Biofilter Research Articles

Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of styrene overloading

This aim of study was to compare the performance of a biofilter (BF) and trickle bed reactor (TBR) under increased styrene loading with a constant acetone load, 2 gc/m3/h. At styrene loading rates up to 30 gc/m3/h, the BF showed higher styrene removal than TBR. However, the BF efficiency started to drop beyond this threshold loading and could never reach steady state, whereas the TBR continued to yield a 50% styrene removal. The acetone removal remained constant (93-98%) in both the reactors at any styrene loading. Once the overloading was lifted, the BF recovered within 26 min, whereas the TBR efficiency bounced back only to 95%, gradually returning to complete removal only in 10 h.

CONVECTIVE METHODS IN CLINICAL PRACTICE OF V.I. SHUMAKOV FEDERAL RESEARCH CENTER OF TRANSPLANTOLOGY AND ARTIFICIAL ORGANS: PAST AND PRESENT

The experience of the introduction of convective methods since the eighties of the 20th century is described. Aim: to evaluate the infl uence of convective transport supplementation on renal replacement therapy results. Methods and results. The number of convective procedures was applied: hemodiafi ltration with commercial substituted fl uid, paired fi ltration dialysis, acetate-free biofi ltration, original hybrid methods, online hemodiafi ltration. The main trend was the magnifi cation of substituted volume. In the long run after switching from conventional dialysis to convective therapy the increase of Kt/V, the decline of phosphate, the rise of serum albumin, the decrease of CRP level and ESA consumption, QOL improvement and the drop in severity of intradialysis complications were observed. Over last six years online hemodiafi ltration has become the standard of dialysis therapy in our Center. Conclusion. The undoubted advantages of convective modalities and accessibility of online hemodiafi ltration make these methods the gold standard of dialysis therapy.

Feeding behavior and trophic relationship of earthworms and other predators in vermifiltration system for liquid-state sludge stabilization using fatty acid profiles

The sludge reduction capability (VSS reduction) of vermifilter (VF) was 14.7% higher than that of conventional biofilter (BF) due to the fact that there was a net loss of biomass and energy when the food web in VF is extended. Therefore, feeding behavior and trophic relationship of earthworms and other predators (leeches, lymnaeidaes and limaxes) in VF were investigated using fatty acid (FA) profiles for the first time. Compared with BF biofilm, microbial community structure of VF biofilm got optimized by earthworms that the percentage of protozoa increased from 14.2% to 20.4%. Furthermore, analysis of specific microbial FAs composition in each predator suggested different trophic level of predators resulted from their selective ingestion of different microorganisms, and earthworms were at the second high trophic level in VF food web. Overall findings indicated earthworms modified microbial community and extended the food web of VF and thus enhanced the sludge reduction.

Influence of Intermittent Loading on the Removal of High Concentrations of VOCs in a Biofilter

In this research, the elimination of a mixture of toluene and hexane vapors from waste air was studied in a compost biofilter under intermittent condition. The system was operated 10 h a day on the air residence times 0.9, 1.5 and 3 min and 2-3.8 gm-3 of pollutant concentration. Regarding the harsh biological condition of biofilter media such as high pollutant concentration and daily intermittent aeration, reaching the steady-state situation and removal efficiency of 90% lasted about 44 days.

Microbial communities from different types of natural wastewater treatment systems: Vertical and horizontal flow constructed wetlands and biofilters

The prokaryotic microbial communities (Bacteria and Archaea) of three different systems operating in Denmark for the treatment of domestic wastewater (horizontal flow constructed wetlands (HFCW), vertical flow constructed wetlands (VFCW) and biofilters (BF)) was analysed using endpoint PCR followed by Denaturing Gradient Gel Electrophoresis (DGGE). Further sequencing of the most representative bacterial bands revealed that diverse and distinct bacterial communities were found in each system unit, being γ-Proteobacteria and Bacteroidetes present mainly in all of them, while Firmicutes was observed in HFCW and BF. Members of the Actinobacteria group, although found in HFCW and VFCW, seemed to be more abundant in BF units. Finally, some representatives of α, β and δ-Proteobacteria, Acidobacteria and Chloroflexi were also retrieved from some samples. On the other hand, a lower archaeal diversity was found in comparison with the bacterial population. Cluster analysis of the DGGE bacterial band patterns showed that community structure was related to the design of the treatment system and the organic matter load, while no clear relation was established between the microbial assemblage and the wastewater influent.

