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Hydrodynamic Treatment of Wastewater Effluent Flocs for Improved Disinfection
Author(s) -
Gibson J.,
Droppo I.G.,
Farnood R.,
Mahendran B.,
Seto P.,
Liss S.N.
Publication year - 2012
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143012x13347678384567
Subject(s) - breakage , effluent , wastewater , flocculation , cavitation , particle (ecology) , sewage treatment , environmental engineering , water treatment , chemistry , pulp and paper industry , environmental science , materials science , composite material , geology , mechanics , oceanography , physics , engineering
Hydrodynamic forces generated by an orifice plate under low pressure were examined as a means of disrupting flocs, in order to improve disinfection of treated wastewater effluents. Changes in cavitation conditions were found to have little impact on the extent of particle breakage in this experimental setup. The rate of strain (flow rate divided by the hole radius cubed), however, was found to be the best predictor of floc breakage. Floc breakage was not affected by changes in floc concentration, but was very sensitive to differences between flocs collected from different sources. Larger flocs (90 to 106 µm) were broken apart to a greater extent than smaller ones (53 to 63 µm). Hydrodynamic treatment decreased the viability of bacteria associated with large flocs, and also increased the ultraviolet dose response by up to one log unit (i.e., a factor of ten). Subjecting final effluent wastewaters to hydrodynamic treatment, therefore, provides a treatment strategy for conditions in which the presence of flocs limits the level of disinfection that can be achieved.