bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel feast-fast technique for filamentous foam control in the activated sludge process – introducing a new foam-measurement method
Authors: Chua H. , Lo W. , Yu P.H. , Sin S.N. , Zhao Y.G. , Tan K.N.
Published: May 2018

Overgrowth of filamentous Nocardia spp. in the activated sludge microbial ecosystem was previously identified as the cause of foaming problems in Hong Kong. In this work, the specific growth rate of N. amarae was found to be significantly higher than that of non-filamentous bacteria under food-to-microorganism (F/M) ratios lower than 0.5 mgBOD/mgMLSS-day, and was used as the basis for the development of a novel Feast-Fast Operation (FFO) for the prevention and control of foaming problems. The F/M ratio in the “feasting” aeration unit was 0.8 mgBOD/mgMLSS-day while that in the “fasting” aeration unit was 0.2 mgBOD/mgMLSS-day, resulting in an overall process F/M ratio that remained within the normal range, while avoided prolonged exposure of the sludge ecosystem to an F/M ratio below 0.5 mgBOD/mgMLSS-day. The FFO suppressed filamentous overgrowth and foaming without adversely affecting the organic treatment efficiency of the modified process. A new and convenient measurement method was developed for quantifying the degree of foaming and foam stability in activated sludge.
Effect of surface functional group on Freundlich adsorption isotherm
Authors: Chang H.T. , Furuya E.G. , Miura Y. , Noll K.E.
Published: May 2018

This study was designed to investigate the relationship between Freundlich isotherm coefficient l/n and the molecular properties of activated carbon adsorbent. The surface of the adsorbent was modified using nitric acid to produce different types and amounts of oxidized groups. These functional groups changed the electron density of graphite rings on the carbon surface. Isotherm data for the adsorption of PCP and PNP on the regular and modified activated carbon were obtained experimentally. Regression analyses showed that Freundlich coefficient l/n was affected by carboxyl groups stronger than three other groups – lactonized carboxyl, hydroxyl, and carbonyl. The results showed that Freundlich 1/n increased linearly with an increase in the amount of carboxyl groups. Molecular modeling using the CAChE program showed that the HOMO density at the adsorption site decreased linearly with an increase in the number of carboxyl groups. The results suggested that Freundlich 1/n could be estimated a priori based on the molecular structure of the adsorbent surface and the HOMO density of the adsorption site.
Destruction of refractory humic acid by electromechanical oxidation process
Authors: Chaing L.-C. , Chang J.-E. , Wen T.-Cn.
Published: May 2018

Electrochemical oxidation of humic acid has been conducted to evaluate the efficacy of the process for the destruction of high-molecular-weight (HMW) compounds. Experimental results show that the destruction of humic acid obtained by the electrolysis supported by chloride ion is much better than that obtained by sulfate ion. Accordingly, HMW compound such as humic substance is suggested to be resistant to directly anodic oxidation, but to be readily destroyed by an indirect oxidation of chlorine/hypochlorite during an electrochemical treatment process. The effects of operating parameters, including anode material, current density, electrolyte concentration, have been investigated in this study. A tertiary-oxide of Sn, Pd, Ru coated titanium (SPR) anode with high electrocatalytic activity was found to have high efficiency for humic acid destruction, and the destruction efficacy of humic substance increased with increasing current density and chloride concentration. In this study, gel permeation chromatography (GPC) and adsorptive organic halide (AOX) had been performed to examine the variation of organic characteristics during the electrochemical oxidation of humic acid. The results from GPC and AOX show that HMW organic compounds could be effectively destroyed by electrochemical oxidation process, and the process also produced less undesirable chlorinated byproducts than the chlorination process. From the above results, the electrochemical oxidation conducted by indirect oxidation effect of chlorine/hypochlorite could be concluded to be a feasible method for the destruction of HMW compounds.
Process development for nitrogen removal of swine waste
Authors: Rim J.M. , Han D.J.
Published: May 2018

This research aims to effectively remove nutrients in swine waste by a combined process of upflow anaerobic sludge blanket (UASB) and biofilm process. For effective removal of nutrients, both anaerobic and anoxic reactors were constructed consecutively within a single anaerobic/denitrification (SAD) reactor to which aerobic reactor for nitrification was connected. The total reactor was operated within range of 0.4 to 3.1 kg COD/m3/d of organics volumetric loading rate (VLR) and the removal rates of TCOD were 80 to 95%. Ammonia nitrogen was removed over 90% in VLR of less than 0.1 kg N/m3/d but removal rate was reduced to 70% in VLR of over 0.6 kg N/m3/d. However, complete denitrification was observed in all VLRs, which might be due to the maintenance of optimal temperature, sufficient inner carbon source, and use of NOx as an electron acceptor by anaerobic and anoxic microorganisms.
Nitrification in a membrane bioreactor (MBR) for wastewater treatment
Authors: Fan X.J. , Urbain V. , Qian Y. , Manem J. , Ng W.J. , Ong S.L.
Published: May 2018

Nitrification of the MBR process for sewage treatment was investigated with a pilot scale plant in this study. Complete nitrifcation occurred where the sludge retention time (SRT) was over 5 days. The maximum nitrification rate (Rmax) of the biomass was determined with batch tests and was found to be around 1.71 – 2.0 mgNO3--N/gVSS-h. Nitrification was affected more by the influent C/N ratio than SRT.
The performance of fermentation wastewater treatment in ultrafiltration membrane bioreactor by contiuous and intermittent aeration processes
Authors: Lu S.G. , Imai T. , Ukita M. , Sekine M. , Fukagawa M. , Nakanishi H.
Published: May 2018

