To improve biogas production from lignocellulosics, methanogenic microbial enrichments were prepared from moose rumen fluid, beaver droppings, and internal circulation (IC) reactor granules amended with cellulose, pine needles, lignosulphonate, tannic acid, and poplar hydrolysate. Tannic acid delayed methanogenesis compared to cellulose only enrichments, both by reducing initial rates (up to 50% in beaver dropping cultures) and increasing lag times (up to 50 days in moose rumen cultures). Biogas yields from poplar hydrolysate were 56 % by beaver droppings, 51% % by IC granules, and 31 % by moose rumen enrichments. Bacterial community profiles, determined via denaturing gradient gel electrophoresis (DGGE) showed divergent populations between enrichments. Enrichment on pine needles or poplar hydrolysate promoted bioconversion of post extraction wash (PEW), and beaver dropping enrichments fed pine needles equaled the yield (about 23%) from IC granules. Together, the DGGE and PEW results provide evidence of acclimatization to previously recalcitrant feeds.

Many industrial activities discharge sulphate- and metal-containing wastewaters, including the manufacture of pulp and paper, mining and mineral processing, and petrochemical industries. Acid mine drainage (AMD) is an example of such sulphate- and metal-containing waste streams. Formation of AMD is generally the result of uncontrolled oxidation of the sulphide minerals present in the terrain in which the drainage flows with concomitant leaching of the metals. Acid mine drainage (AMD) and other sulphate- and metal-containing waste streams are amenable to active biological treatment. Anaerobic reduction of sulphate, reaction of produced sulphide with metal ions present in the waste stream, and biooxidation of excess sulphide are three main sub-processes involved in the active biotreatment of AMD. Anaerobic reduction of sulphate can be achieved in continuous stirred tank bioreactors with freely suspended cells or in immobilized cell bioreactors. The application of freely suspended cells in a continuous system dictates a high residence time to prevent cell wash-out, unless a biomass recycle stream is used. In an immobilized cell system biomass residence time becomes uncoupled from the hydraulic residence time, thus operation of bioreactor at shorter residence times becomes possible. In the present work, kinetics of anaerobic sulphate reduction was studied in continuous immobilized cell packed-bed bioreactors. Effects of carrier matrix, concentration of sulphate in the feed and sulphate volumetric loading rate on the performance of the bioreactor were investigated. The bioreactor performance, in terms of sulphate reduction rate, was dependent on the nature of the carrier matrix, specifically the total surface area which was provided by the matrix for the establishment of biofilm. Among the three tested carrier matrices, sand displayed the superior performance and the maximum volumetric reduction rate of 1.7 g/L-h was achieved at the shortest residence time of 0.5 h. This volumetric reduction rate was 40 and 8 folds faster than the volumetric reduction rates obtained with glass beads (0.04 g/L-h; residence time: 28.6 h) and foam BSP (0.2 g/L-h; residence time: 5.3 h), respectively. Further kinetic studies with sand as a carrier matrix indicated that the extent of volumetric reduction rate was dependent on the feed sulphate concentration and volumetric loading rate. At a constant feed sulphate concentration, increases in volumetric loading rate caused the volumetric reduction rate to pass through a maximum, while increases in feed sulphate concentrations from 1.0 g/L to 5.0 g/L led to lower volumetric reduction rates. The maximum volumetric reduction rates achieved in the bioreactors fed with initial sulphate concentration of 1.0, 2.5 and 5.0 g/L were 1.71, 0.82 and 0.68 g/L-h, respectively. The coupling of lactate utilization to sulphate reduction was observed in all experimental runs and the rates calculated based on the experimental data were in close agreement with calculated theoretical rates, using the stoichiometry of the reactions involved. The maximum volumetric reduction rates achieved in the immobilized cell bioreactors were significantly faster than those reported for freely suspended cells employed in the stirred tank bioreactors.

