas sparged cross-flow microfiltration of biologically treated wastewater
Authors: Vera L. , Delgado S. , Elmaleh S.
Published: May 2018

A novel technique was tested for reducing tubular mineral membrane fouling by injecting gas into a cross-flow stream. The injected gas is thought to form complex hydrodynamic conditions inside the microfiltration module, which increase the wall shear stress, preventing the membrane fouling and enhancing the microfiltration mass transfer. The experimental study was carried out with biologically treated wastewater filtered through a tubular inorganic membrane (Carbosep M14). The flux, monotonously increasing with gas velocity, was more than tripled. New dimensionless quantities of shear stress number and resistance number were developed by generalisation of the dimensional analysis already carried out for the steady state flux of classical unsparged cross-flow filtration. A unique formalism allowed then interpreting the experimental results of both classical diphasic filtration and sparged filtration. The main limiting mass transport process was due to the solid content.
Characterisation of phosphorus in sediments from waste stabilization ponds
Authors: Gómez E. , Paing J. , Casellas C. , Picot B.
Published: May 2018

The waste stabilization pond (WSP) systems are useful for the treatment of wastewater. Despite a good knowledge of these systems, the dynamics of phosphorus elimination in these systems are not well known, especially concerning the forms of phosphorus in the sediment.

Phosphorus dynamics were studied with data collected from the three stabilization ponds of the Mèze (France) system. A conceptual model based on theoretical considerations was developed, and applied to each pond. The percentage of observed variation described by these models ranged between 46.2% and 74.1%. The results showed that the principal variables affecting orthophosphate in WSP systems were phosphorus input and particulate phosphorus. When the model was applied to high rate algal pond (HRAP) data, the role of photosynthesis on pH increase and P precipitation was clear.

Sediments sampled in the three facultative ponds were characterised with a fractionation scheme, currently used for sediments of natural aquatic ecosystems. Inorganic phosphorus accounted for 92-94% of total sediment phosphorus, with 57–59% bound to iron hydroxides and 33–37% bound to calcium. Surprisingly, organic phosphorus represented only between 6 and 8%. Polyphosphate was detected. Phosphorus concentration was greatest in the sediment from the third pond, where an aerobic layer at the sediment surface prevented phosphorus release.
Process design of waste stabilization ponds at high altitude in Bolivia
Authors: Juanico M. , Weinberg H. , Soto N.
Published: May 2018

The Altiplano, located at 15°–20°S, has an altitude of about 4000 m above sea level which determines extreme climatic conditions that may affect the performance of stabilization ponds: strong solar radiation due to a thin atmosphere of rarefied, clean, dry air; low mean temperatures of water and air; strong differences in temperature between day and night; low oxygen pressure. The oxygen pressure at 4000 m altitude is only 60% of that at sea level. However, lower water temperatures increase oxygen solubility in water compensating for the effect of altitude in the actual concentration of dissolved oxygen in water. Lack of oxygen is not a crucial limiting factor for sewage treatment at high altitudes. Anaerobic ponds are effective in the Altiplano, in spite of the low water temperatures (7–9°C). Design criteria for WSP at different altitudes in Bolivia are presented. An important conclusion with social connotations is that the communities of the Altiplano will need to construct waste stabilization ponds which are 3–5 times larger (and more expensive) than those of the “Los Llanos”.
Key tools to accelerate fulfilment of the EU Urban Waste Water Treatment Directive in the Flemish region of Belgium
Authors: Ockier P. , Thoeye C. , De Gueldre G.
Published: May 2018

The EU Urban Waste Water Treatment Directive (UWWTD) has been transposed in 1992. The whole area of the Flemish region was designated as a sensitive area. This implies nutrient removal for all works in agglomerations of more than 10,000 population equivalent (PE). Thanks to an accelerated investment programme, which is in a final phase now, the wastewater treatment plants (WWTPs) will fulfil treatment in 2005. Key tools for a quick and economic execution of the programme are standardisation for new WWTP's and increasing computerisation for retrofitting existing WWTPs. The UWWTD also stipulates the reuse of treated wastewater and sludge. Strategies are explained.
Mechanical disintegration of sewage sludge
Authors: Lehne G. , Müller A. , Schwedes J.
Published: May 2018