Plasma Supported Odour Removal from Waste Air in Water Treatment Plants: An Industrial Case Study

Effects of plasma assisted waste air treatment from a water treatment plant have been investigated in several field tests. In particular the off-air for a thermal sludge dryer was investigated and treated. The intention of this study was to proof whether plasma assisted technologies are a possible solution for the removal of odour from waster air emitted by wastewater treatment facilities. The plasma treatment was combined with a catalytic (cupper-manganese) unit, a scrubbing unit, or a bio filter in order to demonstrate the abilities for waste air deodorization. The inlet and outlet gas was analysed by means of FTIR, FID, and chemical sensors and the odour removal was investigated by standardized olfactometry. A significant reduction of hydrogen sulphide and methane by means of combined plasma-catalyst-treatment has been measured, but the removal of hydrogen sulphide leads to the formation of unwanted by-products. Main effects of plasma treatment in the field tests can be compared to the results of laboratory studies published in the literature. A significant odour reduction up to about 90% was measured. Aldehydes and other hydrocarbons are marginally removed by plasma treatment as well as by the bio filter. The bio filter released sulphur containing substances (DMS, CS2, DMDS) which can be destroyed by plasma-catalytic treatment. Based on the results of the field tests a reliable concept for an industrial after treatment installation has been designed as described. Due to the high content of H2S a scrubber as the first treatment unit is desired. Downstream the scrubber the plasma/catalytic unit combined with the existing bio filter is proposed for the removal of the hydrocarbons and other odorous constituents.

Biofiltration vs conventional activated sludge plants: what about priority and emerging pollutants removal?

This paper compares the removal performances of two complete wastewater treatment plants (WWTPs) for all priority substances listed in the Water Framework Directive and additional compounds of interest including flame retardants, surfactants, pesticides, and personal care products (PCPs) (n = 104). First, primary treatments such as physicochemical lamellar settling (PCLS) and primary settling (PS) are compared. Similarly, biofiltration (BF) and conventional activated sludge (CAS) are then examined. Finally, the removal efficiency per unit of nitrogen removed of both WWTPs for micropollutants is discussed, as nitrogenous pollution treatment results in a special design of processes and operational conditions. For primary treatments, hydrophobic pollutants (log K ow > 4) are well removed (>70%) for both systems despite high variations of removal. PCLS allows an obvious gain of about 20% regarding pollutant removals, as a result of better suspended solids elimination and possible coagulant impact on soluble compounds. For biological treatments, variations of removal are much weaker, and the majority of pollutants are comparably removed within both systems. Hydrophobic and volatile compounds are well (>60%) or very well removed (>80%) by sorption and volatilization. Some readily biodegradable molecules are better removed by CAS, indicating a better biodegradation. A better sorption of pollutants on activated sludge could be also expected considering the differences of characteristics between a biofilm and flocs. Finally, comparison of global processes efficiency using removals of micropollutants load normalized to nitrogen shows that PCLS + BF is as efficient as PS + CAS despite a higher compactness and a shorter hydraulic retention time (HRT). Only some groups of pollutants seem better removed by PS + CAS like alkylphenols, flame retardants, or di-2-ethylhexyl phthalate (DEHP), thanks to better biodegradation and sorption resulting from HRT and biomass characteristics. For both processes, and out of the 68 molecules found in raw water, only half of them are still detected in the water discharged, most of the time close to their detection limit. However, some of them are detected at higher concentrations (>1μg/L and/or lower than environmental quality standards), which is problematic as they represent a threat for aquatic environment.

Microbial community structure and metabolic property of biofilms in vermifiltration for liquid-state sludge stabilization using PLFA profiles

To investigate effects of earthworms on microbial community structure and metabolic properties of biofilms in vermifiltration for liquid-state sludge stabilization, a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared. The Shannon index of fungi in VF was 16% higher than that in BF, which indicated earthworm activities significantly enhanced fungi diversity. The ratio of monounsaturated to saturated (mono:sat) PLFAs of VF biofilms was higher than that of BF biofilms, which indicated the physiological and nutritional stress for microbial community in VF was relieved due to the increasing of soluble substances caused by the earthworm ingestion. Further investigation showed that the burrowing action of earthworms promoted the aeration condition and led to aerobic microorganisms were predominant in VF. Those results indicated earthworms improved microbial community structure and metabolic properties of biofilms and thus resulted in the overall optimization of the vermifiltration system for liquid-state sludge stabilization.