Use of anaerobically digested sludge (ADS) in heavy metal removal, was researched. The raw and dewatered ADS samples collected from the effluent of anaerobic digesters and mechanical dewatering units of Ankara City Wastewater Treatment Plant were used. Sorption kinetic and equilibrium tests were conducted using raw ADS at initial pH of 2.0, 4.0 and without adjusting the initial pH. The highest Pb(II) removal capacity was observed as, 8.5 mmol (or 1760 mg) Pb(II) per g of biomass, when the initial pH was not controlled. When dewatered ADS was used Pb(II) removal capacity of ADS was found to drastically decrease to 2.5 mmol (or 518 mg) Pb(II) per g of biomass. Both biomass samples resulted in an increase in the solution pH from an initial value of 4 &ndash / 5 to an equilibrium value of 7 &ndash / 8. Large floc particles settling rapidly were formed after the ADS samples contacted with Pb(II) solution. The high Pb(II) removal capacities, and visual observations during the experiments indicated that precipitation is a dominant mechanism especially at low initial Pb(II) concentrations. FTIR studies showed that carboxyl groups present in the biomass surface of raw ADS were major functional groups in biosorption of Pb(II). The low capacity values attained at initial pH 2.0 indicated that there was a competition between Pb(II) species and hydrogen ions for carboxyl groups. Single and 3-stage fed-batch reactor systems were operated using raw ADS at different initial Pb(II) concentrations. The efficiency of reactor systems increased when 3-stage fed-batch configuration was used and an effluent Pb(II) concentration below 2 mg/L was reached from an initial value of about 200 mg/L.

Treatment of waste sludge has become an important issue in recent years around the world. However, the trend of waste sludge treatment has shifted from volume minimization and stabilization to reuse of the sludge and recover the energy potential of it. Therefore, anaerobic treatment of sludge is gaining popularity because of byproduct methane production and high percentage of VSS reduction. Pre-treatment of sludge before anaerobic digestion in order to increase methane production, and ozone pre-treatment in this context, is one such option. Domestic sludge also contains the recently recognized, so called, emerging compounds such as Endocrine Disrupting Compounds (EDCs). Therefore treatment of EDCs in sludge is another challenge in waste sludge treatment since direct discharge of such chemicals may harm the environment by causing gender shifts within the fauna. In this context two hormones (estrone and progesterone), three pharmaceuticals (acetaminophen, carbamazepine and diltiazem) and one plasticizer (benzyl-butyl phthalate) were routinely analyzed in sludge samples which were subjected to treatment during this study. Treatment of EDCs during anaerobic digestion and the effect of ozonation both on the performance of digestion and the treatability of EDCs were investigated in this study. Four 2.5L anaerobic jars were used for anaerobic digestion connected to four 1L plastic graduated cylinders immersed in salt-water to collect the off gas. Anaerobic sludge culture of the reactor and the sludge feed to the reactors were obtained from Ankara Tatlar Wastewater Treatment Plant anaerobic digester and return activated sludge (RAS) line, respectively. One of the anaerobic digesters was used as control (no ozonation) and the others were fed with sludge samples ozonated at three different ozone doses 0.65, 1.33 and 2.65 mg ozone/g biomass. Sludge ages of the reactors were initially set to 25 days and the reactors were fed once every 2 days. The TSS, VSS, total gas volume, COD, pH, CH4 percentage and EDCs were analyzed routinely. In the reactors, operated at 25 days, because of the observation of reduction of TSS, SRT was set to infinity / thus, sludge wastage was terminated. Following the startup it was seen that at 2.65 mg ozone/g biomass dose TSS and VSS did not stay constant in the reactor and dropped sharply in the course of operation, indicating that system was not steady at this SRT. However, upon stoppage of sludge wastage from the reactors, thereby setting SRT to infinity, a steady culture could be maintained in the reactors. Both total gas production and CH4 percentage increased with the increasing doses of ozone with respect to control reactor. For 2.65 mg/g ozonated reactor total gas volume doubled the amount produced in the control reactor. All the EDCs within the scope of this study were analyzed in sludge using ultrasound-aided sequential sludge extraction method twice a week and the results showed that ozonation affected treatment of EDCs for up to 96%. The highest removal rate was obtained with natural hormones. Rates of treatment of pharmaceuticals were the second best.