Mechanical disintegration can be used for an accelerated and improved anaerobic digestion of excess sludge. The hydrolysis is the limiting step of this process. Mechanical disintegration can be used to disrupt the cell walls and to cause the release of the organic material from the cells. Particle size analysis describes the size reduction but is not suitable for characterising the release of the organic material and the cell disruption. Two biochemical methods were developed for these phenomena. One of the parameters provides information about the disruption of micro-organisms, the other one gives information about the release of organic material.

Different ultrasonic homogenizers, a high pressure homogenizer and stirred ball mills were used for disintegration experiments using various parameters. The influences of a mechanical disintegration on the particle size and of the energy intensity on the disintegration were investigated. Further investigations had to detect the influence of the solid content on the disintegration results. For sludge with a higher solid content better results in terms of energy consumption could be achieved. An optimum of the bead diameter and the stress intensity in stirred ball mills could be detected. A comparison of the results of different methods of sludge disintegration shows that the investigated ultrasonic homogenizers are inferior to a high pressure homogenizer and a stirred ball mill in terms of energy consumption.
Performance characterization of anaerobic sequencing batch reactor process for digestion of night soil
Authors: Lee J. G. , Hur J. M. , Chang D. , Chung T. H.
Published: May 2018

Laboratory experiments were conducted to investigate the performance of an anaerobic sequencing batch reactor (ASBR) process for night soil treatment. Performances of the reactors were evaluated at an equivalent hydraulic retention time (HRT) of 10 days with an equivalent loading rate of 2.6 kgVS/m3/d (3.1 kgCOD/m3/day) at 35°C. Digestion of a night soil was possible using the ASBR at an HRT of 10 days in spite of high concentration of ammonia nitrogen and settleable solids. Solids were accumulated rapidly in the ASBRs, and their concentrations were 2.3∼2.4 times higher than that in a completely mixed control reactor. Remarkable increases in gas production were observed in the ASBRs compared with the control reactor. Average increases in equivalent daily gas production from the ASBRs were 205∼220% compared with that from the control run. The ASBR with reaction period/thickening period ratio (R/T ratio) of 1 showed a little higher gas production and organic removal efficiency than that with R/T ratio of 3. Volatile solids removals based on supernatant of the ASBRs were 12∼14% higher than that of the control reactor. Thus, the ASBR was a stable and effective process for the treatment of night soil having high concentration of settleable organics and ammonia nitrogen.
Modelling of full-scale wastewater treatment plants with different treatment processes using the Activated Sludge Model no. 3
Authors: Wichern M. , Obenaus F. , Wulf P. , Rosenwinkel K.-H.
Published: May 2018

In 1999 the Activated Sludge Model no. 3 (ASM 3) by the IWA task Group on Mathematical Modeling for Design and Operation of Biological Wastewater Treatment was presented. The model is used for simulation of nitrogen removal. On the basis of a new calibration of the ASM 3 with the easy degradable COD measured by respiration simulation runs of this paper have been done. In 2000 a biological phosphorus removal module by the EAWAG was added to the calibrated version of ASM 3 and is now serving the current requirements for modelling the enhanced biological P-removal. Only little experiences with different load situations of large-scale wastewater treatment plants were made with both new models so far. This article reports the experiences with the simulation and calibration of the biological parameters using ASM 3 and the EAWAG BioP Module. Three different large-scale wastewater treatment plants in Germany with different treatment systems will be discussed (Koblenz: pre-denitrification; Hildesheim: simultaneous denitrification with EBPR; Duderstadt: intermediate denitrification with EBPR). Informations regarding the choice of kinetic and stoichiometric parameters will be given.
Population dynamics of anaerobic microbial consortia in thermophilic granular sludge in response to feed composition change
Authors: Syutsubo K. , Sinthurat N. , Ohashi A. , Harada H.
Published: May 2018

