A new method for assessment of the sludge disintegration degree with the use of differential centrifugal sedimentation

Abstract

A novel method for assessing the disintegration degree (DD) of waste activated sludge (WAS) with the use of differential centrifugal sedimentation method (DCS) was shown herein. The method was validated for a WAS sample at four levels of disintegration in the range of 14.4-82.6% corresponding to the median particle size range of 8.5-1.6 µm. From the several sludge disintegration methods used (i.e. microwave, alkalization, ultrasounds and peroxydisulfate activated by ultrasounds), the activated peroxydisulfate disintegration resulted in the greatest DD 83% and the smallest median particle size of WAS. Particle size distribution of pretreated sludge, measured by DCS, was in a negative correlation with the DD, determined from soluble chemical oxygen demand (SCOD; determination coefficient of 0.995). Based on the obtained results, it may be concluded that the DCS analysis can approximate the WAS disintegration degree.

Disintegration of Wastewater Activated Sludge (WAS) for Improved Biogas Production

“…The often used alkaline reagents are NaOH [67], Ca(OH) 2 [68] and KOH [68]. Alkali pre-treatment can solubilize the cell membranes, releasing the intracellular matter from the cells in solution, which becomes available for the fermentation process.…”

The Effect of Static Magnetic Field on Methanogenesis in the Anaerobic Digestion of Municipal Sewage Sludge

“…[18,19]. There are several pretreatment methods, including for example: mechanical method [20]; high-pressure method [21]; microwave pretreatment [22]; ultrasound energy pretreatment [23]; thermal methods, including heat treatment and freezing/defrosting [24], or low-temperature disintegration [25]; chemical methods, including acidification [26], alkalization [27], ozonation [28], and oxidation technique [29]; as well as biological methods [30]. Coupled disintegration methods, called the hybrid methods, are employed as well [31].…”

Microwave and Ultrasound Based Methods in Sludge Treatment: A Review

“…The estimation of WAS disintegration degree is generally based upon the values of SCOD, STOC and STN, as suggested by Ren et al [14]. From an experimental point of view, there are some novel methods for the assessment of sludge DD, for example, differential centrifugal sedimentation [15].…”

“…This means that the environment becomes hypotonic, which causes the turgor pressure in the microbial cells to increase to an extent the cell can no longer sustain, and, therefore, its cell wall breaks down [14]. By using an alkaline treatment, the biodegradability of the sludge can be significantly increased, as it induces the swelling of particulate organics, making them more accessible to enzymes [15]. Alkaline treatment can also enhance the solubilisation of COD; Kim et al determined that by adding NaOH in a dosage of 5-21 g/L, approximately 40% of COD solubilisation of sludge can be achieved [18].…”