Enhanced anaerobic biodegradability and inactivation of fecal coliforms and Salmonella spp. in wastewater sludge by using microwaves.
During continuous operation of three mesophilic-anaerobic digesters, the effect of microwave irradiation, as sludge thermal pretreatment (60 to 65 degrees C), was studied. The fecal coliforms log inactivation for microwaved/digested sludge was 4.2 +/- 0.4, whereas for conventionally heated/digested sludge and control were 2.9 +/- 0.5 and 1.5 +/- 0.5, respectively. In the case of Salmonella spp., no colonies were detected in 85% of the microwaved/digested samples. Considering the detection limit, the log inactivation of these samples was greater than 2.0 +/- 0.3. The conventionally heated/digested sludge and control showed log inactivations of 1.9 +/- 0.2 and 1.1 +/- 0.3, respectively. At the 95% confidence level, microwaved/digested sludge increased the biogas production by 16.4 +/- 5.6% and 6.3 +/- 2.4%, as compared to control and conventionally heated/digested sludge, respectively. When thermally treated sludge was analyzed for soluble chemical oxygen demand, microwaved waste-activated sludge showed considerable solubilization between 37 and 60 degrees C. Microwaved/digested sludge showed a reduction of capillary suction times by 11.1 +/- 5.9% and 10.7 +/- 5.6%, as compared to control and conventionally heated/digested sludge, respectively.
Pino-Jelcic
Sergio A
SA
U.S. Filter, Envirex Products, Waukesha, Wisconsin, USA.
Hong
Seung Mo
SM
Park
Jae K
JK
D000693:Anaerobiosis; D015169:Colony Count, Microbial; D004755:Enterobacteriaceae / Q000254:growth & development* / Q000472:pathogenicity; D005243:Feces / Q000382:microbiology; D008872:Microwaves; D012475:Salmonella / Q000254:growth & development* / Q000472:pathogenicity; D012722:Sewage / Q000382:microbiology; D013696:Temperature; D018505:Waste Management / Q000379:methods*; D018508:Water Purification / Q000379:methods*
D012722:Sewage