A lab-scale experiment on the performance of highly concentrated activated sludge in high strength fermentation wastewater treatment with rotary disk type UF membrane was carried out. The experiment lasted 252 days and was operated under continuous and various intermittent aeration conditions. TOC and NH4-N removals were quite good and intermittent aeration operations increased T-N removal efficiency. It demonstrated that activated sludge had strong ability for organic shock loading. However, the ability of nitrifier was weak compared with that of heterotrophic bacteria for pH shock. The activity of sludge in the reactor assessed by INT-dehydrogenase activity was not affected significantly after the incursion of anoxic operation, and the smaller coccus-like or rod-type bacteria (1-2μm) performed quite well for organic carbon and nitrogen removals.
Nitrogen removal from hydroponic culture wastewater by autotrophic denitrification using thiosulfate
Authors: Yamamoto-Ikemoto R. , Komori T. , Nomuri M. , Ide Y. , Matsukami T.
Published: May 2018

Using the upflow biological filter reactor, sulfur denitrification using thiosulfate of hydroponic culture wastewater was examined. Start-up periods of the reactor were one to two weeks. About 90% of nitrogen removal ratio were achieved over 80 days, at 6.3 kg/m3·days of nitrogen loading. Shock loading among 0.56-2.8 kgN/m3· day did not affect the reactor performance. However, when temperature went below 15°C, the effluent characteristics became poor. Suitable S/N and IC/N ratios were calculated as 3.3 and 0.15, respectively. The activities of sulfur denitrification, heterotrophic denitrification and sulfur reduction were examined by the bath experiments under several conditions using biomass grown in the reactor. In the anoxic conditions, denitrification using thiosulfate was occurred stoichiometrically in the presence of thiosulfate. The denitrification activity was highest (17 mgN/gBiomass·hr). When the electron donor was not added to the substrate, denitrification occurred using sulfur granules accumulated in the biomass. Seventy mg of sulfur granule were accumulated in one g of biomass. The denitrification activity using sulfur granules was 2.9-5.0 mgN/gBiomass·hr. Heterotrophic denitrification occurred in the presence of organic matter. The activities were 1.4-5.4 mgN/gBiomass·hr. In the anaerobic conditions, the accumulated sulfur was reduced to sulfide at a rate of 1.4 mgS/gBiomass·hr. These results suggested that sulfur denitrification, heterotrophic denitrification and sulfur reduction bacteria coexisted in the biofilm and sulfur cycle was established in the reactor. Accumulated sulfur plays an important role in the sulfur denitrification.
Qxygen transfer in gravity flow sewers
Authors: Pai T.Y. , Ouyang C.F. , Liao Y.C. , Leu H.G.
Published: May 2018

Oxygen diffused to water in gravity sewer pipes was studied in a 21 m long, 0.15 m diameter model sewer. At first, the sodium sulfide was added into the clean water to deoxygenate, then the pump was started to recirculate the water and the deoxygenated water was reaerated. The dissolved oxygen microelectrode was installed to measure the dissolved oxygen concentrations varied with flow velocity, time and depth. The dissolved oxygen concentration profiles were constructed and observed. The partial differential equation diffusion model that considered Fick's law including the molecular diffusion term and eddy diffusion term were derived. The analytic solution of the partial differential equation was used to determine the diffusivities by the method of nonlinear regression. The diffusivity values for the oxygen transfer was found to be a function of molecular diffusion, eddy diffusion and flow velocity.
Aerobic granulation
Authors: Beun J.J. , van Loosdrecht M.C. , Heijnen J.J.
Published: May 2018

Heterotrophic aerobic granular sludge was cultivated in a sequencing batch airlift reactor (SBAR). A steady state operation, at a COD loading of 2.3 kg COD/(m3· d), was run for 50 days after which the experiment was terminated. The granules obtained were smooth, 1.0 mm in diameter and had a density of 48 g/l. Selection of dense granules occurred by applying a short settling time. Slow settling s ludge was washed out with the effluent and only the granules with good settling properties settled fast enough (vmin>16.2 m/h) to be retained in the reactor. Nitrification and almost complete denitrification occurred in the fully aerobic SBAR without any optimization of the process conditions. Compared to a sequencing batch bubble column (SBBC) much more dense granules with a smaller diameter were obtained in the SBAR at the same substrate loading rate and the same mixing intensity. Compared to granules formed in a, continuous fed, biofilm airlift suspension (BAS) reactor much more dense granules were obtained in the SBAR as well. The diameter of the granules in the BAS reactor was smaller than in the SBAR. Possible reasons for the better quality of the sludge granules in the SBAR are discussed.
Growth and novel structural features of tubular biofilms produced under different hydrodynamic conditions
Authors: Wijeyekoon S. , Mino T. , Satoh H. , Matsuo T.
Published: May 2018