Organic matter humification in vermifiltration process for domestic sewage sludge treatment by excitation–emission matrix fluorescence and Fourier transform infrared spectroscopy

Performance of a conventional biofilter (BF) and two vermifilters (VFs, different heights) containing earthworms was investigated for domestic sewage sludge (DWS) treatment. Humic-acid like (HAL) fraction isolated from the influent sludge (IS) and effluent sludge of BF (ESBF) and VFs (ESVFs) were determined the elemental and functional composition, and structural characteristics using various analytical approaches. Results showed that performance of DWS treatment in the VFs was preferable to that in the BF. With respect to IS-HAL and ESBF-HAL, ESVFs-HAL had low C, H and N contents and C/O ratio, and high O, carboxyl and phenolic OH group contents, and C/N, C/H and E4/E6 ratios, and large molecular weight. The excitation–emission (Ex/Em) matrix spectra revealed that an additional peak was found at Ex/Em wavelength pairs of 345/435nm in ESVFs-HAL. Further, Fourier transform infrared spectra showed that vermifiltration led to the loss of aliphatic materials and carbohydrates, and the enrichment of carbonyl and phenolic OH groups in HAL fractions. Additionally, the increase in VF height seemed to accelerate humification degree of organic matter in the effluent sludge. In summary, vermifiltration is alternate technology for transformation of organic matter into humic substances, and thus improves quality of DWS as soil organic fertilizer.

Effect of earthworms on the biochemical characterization of biofilms in vermifiltration treatment of excess sludge

In this study, the biofilms formed in a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared to investigate the effects of earthworms on the characteristics of biofilms during an excess sludge treatment period of 4months. Typical macrographs and micrographs of the biofilms showed that the feeding and casting actions of earthworms remarkably modified the VF morphology. Elemental analysis and fluorescence spectra indicated that earthworms enhanced the stabilization of organic matter by accelerating the mineralization and humification of organic materials during vermiconversion. In addition, bacterial communities inhabiting the VF biofilm showed that earthworms increased both bacterial diversity and metabolic activities in the film, as revealed by automatic testing bacteriology (ATB) expression and sequencing data. These results demonstrate that earthworms influence the structure and biochemical characteristics of biofilms and enhance their bacterial diversity and functions for improved sludge stabilization.

Properties of biofilm in a vermifiltration system for domestic wastewater sludge stabilization

Vermifiltration is an alternative and low-cost technology for stabilizing excess sludge from domestic wastewater treatment plants. The biofilm properties of a vermifilter (VF) with earthworms, Eisenia fetida, for domestic wastewater sludge (DWS) treatment were studied. A biofilter (BF) without earthworms served as the control. VF biofilms had lower levels of suspended solids (SSs), volatile SS, C, H, N and S contents, protein-like groups, and total viable cell numbers and larger humic acid-like fractions and protease, dehydrogenase, lipase, and amylase activities compared with BF biofilms. Furthermore, VF biofilms featured richer diversity in their microbial community and more populations of Proteobacteria than BF biofilms. The relationships between organic matter and microbial eco-physiological indices in VF biofilms were significantly different from those in BF biofilms. Overall findings indicated that earthworm presence remarkably decreases organic matter contents and microbial biomass and improves microbial enzyme activities and the community structure of VF biofilms.

EFFECT HYDRAULIC AGITATION USING ANAEROBIC BIOFILTER FOR TREATED DOMESTIC WASTEWATER

The objective of this study was to investigate the effi ciency the TSS reduction of domestic wastewater by using hydraulic agitation in anaerobic biofi lter. The reactor consists of four columns. Each column has a sampling point. Upfl ow direction was operated in reactor in order to maximize the hydraulic agitation. Gravel was used as fi lter media to support the growth of biofi lm. The reactor treated wastewater of FST Airlangga University canteen which contains 8237.463 mg/l of TSS. Flow used during processing was 0.3 ml/min. Sampling TSS were performed on days 7, 14, 21, and 28. The results showed that the effi ciency of TSS were 64.57%, 76.16%, 94.23% and 98.46% respectively. The average TSS removal was 83.36%.

