Treatment of thermophilic hydrolysis reactor effluent with ceramic microfiltration membranes

Abstract

For an undisturbed operation of two-stage high-pressure fermentation up to 100 bar, a particle-free hydrolysate appears to be necessary. This is even more important if the second stage, i.e., the methane reactor, is designed as fixed bed. Here, we present the potential of microfiltration membranes as separation unit after the first stage, which is the hydrolysis. The study included the selection of membrane material, membrane performance investigations, and long-term-behavior during the filtration period. In a series of experiments, the optimum type of membrane material and the mode of operation [either crossflow (CF) or submerged (S)] were determined. Ceramic membranes proved to be the better option to treat the process stream due to their chemical and temperature resistance. The crossflow filtration achieved a sustainable flux of up to 33 L/(m h), while long-term experiments with the submerged membranes confirmed a critical flux of 7 L/(m h). Comparative analyses of hydrolysate and permeate showed that the rejected chemical oxygen demand (COD) as well as total organic carbon (TOC) fraction and thereby the loss of organic carbon in the permeate does not reduce the methane yield.

Removal of Diverse and Abundant ARGs by MF-NF Process from Pig Manure and Digestate

“…Membrane filtration processes, including MF to RO, have been applied as effective processes to remove ARGs from pig wastewater and digestate in recent years [ 30 , 35 , 83 ]. MF is widely used as a solid–liquid separation process for manure and digestate treatment [ 31 , 32 ]. Therefore, in this study, MF of raw pig manure and digestate was initially used to remove suspended solids from it.…”

“…Membrane filtration processes are also heavily applied as a manure and digestate treatment process. Microfiltration is reported in multiple articles to be used as an effective solid–liquid separator of manure and digestate [ 31 , 32 ], where both fractions have the potential to further be processed to generate bio-fertilizers [ 33 ]. However, ARG removal efficiency by MF is poor and limited mostly to the intracellular ARGs [ 29 , 34 , 35 ].…”

Treatment of hydrothermal liquefaction wastewater with ultrafiltration and air stripping for oil and particle removal and ammonia recovery

“…The data were recorded for every 20 s and the calculations were based on the average value of TMP and permeate flux for every 30 min. Two approaches to determine the mean critical flux value were used, (1) calculating the fouling rate (dTMP/dt) as well as (2) the average TMP for a certain flux [27].…”