Modelling of a recycling sludge bed reactor using AQUASIM: reprint

Abstract

re-published with the correct list of authors, and, due to a change in the process name following the original publication of the article, it is herewith pointed out that the term "falling sludge bed reactor" is replaced with "recycling sludge bed reactor".Modelling of a recycling sludge bed reactor using AQUASIM AbstractThe recycling sludge bed reactor (RSBR) allows for increased solids retention time, resulting in greater substrate conversion for all particulate degradation and biological reactions. The purpose of the RSBR is to hydrolyse primary settled sewage (PSS). Soluble products are then used for the biological treatment of acid mine drainage. A mathematical model has been developed that describes the anaerobic digestion of PSS and biological sulphate reduction in the RSBR. The hydrodynamic processes taking place in the RSBR have been simulated using a system of mixed reactors connected by water flow and mass flux streams. Trends obtained from varying the hydraulic retention time, the sludge recycle ratio, and the feed COD: SO 4 2-ratio allow for identification of the critical biological processes taking place in the RSBR, as well as the influence of the operating parameters. Areas where there is a lack of understanding in the mechanism and kinetics have been identified, and these include the influence of sulphate reduction on the hydrolysis of particulate organic matter, as well as the mathematical influence of sulphide inhibition on the various biological groups. A sensitivity analysis shows that hydrolysis is the rate-limiting process, while sulphide inhibition is of importance when sulphate conversion increases.

The sulfur chain in biogas production from sulfate‐rich liquid substrates: a review on dynamic modeling with vinasse as model substrate

“…Kinetics of sulfate reduction processes have been considered in different ways. A dual term Monod type kinetic is commonly used (Equation ) to represent the bacterial growth rate (ρ growth ), with both concentrations: sulfate () as electron acceptor and the electron donor (S i ) (hydrogen or organic matter) following the equations of Table . The expression is generally written in the form of substrate uptake (ρ uptake ) by dividing the maximum specific growth rate (μ max ) by the yield of biomass on the substrate (μ max /Y = k m ) to obtain Equation .…”

“…In general, substrate competition in anaerobic systems has been modeled in most cases on three levels (I, II and III) (Fig. ) . Starting from the volatile fatty acids, butyrate and propionate sulfate reducing bacteria (bSRB and pSRB respectively) compete with acetogenic bacteria to form hydrogen sulfide, carbon dioxide, water and acetic acid (level I).…”

“…As an extension of ADM1, Fedorovich et al . included the modeling of sulfate reduction starting from previous work . Nevertheless, these models were developed and validated for substrates with different sulfate and organic matter content and hence, the best approach to model sulfate reduction in sulfate‐rich liquid substrates, such as sugar cane vinasse should be defined to predict H 2 S concentrations in biogas streams.…”

Modeling the anaerobic digestion of cane-molasses vinasse: Extension of the Anaerobic Digestion Model No. 1 (ADM1) with sulfate reduction for a very high strength and sulfate rich wastewater

“…Despite the fact that S h2s has been found to inhibit anaerobic digestion (Visser et al, 1996), S h2s,free was assumed to be inhibitory for modeling purposes Knobel and Lewis, 2002;Ristow et al, 2002). A non-competitive inhibition function for sulfides (I h2s,j ) was considered in all cases (Knobel and Lewis, 2002).…”

“…The simple approach of Batstone (2006) to model sulfate reduction as an extension of ADM1 has been used to model the anaerobic digestion of vinasse under dynamic conditions without success, exhibiting under prediction of H 2 S and over prediction of volatile fatty acids (Hinken et al, 2013). In order to extend ADM1, Fedorovich et al (2003) included the sulfate reduction process starting from previously reported work Knobel and Lewis, 2002;Ristow et al, 2002). The approach of Fedorovich et al (2003) can be considered as complex because of the inclusion of valerate/ butyrate, propionate, acetate and hydrogen in the sulfate degradation reactions (Batstone, 2006).…”