Horizontal-flow Anaerobic Immobilized Biomass Research Articles

Continuous removal of caffeine in a horizontal-flow anaerobic immobilized biomass bioreactor: identification of transformation products.

Anaerobic bioreactors are an efficient technology for the biodegradation of emerging contaminants in environmental matrices. In this work, a horizontal-flow anaerobic immobilized biomass (HAIB) bioreactor was used to remove caffeine (CAF), which is frequently found in various aqueous matrices. The acrylic bench top bioreactor, with dimensions of 100 × 5.00cm, was operated with a hydraulic retention time (HRT) of 12h, during 45weeks, under mesophilic conditions. The operation was performed in 4 phases: without CAF addition (phase I); CAF spiked at 300μg L-1 (phase II); CAF at 600μg L-1 (phase III); and CAF at 900μg L-1 (phase IV). Samples of bioreactor influent and effluent were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The bioreactor removed organic matter (OM) and CAF with efficiencies of 88 and 93%, respectively. The first-order apparent removal constant (Kapp) values for OM and CAF were 0.419 and 0.304h-1, respectively. Five transformation products (TPs) were identified, with m/z 243, 227, 211, and 181 (two products). The HAIB bioreactor is a suitable system for the removal of CAF present in wastewater, even at a concentration level of µg L-1.

Enhanced anaerobic degradation of thiobencarb using a horizontal-flow anaerobic immobilized biomass bioreactor.

Thiobencarb is a herbicide globally used in the agricultural sector, and its extensive application leads to severe environmental pollution. In this study, the thiobencarb supplementation caused a significant shift in the bacterial community in the sediment slurry. An analysis of the degradation metabolites of microorganisms from the sediment indicated that deschlorothiobencarb, S-4-chlorobenzyl ethylthiocarbamate, 4-chlorobenzyl mercaptan, 4-chlorobenzyl alcohol, 4-chlorobenzoic acid and chlorobenzene were the main intermediates. The degradation rates were significantly enhanced using a horizontal-flow anaerobic reactor with immobilized cells in polyurethane foam. The degradation rates at 2.6, 12.9 and 25.6mg L-1 concentrations by suspended microorganisms from the sediment in the mineral medium supplemented with glucose were 0.085±0.000, 0.383±0.010 and 0.500±0.045mg day-1, respectively. The corresponding data for degradation in the reactor were 2.54±0.03, 11.69±0.72 and 18.58±1.83mg day-1 at the sixth operation period. Moreover, COD removal efficiencies were >90% achieved in the reactor. The proposed method facilitates degradation using a horizontal-flow anaerobic immobilized biomass bioreactor. Moreover, this study reveals the degradation of metabolites of thiobencarb under anaerobic conditions.

Application of O3 and O3 /H2O2 for post-treatment of horizontal-flow anaerobic immobilized biomass (HAIB) effluent, treating hospital wastewater.

Introduction: In recent years, the "emerging pollutants" in urban, industrial, and surface water bodies have called the attention worldwide. In many cases, these substances correspond to pollutants that have not been yet regulated by the environmental authorities. Hospitals are considered the main source of these contaminants as a result of different activities. However, there is no consensus about the appropriate treatments for removing this kind of pollutants in the wastewaters; independent conventional biological processes do not reach the desirable values of discharge limits. Advanced oxidation processes (AOP) are known as an appropriate technology, not only to improve the biodegradability of recalcitrant compounds, but also to contribute to the removal of certain substances that are difficult to treat during the biological process. 
 Objective: Thus, this study evaluated the application of O3z and O3 /H2O2 to the effluent of an anaerobic horizontal flow reactor and immobilized biomass (HAIB).
 Methodology: The oxidizers were applied in a lab-scale batch borosilicate glass reactor. The reaction time was 60 min and samples were taken at intervals of 15 min. Parameters such as absorbance at UV254, biodegradability ratio expressed as COD/BOD5, and color as VIS436 were measured. All samples were analyzed in duplicate.
 Results. The results showed that the application of Ozone and O3/H2O2 results in an increase in the biodegradability of 25% and 67% respectively. Concerning color, an efficiency of 85 % for Ozone and 100 % for O3 /H2O2 was observed. Besides, the AOPs applied also showed their effectiveness in removing aromatic organics, removing 40 to 50% of UV254.
 Conclusions: Finally, it is important to mention that the application of advanced oxidation processes as a post-treatment of anaerobic effluents increases biodegradability mainly due to the transformation suffered by recalcitrant compounds.

