Composting domestic sewage sludge with natural zeolites in a rotary drum reactor.
This work aimed the influence of zeolites addition on a sludge-straw composting process using a pilot-scale rotary drum reactor. The type and concentration of three commercial natural zeolites were considered: a mordenite and two clinoptilolites (Klinolith and Zeocat). Mordenite caused the greatest carbon removal (58%), while the clinoptilolites halved losses of ammonium. All zeolites removed 100% of Ni, Cr, Pb, and significant amounts (more than 60%) of Cu, Zn and Hg. Zeocat displayed the greatest retention of ammonium and metals, and retention efficiencies increased as Zeocat concentration increased. The addition of 10% Zeocat produced compost compliant with Spanish regulations. Zeolites were separated from the final compost, and leaching studies suggested that zeolites leachates contained very low metals concentrations (<1 mg/kg). Thus, the final compost could be applied directly to soil, or metal-polluted zeolites could be separated from the compost prior to application. The different options have been discussed.
Institute for Chemical and Environmental Technology (ITQUIMA), Department of Chemical Engineering, University of Castilla-La Mancha, Ciudad Real 13071, Spain. Jose.Villasenor@uclm.es
J
J
Villaseñor
L
L
Rodríguez
F J
FJ
Fernández
D000641:Ammonia / Q000032:analysis; D000704:Analysis of Variance; D002244:Carbon / Q000032:analysis; D019216:Metals, Heavy / Q000302:isolation & purification; D009584:Nitrogen / Q000032:analysis; D010865:Pilot Projects; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012722:Sewage / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D013696:Temperature; D013997:Time Factors; D014835:Volatilization; D014867:Water; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*; D017641:Zeolites / Q000737:chemistry*
D019216:Metals, Heavy; D000644:Quaternary Ammonium Compounds; D012722:Sewage; D012987:Soil; D014874:Water Pollutants, Chemical; D014867:Water; D017641:Zeolites; D002244:Carbon; D000641:Ammonia; D009584:Nitrogen