The performance of a compost biofilter inoculated with mixed microbial consortium was optimized for treating a gas-phase mixture of benzene and toluene. The biofilter was acclimated to these VOCs for a period of similar to 18 d. The effects of concentration and flow rate on the removal efficiency (RE) and elimination capacity (EC) were investigated by varying the inlet concentration of benzene (0.12-0.95 g/m(3)), toluene (0.14-1.48 g/m(3)) and gas-flow rate (0.024-0.072 m(3)/h). At comparable loading rates, benzene removal in the mixture was reduced in the range of 6.6-41% in comparison with the individual benzene degradation. Toluene removal in mixture was even more affected as observed from the reductions in REs, ranging from 18.4% to 76%. The results were statistically interpreted by performing an analysis of variance (ANOVA) to elucidate the main and interaction effects. (C) 2015 Elsevier Ltd. All rights reserved.

Biofiltration, a simple technique involving microorganisms supported on a solid matrix, offers an attractive solution for the removal of volatile organic compounds (VOCs). The removal of benzene, toluene and xylene (model VOCs) in vapour phase has been compared individually in the present study using three biofilters. These biofilters were operated at different flow rates and concentrations (<2.7g m–3), to achieve different loading rates of these pollutants. Removal efficiencies greater than 80% for toluene and between 70–82% for benzene and xylene, respectively, were obtained. The maximum VOC elimination capacity in the biofilter ranged between 52–107g m–3 h–1 for benzene, toluene or xylene under the tested condition. High removal efficiencies over the entire range of operating conditions proved the effectiveness and reliability of the biofilter for industrial applications.

The conventional treatment methods employed in decolourisation of industrial wastewater are not effective and lead to generation of hazardous sludge. In the present investigation, a systematic study of three important process variables (concentration of initial colour, glucose and ammonium chloride) influencing the decolourisation and Chemical Oxygen Demand (COD) removal in screen-printing wastewater by Trametes versicolor was carried out using a full-factorial Central Composite Design. The statistical significance of the regression model equation using Analysis of Variance (ANOVA) showed that the model was highly significant. The multiple response optimisation showed that decolourisation and COD removal efficiency in this case were 72.8 and 76.3%, respectively.

During the production of cephradine (a main constituent of anti-osmotic drug) a large quantity of concentrated effluent was produced. The main polluting compounds in this effluent are osmotic drug, acetic acid and ammonia. The main objectives of the study were to assess the toxicity in terms of specific methanogenic activity on anaerobic degradation of cephradine with Volatile Fatty Acid (VFA) as co-substrate in batch systems using adapted and non-adapted cultures and to study the effect of bioaugmentation with adapted and non-adapted cultures on anaerobic treatment of anti-osmotic drug based pharmaceutical effluent in continuous mode using a fluidised bed reactor. The toxicity assessment was measured in terms of specific methanogenic activity (ml CH4 g-1 VSS d-1), which was found to decrease with increase in cephradine concentration and attained a maximum at 100 mg l-1. The COD reduction (%) in continuous mode reached maximum of 88.5 at a Hydraulic Retention Time (HRT) of 12 h using bioaugmentation through periodic addition of 14 to 20 g l-1 of biomass (acclimated cells) every 2 days from an off-line enricher-reactor.

Among the different waste gas treatment techniques developed to eliminate odorous and toxic pollutants from air, biological techniques have emerged as an effective, reliable, eco-friendly, simple, and economical option. Biological waste gas treatment systems such as biofilters are commonly used in industrial complexes to handle emissions at high gas flow rates and low pollutant concentrations (<5 g/m(3)). However, from a practical view-point, variation in concentrations and gas flow rates are common to any industrial emission, and it is a pre-requisite to simulate these conditions (shock loads) at the laboratory scale. This chapter provides sufficient theoretical background information on the different waste gas treatment systems, literature review on shock loads in biofilters, and the different steady and transient state models developed in the field of biofiltration. A fundamental overview of artificial neural networks and the different steps of the modeling process are also presented.