Biofiltration of a mixture of ethylene, ammonia, n-butanol, and acetone gases

This study describes cleaning of a waste gas stream using bench scale biofilters (BFs) or biotrickling filters (BTFs). The gas stream contained a mixture of acetone, n-butanol, methane, ethylene, and ammonia, and was diverted uniformly to six biofilters and four biotrickling filters. The biofilters were packed with either perlite (BF-P), polyurethane foam (BF-F), or a mixture of compost, wood chips, and straw (BF-C), whereas the biotrickling filters contained either perlite (BTF-P) or polyurethane foam (BTF-F). Experimental results showed that both BFs and BTFs packed with various media were able to achieve complete removal of highly soluble compounds such as acetone, n-butanol, and ammonia of which the dimensionless Henry’s constants (H) are less than 0.01. Methane was not removed due to its extreme insolubility (H>30). However, the ethylene (H≈9) removal efficiencies depended on trickle water flow rates, media surface areas, and ammonia gas levels.

Improving biotreatment efficiency of hot waste air streams: experimental upgrade of a full plant

Biological methods as bio and biotrickling filtration are an energy-efficient and economical alternative to treat biodegradable odorants and volatile organic compounds (VOCs) in order to obey stringent releases regulations that have arisen during the last few decades. In this work a plant upgrade case study, employing these techniques, is presented. It refers to a critical situation in which off air streams, characterized by medium odorous compounds loads and high temperatures, were treated using a biofilter only. In that context, sufficient removal efficiencies were not achieved. Therefore, it has been proposed to replace the existing biofilter by a biotrickling one implementing a minimal number of structural plant modifications.

Removal of Trimethylamine in a Biofilter Packed with Waste Tire Chips

Abstract Trimethylamine (TMA) is a product of decomposition of living things and it has a strong odor. A biofilter (BF) packed with waste tire chip for reuse as a new media, and inoculated with activated sludge was tested for TMA removal. Gas-phase 0.024–0.036 g TMA m−3 was removed by up to 95% with empty bed residence time (EBRT) of 30 and 20 s, but the removal efficiency (RE) reduced to 80% at an EBRT of 15 s. For concentrations varying between 0.012 and 0.024 g TMA m−3 at an EBRT of 20 s, 95% of TMA was removed, which then decreased to as low as 80% for concentrations varying between 0.049 and 0.056 g m−3. As a result, the RE of TMA in the BF was found to be a strong function of both concentration and EBRT. The critical elimination capacity (EC) point of TMA was inlet loading rate (ILR) of 5 g m−3 h−1 and the maximum EC was determined to be 14 g m−3 h−1 at an ILR of 23 g m−3 h−1. It was concluded that tire chips can be effectively used as a biofilm support material in BFs where the REs for TMA can be m...

Biofiltration of paint solvent mixtures in two reactor types: Overloading by polar components

Steady-state performances of a trickle bed reactor (TBR) and a biofilter (BF) in loading experiments with increasing inlet concentrations of polar solvents, acetone, methyl ethyl ketone, methyl isobutyl ketone and n-butyl acetate, were investigated, along with the system's dynamic responses. Throughout the entire experimentation time, a constant loading rate of aromatic components of 4 gc·m−3·h−1 was maintained to observe the interactions between the polar substrates and aromatic hydrocarbons. Under low combined substrate loadings, the BF outperformed TBR not only in the removal of aromatic hydrocarbons but also in the removal of polar substrates. However, increasing the loading rate of polar components above the threshold value of 31–36 gc·m−3·h−1 resulted in a steep and significant drop in the removal efficiencies of both polar (except for butyl acetate) and hydrophobic components, which was more pronounced in the BF; so the relative TBR/BF efficiency became reversed under such overloading conditions. A step-drop of the overall OLPOLAR (combined loading by polar air pollutants) from overloading values to 7 gc·m−3·h−1 resulted in an increase of all pollutant removal efficiencies, although in TBR the recovery was preceded by lag periods lasting between 5 min (methyl ethyl ketone) to 3.7 h (acetone). The occurrence of lag periods in the TBR recovery was, in part, due to the saturation of mineral medium with water-soluble polar solvents, particularly, acetone. The observed bioreactor behavior was consistent with the biological steps being rate-limiting.

