Optimization Study of Municipal Sludge Conditioning, Filtering, and Expressing Dewatering by Partial Least Squares Regression

Abstract

The effect of different conditioner doses and different applied pressures on the dewaterability of municipal sludge during the filtration and expression stage was assessed using a series of experiments referred to as a uniform design. The relative importance of conditioner dose and applied pressure on the dewatering characteristics of municipal sludge was evaluated with a quadratic model using partial least squares (PLS) regression analysis. It was shown that the developed quadratic model was able to accurately predict the dewatering characteristics during the whole process. It was further shown that lime as a physical conditioner had the most significant impact on filtration rate, expression rate, cake dry solids content, net sludge solids yield, and total cycle time. Aluminum polychloride as the inorganic flocculant had a quite complex effect although not as significant as lime. Filtration pressure had only a slight effect on dewaterability of the municipal sludge, though higher feeding pressure was needed in order to enhance the total feeding amount. Furthermore, expression pressure was only of benefit to cake dry solids content and expression rate and failed to improve other dewatering characteristics of the municipal sludge.

Wet Oxidation as an Advanced and Sustainable Technology for Sludge Treatment and Management: Results from Research Activities and Industrial-Scale Experiences

“…[2] This global increase in sludge production has led to the recent development of studies aimed at finding new possibilities to reduce and optimize the amount of sludge disposal. [3][4][5] Currently, the main final sewage sludge disposal methods are agricultural use, landfilling, and incineration. With respect to the reference Sewage Sludge Directive (86=278=EEC), several countries have set more stringent limits for agricultural reuse in the case of different pollutants commonly detected in sludge, such as pathogens, heavy metals, and organic micropollutants.…”

“…In particular, WO allows to obtain, beyond a reduction in sludge volume, the stabilization of sludge and dissolved metals, the reduction of the microbial load, the partial or full mineralization of the sludge, and the absence of hazardous gaseous compounds. [5] WO is a chemical oxidation of dissolved or suspended compounds in wastewater or sludge at high temperatures and high pressures, during which the transformation of non-biodegradable and toxic organic compounds into CO 2 , water, and biodegradable compounds occurs. The high biodegradability of WO effluent is well known in the literature [7,8] and also confirmed by the applications of the WO effluent as a carbon source for the denitrification process [9] and as a substrate for biopolymers' production.…”

Characterization and sludge dewaterability evaluation of a chitosan‐based flocculant CMCTS‐g‐CPAM

“…CMCTS‐g‐CPAM with high intrinsic viscosity has long molecular chain length with good adsorption and bridging function, promoting the settlement of sludge (Liu et al , 2014). In addition, the CMCTS‐g‐CPAM molecules with a small amount of negatively charged carboxyl groups also can react with the positive charges exposed on the outside of the floccule particles to further form larger flocs and promote sedimentation (Feng et al , 2014). The effect of pH on the sedimentation of sludge is shown in Fig.…”

Establishment of the Permeability Model for Soft Solid Sludge Conditioned with Flocculants

“…On the basis of previous studies, dosages of CPAM, FC, and PAC were determined as 0–3, 0–140, and 0–120 mg/g, respectively (relative to dry solid mass in sludge). 14,41−43 The particle size and specific surface area of the sludge suspensions were measured by a laser particle size distribution analyzer (Bettersize 2000, China). Optical microscopy (Olympus, Japan) was used to observe and photograph sludge microscopic morphology was used to calculate sludge one-dimensional fractal dimension.…”