Hydrogen sulfide removal from biogas using a salak fruit seeds packed bed reactor with sulfur oxidizing bacteria as biofilm

A packed bed reactor was evaluated for hydrogen sulfide (H2S) removal by sulfur-oxidizing bacteria attached as a biofilm on salak fruit seeds (SFS). The bacteria were isolated from the sludge of the wastewater of a biogas plant. The promising isolate from the previous work was used in a biofilter, and its capacity to remove H2S was evaluated at effects of time of operation, effects of biogas flow rate, effects of axial distance, and packing material. Obtained results showed that isolate attached to SFS in an 80 cm height and 8 cm inside diameter biofilter column could decrease H2S in biogas from 142.48 ppm to 4.06 ppm (97.15% removal efficiency) for a biogas flow rate of 8550 g m3 h1 corresponding to a residence time of 4 h. Simple kinetic models of sulfide removal and bacterial growth was proposed to describe the operation of the biofilter. The radial H2S concentration gradient in the flowing gas is to be neglected so is the H2S concentration in the biofilm at certain axial distance. Meanwhile, the rate of H2S degradation was approximated by Monod type equation. The obtained simultaneous ordinary differential equations solved by Runge-Kutta method. Comparing the calculated results and the experimental data, it can be concluded that model proposed can sufficiently describe the performance of the H2S removal. The suitable values of the parameters are as follows: max = 0.0000007 (s1), KS = 0.0000039 (g cm3), kG = 0.0086 (cm s1), HS = 0.9 ((g cm3)/(g cm3)), and Yx/s = 10.Directorate General of Higher Educations of Indonesia - scholarship of doctorate program (BPPDN) at Gadjah Mada University ; Hibah Bersaing 2015 and Sandwich-Like program 201

Performance of an industrial biofilter from a composting plant in the removal of ammonia and VOCs after material replacement

BACKGROUND: Biofiltration is a suitable odor reduction technique for the treatment of gaseous emissions from composting processes, but little is known about the start-up of full-scale biofilters after material replacement and their performance after several years of operation. - RESULTS: Biofilter material (wood chips used previously as bulking agent in a composting process) can effectively remove ammonia and most of the volatile organic compounds (VOCs) content, achieving removal efficiencies greater than 70% for VOCs and near 90% for ammonia immediately after material replacement. These removal efficiencies were maintained for several months after material replacement. In the studied full-scale biofilter no lag phase was observed in the removal of ammonia whereas in the case of VOCs different patterns were detected during biofilter start-up. For the old biofilter material, after 4 years of operation, a statistically significant decrease of removal efficiency for ammonia in comparison with the new material was detected. No statistically significant differences were found in the case of VOCs. - CONCLUSIONS: Data on the emissions of several pollutants from biofilters treating composting exhaust gases have been systematically obtained. The tested filtering media presented adequate properties for biofiltration of gases emitted during the composting process

Biotrickling filtration of isopropanol under intermittent loading conditions

This paper investigates the removal of isopropanol by gas phase biotrickling filtration. Two plastic packing materials, one structured and one random, have been evaluated in terms of oxygen mass transfer and isopropanol removal efficiency (RE). Oxygen mass transfer experiments were performed at gas velocities of 104 and 312 m h-1 and liquid velocities between 3 and 33 m h-1. Both materials showed similar mass transfer coefficients up to liquid velocities of 15 m h-1. At greater liquid velocities, the structured packing exhibited greater oxygen mass transfer coefficients. Biotrickling filtration experiments were carried out at inlet loads (IL) from 20 to 65 g C m-3 h -1 and empty bed residence times (EBRT) from 15 14 to 160 s. To simulate typical industrial emissions, intermittent isopropanol loading (16 h/day, 5 16 day/week) and intermittent spraying frequency (15 min/1.5 hours) were applied. Maximum elimination capacity (EC) of 51 g C m-3 h -1 has been obtained for the random packing (IL of 65 g C m-3 h -1 17 , EBRT of 18 50 s). The decrease in irrigation frequency to 15 min every 3 hours caused a decrease in the outlet emissions from 86 to 59 mg C Nm-3 (inlet of 500 mg C Nm-3). The expansion of spraying to night and weekend periods promoted the degradation of the isopropanol accumulated in the water tank during the day, reaching effluent concentrations as low as 44 mg C Nm-3. After a 7 week starvation period, theperformance was recovered in less than 10 days, proving the robustness of the proces