Performance and mechanism of vermifiltration system for liquid-state sewage sludge treatment using molecular and stable isotopic techniques

Performance and mechanism of a conventional biofilter (BF) and a vermifilter (VF) containing earthworms were studied for liquid-state sewage sludge treatment. Results showed that removal rates of the VF for suspended solid (SS), volatile SS, total chemical oxygen demand (TCOD) and 5-day biological oxygen demand (BOD5) were higher than that of the BF. The effluent sludge of VF (ESVF) had lower N, C and H contents, with higher quantities of δ15N, δ13C and aromatic groups than that of BF (ESBF). Compared to ESBF, ESVF had higher activities of protease, glucosidase, lipase and amylase, and less densities of total bacteria, α-, β- and γ-proteobacteria. These indicated the presence of earthworm improved the treatment performance of the VF and promoted the stabilization of ESVF. Additionally, passage through the intestinal tract of earthworms caused a decrease in the densities of α- and β-proteobacteria, and an increase in the density of Nitrospira of the VF biofilms. Stable isotopic analyses implied that earthworm adults, hatchlings and cocoons appeared to be found in the highest position; hirudinea in the second highest position; gastropoda adults and larvae, diptera adults at intermediate level; diptera larvae in the lower position of food web in VF system.

Effect of earthworms on the performance and microbial communities of excess sludge treatment process in vermifilter

Previous studies have shown that the stabilization of excess sludge by vermifiltration can be improved significantly through the use of earthworms. To investigate the effect of earthworms on enhancing sludge stabilization during the vermifiltration process, a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared. The sludge reduction capability of the VF was ∼85% higher than that of the BF. Specifically, elemental analysis indicated that earthworms enhanced the stabilization of organic matter. Furthermore, earthworm predation strongly regulated microbial biomass while improving microbial activity. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the most abundant microbes in the VF biofilms and earthworm casts were Flavobacterium, Myroides, Sphingobacterium, and Myxococcales, all of which are known to be highly effective at degrading organic matter. These results indicate that earthworms can improve the stabilization of excess sludge during vermifiltration, and reveal the processes by which this is achieved.

Removal of Air Containing Tri Ethyl Amine (Tea) Using Vapor Phase Biofilter Packed With Wood Chips and Rice Husk

Mixed bacterial strains named as AGR/IICT/1- 5B was isolated from the active sludge of ETP of a polymerization industry. Strains AGR/IICT/1-5B was primarily identified as 3 gram positive and 2 gram negative bacteria. These strains were used for the abatement of TEA in bio filters. Experiments were conducted on biofilter having the working volume of 1.2 L. Microorganism was immobilized on mixture of wood chips and rice husk (1:1 v/v) which is used as the filter medium. The biofilter was operated at the following conditions; Temperature 30±1°C, pH values in the range of 7.0 -7.6, Loading rate at 1-144 g m -3 h -1 , EBRT at 20-40 s, moisture content at 50-59%. Removal efficiency in the range of 90-95% was obtained during the study.

Biofiltration of a styrene/acetone vapor mixture in two reactor types under conditions of acetone overloading

AbstractBACKGROUND: Evaluation of the biodegradation interactions between styrene and acetone, two typical paint solvents and vapor phase pollutants differing in water solubility and biodegradability, was conducted both in a trickle bed reactor (TBR) and a biofilter (BF). The loading rate experiments were performed by increasing the acetone concentration in the inlet air while keeping the styrene concentration and loading rate constant.RESULTS: At acetone loading rates (OLAC) between 25 and 35 gc m−3 h−1, the BF featured greater steady state performance characteristics for styrene degradation. At OLAC between 35 and 48 gc m−3 h−1, a decline of removal efficiency (RE) was observed for both pollutants, due to the system's overloading with acetone. Increasing OLAC above 52‐55 gc m−3 h−1 in both reactors resulted in drifts of RE and EC over time to much lower values. A step‐drop of acetone loading rate back to OLAC of 3 gc m−3 h−1 (gc denotes grams of carbon) resulted in lag periods lasting for several hours.CONCLUSIONS: Two important issues inherent for acetone biofiltration, e.g., from paint booths or polystyrene production, were identified: (1) poor performance at high loadings of this aggressive solvent and (2) acetone back‐stripping into the air following periods of high overloading. Copyright © 2012 Society of Chemical Industry