Biofilm growth and internal structures were investigated by Confocal Scanning Laser Microscopy and fluorescently labeled oligonucleotide probe hybridization. Biofilms on smooth flat surfaces such as glass slides grew as isolated cell clusters. Under a hydraulic linear flow velocity of 1.7 cm/s mature biofilms exhibited a network like structure consisting of large interconnected cell clusters leading to possible three-dimensional mass transport. Smooth curved tube surfaces were also colonized by isolated cell clusters. However a clustered structure was not observed in mature tubular biofilms which grew as a continuum. Under laminar flow conditions, the tubular biofilms had a uniform cell distribution along the depth with a flat surface profile. The dense tubular biofilms produced under turbulent flow had a stratified structure with thickness. Morphologically these had an irregular surface profile with protrusions extending from a thick base layer. The production of extracellular polymeric substances were both cell physiology and growth related. While hydrodynamic condition was shown to be an effective tool for manipulation of biofilm structures, the relationship of the structure to biological activity and process control needs further investigation.
Detachment of Aeromonas hydrophila and Pseudomonas aeruginosa due to variations in nutrient supply
Authors: Sawyer L.K. , Hermanowicz S.W.
Published: May 2018

Growth and detachment rates of Aeromonas hydrophila and Pseudomonas aeruginosa were measured to determine if nutrient depletion causes detachment of attached cells. A glass parallel plate, continuous observation flow cell placed on a phase contrast microscope was used to monitor bacterial behaviour on the surface under defined flow and mass transfer conditions. Shear stress was held constant at 3 N m−2. Images were taken every 15 minutes, and digital image analysis was used to quantify specific growth, detachment and accumulation rates for the attached organisms. An observable parameter proportional to the nutrient depletion at the surface was used to determine the effect of nutrient depletion on detachment rates. Increases in the depletion parameter corresponded with increases in detachment rate after the cells were rod, but the depletion parameter was not scaleable between different experiments. These experiments showed that as nutrients were depleted, detachment increased. If the detachment mechanism postulated in this work is more universal and applicable to other microbial species, new methods of detachment control through dynamic changes of nutrient supply might be devised.
In situ monitoring of natural genetic transformation of Acinetobacter calcoaceticus BD413 in monoculture biofilms
Authors: Hendrickx L. , Hausner M. , Wuertz S.
Published: May 2018

Confocal laser scanning microscopy (CLSM) was used for the detection of natural genetic transformation in a defined pure culture Acinetobacter calcoaceticus BD413 biofilm, with the enhanced yellow fluorescent protein (EYFP) as a nonselective genetic marker. The effect of free DNA concentration and of exposure time to free DNA on transformation frequency was explored. Transformation studies indicated that Acinetobacter calcoaceticus BD413 cells exposed to as little as 0.1 ng free DNA/ml resulted in detectable transformation frequencies (1×10−4 transformed cells/recipient cell). Within 2 hours about 20% of the biofilm cells expressed eyfp after exposure to 1 μg free DNA/ml. Microscopic analysis revealed a unique distribution of transformation frequencies in the biofilm. The highest frequencies were found near the substratum or near the biofilm/medium interface.
Influence of the suspended and attached biomass on the nitrification in a two submerged biofilters in series system
Authors: Villaverde S. , Fdz-Polanco F. , Lacalle M.L. , García P.A.
Published: May 2018

The performance and stability of a system formed by two submerged filters in series for removing organic matter, solids and ammonia nitrogen from urban wastewater were tested. The wastewater was pretreated through a fine screening (through a 1.5 mm sieve) and primary settlement, before entering the first filter. The hydraulic retention time (HRT) in both filters was adjusted to 2 hours. Superficial velocities of 1 m/h for the liquid and 8 m/h for the air were maintained throughout all the experiments. The averaged removal percentages of organic carbon and solids were the following: 84% of TSS, 85% of VSS, 88% of total COD, 86% of soluble COD and 93% of total BOD5. Filter backwash was conducted when the observed head loss through the filter raised up to 1.2 m of water column.

Substratum particles were sampled from both filters for measuring the concentration of retained biomass in the two forms: attached (as Volatile Attached Solids, VAS) and suspended (as Volatile Suspended Solids, VSS) biomass. The activity of these solids was also determined by closed respirometry assays, which revealed that the biomass retained between the substratum particles as suspended biomass showed much higher activity that the attached biomass. The suspended biomass retained in the filter was responsible for removing most of the soluble COD and ammonia, while most of the nitrite oxidizers were inside the biofilm.
A novel hollow-fibre membrane biofilm reactor for autohydrogenotrophic denitrification of drinking water
Authors: Lee K-C. , Rittmann B.E.
Published: May 2018

A novel hollow-fiber membrane biofilm reactor (HFMBR) was developed to remove nitrate from contaminated drinking water using molecular hydrogen as a clean electron-donor substrate. The hollow fibers were sealed on one end and were pressurized with hydrogen on the other end. The counter-diffusion transfer of nitrate and hydrogen allowed 100% hydrogen transfer efficiency into the biofilm and achieved up to 99.9% hydrogen-utilization efficiency for denitrification. Partial denitrification met regulatory standards for nitrate and nitrite at the same time that relatively high steady-state nitrate fluxes (0.08 and 0.1 mg N/cm2−d) were achieved with liquid-phase hydrogen concentrations (0.009 and 0.07 mg H2/l) magnitudes lower than in previous studies. The low frequency of fiber-to-fiber contact in the upflowing liquid established good biofilm accumulation. The specific biofilm detachment rates were between 0.015 and 0.017 day−1, which attained biofilm thickness up to 179 μm. Finally, DOC and BDOC analyses showed that the DOC was increased, while the effluent BDOC was 0.5 mg/l.
Trinitrophenol treatment in a hollow fiber membrane biofilm reactor
Authors: Grimberg S.J. , Rury M.J. , Jimenez K.M. , Zander A.K.
Published: May 2018