Anaerobic digestion of excess biological wastewater treatment sludge (WAS) from pulp mills has the potential to reduce disposal costs and to generate energy through biogas production. The organic matter in WAS is highly structured, which normally hinders biogas production. This study investigated three methods of pretreating WAS from two different pulp mills before anaerobic digestion to improve biogas yield and production rate. The three pretreatment methods tested were: i) thermal pretreatment at 170oC, ii) caustic pretreatment at 140oC and pH 12, and iii) sonication at 20 kHz and 1 W/mL. Thermal pretreatment proved to be the most effective, increasing biogas yield by 280% and 50% and increasing production rates 300-fold and 10-fold for the two samples, respectively. Caustic pretreatment showed similar results, but resulted in the formation of soluble non-biodegradable compounds. Sonication was the least effective pretreatment and did not substantially increase biogas yield, but increased biogas production rate.

Els residus carnis, o subproductes animals, són interessants per al procés de digestióanaeròbia i producció de biogàs, donat el seu elevat potencial energètic i l'actual marc legislatiu que prima la producció d'energia renovable. Tot i així, l'elevat contingut en lípids i proteïnes d'aquests residus pot limitar el seu tractament en introduir fenòmens d'inhibició, dels quals el més important és el produït pels àcids grassos de cadena llarga (AGCL), resultants de la hidròlisi dels lípids. L'objectiu de la present tesis és aprofundir en el coneixement d'aquest procés d'inhibició, en la capacitat d'adaptació dels microorganismes i en la recuperació o prevenció dels fenòmens d'inhibició. En una primera aproximació a la problemàtica, es caracteritzen residus orgànics d'escorxador, s'estudia la seva biodegradabilitat anaeròbia amb diferents relacions lípids/proteïnes i es realitzen assaigs discontinus seqüencials incrementant la concentració de substrat mitjançant pulsos consecutius. Es comprova que la hidròlisi i acidogènesi de proteïnes és molt ràpida i que la degradació dels lípids i AGCL limita la velocitat global del procés. Malgrat aquesta limitació, el sistema es recupera després dels pulsos aplicats, tot augmentant la taxa màxima de producció de metà. Per tal d'estudiar el fenòmen de recuperació, s'estudien i desenvolupen diferents estratègies en reactors sotmesos a processos d'inhibició per AGCL. L'increment dels ratis biomassa/AGCL o l'adició d'additius com la bentonita, per tal de reduir la biodisponibilitat o l'adsorció dels AGCL sobre la biomassa activa, es mostren com estratègies funcionals d'utilitat en l'operació de plantes industrials. Els resultats obtinguts reforcen la hipòtesi de que la inhibició és deguda a adsorció d'AGCL sobre la membrana cel·lular i que la recuperació es pot mesurar mitjançant un augment de l'activitat dels microorganismes. Per tal de dilucidar sobre la natura del augment de l'activitat en els processos de recuperació es caracteritza la inhibició-recuperació mitjançant tres tècniques: 1) estudi de les activitats dels microorganismes a diferents substrats 2) utilització de tècniques de biologia molecular per caracteritzar les poblacions, i 3) desenvolupant expressions cinètiques del procés d'inhibició, basades en l'adsorció, en el marc del model matemàtic ADM1 de la International Water Association. Mitjançant aquestes metodologies es comprova que els fenòmens d'inhibició i adaptació es poden explicar mitjançant un creixement poblacional específic i la inclusió dels fenòmens físic d'adsorció en el procés d'inhibició metabòlica. Finalment, s'avalua de forma més detallada el procés d'adsorció-inhibició mitjançant la determinació de les isotermes d'adsorció i monitoritzant mitjançant assaigs amb biomassa granular i tècniques de microscòpia de fluorescència. Aquesta caracterització ha permès obtenir estratègies de prevenció de la inhibició per AGCL, mitjançant competència amb adsorbents sintètics, i concloure que l'àcid palmític és el limitant en el procés de -oxidaciódels AGCL. Els resultats obtinguts constitueixen una base per al millor coneixement de les possibilitats de tractament anaerobi del residus carnis i dels processos d'inhibició per AGCL i adaptació de la biomassa. El procés físic d'adsorció ha estat directament relacionat amb el fenòmen d'inhibició metabòlica, obtenint-se una descripció matemàtica del mateix. Els resultats han permès plantejar estratègies operacionals, sent una eina a disposició d'operadors de plantes de biogàs per