The conventional biological treatment methods employed in the pulp and paper industries are not effective in reducing the colour and chemical oxygen demand (COD). The white-rot fungi are reported to have the ability to biodegrade the lignin and its derivatives. This paper is focused on the biological treatment of pulp mill effluent from a bagasse-based pulp and paper industry using fungal treatment. Experiments were conducted using the white rot fungus, Trametes versicolor in shake flasks operated in batch mode with different carbon sources. The decolourisation efficiencies of 82.5% and 80.3% were obtained in the presence of 15 g/L and 5 g/L of glucose and sucrose concentrations respectively with a considerable COD reduction. The possibility of reusing the grown fungus was examined for repeated treatment studies.

Among the different waste gas treatment techniques developed to eliminate odorous and toxic pollutants from air, biological techniques have emerged as an effective, reliable, eco-friendly, simple, and economical option. Biological waste gas treatment systems such as biofilters are commonly used in industrial complexes to handle emissions at high gas flow rates and low pollutant concentrations (<5 g/m3). However, from a practical view-point, variation in concentrations and gas flow rates are common to any industrial emission, and it is a pre-requisite to simulate these conditions (shock loads) at the laboratory scale. This chapter provides sufficient theoretical background information on the different waste gas treatment systems, literature review on shock loads in biofilters, and the different steady and transient state models developed in the field of biofiltration. A fundamental overview of artificial neural networks and the different steps of the modeling process are also presented.

The conventional treatment of dark coloured textile wastewater using chemical coagulation generates large volume of sludge, which requires further treatment and disposal. In the present investigation, a systematic optimization study of the important variables influencing the decolorization of Reactive Orange-16 (RO-16) and Reactive Red-35 (RR-35) dyes by the white-rot fungus (Trametes versicolor) was carried out. A full factorial central composite design was employed for experimental design and optimization of results. The effect of concentrations of dye, glucose and ammonium chloride on decolorization was studied and optimized using Response Surface Methodology (RSM). Maximum decolorization of 94.5% and 90.7% for RO-16 and RR-35 was obtained at optimum concentrations of dye, glucose and ammonium chloride i.e., 0.66, 17.50 and 2.69 g/L for RO-16 and 0.68, 16.67 and 2.13 g/L for RR-35, respectively.

Biofiltration is an aerobic degradation process in which a well-humidified contaminated air stream is passed through a porous packed medium that supports a thriving population of microbes. The removal of benzene vapor was investigated in a laboratory-scale biofilter packed with compost, inoculated with a mixed microbial consortium. This biofilter was operated continuously in six different phases for a period of 8 months at different flow rates, 0.024–0.144 m3 h−1 with benzene concentrations ranging up to 1.7 g m−3. Under steady-state conditions, the removal efficiencies (REs) in the biofilter was consistently greater than 78% when benzene loading was less than 20 g m−3 h−1. The maximum elimination capacity (EC) achieved in this study is 64 g m−3 h−1 at an inlet loading rate of 128 g m−3 h−1. The response of the biofilter to shutdown, restart operations and fluctuations in inlet concentration, and flow rate was determined by subjecting the biofilter to inlet loads of up to 120 g m−3 h−1. The biofilter responded effectively to these loading conditions and was found to recover rapidly. The results from this study suggest that a compost biofilter is effective in treating benzene vapor under steady- and transient-conditions.

