A three stage and a one-stage bench-scale Biofilter with effective heights of 129 cm filled with same type of packing material were operated at different influent concentrations of ammonia in order to investigate their performance in treating waste gas streams. The columns contained a mixture of municipal compost inoculated with thickened municipal activated sludge as a base material and shredded hard plastic as a bulking agent in a 3:2 v/v ratio; the porosity, density and pH were 52 %, 0.65 and 7.2 respectively. Microbial acclimation to ammonia was achieved by exposing the three stage Biofilter to an average inlet loading rate of 2.15g-NH3/m3 h and the one-stage to an average inlet loading rate of 1.32 g NH3/m3 h and an empty bed residence time of 60 s, for 10 days and 17 days respectively. Under steady-state condition, maximum elimination capacity (EC) was 9.85 g-NH3/m3h at a loading rate of 9.86 g-NH3/m3h for three-stage Biofilter and 8.08 g NH3/m3h at a loading rate of 8.13 g-NH3/m3h for one-stage Biofilter. The average pressure drop across Biofilters bed was determined 33.76 Pa/m1 in three-stage Biofilter and 180.7 Pa/m1 in one-stage Biofilter. The three stage Biofilter showed superior performance and gained more elimination capacity, shorter acclimation time, longer operation in steady-state condition and less pressure drop than one-stage Biofilter.    

Introduction: Styrene's produced in large quantities in the chemical industries and it has been listed among the 189 hazardous and toxic atmospheric contaminants under Clean Air Act Amendments, 1990, due to its adverse effects on human health. The biofiltration has been widely and efficiently applied during recent decades for the treatment of air streams contaminated by volatile organic compounds at low concentrations. Also this technology has been applied widely and efficiently in the removal of styrene from waste gas streams.Methods: Biofiltration of waste gas stream polluted by styrene vapor was investigated in a three-stage bench scale reactor.Yard waste compost using shredded hard plastics as a bulking agent in a 75:25 v/v mix of plastics: compost was used to packing Biofilter. The system inoculation was achieved by adding thickened activated sludge obtained from municipal wastewater treatment plant and the effects of loading rate, inlet concentration, and empty bed retention time variations on the performance and operation of Biofilter were studied.Results: Microbial acclimation to styrene was achieved with inlet concentration of 65±11 ppm and bed contact time of 360 s after 57 days of operation. Under steady state conditions experimental results showed equal average removal efficiency of about 84% at loading rates of 60 and 80 gm-3 h-1 with empty bed retention time of 60 s. Maximum elimination capacity was obtained up to 81 g m-3h-1 with organic loading rate of about 120 g m-3 h-1. Reduction in performance was observed at inlet concentrations of upper than 650 ppm related to organic loading rates up to 160 g m-3 h-1 and then removal efficiency was decreased sharply. Evaluation of the concentration profile along the bed height of column indicated that the most value of elimination capacity occurred in the first section of Biofilter. Elimination capacity also showed higher performance when emptybed retention time was reduced to 30s.Conclusion: Microbial acclimation period for biofiltration of styrene inoculated with activated sludge was longer than inoculation with adapted or enriched bacteria. Addition of compost improved performance of the Biofilter because of high water retention capacity. Also high pollutant load with significant concentration to the first sections has a clear initiative effect on Biofilter performance along the bed height of biofillter.

Laboratory scale experiments were performed to evaluate the feasibility of Biofilters for the removal of H2S from wastewater treatment plant waste air. The effects of changes in air flow rate and contaminant concentration on Biofilter performance treating H2S odours were also assessed.Compost was used as media in Biofilter. The study was carried out in six different phases, by increasing H2S concentrations gradually. In the first phase only humidified air was supplied to acclimatize and develop the biofilm, within the Biofilter conditions. In the second phase, inlet H2S concentration was kept up to 10 ppm with the humidified air, H2S removal efficiency was very high around 98%. It was concluded that the Biofilter, used in the study, was more efficient (>95% removal efficiency) for low contaminant concentrations (up to 30 ppm). However, as the concentration of H2S was increased to 50 ppm the removal efficiency decreased to 85%. The study results showed that Biofilter could withstand longer starvation period and required less time to recover to its full efficiency. The effect of operating parameter such as moisture content was also assessed. The study revealed that the compost Biofilter may be successfully adopted for various industrial operations where a reduction in emissions of H2S is required.