Treatment of recalcitrant wastewaters in traditional suspended growth systems is ineffective due to the required large contact times and large aeration basins. Hollow-fiber gas permeable membranes are being investigated as a novel approach to overcome oxygen and 2,4,6-trinitrophenol (TNP) mass transfer limitations of conventional fixed film systems. Three independent hollow fiber biofilm reactors using bubbleless membrane aeration technology were used to treat TNP. The reactors contained 14, 30, or 57 fibers, with a fiber spacing of 3, 2.7, or 2.1 mm, respectively, which resulted in a packing factor of 0.5%, 1% and 2%. A pure culture of Nocardioides simplex (strain Nb), which has been shown to mineralize TNP, was immobilized on the surface of 281.5 (m outer diameter microporous fibers. Pure oxygen was supplied through the lumen of the fibers and diffused throughout the biofilm and into the reactor. Removal of TNP in the 14, 30, and 57 fiber reactors was 99.1, 83.2, and 85.4%, respectively at a contact time of approximately 14 hours and a TNP loading of 40 mg/day. Results indicate TNP diffusion into the biofilm limited performance at high substrate concentrations.
Monitoring protozoa and metazoa biofilm communities for assessing wastewater quality impact and reactor up-scaling effects
Authors: Fried J. , Mayr G. , Berger H. , Traunspurger W. , Psenner R. , Lemmer H.
Published: May 2018

The succession of biofilm communities with special emphasis on ciliates, rotifers, and nematodes was monitored for half a year and compared to different operating conditions in order to evaluate plant performance and effect of up-scaling lab scale to large scale reactors. Ciliates and metazoa are able to rapidly change their communities as a reaction to changed plant operating conditions as has been proven true by comparing lab scale and pilot scale reactors. Even slight operational changes are causing major shifts in biofilm communities. Nematodes and rotifers in lab scale and large scale reactors seem to be in competition with peritrich ciliates. In both lab scale and pilot scale systems ciliates of the subclass Peritrichia proved to be dominant and thus to play an important role in both the species composition of the biofilm biocenosis and biofilm structure. Interpretation of biocenosis composition changes for large scale reactors is much more complex than for lab scale reactors. This conflicts with up-scaling of lab scale results to full scale reactors.
The influence of carrier size and shape in the moving bed biofilm process
Authors: Ødegaard H. , Gisvold B. , Strickland J.
Published: May 2018

The moving bed biofilm process is based on plastic carriers on which biomass attaches and grows. The original Kaldnes carrier was made of high-density polyethylene (density 0.95 gcm−1) that could be used in filling fractions (volume of carriers in empty reactor) up to 70% that gives a specific area of 350 m2m−3. Lately there has been an interest in the use of larger carrier elements, especially when using the process for upgrading of activated sludge plants. This paper analyses the influence of the carrier size and shape on performance, especially related to highly loaded plants working on municipal wastewater. The results demonstrate that moving bed biofilm reactors should be designed based on surface area loading rate (g COD/m2d) and that shape and size of the carrier do not seem to be significant as long as the effective surface area is the same. The results indicate that very high organic loads can be used in order to remove soluble COD but that the settleability of the sludge is negatively influenced at high loading rates.
Full scale moving bed biofilm reactor results from refinery and slaughter house treatment facilities
Authors: Johnson C.H. , Page M.W. , Blaha L.
Published: May 2018

Two Kaldnes moving bed biofilm reactor (MBBR™) full scale treatment plants were commissioned in 1999, following successful pilot tests which generated the design data. The MBBR plants are incorporated into each facility as roughing reactors ahead of existing activated sludge processes. Results from the first three months of operation at the Phillips refinery showed surfa ce area loading rates (SALR) averaging 27 g COD/m2/day or twice those seen in the pilot study while percent removals remained constant at 62%. Performance at the Valley Pride Pack facility showed >90% removal of soluble BOD at SALR of 20 g/m2/day in one reactor while nitrification removal rates up to 0.83 g NH3–N/m2/day have been seen in the second stage of the MBBR treatment system.
Application of aerated biofilters for production of high quality water for industrial reuse in West Basin
Authors: Lazarova V. , Perera J. , Bowen M. , Sheilds P.
Published: May 2018

The results of 5 years operation of 8 full-scale up-flow aerated Biofor® biofilters, installed at the West Basin Recycling Plant treatment plant (California), demonstrated the efficiency and reliability of this technology in the production of high quality ammonia free water for industrial reuse as cooling water in oil refineries. High nitrification rates up to 0.75 kg d−1 m−3 (0.047 lb d−1 ft−3) were obtained atwater velocities of 6.7 m h−1 (867.5 gpm). The hydraulic retention time in the biofilters was short without any negative consequences on the process. During all five years of operation, all Biofor® units demonstrated very reliable performances with 100% ammonia removal efficiency and very low residual suspended solids concentration of about 4.0 mg TSS L−1.
Side stream biofiltration for improved biofouling control in cooling water systems
Authors: Daamen E.J. , Wouters J.W. , Savelkoul J.T.G.
Published: May 2018