Biological treatment systems such as biofilters offer a potential alternative to the existing physicochemical techniques for the removal of volatile organic compounds from gaseous emissions. In this experimental work, continuous phase biofiltration of xylene vapors were performed in a laboratory scale compost biofilter that was inoculated with a xylene-acclimatized consortium. The performance was assessed by continuously monitoring the removal efficiency (RE) and elimination capacity (EC) of the biofilter at loading rates varying between 2–220 g m−3 h−1. The steady-state removal efficiencies were maintained between 60% and 90% up to a loading rate of 80 g m−3 h−1. The removal efficiency decreased significantly at loading rates higher than 100 g m−3 h−1. The pressure drop values were consistently less and insignificant in affecting the performance of the system. The present study also focuses in evaluating the stability of biofilter during shut down, restart, and shock-loading operations. An immediate restoration of biological activity after few days of starvation indicated their capability to handle discontinuous treatment situations which is more common to industrial biofilters. The sensitiveness of the biofilm to withstand shock loads was tested by abruptly increasing/decreasing the loading rates between 9–55 g m−3 h−1, where, removal efficiencies between 60–90% were achieved. These results prove the resilience of the biomass and the stability of the compost biofilter. Anew, results from kinetic analysis reveal that, steady-state xylene removal in the biofilter can be adequately represented by Michaelis–Menten type kinetics, and the kinetic constants namely, ECmax (120.4 g m−3 h−1) and K s (2.21 g m−3) were obtained.

Biofiltration is fast emerging as a feasible option for treating odorous compounds and other volatile organic compounds (VOCs) from process waste - gas streams using microorganisms attached to porous support matrix. Compost, owing to its inherent physico-chemical and biological characteristics, has shown to be a promising filter material in biofiltration to treat both hydrophobic and hydrophilic gas phase VOCs at low concentrations and high gas flow rates. This study aimed at evaluating the potential of a laboratory-scale biofilter, inoculated with mixed culture, to remove gas-phase xylene from a synthetic waste gas stream. The performance of the biofilter was studied by varying the flow rate from 0.024 to 0.072 m(3)/h, corresponding to empty bed residence times varying between 0.81 - 2.45 min and by changing the inlet loading rates (ILR) between 3.5 to 208 g/m(3).h. Removal efficiencies higher than 68% were achieved for xylene loading rates lesser than 60 g/m(3).h. However, due to the hydrophobic nature of the pollutant, xylene, that hinders mass transfer, and/or substrate inhibition to the microorganisms, a significant reduction in the removal efficiency was observed at high xylene concentrations. The results demonstrate the potential of compost biofilter to handle microorganism- tolerable xylene loads under steady-state conditions.

Biofiltration of process waste–gas streams using microorganisms attached to porous support matrix, at low concentrations and high gas flow rates, has gained importance as a versatile treatment technology ever since the Clean Air Act Amendments (1990), by the US – EPA came into existence. In this study, we evaluated the potential of a laboratory–scale biofilter, inoculated with mixed culture, to remove gas–phase benzene from a synthetic waste gas stream. Experiments were conducted in three different phases, after the acclimatization step, corresponding to empty bed residence times (EBRT) varying between 0.81–2.45 min and benzene concentrations up to 1.7 g/m3. At high concentrations, significant reduction in removal efficiency was observed, which may be due to insufficient biomass in the filter bed to utilize the substrate, or due to substrate inhibition at high concentrations. Removal efficiencies higher than 90% were achieved for inlet benzene loading rates lesser than 40 g/m3hr.

Anaerobic treatment systems have been used widely for treating wastewater arising from agro processing industries. The typical treatment systems include; up-flow anaerobic sludge blanket reactor (UASB), anaerobic digester, fixed film reactor, anaerobic fluidized bed reactor and anaerobic baffled reactor. In this work, studies were carried out in an up-flow anoxic bioreactor using synthetic fertilizer wastewater for evaluating the denitrification efficiency using ethanol and topioca starch as carbon sources.

Laboratory scale studies were conducted in an up-flow anoxic bioreactor using synthetic fertilizer wastewater for ascertaining the denitrification efficiency. The performance of the reactor was compared using ethanol and topioca starch as the carbon source. The initial No3-N concentrations (50–250 mg/L) and hydraulic retention time (FTRT, 12–24 h) were varied to evaluate the COD and No3-N removal. The results from this study shows that ethanol gave very good denitrification efficiency (78–98%) compared to topioca starch (68–96%).

