Anaerobic digestion and dewatering characteristics of mechanically disintegrated excess sludge

Abstract

Mechanical cell disintegration and its influence on anaerobic digestion was investigated using four different methods. Methods to describe the degree of cell-disruption were developed and the release of organic components into the sludge water was measured. The best results were optained using a stirred ball mill and a high-pressure homogenizer. The influence of disintegration rate and digestion time on the performance of the anaerobic process and the dewatering characteristics were investigated. The degradation is accelerated and the digestion time can be reduced, especially when using immobilised microorganisms. It could be shown that the mechanical disintegration results in a disruption of particle structure and an increase of polymer-demand. As a result of better anaerobic degradation the density and dewatering results of disintegrated sludges are improved in comparison to non-treated sludges.

Anaerobic treatment of activated sludge from Swedish pulp and paper mills – biogas production potential and limitations

“…The dewatering of the activated sludge was improved by digestion, which is in agreement with observations by Kopp et al [29] and Xu et al [30]. The latter demonstrated a correlation between sludge dewaterability and molecular weight of the sludge compounds.…”

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.…”

Ultrasonic treatment of waste activated sludge

“…Ultrasonics and other treatments were described in Chiu et al [9] and Kopp et al [23]. Purely mechanical effects (pressure homogenization, ball mill, etc.)…”