Limonene removal using a horizontal-flow anaerobic immobilized biomass bioreactor

In Brazil, a large amount of liquid wastewater generated during orange juice production has a significant negative impact on the citric industries. The treatment of this wastewater has been carried out in biological treatment plants. However, low organic removal efficiency has been achieved while using anaerobic or/and aerobic processes probably due to biological inhibition by toxic compounds like limonene. In this context, the objective of this study was to evaluate the limonene removal by a bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) bioreactor (12L) and the transformation products formed during the applied treatment. The bioreactor was filled with three different matrices (mineral coal, polyurethane foam and gravel) containing immobilized anaerobic sludge. The used substrate contained chemical oxygen demand (COD) of 480 to 1251 mg L−1 and the concentrations of limonene ranging from 10 (period I) to 500 mg L−1 (period X) were monitored by GC–MS. The HAIB bioreactor removed organic matter (>60%), and limonene was removed with high efficiency (>95%), while operated at hydraulic retention time (HRT) of 48 and 24 h.

Continuous Anaerobic Treatment of the Aqueous Phase of Hydrothermal Liquefaction from Spirulina Using a Horizontal-Flow Anaerobic Immobilized Biomass (HAIB) Reactor

Anaerobic digestion is a possibility for post-hydrothermal liquefaction wastewater (PHWW) treatment because this wastewater is rich in nutrients and organic compounds. However, the PHWW presents many toxic compounds. A strategy for the anaerobic treatment of toxic compounds is using biomass adhered to inert supports forming biofilms, which can offer more resistance to the microorganism and protection from such compounds. The continuous treatment of PHWW is the essential key to obtaining a sustainable hydrothermal liquefaction process. In this work, the use of immobilized biomass was evaluated for the anaerobic degradation of PHWW from Spirulina in batch assays and continuous treatment. Higher methane production potential and volatile fatty acid mass balance showed the advantages of using biomass immobilized in polyurethane foam. Continuous treatment in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor reached chemical organic demand (COD) removal efficiencies of 67% and 58% for volumetric organic load rates of 0.8 and 1.6 g COD.L−1.d−1, respectively. After 200 days of continuous treatment, Anaerobaculum and Coprothermobacter, fermentative proteolytic genera of bacteria with potential for hydrogen production, were favored.

Horizontal-flow anaerobic immobilized biomass (HAIB) reactor for organic matter and sulfate removal from paper recycling plant wastewater with simultaneous conversion of sulfide into elemental sulfur

Recycling helps reduce organic matter and sulfur content in effluents from the paper industry, as well as minimize large volumes usually generated, making the anaerobic process a feasible alternative to treat such waste. The objective of this paper is to evaluate simultaneous sulfate and organic matter removal in a bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor continuously fed with diluted wastewater from a full paper recycling plant. The reactor was filled with wood charcoal matrices containing immobilized anaerobic sludge. The tested wastewater contained Chemical Oxygen Demand (COD) of 1745 mg L−1 and concentrations of sulfate ranging from 220 (phase 1) to 585 mg L−1 (phase 2). The anaerobic process from paper recycling effluent was followed by partial oxidation of sulfide to elemental sulfur. Sulfate reduction, methanogenesis and effluent desulfurization occurred in the same reactor and were spatially segregated by the plug-flow regime. The investigated HAIB reactor anaerobically removed organic matter and sulfate at high removal efficiencies (>90%), converting about 30% of the inconvenient dissolved sulfide to elemental sulfur. Therefore, integrated sulfate reduction and elemental sulfur production, as presented herein, can be considered an attractive component for sustainable wastewater treatment.