optimitzar la producció d'energia d'aquests residus >mitjançant la seva digestió anaeròbia. / Los residuos cárnicos, o subproductos animales, son interesantes para el proceso de digestión anaerobia y producción de biogás, dado su elevado potencial energético y el actual marco legal que prima la producción de energía renovable. A pesar de esto, el elevado contenido en lípidos y proteínas puede limitar su tratamiento, al introducir fenómenos de inhibición, de los cuales el más importante es el producido por ácidos grasos de cadena larga (AGCL), resultado de la hidrólisis de los lípidos. El objetivo de la presente tesis es profundizar en el conocimiento de este proceso de inhibición, en la capacidad de adaptación de los microorganismos t en la recuperación de sistemas inhibidos. En una primera aproximación a la problemática, se caracterizan los residuos orgánicos de matadero, se estudia su biodegradabilidad anaerobia con diferentes relaciones lípido/proteína y se realizan ensayos discontinuos secuenciales incrementando la concentración de substrato mediante pulsos consecutivos. Se comprueba que la hidrólisis y acidogénesis de las proteínas es muy rápido y que la degradación de lípidos y AGCL limita la velocidad global del proceso. A pesar de esta limitación, el sistema se recupera después de los pulsos aplicados aumentando la tasa máxima de producción de metano. A fin de estudiar el fenómeno de recuperación, se estudian y desarrollan diferentes estrategias en reactores inhibidos por AGCL. El incremento de los ratios biomasa/AGCL o la adición de aditivos como la bentonita, a fin de reducir la biodisponibilidad o la adsorción de los AGCL sobre la biomasa activa, se muestran estrategias funcionales de utilidad en la operación de plantas industriales. Los resultados obtenidos refuerzan la hipótesis de que la inhibición es debida a adsorción de AGCL sobre la membrana celular y que la recuperación se puede medir mediante un aumento de la actividad de los microorganismos. A fin de dilucidar sobre la naturaleza del aumento de la actividad en los procesos de recuperación se caracteriza la inhibición mediante tres técnicas: 1) estudio de las actividades de los microorganismos a diferentes substratos, 2) utilización de técnicas de biología molecular para caracterizar las poblaciones, y 3) desarrollando expresiones cinéticas del proceso de inhibición, basado en la adsorbió, en el marco del modelo ADM1 de la International Water Association. Mediante estas metodologías se comprueba que los fenómenos de inhibición y adaptación se pueden explicar mediante un crecimiento poblacional específico y la inclusión de la adsorción en el proceso de inhibición metabólica. Finalmente, se evalúa de forma detallada el proceso de adsorción-inhibición mediante la determinación de las isotermas de adsorción y monitorizando estos procesos mediante ensayos discontinuos con biomasa granular y técnicas de microscopia de fluorescencia. Esta caracterización ha permitido obtener estrategias de prevención de la inhibición por AGCL, mediante competencia con adsorbentes sintéticos, y concluir que el ácido palmítico es el limitante en el proceso de mutante -oxidación de los AGCL. Los resultados obtenidos constituyen una base para el mejor conocimiento de las posibilidades de tratamiento anaerobio de residuos cárnicos y de los procesos de inhibición por AGCL y adaptación de la biomasa. El proceso físico de adsorción se ha relacionado directamente con el fenómeno de inhibición metabólica, obteniéndose una descripción matemática del mismo. Los resultados han permitido plantear estrategias operacionales, siendo una herramienta a disposición de operadores de plantas de biogás para optimizar la producción de energía de estos residuos mediante su digestión anaerobia. / Slaughterhouse wastes are interesting for the anaerobic digestion process regarding its high biogas production potential and because the current legal scenario promotes renewable energy production. The high lipid and protein content of those residues limit its treatment due to inhibitory processes, in particular the inhibition caused by long chain fatty acids (LCFA). The objective of the present disertation is to obtain a deeper insight on the LCFA inhibition process, the microorganism adaptation ability and the prevention/recovery of inhibitory phenomena. In a preliminary approach, organic wastes generated in slaughterhouses are characterized, by studying the anaerobic biodegradability of waste mixtures containing diferents lipid/proteins concentrations. Anaerobic batch tests