Biological activity in open recirculating cooling water systems may lead to Microbial Induced Corrosion (MIC) and lower heat exchange efficiencies. The use of oxidizing biocides as a tool to control excessive biofilm formation in a cooling water system can be characterised as fighting the symptoms, because it does not take away the main cause of biofilm growth: the availability of nutrients. Due to frequent use of oxidizing biocides the microbial growth rate in the cooling water system studied (1–2 d−1) was even higher than the dilution rate (0.33 d−1). By means of an ASTRASAND®continuous sand filter used as a side stream biofilter it is possible to achieve considerable reductions in nutrients and in suspended biomass contents. The content of nutrients in the filter influent and effluent was expressed in terms of growth rates and was determined by batch experiments. Based on the assumptions of plug flow characteristics and first order reaction kinetics, the kinetic coefficients for nutrient removal were determined at k1=6 h−1 for fine (0.8–1.25 mm) and at k1=4.5 h−1 for coarse (1.4–2.0 mm) filter material. Due to the first order kinetics of nutrient removal and due to the improved filtration efficiencies at increasing influent biomass contents, it is concluded that a side stream biofilter introduces a self regulating process element in the cooling water system, leading to a faster recovery of the cooling water quality after upset conditions. Considerable savings in the use of oxidizing agents can be established.
Strategies to improve the efficiency of tertiary nitrifying trickling filters
Authors: Wilk T.
Published: May 2018

The long term effects of the conditions for a biofilm reactor are governed by slow microbial processes, such as the growth and decay of the bacteria. Simulations of a trickling filter model based on a multi species dynamic biofilm model and data from an experiment, where an NTF had been alternatingly fed unnitrified and completely nitrified wastewater, agree fairly well. Two different operating strategies of NTFs are studied by simulation: periodically inversing the order of two NTFs in series and varying the flow through NTFs operating in parallel. The simulations indicate that both strategies have a potential of increasing the nitrifying capacity of filters operating at low ammonium load, provided the influent concentrations of organic matter are low. However, to what extent the capacity is increased depends on the specific death rate of the nitrifiers, which needs to be further studied.
Minimisation strategy of petrochemical wastewater organic load
Authors: El Khorassani H. , Trebuchon P. , Bitar H. , Thomas O.
Published: May 2018

Industrial wastewater management is nowadays a reality in most industries and particularly in petrochemical ones. As a consequence, some treatment plants appear to be over designed because of waste minimization. Actually supplementary organic loads coming from incidents or external effluents have to be treated. As classical parameters or compound analyses are not well adapted, a new methodology based on the use of UV spectrophotometry is proposed. Starting from several samplesof wastewater in different points of sewage network, a procedure, called UVDIAG is used for the exploitation of the corresponding UV spectra. Some complementary measurements such as pH or conductivity can be carried out. This methodology allows a better characterization of wastewater including the detection of incidents and most often the determination of the major pollutant(s). Several months of application in a large petrochemical site located in the south of France have lead to a better knowledge of the waste production andthus to the reduction of organic load to be treated. At the same time, the company has decided to consider external wastes for treatment and to check the effluent conformity with the proposed procedure.
Testing and implementation of an advanced wastewater reclamation and recycling system in a major petrochemical plant
Authors: Wong J.M.
Published: May 2018

This paper describes a major water reclamation project utilizing a membrane-based advanced treatment system to recover organic wastewater treatment system (OWWTS) effluent and cooling tower blowdown (CTB) for reuse in a large petrochemical plant in the Far East. The treatment process train includes chemical oxidation, dual media filtration (DMF), granular activated carbon (GAC) adsorption, ultrafiltration (UF), ultraviolet (UV) disinfection, reverse osmosis (RO), and degasification. The reclaimed pure water, which has a conductivity <240 μS/cm, is used as makeup water for the plant's ion exchange deionization (DI) system. Using this water for DI system makeup saves more than 80% of the expensive DI system regeneration cost and drastically reduces water purchase cost and wastewater discharge fees. The treatment system was tested on a pilot-scale (110 m3/d) basis for nearly 18 months. Various flux rates for UF/RO and accelerated biofouling tests for the hollow-fiber UF membranes were conducted. With excellent pretreatment, the thin film composite polyamide RO membranes were relatively clean and non-fouling after more than 2,000 hours of operation without chemical cleaning. A total overall water recovery of 73.6% was achieved consistently in the pilot plant. A full-scale plant treating an influent blended flow of 9,000 m3/d and recovering 6,600 m3/d of pure water has been constructed at the petrochemical plant. System startup and commissioning are expected to be completed in September 1999. The treatment system may be expandable by 50% with minimal facility addition in the future.
Pollutant characteristics of the pyrolysis of petrochemical wastewater sludge by an electric furnace
Authors: Chiang H.-L. , Chen T.-C. , Tsai J.-H. , Hsu Y.-C.
Published: May 2018

Organic sludge represents significant reservoirs of renewable energy. However, the pollution-control costs of incinerator flue gases are high. An alternative to treating the sludge is low temperature pyrolysis process, which produces liquid oil rather than gases. The objective of this study is to examine pyrolysis of a petrochemical industrial sludge in an electric furnace. The pyrolysis was carried out in an isothermal reactor heated by a horizontal electric furnace. The element compositions of the sludge residues were analyzed with ICP. Concentrations of Zn, Cu, and Sb in a pyrolysis residue were increased with increased temperatures. This indicates that Zn, Cu, and Sb were concentrated during pyrolysis process. Volatile organic compounds (VOCs) and volatile sulfur compounds were analyzed with GC/MS to assess the exhaust gas compositions. The VOCs were generated from 400 to 900°C, but their concentration was significantly decomposed at 900°C. The concentration of volatile sulfur compounds increased when the pyrolysis temperature was increased from 400 to 700°C. When the pyrolysis temperature reached 800°C, concentrations decreased. The rate constants, reaction orders, activation energy, and frequency factor were found by fitted nonlinear and linear regression. The average reaction order was 2.5, when pyrolysis temperatures ranged from 400 to 900°C. The slope of activation energy (Ea/R) was 3243 and the frequency factor was 0.99 sec-1.
From UV spectra to degradability of industrial wastewater/definition and use of a “shape factor”
Authors: Muret C. , Pouet M.F. , Touraud E. , Thomas O.
Published: May 2018