Removal of the veterinary antimicrobial sulfamethazine in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor subjected to step changes in the applied organic loading rate

A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor treating synthetic swine wastewater was operated under different applied organic loading rates (OLR) through both variations in feed strength and in hydraulic retention time (HRT). The influence of step changes in OLR on the removal of the veterinary antimicrobial sulfamethazine (SMZ) was assessed. The highest observed SMZ removal efficiency, 75 ± 6%, was achieved with an OLR of 2.7 ± 0.4 kg O2 m−3 d−1 when a significant increase in COD removal rate was observed. The SMZ removal rate was positively correlated (r = 0.899) to the COD removal rate in all of the experimental conditions in which the HRT was kept at 24 h, indicating a cometabolic transformation of the antimicrobial. Decreasing the HRT caused a significant decrease in SMZ removal efficiency without affecting the HAIB reactor performance in terms of stability, COD removal or metabolic intermediates production. Functionally equivalent steady states were observed in four different operational phases with similar operating conditions but with widely different behavior in relation to SMZ removal. The experimental results showed the potential of anaerobic technology in removing environmentally relevant concentrations of SMZ, and the possibility of enhancing reactor performance by controlling operating conditions.

Long-term operation of anaerobic immobilized biomass reactor treating organic wastewater containing sulfate

This work evaluates the long-term performance (888 days) of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor fed with synthetic wastewater containing organic matter and sulfate. The HAIB reactor achieved stable performance, exhibiting high sulfate and organic matter removal efficiencies subjected to organic matter concentration (expressed as chemical oxygen demand – COD) of 1500mg/L and sulfate of 500mg/L. Sulfate removal efficiency close to 100% was obtained for COD/sulfate ratios equal to or higher than 2.6, decreasing to ∼80% for COD/sulfate ratio of 1.4. Sulfidogenesis was clearly dependent on the availability of electron donor; but not methanogenesis. The smaller COD removal efficiencies (∼93%) were observed at the higher sulfate (1980mg/L) and organic matter (COD of 7000mg/L) concentrations, with COD/sulfate ratio of 3.5. Under these conditions, the presence of volatile fatty acids in the effluent indicates the occurrence of methanogenesis inhibition probably due to sulfide. The fixed-film HAIB reactor did not present bed clogging throughout the entire long-term operation period, thereby leading the way to new perspectives to use the efficient treatment of sulfate-rich wastewater.

Hydrodynamic study of a horizontal-flow anaerobic immobilized biomass reactor: Radial porosity and velocity distribution of wastewater flow

In this work, a mathematical model based on an extended Brinkman equation was used to evaluate the porosity and velocity distribution along the radial direction of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor; the model considers the fluid flow within the bed. The study was performed using two different particle geometries and three tube-to-particle diameter ratios (D/dp) to understand the effects of the shape and particle size on the flow velocity distribution. The results show that the oscillation in the velocity profile is dependent on the D/dp ratio, particle shape and bed porosity. Better results were obtained with irregular shapes, such as hollow cylindrical rings, and a D/dp ratio of 10. The model adapted for this study may be a suitable tool for the design and optimization of horizontal-flow anaerobic immobilized biomass reactors used in wastewater treatment processes.

Application of horizontal-flow anaerobic immobilized biomass reactor for bioremediation of acid mine drainage.

The production of low-pH effluent with sulfate and metals is one of the biggest environmental concerns in the mining industry. The biological process for sulfate reduction has the potential to become a low-cost solution that enables the recovery of interesting compounds. The present study analyzed such a process in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor, employing ethanol as the carbon and energy source. Results showed that a maximal efficiency in the removal of sulfate and ethanol could only be obtained by reducing the applied sulfate load (225.1 ± 38 g m(-3) d(-1)). This strategy led to over 75% of chemical oxygen demand (COD) and sulfate removal. Among the COD/SO4(2-) studied ratios, 0.67 showed the most promising performance. The effluent's pH has naturally remained between 6.8 and 7.0 and the complete oxidation of the organic matter has been observed. Corrections of the influent pH or effluent recirculation did not show any significant effect on the COD and sulfate removal efficiency. Species closely related to strains of Clostridium sp. and species of Acidaminobacter hydrogenomorfans and Fusibacter paucivorans that can be related to the process of sulfate reduction were found in the HAIB reactors when the initial pH was 5 and the COD/SO4(2-) ratio increased to 1.0.