Mathematic modeling and simulation of a Biofilter system was developed for Biofilters filled by three different packing materials such as granular activated carbon (GAC), compost mixed with diatomaceous earth (DE), and compost, respectively, and the effects of Biofilter length, packing material, biological activity and the operation time of system on the removal of ethanol (influent contaminant) were studied. The mathematical model for analysis of mass transport phenomena in the Biofilter was solved using a two-step, explicit finite difference approximation technique and computer simulation was carried out. The obtained results show that at the early stage of biofiltration the dominant mechanism is adsorption and after saturation of packing by contaminant, biological processes became the dominant mechanism. GAC packed Biofilter needs more time to reach to steady state in comparison to the two other packing. GAC is the best adsorbent for contaminant removal; however, compost provides a better environment for microbial growth and activity. The proposed procedure is applicable to analyze the behavior of a biofiltration system used in removal of volatile organic compounds.

Phenol is a toxic hydrocarbon that has been found in the wastewater of several industries, including the petroleum and petrochemical industries. The discharge of untreated wastewater from these industries causes environmental pollution, especially in water. The aim of this study was to evaluate the efficiency of phenol removal from wastewater using a bio filtration system. In this experimental study, a cylindrical plexiglass bio filter reactor with an effective volume of 12 liters was used. A total of 30 pcs of plastic grid discs were placed inside the reactor by plastic pipes to maintain the biofilm media in the reactor. The microorganisms used in this study were obtained from the biological sludge of a municipal wastewater treatment plant. The reproduction and adaptation of the microorganisms to 500 mg/L of phenol lasted three months. The effects of pH, phenol, nitrogen, phosphorus, glucose concentration, and hydraulic retention time on the bio filter system’s performance was evaluated. The results of this study showed that in optimal conditions, this system can reduce the phenol concentration from 500 mg/L to zero within about 4 hr. Maximum efficiency occurred in pH=7, and the proper COD/N/P ratio was 100/10/2, respectively. In general, this bio filter system is capable of removing 500 mg/L of phenol concentrations and an organic load of 4 - 4.5 kg COD/m3.d within 4 - 5 hr. with high efficiency.

Background: Inappropriate management of textile wastewater results in environmental pollution. To counter this, Biofilters or biofilm systems serve as alternatives. Biofilters work like a filter, with a media stack that aids in the filtration process. In this study, pozzolan and sawdust were used as media. The present study aimed to identify the difference in average color content, chemical oxygen demand (COD), and chromium of textile wastewater after passing through a single Biofilter versus a combination Biofilter. Methods: This study employs a post-test with a control design experimental research design. The research population is the total textile wastewater produced by the X industry located in Cimahi city, Indonesia. The grab sampling technique was employed to collect 30 L of textile wastewater for each treatment using both the single Biofilter (composed solely of sawdust) and the combination Biofilter (mixture of sawdust and pozzolan). Results: There are significant differences in color, COD, and chromium content averages between single and combined Biofilter treatments, supported by P values of 0.012, 0.004, and 0.010. The single Biofilter exhibited higher percentage reductions in color and chromium (14.25% and 90.83%, respectively) compared to the combination Biofilter. In contrast, the combination Biofilter achieved a remarkable COD reduction of up to 79.45%compared to the single Biofilter. Conclusion: The results of the present study showed that the single Biofilter had a higher capacity to remove color and chromium compared to the combination Biofilter. Meanwhile, the combination Biofilter was found to be more effective in removing COD compared to the single Biofilter.