Development of Anaerobic High-Rate Reactors, Focusing on Sludge Bed Technology

Abstract

In the last 40 years, anaerobic sludge bed reactor technology has evolved from localized laboratory-scale trials to worldwide successful implementations in a variety of industries. High-rate sludge bed reactors are characterized by a very small footprint and high applicable volumetric loading rates. Best performances are obtained when the sludge bed consists of highly active and well settleable granular sludge. Sludge granulation provides a rich microbial diversity, high biomass concentration, high solids retention time, good settling characteristics, reduction in both operation costs and reactor volume, and high tolerance to inhibitors and temperature changes. However, sludge granulation cannot be guaranteed on every type of industrial wastewater. Especially in the last two decades, various types of high-rate anaerobic reactor configurations have been developed that are less dependent on the presence of granular sludge, and many of them are currently successfully used for the treatment of various kinds of industrial wastewaters worldwide. This study discusses the evolution of anaerobic sludge bed technology for the treatment of industrial wastewaters in the last four decades, focusing on granular sludge bed systems.

Geobacter Dominates the Inner Layers of a Stratified Biofilm on a Fluidized Anode During Brewery Wastewater Treatment

“…However, for developing a scalable prototype, each of the elements of design (the electrode material and active surface, distance between anode and cathode, recirculating flow, bed quantity, particle size or pH-control) should be properly studied and optimized. To compete on a commercial scale with high-rate anaerobic reactor configurations, such as UASB (Upflow Anaerobic Sludge Blanket), EGSB (Expanded Granular Sludge Bed), or fluidized bed configurations, which can already treat up to 40 kg-COD m -3 NRV d -1 ( van Lier et al, 2016 ), the OLRs in the ME-FBR should be considerably enhanced. However, under this scenario METs so far face the problem of low electron recovery efficiencies.…”

Anaerobes in Industrial- and Environmental Biotechnology

“…With this transition came several interesting challenges for improvement in productivity by, e.g., optimization of the substrate feed and possibilities to use better process monitoring and control to achieve high volumetric organic loading rates. High-rate anaerobic reactors such as UASB, Expanded Granular Sludge Bed (EGSB), anaerobic filter, anaerobic sequencing batch reactor (ASBR) and FBR can provide loading rates of 10-40 kg COD/m 3 day [8,112,113]. Such systems are characterized by high solids retention time caused by biomass immobilization or granulation, and can operate under high hydraulic retention times without any fear of biomass washout [112].…”

“…They have also been used for the production of chemicals including solvents, organic acids [6], vitamins, and pharmaceutical products [7]. An area of great importance where anaerobes have made enormous impact is that of environmental remediation wherein their metabolic diversity in transforming a range of organic and inorganic compounds is utilized for treatment of solid and liquid municipal and industrial waste streams [8].…”

“…The main limitation, however, is their low growth rate and hence long process times caused by the limited amount of energy generated in the absence of O 2 . Hence process intensification by, for example, implementing approaches for maintaining high cell density, good mass transfer, and removal of product inhibition is needed to develop efficient processes [6,8].…”