Sulfamethoxazole and ciprofloxacin removal using a horizontal-flow anaerobic immobilized biomass reactor

ABSTRACTThe antibiotics sulfamethoxazole (SMTX) and ciprofloxacin (CIP) are commonly used in human and veterinary medicine, which explains their occurrence in wastewater. Anaerobic reactors are low-cost, simple and suitable technology to wastewater treatment, but there is a lack of studies related to the removal efficiency of antibiotics. To overcome this knowledge gap, the objective of this study was to evaluate the removal kinetics of SMTX and CIP using a horizontal-flow anaerobic immobilized biomass reactor. Two different concentrations were evaluated, for SMTX 20 and 40 μg L−1; for CIP 2.0 and 5.0 μg L−1. The affluent and effluent analysis was carried out in liquid chromatography/tandem mass spectrometry (LC-MS/MS) with the sample preparation procedure using an off-line solid-phase extraction. This method was developed, validated and successfully applied for monitoring the affluent and effluent samples. The removal efficiency found for both antibiotics at the two concentrations studied was 97%. Chemical oxygen demand (COD) exhibited kinetic constants that were different from that observed for the antibiotics, indicating the absence of co-metabolism. Also, though the antibiotic concentration was increased, there was no inhibitory effect in the removal of COD and antibiotics.

The effect of enzymatic pre-hydrolysis of dairy wastewater on the granular and immobilized microbial community in anaerobic bioreactors

The effect of a lipase-rich enzyme preparation produced by the fungus Penicillium sp. on solid-state fermentation was evaluated in two anaerobic bioreactors (up-flow anaerobic sludge blanket (UASB) and horizontal-flow anaerobic immobilized biomass (HAIB)) treating dairy wastewater with 1200 mg oil and grease/L. The oil and grease hydrolysis step was carried out with 0.1% (w/v) of the solid enzymatic preparation at 30°C for 24 h. This resulted in a final concentration of free acids eight times higher than the initial value. The bioreactors operated at 30°C with hydraulic retention times of 12 h (HAIB) and 20 h (UASB) for a period of 430 days, and had high chemical oxygen demand (COD) removal efficiencies (around 90%) when fed with pre-hydrolyzed wastewater. There was, however, an increase in the effluent oil and grease concentration (from values as low as 17 mg/L to values above 150 mg/L in the UASB bioreactor, and from 38–242 mg/L in the HAIB bioreactor), and oil and grease accumulation in the biomass throughout the operational period (the oil and grease content reached 1.7 times that found in the inoculum of the UASB bioreactor). The HAIB bioreactor gave better results because the support for biomass immobilization acted as a filter, retaining oil and grease at the entry of the bioreactor. The molecular analysis of the Bacteria and Archaea domains revealed significant differences in the microbial profiles in experiments conducted with and without the pre-hydrolysis step. The differences observed in the overall parameters could be related to the microbial diversity of the anaerobic sludge.

Anaerobic Fixed-Bed Reactors for Treatment of Synthetic Wastewater and Estuarine-Like Water Containing Pentachlorophenol