A thermophilic UASB reactor was operated at 55°C for greater than 470 days in order to investigate the effects of feed composition on the changes in microbial community structure where thermophilic granular sludge was used as the inoculum source. The feed compositions were changed with cultivation days; phase 1 (1–70 days), alcohol distillery wastewater; phase 2 (71–281 days), artificial acetate wastewater; phase 3 (282–474 days), artificial sucrose wastewater. During the first one month of each phase, the methanogenic activity and cell density of methanogens quantified by fluorescence in situ hybridization (FISH) drastically changed as a result of shift in feed composition. When artificial acetate wastewater was used as feed, retained granular sludge was partially disintegrated due to a decrease in the number of symbiotic bacterial community members: acetogens (acidogens) and hydrogenotrophic methanogens. In contrast, when the feed was shifted to sucrose (phase 3), granulation of biomass was promoted by a remarkable proliferation of the symbiotic community. The presence of hydrogen-utilizing methanogens and acetogens (acidogens) are shown to be effective for the enhancement of thermophilic granulation. The cell density of methanogens determined by FISH was strongly correlated with the methane-producing potential of the retained thermophilic granular sludge.
Study of microbial community of brewery-treating granular sludge by denaturing gradient gel electrophoresis of 16S rRNA gene
Authors: Chan O.-C. , Liu W.-T. , Fang H. H.
Published: May 2018

The microbial community structure of granular sludge from an upflow anaerobic sludge blanket (UASB) reactor treating brewery effluent was studied by denaturing gradient gel electrophoresis (DGGE). Twelve major bands were observed in the DGGE fingerprint for the Bacteria domain and four bands for the Archaea domain. Of the bacterial bands observed, six were successfully purified and sequenced. Among them, three were related to the gram-positive low G+C group, one to the Delta subclass of the Proteobacteria, one to the Gamma subclass, and one to the Cytophaga group with no close related sequence. The 16S rRNA sequences of the four archaeal bands were closely associated with Methanosaeta concilii and Methanobacterium formicum.
Characterization of microbial community in an activated sludge process treating domestic wastewater using quinone profiles
Authors: Hu H.-Y. , Lim B.-R. , Goto N. , Bhupathiraju V. K. , Fujie K.
Published: May 2018

The dynamics of microbial community structure of activated sludges in a small-scale domestic wastewater treatment process were examined using a novel approach of quinone profiles. The composition and content of quinones in the activated sludges were analyzed monthly over a period of one year. More than 4 types of ubiquinones and 12 types of menaquinones were observed in the activated sludges, with the dominant quinones being ubiquinone (UQ) -8, menaquinone (MK) -7, followed by UQ-10, MK-8 and MK-6. The total quinone contents in the activated sludges varied from 0.93 to 2.28μmol per gram of particle organic carbon. The molar ratio of ubiquinones to menaquinones (UK/MK) changed from 0.38 to 0.98, indicating that anaerobic bacteria dominated the microbial community of the activated sludges examined. The ratio of UQ/MK varied similar to that of dissolved oxygen in the bulk. The microbial diversity of the activated sludges calculated from the quinone compositions was 13.4–16.8. The diversity of menaquinones was much higher than that of ubiquinones, and increased slightly with increasing temperature. The microorganisms containing menaquinones appear to be sensitive to the change in temperature than those containing ubiquinones.
Innovative low cost procedure for nutrient removal as an integrated element of a decentralised water management concept for rural areas
Authors: Burde M. , Rolf F. , Grabowski F.
Published: May 2018