are performed at increasing substrate concentrations by sequential pulse feeding. From those experiments, the fast hydrolysis-acidogenesis of proteins is verified, being the lipids and LCFA degradation the main limiting step of the overall anaerobic process. Despite this limitation, the system is able to recover up to a higher methane production rate after each applied pulse. In order to elucidate on the mechanisms of the recovery process, several strategies to recover LCFA inhibited reactors are tested. The increase of the biomass/LCFA ratio and the adition of bentonite to reduce the biodisponibility or the adsorption of LCFA over microbial cell walls, are found to be effective approaches in the operation of fullscale biogas plants. The obtained results reinforce the hypothesis of the adsorptive nature of the LCFA inhibition, and that the recovery process can be followed as an increase in the microbial activity. The nature of the reported microbial activity improvement after subsequent sytem inhibition is characterized by three different techniques: 1) the study of specific microbial activities on different model substrates, 2) the application of molecular biology tools to monitor the microbial population structure and, 3) the development of kinetic expressions of the LCFA inhibition phenomena, based on the adsorption process, within the framework of ADM1 model of the International Water Association. The combined analysis of those confirmed that inhibition and adaptation phenomena are explained by a specific microbial growth, including adsorption in the metabolic LCFA inhibition process. The adsorption-inhibition process is evaluated in detail by determining LCFA adsorption isotherms on granular sludge, LCFA toxicity test, and fluorescence microscopy techniques. This multidisciplinary approach results in the definition of an inhibition preventing strategy based on the introduction of competitive adsorbents, and on stating the importance ofpalmitate during ß-oxidation of LCFA. This study contributes to the understanding of slaughterhouse wastes anaerobic treatment, the LCFA inhibition process, and the biomass adaptation phenomena. The physical adsorption process has been directly related with the LCFA metabolic inhibition, and a new mathematical kinetic expression is proposed. New strategies guiding the operation of anaerobic reactors are suggested in order to obtain high renewable energy yields from slaughterhouse wastes digestion.

Pentaerythritol tetranitrate (PETN), a nitrate ester, is widely used as a powerful explosive and is classified as a munitions constituent of great concern by DoD in U.S.A. It is an environmental concern and poses a threat to ecosystem and human health. Our objective was to examine potential remediation strategies for both PETN-contaminated water and soil. Flow-through iron columns were used to determine the potential for using granular iron to degrade PETN in aqueous phase. PETN transformation in both a 100% iron column and a 30% iron and 70% silica sand column followed pseudo-first-order kinetics, with average half-lives of 0.26 and 1.58 minutes, respectively. Based on the identified intermediates and products, the reaction pathway was proposed to be a sequential denitration process, in which PETN was stepwisely reduced to pentaerythritol with the formation of pentaerythritol trinitrate (PETriN) and pentaerythritol dinitrate (PEDN). Although pentaerythrito mononitrate was not detected, an approximately 100% nitrogen mass recovery indicated that all nitro groups were removed from PETN. Nitrite was released in each denitration step and subsequently reduced to NH4+ by iron. Nitrate was not detected during the experiment, suggesting that hydrolysis was not involved in PETN degradation. Furthermore, batch experiments showed that PETN dissolution was likely a rate-limiting factor for PETN degradation, especially in the case with high amount of iron. Using 50% methanol as a representative co-solvent, PETN solubility was greatly enhanced and thus the removal efficiency was improved. The results demonstrate the use of granular iron to remediate PETN-contaminated water. The biodegradability of aqueous PETN was examined with a mixed microbial culture from a site contaminated with PETN. The mixed culture was enriched and selected using a mineral medium containing acetate and yeast extract as carbon and nutrient sources in the presence of nitrate or sulfate. The final enrichment cultures were used as inocula for studying PETN biodegradation under nitrate-reducing and