TITLE:
Sludge Density Prediction in a Wastewater Chemical Coagulation Process
AUTHORS:
Margarita Teutli-León, María Elena Pérez-López
KEYWORDS:
Coagulant; Flocculant; Wastewater Treatment; Sludge Density
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.5 No.7A,
July
18,
2013
ABSTRACT:
This paper reports an approach to estimate the sludge
density in a physicochemical treatment of municipal wastewater, experiments
considered 4 coagulants (aluminum sulfate SAl, iron sulfate SFe, aluminum
polychloride PAX, iron polychloride PIX), and 2 flocculant products (cationic
CP and anionic AP polymers). Experimental approach is based on running a set of
jar tests at different coagulant concentrations. After the stirring and resting
times took place, pH and conductivity were registered finding that SAl and SFe
either with or without polymers are the coagulants producing the higher pH
drop. Conductivity measures also establish two kind of data since higher
conductivity (about 2000 ) was observed for SAl, and
PIX, PIX + CP, PIX + AP; otherwise a conductivity about 1300 was observed for SAl + PC, SFe and PAX alone and with CP or AP.
Settleable solids (SST) determined with an Imhoff cone were similar for
sulfates and polychlorides, but dry sludge (DS) clearly set up two groups the
one with higher sludge content corresponds to sulfates group. The quotient of
DS divided by the SST provided an estimation of the apparent sludge density, in this way it was observed that higher densities
were obtained for sludge from sulfates at lower coagulant concentrations; also
sludge from SFe was heavier than the one from SAl. Otherwise, polychlorides produced a lighter sludge in respect to the one obtained with
sulfates, and between them the PIX
coagulant provided a heavier sludge than the PAX coagulant.