Detection, Composition and Treatment of Volatile Organic Compounds from Waste Treatment Plants

Environmental policies at the European and global level support the diversion of wastes from landfills for their treatment in different facilities. Organic waste is mainly treated or valorized through composting, anaerobic digestion or a combination of both treatments. Thus, there are an increasing number of waste treatment plants using this type of biological treatment. During waste handling and biological decomposition steps a number of gaseous compounds are generated or removed from the organic matrix and emitted. Different families of Volatile Organic Compounds (VOC) can be found in these emissions. Many of these compounds are also sources of odor nuisance. In fact, odors are the main source of complaints and social impacts of any waste treatment plant. This work presents a summary of the main types of VOC emitted in organic waste treatment facilities and the methods used to detect and quantify these compounds, together with the treatment methods applied to gaseous emissions commonly used in composting and anaerobic digestion facilities

Pilot-scale biofiltration at a materials recovery facility: The impact on bioaerosol control

This study investigated the performance of four pilot-scale biofilters for the removal of bioaerosols from waste airstreams in a materials recovery facility (MRF) based in Leeds, UK. A six-stage Andersen sampler was used to measure the concentrations of four groups of bioaerosols (Aspergillus fumigatus, total fungi, total mesophilic bacteria and Gram negative bacteria) in the airstream before and after passing through the biofilters over a period of 11 months. The biofilters achieved average removal efficiency (RE) of 70% (35 to 97%) for A. fumigatus, 71% (35 to 94%) for total fungi, 68% (47 to 86%) for total mesophilic bacteria and 50% (-4 to 85%) for Gram negative bacteria, provided that the inlet concentration was high (103–105 - cfu m�3), which is the case for most waste treatment facilities. The performance was highly variable at low inlet concentration with some cases showing an increase in outlet concentrations, suggesting that biofilters had the potential to be net emitters of bioaerosols. The gas phase residence time did not appear to have any statistically significant impact on bioaerosol removal efficiency. Particle size distribution varied between the inlet and outlet air, with the outlet having a greater proportion of smaller sized particles that represent a greater human health risk as they can penetrate deep into the respiratory system where gaseous exchange occurs. However, the outlet concentrations were low and would further be diluted by wind in full scale applications. In conclusion, this study shows that biofilters designed and operated for odour degradation can also achieve significant bioaerosol control in waste gas

Synergistic effects of climate change and local stressors: CO(2) and nutrient-driven change in subtidal rocky habitats

Journal compilation © 2009 Blackwell Publishing. Copyright © 2009 John Wiley & Sons, Inc. All Rights ReservedClimate-driven change represents the cumulative effect of global through local-scale conditions, and understanding their manifestation at local scales can empower local management. Change in the dominance of habitats is often the product of local nutrient pollution that occurs at relatively local scales (i.e. catchment scale), a critical scale of management at which global impacts will manifest. We tested whether forecasted global-scale change [elevated carbon dioxide (CO2) and subsequent ocean acidification] and local stressors (elevated nutrients) can combine to accelerate the expansion of filamentous turfs at the expense of calcifying algae (kelp understorey). Our results not only support this model of future change, but also highlight the synergistic effects of future CO2 and nutrient concentrations on the abundance of turfs. These results suggest that global and local stressors need to be assessed in meaningful combinations so that the anticipated effects of climate change do not create the false impression that, however complex, climate change will produce smaller effects than reality. These findings empower local managers because they show that policies of reducing local stressors (e.g. nutrient pollution) can reduce the effects of global stressors not under their governance (e.g. ocean acidification). The connection between research and government policy provides an example whereby knowledge (and decision making) across local through global scales provides solutions to some of the most vexing challenges for attaining social goals of sustainability, biological conservation and economic development