sulfate-reducing conditions. In addition, PETN degradation was tested using the original microbial culture under the mixed electron acceptor conditions of nitrate and sulfate. The results showed that under all conditions tested, PETN was sequentially reduced, apparently following the same pathway as the abiotic reduction by granular iron. Pentaerythritol mononitrate, a suspected intermediate in the abiotic degradation by iron, was identified in this experiment. The presence of nitrate seemed not to affect the kinetics of PETN degradation, with both PETN and nitrate degrading simultaneously. However, the rate of nitrate reduction was much faster than PETN degradation. With respect to sulfate, its presence did not have an adverse effect on PETN degradation, indicated by the very similar degradation rates of PETN in the presence and absence of sulfate. Under all conditions, PETN appeared to act as a terminal electron acceptor for energy generation during biodegradation. A utilization sequence by bacteria in the order of nitrate, PETN, PETriN, PEDN and sulfate was clearly observed. The study in this phase demonstrated that under anaerobic conditions, with carbon sources provided, PETN can be effectively biodegraded by indigenous bacteria in contaminated soil, most likely by denitrifying bacteria. Based on the successful demonstration of abiotic and biotic degradation of PETN in the aqueous phase, both methods were further tested for remediating PETN-contaminated soil in both laboratory and pilot scale. In the laboratory, a systematic soil microcosm experiment was conducted using soil from a contaminated site and additions of either granular iron or organic materials, with deoxygenated Millipore water. Because of the high concentration in the contaminated soil, solid-phase of PETN was initially present in the microcosms. Two types of DARAMEND products, D6390Fe20 (containing 20% iron + 80% botanical materials) and ADM-298500 (100% botanical materials), were used as sources of carbon and other nutrients. During the 84-day incubation period, more than 98% was removed in all DARAMEND treatments, following pseudo-first-order kinetics with half-lives ranging between 8 and 18 days. The results clearly demonstrated that PETN can be effectively degraded under anaerobic conditions with the addition of carbon and possibly nutrients. As in the aqueous tests, the sequence of microbial utilization was nitrate followed by PETN and sulfate. In contrast to the tests with aqueous PETN, iron was not effective in removing PETN in the contaminated soil, due to iron passiviation caused by the presence of high levels of nitrate in the soil. In addition, a slight enhancement was observed in a combined system of iron and biodegradation over biodegradation only. However, the extent of enhancement is not believed to be significant relative to the extra cost for iron addition. A pilot scale test was conducted at a PETN-contaminated site at Louviers, CO, a waste pond which had received waste water from PETN manufacture for over 20 years. The test involved 10 treatments, one control without amendment, one amended with iron (10%), eight with different types and amounts of organic carbon (1%, 2% and 4% of D6390Fe20; 2% and 4% of ADM-298500 and 1%, 2% and 4% of brewers grain). Each treatment was performed in a plastic tub (45 cm wide × 90 cm long × 25 cm deep), containing approximately 18 cm thick layer of soil and 6-8 cm of standing water. Over 74 days, very little consistent reduction of PETN was found in the iron treatment, which was also due to iron passivation in the presence of nitrate in the soil. In contrast, significant removal of PETN (11,200 to 33,400 mg/kg) was observed in the treatments amended with organic materials, and the extent of removal increased with increasing amounts of organic materials. The pilot test was consistent with the results of the laboratory experiments for iron and biodegradation with carbon addition. For biological treatment, the stoichiometric estimation suggests that the complete remediation in many of the treatments will be ultimately limited by carbon sources. Results of this study showed the great potentials of using granular iron to degrade PETN in solution and using indigenous bacteria present in contaminated soils to biodegrade PETN in both the solution and soil phase. Both iron and biodegradation with carbon addition represent viable approaches for remediation of PETN-contaminated water and soil, though iron may not be appropriate in the presence of high concentration of nitrate.