The measurement of global parameters such as TOC or specific compounds as phenol is not sufficient for the characterization of high loaded industrial wastewater. A previous study dealing with a treatability test based on the use of a photochemical reactor and the UV spectrophotometric control of the experiment has shown the interest of this alternative procedure for the biodegradability estimation of samples. Starting from a simple typology of wastewater based on the structure of UV spectra, a factor called “Shape Factor”, or SF, ratio of second derivative value at a maximal wavelength on the corresponding peak absorbance, is proposed for the characterization of UV spectra shape. The interest of the use of SF, related to the probable presence of a major absorbing pollutant, is shown after a short kinetic study of the photochemical test for chemical and petrochemical wastewater. The degradation rate constant of the pseudo first order photo-reaction (calculated for the degradation of a major pollutant) seems to be linked to the SF factor. For samples characterized by UV absorption peak(s) and thus a high SF value, the degradation rate constant is relatively important. For example, for effluents the UV spectra of which are very structured, the degradation rate constant is above 2.3 s-1. In conclusion, this simple procedure based on the UV spectroscopic typology of samples must be, on one hand, validated from several industrial effluents, and, on the other hand, improved with a more complete kinetic study.
A kinetic model that describes removal of chromium VI from rinsing waters of the metal finishing industry by electrochemical processes
Authors: Martínez S.A. , Rodríguez M.G. , Barrera C.
Published: May 2018

A study was made to remove Chromium VI (Cr6+), present in large quantities in the rinsing waters from the plating industry, using electrochemical treatment. Large amount of Cr6+ are found. It was found that the reaction rate followed a variable kinetic order at concentrations up to 1700 mg Cr6+/L. It was also noticed that Cr6+ reduction depended on the ferrous ions (Fe2+) released at the anode, the cathode reactions and the acidic corrosion on electrodes. Iron salts produced electrode passivation and it caused a 50% increase in treatment time and power requirements. Eliminating the salt formation at the anode could reduce this effect. Using electrochemical processes it is possible to reuse treated waters in the rising stages of the plating industry owing to the fact that final Cr6+ concentration is less than 0.5 mg/L. Finally, a sludge characterization study revealed that residue generated in the process is not considered dangerous according to Mexican environmental protection standards.
Optimisation of the operation variables of a supercritical water oxidation process
Authors: Cocero M.J. , Vallelado D. , Torio R. , Alonso E. , Fdez-Polanco F.
Published: May 2018

The unique physical-chemical properties of water above its critical point (374.2°C and 22.1 MPa) makes supercritical water (SCW) an effective reaction medium for oxidation of organic compounds. Gases and many organic compounds are miscible in SCW, so reaction between oxygen and waste is carried out without interface transport constraints. Supercritical water oxidation (SCWO) can give high destruction efficiencies for a wide variety of hazardous wastes, at low reactor residence times.

To study the SCWO, experiments were carried out in a pilot plant equipped with a pressure shell and cooled wall reactor. Effect of operation variables: oxidant excess, reaction temperature and residence time, is studied in order to optimise the contaminant removal efficiency. Aqueous solutions of isopropyl alcohol were used as feed. No effect of air excess and residence time higher than 1 minute on removal efficiency was found, so exclusive dependence of temperature is concluded. Whereas temperature is above 650°C, reactor can work in a wide range of operation conditions with destruction efficiency over 99%. In addition, operation at optimal conditions is reported, using 10%(w) isopropyl alcohol – 1%(w) aniline as feed. Removal efficiencies higher than 99.9% and nitrite-nitrate concentrations less than 10 ppm were obtained.
Aerobic biodegradation of organic synthesis wastewater
Authors: Mijaylova Nacheva P. , Ramírez Camperos E. , Mendoza Roque J. , Inés Rocha Barrón M.
Published: May 2018

The treatability of organic synthesis industry wastewater using aerobic suspended biomass systems was studied. The wastewater had a high COD, 27–60 g/l, and low TSS, less than 200 mg/l. The organic matter was made up of alcohols, amines, ketones and aromatic compounds. Some toxic organics were present, such as toluene, up to 700 mg/l, and phenol, up to 170 mg/l. Nitrogen was present at a concentration of 200–1,900 mg/l as TKN and phosphates at 0.1 to 4 mg/l. Kinetic coefficients and design parameters obtained from bench-scale tests were used to construct pilot-scale continuous and batch bioreactors. Results from the pilot plant study showed that a removal of more than 99% can be obtained. The operating parameters for the biodegradation system applicable to this kind of wastewater are specific and depend on its strength. Using continuous feed system, efficiencies above 99% can be obtained with organic loads of 0.20–0.38 gCOD/gMLVSS/d and an HRT of 13–23 d. With greater loads and influent COD concentrations from 36,000 to 42,000 mg/l, the efficiency declines to 98%. Loads above 0.34 gCOD/gMLVSS/d and influent CODs above 34,000 mg/l inhibit biomass growth. The efficacy of the batch process is similar to that of the continuous feed system. In spite of the flexibility of the system's response to variations in the influent COD concentration, the SBR is not recommended for the treatment of the study wastewater because of the deficient sedimentability of the biomass formed during the process. The capacity of the SBR system was considerably reduced when the wastewater had a COD above 60,000 mg/l. Toxicity was observed at loads exceeding 0.25 gCOD/gMLVSS/d even with a long HRT of 47–50 d.
Observer-based time-optimal control of an aerobic SBR for chemical and petrochemical wastewater treatment
Authors: Vargas A. , Soto G. , Moreno J. , Buitrón G.
Published: May 2018