Pentachlorophenol (PCP) is an important hazardous compound present in industrial wastewaters and in the leachate of contaminated sites. This article reports on the application of horizontal-flow anaerobic immobilized biomass (HAIB) reactors (R1, R2, and R3) for PCP and chemical oxygen demand (COD) removal from contaminated waters. The reactors' feed consisted of synthetic wastewaters containing different cosubstrates, inoculated with different types of sludge. A mixture of glucose, organic acids, and alcohols fed R1 and R2, and estuarine-like water supplemented with glucose and formate fed R3. R1 and R2 inocula consisted of a mixture of sludge from up flow anaerobic sludge blanket reactors treating sewage and paper-recycling wastewater. R3 received inoculum derived from estuarine sediment contaminated with chlorophenols. Different start-up strategies were applied. COD removal efficiencies were 99% (R1), 95% (R2), and 80% (R3). Independent of the start-up strategy applied, efficient PCP (0.2–13.0 mg/L) removal occurred in the three HAIB reactors. Adsorption of PCP onto polyurethane foam matrix bioparticles was negligible. Tri- and dichlorophenol were observed in all reactors, suggesting that PCP removal occurred by reductive dechlorination. PCP was effectively removed by the reactor but high concentrations of other chlorinated phenols were still present in the effluent of the reactor.

BTEX removal in a horizontal-flow anaerobic immobilized biomass reactor under denitrifying conditions

Because benzene, toluene, ethylbenzene, and xylenes (BTEX) and ethanol are important contaminants present in Brazilian gasoline, it is essential to develop technology that can be used in the bioremediation of gasoline-contaminated aquifers. This paper evaluates the performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor fed with water containing gasoline constituents under denitrifying conditions. Two HAIB reactors filled with polyurethane foam matrices (5mm cubes, 23kg/m(3) density and 95% porosity) for biomass attachment were assayed. The reactor fed with synthetic substrate containing protein, carbohydrates, sodium bicarbonate and BTEX solution in ethanol, at an Hydraulic retention time (HRT) of 13.5h, presented hydrocarbon removal efficiencies of 99% at the following initial concentrations: benzene 6.7mg/L, toluene 4.9mg/L, m-xylene and p-xylene 7.2mg/L, ethylbenzene 3.7mg/L, and nitrate 60mgN/L. The HAIB reactor fed with gasoline-contaminated water at an HRT of 20h showed hydrocarbon removal efficiencies of 96% at the following initial concentrations: benzene, 4.9mg/L; toluene, 7.2mg/L; m-xylene, 3.7mg/L; and nitrate 400mgN/L. Microbiological observations along the length of the HAIB reactor fed with gasoline-contaminated water confirmed that in the first segment of the reactor, denitrifying metabolism predominated, whereas from the first sampling port on, the metabolism observed was predominantly methanogenic.

Advanced oxidation process H2 O2 /UV combined with anaerobic digestion to remove chlorinated organics from bleached kraft pulp mill wastewater

This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H2 O2 /UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 ± 3%), TOC (69 ± 9%), BOD5 (90 ± 5%) and AOX (55 ± 14%). However, the anaerobic treatment did not achieve acceptable removal of UV254 compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H2 O2 /UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV254 from16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%. All peroxide dosages applied in this work promoted an increase in the BOD5 /COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H2 O2 /UV for posttreatment of bleaching effluents submitted to anaerobic pre-treatment.

Solution of a heterogeneous modeling of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor by the sequencing method

A modeling study was completed to develop a methodology that combines the sequencing and finite difference methods for the simulation of a heterogeneous model of a tubular reactor applied in the treatment of wastewater. The system included a liquid phase (convection–diffusion–transport) and a solid phase (diffusion reaction) that was obtained by completing a mass balance in the reactor and in the particle, respectively. The model was solved using a pilot-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor to treat domestic sewage, with the concentration results compared with the experimental data. A comparison of the behavior of the liquid phase concentration profile and the experimental results indicated that both the numerical methods offer a good description of the behavior of the concentration along the reactor. The advantage of the sequencing method over the finite difference method is that it is easier to apply and requires less computational time to model the dynamic simulation of outlet response of HAIB.

Bioremediation of gasoline-contaminated groundwater in a pilot-scale packed-bed anaerobic reactor

This work reports on the anaerobic treatment of gasoline-contaminated groundwater in a pilot-scale horizontal-flow anaerobic immobilized biomass reactor inoculated with a methanogenic consortium. BTEX removal rates varied from 59 to 80%, with a COD removal efficiency of 95% during the 70 days of in situ trial. BTEX removal was presumably carried out by microbial syntrophic interactions, and at the observed concentrations, the interactions among the aromatic compounds may have enhanced overall biodegradation rates by allowing microbial growth instead of co-inhibiting biodegradation. There is enough evidence to support the conclusion that the pilot-scale reactor responded similarly to the lab-scale experiments previously reported for this design.