Oil sand deposits in the Athabasca Basin in Alberta represent one of the largest global oil reserves. The bitumen contents of oil sand shallow deposits are recovered by surface mining using modified version of the Clark hot water process. Extraction of bitumen results in extremely large volumes of process water, which are contaminated with naphthenic acids. Various ex-situ treatment techniques including ozonation, advanced oxidation, adsorption, and bioremediation have been evaluated for the treatment of these waters. Previous studies conducted by Paslawski et al. (2009) investigated aerobic biodegradation of naphthenic acids in properly designed and carefully operated bioreactors. In the current work, anaerobic biodegradation of naphthenic acids under denitrifying condition was examined as a potential approach to eliminate the aeration cost in ex-situ treatment and as an alternative for application of in-situ treatment of oil sand process water in stabilization ponds was examined. Using trans-4-methyl-1-cyclohexane carboxylic acid (trans-4MCHCA), a microbial mixed culture developed in earlier works (Paslawski et al., 2009), and nitrate as an electron acceptor, anaerobic biodegradation of trans-4MCHCA were studied in batch and continuous bioreactors: continuous stirred tank reactor (CSTR) and biofilm system. Effects of naphthenic acid concentration, temperature, and loading rate on biodegradation process were investigated. The batch studies showed that initial concentration of trans-4MCHCA influenced the biodegradation rate where the increase in initial concentration of trans-4MCHCA from 100 to 250 mg L-1 led to a higher rate but further increase in concentration did not have a marked effect. Moreover, batch experiments at temperatures ranging from 10° to 35°C demonstrated that the optimum temperature was in the range of 20 - 24°C. Continuous anaerobic biodegradation in the CSTR showed that increase in loading rate of trans-4MCHCA caused an increase in removal rate of both trans-4MCHCA and nitrate. Rates were decreased as the system approached the cell washout. The maximum biodegradation rate and nitrate removal rate, achieved at trans-4MCHCA loading rate of 157.8 mg L-1 h-1, were 105.4 mg L-1 h-1 and 144.5 mg L-1 h-1, respectively. A similar dependency between the loading and removal rates was also observed in the biofilm reactor. The maximum removal rate of trans-4MCHCA and nitrate in the biofilm reactor, operated at room temperature (24 ± 2ºC) were 2,028.1 mg L-1 h-1 and 3,164.7 mg L-1 h-1, respectively and obtained at trans-4MCHCA loading rate of 2,607.9 mg L-1 h-1. Comparison of the results from aerobic batch systems obtained by Paslawski et al. (2009) and the current results showed similar profile where increase in initial concentration of naphthenic acid increased the biodegradation rate of trans-4MCHCA. As far as the effect of temperature is concerned, room temperature (20 - 24ºC) was identified as optimum temperature regardless of mode of biodegradation. Under continuous mode of operation (CSTR and biofilm reactors), anaerobic biodegradation was much faster than its aerobic counterpart. For instance the maximum anaerobic removal rate of trans-4MCHCA in the CSTR was 105.4 mg L-1 h-1, while the highest removal rate achieved in the aerobic CSTR was 9.6 mg L-1 h-1. Similarly, anaerobic biofilm reactor achieved a higher maximum removal rate of 2,028.1 mg L-1 h-1 compared to a 924.4 mg L-1 h-1 removal rate in the aerobic biofilm reactor. The overall finding indicated that biodegradation of trans-4MCHCA can be achieved effectively under anaerobic condition with the rates markedly higher than those for aerobic system.