The present study implements a time-optimal control strategy for a discontinuous aerobic bioreactor, used to treat highly concentrated toxic wastewater present in some effluents of the chemical and petrochemical industries, using respirometric techniques. The control strategy regulates the feed rate to maintain a constant optimal substrate concentration in the reactor, which in turn minimizes the reaction time. Since this control requires on-line knowledge of unmeasurable variables, an Extended Kalman Filter is used as a nonlinear observer. The experimental setup was a 7 litre laboratory bioreactor used to treat synthetic wastewater with high concentrations of 4-chlorophenol. The controller consisted of a personal computer with data acquisition hardware and real-time software tools, peristaltic pumps and an electronic oxygen meter. Three experiments were performed: one to obtain parameters and calibrate the observer, another one to validate the time-optimal strategy and a final one to evaluate theperformance of a fully automated time-optimal operation. When well calibrated, the observer provided good enough estimates and the controller worked as expected, reducing reaction time and increasing the overall efficiency of the bioreactor, when compared with the usual SBR-type operation.
Role of quinones in the biodegradation of priority pollutants: a review
Authors: Field J.A. , Cervantes F.J. , van der Zee F.P. , Lettinga G.
Published: May 2018

Evidence is accumulating that inert humic substances can play important roles in the anaerobic degradation of priority pollutants by shuttling electrons. This paper reviews the roles of humus and quinone analogues as electron acceptors, redox mediators and electron donors for microbial and abiotic degradation processes. An eventual technology based on pumping quinones as terminal electron acceptors into aquifers and sediments to stimulate xenobiotic degradation offers promising potential. Also quinone redox mediators can be considered to accelerate reductive transformations (e.g. dechlorination, azo cleavage) of priority pollutants.
Formaldehyde toxicity in anaerobic systems
Authors: Gonzalez-Gil G. , Kleerebezem R. , Lettinga G.
Published: May 2018

Formaldehyde toxicity during acetoclastic methanogenesis exerted a dual character: It was in part reversible and in part irreversible. Toxicity was only reversible at very low formaldehyde concentration. The degree of irreversible toxicity was proportionally related to the initial sludge concentration, but was independent of the initial specific acetoclastic activity. Formaldehyde conversion seemed to be dependent on the concentration of the various trophic groups present in the anaerobic granular sludge used. Hence biomass diversity may play an important role in the outcome of toxicity studies and may furthermore contribute to the explanation of the controversies with respect to toxicity values reported in literature.
Two-stage anaerobic treatment of purified terephthalic acid production wastewaters
Authors: Young J.C. , Kim I.S. , Page I.C. , Wilson D.R. , Brown G.J. , Cocci A.A.
Published: May 2018

A full-scale two-stage anaerobic treatment plant has been treating the wastewaters from a purified terephthalic acid (PTA) production facility in South Korea for over 4 years. A study was conducted to evaluate the performance characteristics of this system over a 17-month period of operation. The system has provided stable operation with COD removals consistently averaging over 90%. The removal of specific phthalic acid isomers and related chemicals has been essentially 100% except for terephthalic acid which has averaged about 90% and paratoluic acid which had only about 30% removal. About 80% of the removal occurred in the first stage of the two-stage hybrid process. A companion single-stage anaerobic contact process removed only 80 to 85% of the COD and only 35 to 67% of the phthalic acids.
Start-up of a sequential anaerobic/aerobic batch reactor for the mineralization of p-nitrophenol
Authors: Melgoza R.M. , Chew M. , Buitrón G.
Published: May 2018

The start-up of a sequencing batch biofilter integrating anaerobic and aerobic conditions, for the mineralization of P-nitrophenol (PNP) was studied. In this study a reactor packed with volcanic stones and inoculated with microorganisms from activated sludge processes treating municipal and industrial wastewater was used. The reactor was acclimated with a concentration of PNP of 25 mg/l during 75 days (25 cycles). The duration of the first two operation cycles was 8 days. As the bacterial population acclimated to the anaerobic/aerobics conditions, cycles duration was reduced to 40 h (30 h anaerobic stage and 10 h aerobic one). The PNP was transformed to p-aminophenol (PAP) in the anaerobic phase. The mineralization of PAP was found in the oxidative phase. Removal efficiencies of 100% were obtained for initial concentrations of 25 and 55 mg/l of PNP. In the reductive phase (anaerobic) 60% of biotransformation of the PNP to PAP was observed. In the aerobic phase the amines mineralization was 100%.
Treatment of wastewaters from a formaldehyde-urea adhesives factory
Authors: Garrido J.M. , Méndez R. , Lema J.M.
Published: May 2018

