Oxygen uptake rate inhibition with PACT sludge.
Oxygen uptake rate (OUR) experiments were performed with sludge from six laboratory-scale, continuously fed, activated sludge and PACT reactors (sludge ages of 4-, 8-, and 12-days) to evaluate the sludge's resistance to inhibitory compounds. Three inhibitory compounds with varied ability to sorb on activated carbon were tested: 3,5-dichlorophenol (3,5-DCP, strongly adsorbed), phenol (moderately adsorbed), and zinc (poorly adsorbed). The inhibitory compound concentration that reduced the unacclimated sludge's specific oxygen uptake 50% from its maximum rate was determined (IC(50)). For the organic compounds, PACT sludge resisted acute inhibition better for all sludge ages; sorption studies indicate that phenol sorbed onto the PACT sludge could account for the IC(50) difference at the higher sludge ages. With 3,5-DCP, the 4- and 8-day-old PACT and activated sludge solids sorbed similar amounts of 3,5-DCP at concentrations near the IC(50) values, yet the PACT sludge exhibited higher IC(50) values; biomass differences may have accounted for the improved resistance to inhibition. With the poorly adsorbed zinc, no difference in IC(50) or sorption was noted with the 4-day-old sludge. For the 12-day-old sludge, the PACT sludge was much more resistant to zinc exposure, with changes in the biomass rather than sorption on carbon the apparent reason.
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Dodson-Stilson, 6121 Huntley Road, Columbus, OH 43229-1003, USA.
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D000327:Adsorption; D001673:Biodegradation, Environmental; D018533:Biomass; D002244:Carbon / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry; D003116:Color; D004785:Environmental Pollutants; D006256:Hazardous Waste; D006801:Humans; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D019800:Phenol / Q000737:chemistry; D015203:Reproducibility of Results; D012722:Sewage / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
D002733:Chlorophenols; D004785:Environmental Pollutants; D006256:Hazardous Waste; D012722:Sewage; D014867:Water; D002606:Charcoal; D019800:Phenol; D002244:Carbon; C116190:3,5-dichlorophenol; D015032:Zinc; D010100:Oxygen