Disinfection of sludge with high pathogenic content using silver and other compounds.
A physicochemical sludge with high microbial content (10(2)-10(4) FPU/g TS bacteriophages, 10(6)-10(7) MPN/g TS faecal coliforms, 10(4) MPN/g TS Salmonella spp., 10(4) MPN/g TS Shigella spp., 10(3) MPN/g TS Pseudomonas aeruginosa, 10(2) MPN/g TS Vibrio cholerae, 10(2)-10(3) cysts/g TS Giardia sp., 10(2)-10(4) oocyts/g TS Cryptosporidium sp., 168-215 viable helminth ova/g TS) was disinfected using silver, silver-copper, and silver-copper plus a synergistic agent (SA). Twenty milligrams Ag/g TS inactivated 4.8 log of faecal coliforms in 1 h; however, 40 mg Ag/g TS are needed to reduce helminth ova viability from 84 to 38.4% in the same period of time. Combinations of Ag-Cu (60:600 mg Ag-Cu/g TS) and Ag-SA (60:24 mg Ag-SA/g TS) inactivated 7.8 log of faecal coliforms and around 90% of helminth ova in 60 min. To produce USEPA class A biosolids, 10:100:8 and 5:50:13.3 mg Ag-Cu-SA/gTS are needed. Bacterial regrowth was not observed for all conditions producing <1000 MPN/gTS faecal coliforms, suggesting a residual disinfection effect. Recommended doses to produce class A biosolids inactivated 2-4 log of bacteriophages, 4 log of Salmonella spp., 4 log of Shigella spp., 3 log of Pseudomonas aeruginosa, 2 log of Vibrio cholerae, 87-99.9% of Giardia sp., and 75-99.9% of Cryptosporidium sp.
Aguilar
P
P
Engineering Institute, UNAM, Apdo. Postal 70-472, Ciudad Universitaria, 04510, DF Mexico.
Jiménez
B
B
Maya
C
C
Orta de Velasquez
T
T
Luna
V
V
D000818:Animals; D001419:Bacteria / Q000187:drug effects; D001435:Bacteriophages / Q000187:drug effects; D003300:Copper / Q000633:toxicity*; D003458:Cryptosporidium / Q000187:drug effects; D004203:Disinfection / Q000379:methods*; D005243:Feces / Q000382:microbiology / Q000469:parasitology; D005872:Giardia / Q000187:drug effects; D006376:Helminths; D010063:Ovum / Q000187:drug effects; D012722:Sewage / Q000382:microbiology / Q000469:parasitology; D012834:Silver / Q000633:toxicity*
D012722:Sewage; D012834:Silver; D003300:Copper