Enhanced anaerobic degradation of mechanically disintegrated sludge

Abstract

Mechanical disintegration - wet milling - was chosen to physically disrupt cellular material. By breaking up microbial or plant cell walls intracellular carbon sources as well as nutrients are made available for further anaerobic digestion. Ball milling consistently showed better disintegration results than high speed cutter milling. With respect to solubilisation of COD a high degree of cell disruption could be achieved in a variety of aerobic and anaerobic sewage sludges, where the fraction of soluble COD could be changed from 1–5% in original sludges to up to 47% after wet milling. In distillery slops and brewery residues milling failed to enhance soluble COD significantly. Anaerobic digestion testing showed a good digestability of the solubilized intracellular material and consistently enhanced overall COD-degradation of the sludges by a factor of 1.2–1.5. Net biogas production was enhanced in the same order of magnitude. Stabilised sludges showed a higher beneficial effect of wet milling than raw excess sludge.

A Review on Enhancement of Biogas Yield by Pre-treatment and addition of Additives

“…Lack of available literatures on mechanical pre-treatment, the methods mentioned above is not comprehensive. However, it's seen that their efficiency of improving anaerobic digestion of waste activated sludge is rather lower than other methods [14].…”

Minimization of excess sludge production for biological wastewater treatment

“…The rate-limiting step of lysis-cryptic growth is the lysis stage, and an increase of the lysis efficiency can therefore lead to an overall reduction of sludge production. Several methods have been applied for sludge disintegration so far: (i) thermal treatment in the temperature range from 40 C to 180 C [10,11], (ii) chemical treatment using acids or alkali [12], (iii) mechanical disintegration using ultrasounds, mills, and homogenizers [13][14][15][16][17][18][19][20], (iv) freezing and thawing [21], (v) biological hydrolysis with enzyme addition [22], (vi) advanced oxidation processes such as wet air oxidation, using H 2 O 2 and ozone [23][24][25][26], and (vii) combination ways such as thermo-chemical treatment [27][28][29], combination of alkaline and ultrasonic treatment [30]. But the comparison and evaluation of these processes for sludge lysis is not considered in this paper.…”

Optimization and microbial community analysis of anaerobic co-digestion of food waste and sewage sludge based on microwave pretreatment

“…Thus, the anaerobic codigestion of FW and SS became increasingly popular, with the advantage of adjusting the C/N ratio, increasing the methane yields, diluting harmful substances, and also mediating the hydrolysis of FW and SS (Kawai et al, 2014;Lee et al, 2009;Yong et al, 2015). Cell wall disruption or destruction is considered as an effective way of enhancing AD efficiency of SS which is mainly composed of microbial cells within an extra-cellular polymeric floc matrix (Baier and Schmidheiny, 1997), because hydrolysis was enhanced through SS pretreatment by releasing the intracellular organics that were easily biodegraded. Microwave pretreatment (MW) of SS (MW-SS) was widely investigated to enhance the AD efficiency of SS, and volatile solids (VS) removal, methane production and AD stabilization were improved (Coelho et al, 2011).…”