Measurement of chemical sludge floc density and implications related to sludge dewatering

Abstract

An isopyenic centrifugation procedure was developed for estimating the characteristic floe density present in several chemical sludges. Issues addressed included selection of a low osmotic pressure gradient medium; selection of appropriate centrifugal acceleration and time values for testing; viscosity effects; and need for temperature control. Increases in sludge floe density were predictive of an increase in cake solids concentration following mechanical dewatering. Most sludge water removal during dewatering was hypothesized to be external to the floe structure. Water Environ. Res., 65, 735 (1993).

Dynamic multidimensional modelling of submerged membrane bioreactor fouling

“…The value of P a is sludge specific as sludge cake compressibility can vary with floc size, sludge type, sludge conditioning, operating temperature and pH [13,24,28,29]. Therefore, P a was estimated via parameter estimation during model calibration using a non-linear least squares parameter estimation method (Levenberg-Marquardt algorithm) with TMP as fitted output and residual sum of squares (J)…”

Waste activated sludge dewaterability: comparative evaluation of sludge derived from CAS and MBR systems

“…Indeed, after the solid-liquid separation by sedimentation or filtration operation, an additional separation is required to achieve a reduction in sludge volume to facilitate transport and handling operations [1]. Sludge dewatering, recognized as one of the most complex and expensive operation involved in wastewater treatment cycle [1][2][3][4][5], requires significant technical as well as economical efforts [6]. As a matter of a fact, 1t of fresh sludge to be disposed is composed, on average, by 0.25-0.30t of suspended solids (SS), with a cost for treatment and disposal around €280-470/t [7].…”

“…A better understanding of sludge dewatering features, could lead to an improvement in pretreatment approaches focused to enhance the dewaterability efficiency [6]. In detail, Vesilind et al [8] have defined four different types of water contained in sludge: free [1][2][3][4][5][6][7][8][9] www.deswater.com doi: 10.1080/19443994.2016.1180478 water, interstitial water, vicinal water, and water of hydratation. More in detail, free water can be easily separated by gravitational settling; interstitial water separation can be achieved only by mechanical dewatering devices, such as centrifugation or vacuum filtration; vicinal water, physically bound to solid particles surface, cannot be separated by any mechanical device.…”

Application of Enteromorpha as a new kind of coagulant aid in municipal sludge treatment

“…Wastewater treatment processes produce large amounts of sludge, which commonly contains over 90% water [1], and has been addressed as an environmental issue for the past decades [2,3]. Sludge handling and disposal treatments account for up to 50% of total wastewater treatment costs for large plants [4].…”