Hydrodynamics of 3-phase inverse fluidized bed is studied experimentally using low density particles for different liquid and gas velocities. The hydrodynamic characteristics studied include pressure drop, minimum liquid and gas fluidization velocities and phase holdups. The minimum liquid fluidization velocity determined using the bed pressure gradient, decreases with increase in gas velocity. The axial profiles of phase holdups shows that the liquid holdup increases along the bed height, whereas the solid holdup decreases down the bed. However, the gas holdup is almost uniform in the bed.

A monitoring program for particulate matter pollution was designed and implemented in six Asian cities/metropolitan regions including Bandung, Bangkok, Beijing, Chennai, Manila, and Hanoi, within the framework of the Asian regional air pollution research network (AIRPET), coordinated by the Asian Institute of Technology. As uniform the methodologies as possible were intended with an established QA/QC procedure in order to produce reliable and comparable data by the network. The monsoon effects and seasonal changes in the sources/activities require long-term monitoring to understand the nature of air pollution in the cities. During phase 1 (2001–2004) of the AIRPET around 3000 fine and coarse particulate matter samples were collected from characteristic urban sites, which provide insight into temporal and spatial variations of PM in the cities. In all six cities, the levels of PM10 and PM2.5 were found high, especially during the dry season, which frequently exceeded the corresponding 24h US EPA standards at a number of sites. The average concentrations of PM2.5 and PM10 in the cities ranged, respectively, 44–168 and 54–262μgm−3 in the dry season, and 18–104 and 33–180μgm−3 in the wet season. Spatial and temporal distribution of PM in each city, the ratios of PM2.5 to PM10, and the reconstructed mass were presented which provide useful information on possible PM sources in the cities. The findings help to understand the nature of particulate matter air pollution problems in the selected cities/metropolitan regions.

Biofiltration is a versatile waste gas and odour treatment technology that has gained much acceptance in recent years to treat Volatile Organic Compounds (VOCs). A compost-based biofilter unit inoculated with a mixed microbial population was examined to treat toluene vapours from a synthetic and real gas stream. This biofilter was operated continuously for a period of 8 months at different flow rates, 0.024–0.144m3h−1, with toluene concentrations ranging up to 2.3gm−3. Removal efficiencies ranging from 40 to 95% and elimination capacities ranging from 3.5 to 128gm−3h−1 were observed depending on the initial loading rates. The dynamic behaviour of the biofilter was evident from the changes in the process conditions. The stability of the biomass was evident from the fast response of the biofilter to intermittent shut down and restart operations. The potential of the biofilter to handle industrial gas mixtures was proved with operation using a real sample from a pharmaceutical industry. Removal efficiencies of 60–90% for toluene and 60–80% for benzene from the gas mixture were achieved.

The starch manufacturing industrial units, such as sago mills,both in medium and large scale, suffer from inadequate treatment and disposal problems due to high concentration of suspended solids present in the sludge. A laboratory scale study was conducted to investigate the viability of anaerobic treatment of sago waste sludge, enriched in particulate organicmatter, using a fluidized bed reactor. The start-up of the reactor was carried out using a mixture of digested supernatantsewage sludge and cow dung slurry in different proportions. The effect of operating variables such as COD of the effluent, bed expansion, minimum fluidization velocity on efficiency oftreatment and recovery of biogas was investigated. The maximum efficiency of treatment was found to be 82% and the nitrogen enriched digested sludge was recommended for agricultural use. A kinetic model was developed for the degradation of particulate organic matter using the general kinetic equation [dS/dt = KHC SXC] which allowed for a more accurate mathematical representation of the hydrolysis process. Analysing data from a series of batch tests, the best fit value of C was found to be in the range 0.43 to 0.62.