An analysis of a specific application of anaerobic wastewater treatment at a pulp and board mill, Stora Enso Skoghall, was carried out. A literature study was done and effluent wastewater from CTMP pulp production was analyzed. The analysis consisted of a broad constituent analysis and an anaerobic treatment trial. Results from these test where used to calculate the treatment effectiveness and resulting energy potential at the mill. The literature study and constituent analysis showed that toxicity of the water to be treated, due to wood extractives and sulphur content, was of concern. Detoxification chemicals targeting these constituents where used in the anaerobic treatment trial. The trial consisted of a two chamber upflow reactor and aerobic post treatment. The result of the trial is that the water of concern has about 50% anaerobically degradable content. A full scale implementation of anaerobic wastewater treatment would result in a methane production of 3,76 to 7,76 GWh/yr. An application of anaerobic wastewater treatment will also result in electricity savings, in aerated pond, and increase the capacity margin on current sludge handling techniques.

This master's theses was carried out on assignment from Stockholm Vatten AB as a part of a project developing new waste water treatment techniques. The goal of the theisis has been to evaluate an anaerobic membrane bioreactor for treatment of waste water from Hammarby Sjöstad. The bioreactor has not been heated and the main interest has been to study the gas production, power consumption and the reduction of organic matter and nutrients. The system has been completed with a reverse osmosis unit and a total of four batch runs have been made with good results. The use of reverse osmosis allows nutrient in the waste water to be reintroduced into circulation as the reverse osmosis concentrate can be used as crop nutrient. The membrane unit is of VSEP ("Vibratory Shear Enhanced Processing") type and an extensive membrane test has been conducted. This so called L-test helped determine the most suitable type of membrane for the system to allow a higher ±ux and thus lower power consumption. The L-test gave good results and a new membrane with a poresize diameter of 0,45 μm was used. The organic load on the bioreactor has been more or less constant, around 0,7 kg COD/day, during the seven weeks of testing. The reduction over the entire system including reverse osmosis has been large, around 99 % regarding organic matter and phosporus and 93 % for nitrogen, making the system suitable for waste water treatment except for high power consumption, around 2 kWh/m3. The production of methanegas has worked although it has been quite low, with average values of 0,13 m3 CH4/kg reduced COD. / Examensarbetet är utfört på uppdrag av Stockholm Vatten AB som en del av det pilotprojekt som utvärderar nya tekniker för avloppsvattenrening för Hammarby Sjöstad. Målsättningen med studien har varit att utvärdera ett system bestående av en anaerob membranbioreaktor för behandling av avloppsvatten från Hammarby Sjöstad. Bioreaktorn har inte varit uppvärmd och det som har studerats är reningseffekten, biogasproduktionen samt energiåtgången. Systemet har även innefattat en omvänd osmosanläggning och totalt har fyra försök med denna gjorts med goda resultat. Analyser har koncentrerats till att utvärdera reduktion av organiskt material över membranbioreaktorn och av närsalter och metaller över omvänd osmos anläggningen. Bakgrunden till att använda omvänd osmos är att öka återföringen av näringsämnen från avloppsvatten. Resultatet av försöken med omvänd osmos gav ett koncentrat med högt näringsinnehåll och låg halt av tungmetaller vilket ger möjligheten att sprida det på åkermark. Membranenheten är av typen VSEP ("Vibratory Shear Enhanced Processing") och ett membrantest har även utfötts för att finna det membran som passar systemet bäst med avseende på flöde och energiförbrukning. Det så kallade L-testet var omfattande och gav en klar bild över vad som skulle vara det bästa membranet. Det membran som visade sig passa systemet bäst var ett membran med en porstorlek på 0,45 μm. Belastningen av organiskt material på reaktorn under försöksperiodens sju veckor har varit mer eller mindre konstant och låg, cirka 0,7 kg COD/dygn. Reduktionen över hela systemet inklusive omvänd osmosanläggningen med avseende på organiskt material och fosfor har varit mycket hög, omkring 99 %. Reduktionen av kväve var som högst 93 %. Gasproduktionen har fungerat och har i genomsnitt varit omkring 0,13 m3 CH4/kg reducerad COD. Energiförbrukningen för systemet i motsvarande fullskala blev omkring 2 kwh/m3.