Pentachlorophenol (PCP) dechlorination in horizontal-flow anaerobic immobilized biomass (HAIB) reactors

This study verifies the potential applicability of horizontal-flow anaerobic immobilized biomass (HAIB) reactors to pentachlorophenol (PCP) dechlorination. Two bench-scale HAIB reactors (R1 and R2) were filled with cubic polyurethane foam matrices containing immobilized anaerobic sludge. The reactors were then continuously fed with synthetic wastewater consisting of PCP, glucose, acetic acid, and formic acid as co-substrates for PCP anaerobic degradation. Before being immobilized in polyurethane foam matrices, the biomass was exposed to wastewater containing PCP in reactors fed at a semi-continuous rate of 2.0 μg PCP g −1 VS. The applied PCP loading rate was increased from 0.05 to 2.59 mg PCP l −1 day −1 for R1, and from 0.06 to 4.15 mg PCP l −1 day −1 for R2. The organic loading rates (OLR) were 1.1 and 1.7 kg COD m −3 day −1 at hydraulic retention times (HRT) of 24 h for R1 and 18 h for R2. Under such conditions, chemical oxygen demand (COD) removal efficiencies of up to 98% were achieved in the HAIB reactors. Both reactors exhibited the ability to remove 97% of the loaded PCP. Dichlorophenol (DCP) was the primary chlorophenol detected in the effluent. The adsorption of PCP and metabolites formed during PCP degradation in the packed bed was negligible for PCP removal efficiency.

Dynamics of sulfidogenesis associated to methanogenesis in horizontal-flow anaerobic immobilized biomass reactor

Two bench-scale horizontal anaerobic fixed bed reactors were tested to remove both sulfate and organic matter from wastewater. First, the reactors (R1 and R2) were supplied with synthetic wastewater containing sulfate and a solution of ethanol and volatile fatty acids. Subsequently, R1 and R2 were fed with only ethanol or acetate, respectively. The substitution to ethanol in R1 increased the sulfate reduction efficiency from 83% to nearly 100% for a chemical oxygen demand to sulfate (COD/sulfate) ratio of 3.0. In contrast, in R2, the switch in carbon source to acetate strongly decreased sulfidogenesis and the maximum sulfate reduction achieved was 47%. Process stability in long-term experiments and high removal efficiencies of both organic matter and sulfate were achieved with ethanol as the sole carbon source. The results allow concluding that syntrophism instead of competition between the sulfate reducing bacteria and acetoclastic methanogenic archaeal populations prevailed in the reactor.

Performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor and dynamics of the microbial community during degradation of pentachlorophenol (PCP)

The anaerobic biological treatment of pentachlorophenol (PCP) and methanol as the main carbon source was investigated in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor at 30 ± 1 °C, during a 220-day trial period. The reactor biomass was developed as an attached biofilm on polyurethane foam particles, with 24 h of hydraulic retention time. The PCP concentrations, which ranged from 2.0 to 13.0 mg/L, were controlled by adding synthetic substrate. The HAIB reactor reduced 97% of COD and removed 99% of PCP. The microbial biofilm communities of the HAIB reactor amended with PCP, without previous acclimatization, were characterized by polymerase chain reaction (PCR) and amplified ribosomal DNA restriction analysis (ARDRA) with specific Archaea oligonucleotide primers. The ARDRA technique provided an adequate analysis of the community, revealing the profile of the selected population along the reactor. The biomass activities in the HAIB reactor at the end of the experiments indicated the development of PCP degraders and the maintenance of the population of methanogenic Archaea, ensuring the high efficiency of the system treating PCP with added methanol as the cosubstrate. The use of the simplified ARDRA method enabled us to monitor the microbial population with the addition of high concentrations of toxic compounds and highlighting a selection of microorganisms in the biofilm.