The absence of large rivers with rather high niveau of self purifying effect in parts of east Germany leads to a discharging of the effluent of wastewater treatment plants into the groundwater in many cases. One useful consequence is the idea of realisation of decentralised measures and concepts in urban water resources management concerning municipal wastewater as well as rainfall, precipitation. At the same time, only the upper soil zone - a few decimetres - is water - saturated and thus discharge effective, even when extreme rainfall takes place. Underneath, however, there generally exists an unsaturated soil zone, which is up to now a rather unexplored retardation element of the hydrologic- and substrate-cycle. Nutrient removal in small wastewater treatment plants that are emptying into ground waters is often beneficial. The presented studies optimised an inexpensive method of subsequent enhanced wastewater treatment. The developed reactor is similar to a concentrated subsoil passage. The fixed bed reactor is divided in two sections to achieve aerobic and anoxic conditions for nitrification/denitrification processes. To enhance phosphorus removal, ferrous particles are put into the aerobic zone. Two series of column tests were carried out and a technical pilot plant was built to verify the efficiency of the process. The results show that this method can be implemented successfully.
What to do after nutrient removal?
Authors: van der Graaf Jaap H.J.M.
Published: May 2018

In the Netherlands, interest in advanced treatment is increasing now that almost all wastewater treatment plants apply full biological treatment and nutrient removal. The resulting effluents have an excellent quality which can be improved further by applying advanced treatment processes like flocculating filtration, membrane filtration, UV or activated carbon, and others. The treated effluent can be re-used for various purposes, as process water, household water, urban water, for groundwater suppletion and drinking water. Nowadays many applications are investigated. In order to confirm the applicability pilot test investigations are done at various WWTPs. The results are promising; the cost estimations show increasing prospects. This will finally lead to the maturity of the advanced treatment. It will certainly contribute to a more sustainable water cycle.
Contributions of biofilm versus suspended bacteria in an aerobic circulating-bed biofilm reactor
Authors: Yu H. , Kim B. J. , Rittman B. E.
Published: May 2018

This study demonstrated that, during the two-step biodegradation of toluene in an aerobic circulating-bed biofilm reactor, biofilm and suspended bacteria played critical roles. Although the suspended bacteria were less than 1% of the total amount of biomass in the system, they transformed up to 30% of the toluene into its intermediate in the bulk liquid phase. On the other hand, most of the toluene intermediate was removed inside the biofilm, where diffusion resistance reduced the toluene concentration, thereby relieving inhibition to the degradation reaction of the intermediate. The suspended bacteria are most important for rapidly biodegraded substrates, for which diffusion limitation controls the kinetics in the biofilm. They lose importance when the effects of an inhibiting substrate must be overcome.
Comparison of a novel electro-Fenton method with Fenton's reagent in treating a highly contaminated wastewater
Authors: Huang Y.-H. , Chen C.-C. , Huang G.-H. , Chou S. S.
Published: May 2018

This study applied a novel electrochemical process called the Fered-Fenton method to treat a highly concentrated wastewater. By combining electrochemical reduction and chemical oxidation, the process can remove organic compounds and heavy metals in a batch reactor. A PVC-stabilizer processing wastewater was treated in this investigation owing to its high heavy metal concentration (Pb = 7,500 mg/l) and high organic concentration (COD = 11,000 mg/l). The major organic component was acetate. Direct anodic oxidation showed no effect on COD removal. Fenton's method only removed 36% of COD using 4,000 mg-Fe2+/l and 28,000 mg-H2O2/l dosage. In the Fered-Fenton process, about 89% of COD was removed with 2,000 mg-Fe3+/l and 28,000 mg-H2O2/l. Furthermore, the COD removal attained an efficiency of about 98% for 56,000 mg-H2O2/l used. Results presented herein demonstrate that the Fered-Fenton method is superior to direct anodic oxidation and Fenton's method in this case. Furthermore, the changes of the intermediate compounds including acetate, oxadate, and formate during the reaction were analyzed, which provided us with the information to propose degradation reactions of the wastewater in this system.