The existence of a biological equilibrium in a trickling filter for waste gas purification

Abstract

Clogging is a well-known phenomenon in the application of a biological trickling filter for both waste gas and wastewater treatment. Nevertheless, no such observations or even significant changes in pressure drop have ever been recorded during the long-term processing of a waste gas containing dichloromethane (DCM) as a sole carbon source. To obtain more information about this phenomenon, a detailed investigation into the carbon balance of this system has been performed. During a period of operation of about 200 days the rate of DCM elimination and the overall rate of CO, production in a continuously operating filter were therefore recorded daily, thus allowing an evaluation of the overall conversion process. Furthermore pseudo-steady-state measurements were carried out on a regular basis. These experiments reveal more detailed information on the actual DCM conversion by Hyphornicrobiurn GJ21 within the biofilm. The combined results of the experiments de-scribed in this article show that on an overall basis a so-called biological equilibrium, i.e., a situation of no net biomass accumulation, is obtained in the course of time. It appeared that the overall rate of CO, production slowly increased until, after some 200 days, it finally counterbalanced the conversion rate of DCM on a molar basis. As opposed to this result, all pseudo-steady-state experiments indicated that about 60% of the eliminated primary carbon source is converted into biomass. This is in good agreement with results from microkinetic experiments. Based on these results and evaluation of the experimental data, it is concluded that interactions between several microbial populations are involved in this biological equilibrium. These interactions include both biomass growth and biomass degradation.

Biomass accumulation and clogging in biotrickling filters for waste gas treatment. Evaluation of a dynamic model using dichloromethane as a model pollutant

“…The temperature of the injector, oven and detector were 120, 110, and 120°C, respectively. The liquid phase DCM and CO 2 concentrations were determined by the head-space method described by Diks et al (1994).…”

Removal of Low Concentrations of Carbon Tetrachloride in Compost-Based Biofilters Operated under Methanogenic Conditions

“…Increased biomass in biotrickling filters typically leads to efficient treatment at higher contaminant loading to the reactor, as has been demonstrated for dichloromethane. [17][18][19] Biotrickling filters also have been shown to better control pH and the buildup of toxic metabolites. 20 Inhibition of the methanogenic microbes by high CT concentrations was apparent during the initial attempt to establish contaminant flow to the biofilter.…”

A Fundamental Study of Biofiltration Processes for VOC Removal From Waste Gas Streams

“…Until now, only a few fundamental experimental studies were reported (Diks and Ottengraf 1991;Diks, Ottengraf, and Vrijland 1994;Hartmans and Tramper 1991;Johnson and Deshusses 1996;Kirchner, Schlacter, and Rehm 1989;and Kirchner, Kramer, and Rehm 1985;Kirchner, Wagner, and Rehm 1992). others (1989 and investigated the effects of VOC solubility and the oxygen diffusion rate on biofilter performance.…”

“…Periodic fluidization or backwashing was found to be an effective biomass management strategy for maintaining effective reactor efficiency and controlling headloss (Smith et al 1994 andSorial et al 1994b). Diks, Ottengraf, and Vrijland (1994) indicated that a biological equilibrium or no net biomass accumulation can be achieved after 200 days of operation in a trickling bed biofilter, which may be related to the establishment of a certain microbial population and the use of a high liquid recirculating rate. Others reported ways of preventing clogging that include the addition of high concentrations of salts (Diks, Ottengfraf, and Vrijland 1994) and nutrient limitation (Holubar, Andorfer, and Braun 1995).…”