Wastewater from a formaldehyde-urea adhesives factory is characterised by a high organic matter content (COD between 460 and 3900 mg/L mostly due to formaldehyde 220–4000 mg/L) and organic nitrogen (TKN 110–805 mg/L). Besides, a fraction of COD is given by a formaldehyde-urea polymer with a relatively high molecular weight. In a lab-scale (2 L) activated sludge unit, a high formaldehyde removal (higher than 99%) was obtained while the total COD and TKN removal ranged between 70–85 % and 30–50%, respectively. Formaldehyde was used by microorganisms as carbon source and also for the conversion of nitrate to nitrogen gas. The Organic Loading Rate (OLR) was between 0.2 and 1.2 kg–COD/m3·d and the Hydraulic Retention Time (HRT) between 0.5 and 1.4 d. The non degraded TKN and COD, mostly corresponding to the polymeric fraction, was further treated in an ozonation unit, which increased very efficiently the bioavailability of TKN towards nitrification and allowed an additional COD removal. Results from lab-scale reactors were used for designing and operating an industrial scale activated sludge unit, being the efficiency attained at full-scale similar to the laboratory unit.
The use of a thermophilic anaerobic system for pretreatment of textile dye wastewater
Authors: Willetts J.R.M. , Ashbolt N.J. , Moosbrugger R.E. , Aslam M.R.
Published: May 2018

A thermophilic up-flow anaerobic sludge blanket (UASB) reactor was investigated for the decolouration of a synthetic textile wastewater. Textile wastewater is produced at high temperature and dyes are amenable to decolourisation under anaerobic conditions, however this is the first report of the use of such a thermophilic system to aid in the treatment of this wastewater. The decolouration efficiency and robustness of the thermophilic system were compared with a corresponding mesophilic anaerobic system to study the reduction of a selection of reactive dyes, the toxic effect of increasing influent dye concentration (up to 0.64 g.L-1), and the response during acclimation to high salinity conditions (up to 20 g.L-1 as sodium chloride) in three separate stages of experimentation. It was shown that compared with the mesophilic system, the thermophilic UASB treatment gave considerably higher dye decolouration with all the dyes tested, and under all operating conditions investigated. No loss in decolourisation potential was observed during an increase in influent dye concentration. However, toxicity effects were evident, noted by a decrease in COD removal and methane gas production. Acclimation to high salt concentrations also showed an adverse effect upon COD removal and gas production, however dye removal again remained virtually 100 % efficient.
Biotransformation of disperse blue 79 by an anaerobic sequencing batch biofilter
Authors: Cruz A. , Buitrón G.
Published: May 2018

The mineralization of the azo dye Disperse Blue 79 (DB79) was studied under sequenced anaerobic/aerobic environments. This paper presents the results of the first stage of the process, i.e., the anaerobic decolouration of the azo dye. A sequencing batch biofilter was used. The results showed that DB79 was only biotransformed to amines, resulting in a decolorization of the effluent. The anaerobic bacteria, without using co-substrate, achieved the decolouration when the concentration of DB79 was lower than 48 mg/l. It was necessary to use a co-substrate to reach decolouration efficiencies higher than 95%, when the concentration of DB79 in the influent was superior to 48 mg/l. In 72 h more than 95% of the initial colourant was biotransformed.
On-site and in situ bioremediation of wood-preservative contaminated groundwater
Authors: Puhakka J.A. , Järvinen K.T. , Langwaldt J.H. , Melin E.S. , Männistö M.K. , Salminen J.M. , Sjölund M.T.
Published: May 2018

This paper reviews ten years of research on on-site and in situ bioremediation of chlorophenol contaminated groundwater. Laboratory experiments on the development of a high-rate, fluidized-bed process resulted in a full-scale, pump-and-treat application which has operated for several years. The system operates at ambient groundwater temperature of 7 to 9°C at 2.7 d hydraulic retention time and chlorophenol removal efficiencies of 98.5 to 99.9%. The microbial ecology studies of the contaminated aquifer revealed a diverse chlorophenol-degrading community. In situ biodegradation of chlorophenols is controlled by oxygen availability, only. Laboratory and pilot-scale experiments showed the potential for in situ aquifer bioremediation with iron oxidation and precipitation as a potential problem.
Behaviour of nonylphenol ethoxylates in sewage treatment plants in Japan – biotransformation and ecotoxicity
Authors: Fujita M. , Ike M. , Mori K. , Kaku H. , Sakaguchi Y. , Asano M. , Maki H. , Nishihara T.
Published: May 2018

Behavior of nonylphenol polyethoxylates (NPnEOs, n; number of ethoxy units) in 40 full-scale sewage treatment plants (STPs) in Japan was studied. Primary effluent (PE), secondary effluent (SE) and final effluent (FE) samples were collected from the STPs, and NPnEOs, their metabolic intermediates and related halogenated derivatives were quantitatively analyzed. Parent NPnEOs (n=4–18) were detected at concentrations between 5.1 and 1035 μg/l with the average value of 296 μg/l in the PEs from all the STPs, indicating widespread pollution of NPnEOs in Japan. The analyses of SEs revealed that normal biological treatment can relatively efficiently remove NPnEOs, however, the biotransformation led to the formation of biologically-refractory metabolites like nonylphenol (NP), NPnEOs with shorter ethoxy chains (n=1–3; NP1-3EO) and nonylphenol carboxylic acids (NP1-3EC). Halogenated (chlorinated or brominated) NPnEOs and/or NPnECs (n=1–2), which are considered to be produced as by-products during the disinfection processes using chlorination, were also found in SEs and/or FEs from 25 STPs. The ecotoxicity assays showed that the metabolic intermediates of NPnEOs possess higher acute toxicity against Daphnia magna and estrogenic activity than the parent surfactant NPnEOs.