Effect of compost utilization on landfill management of organic waste contaminated with lead

Abstract

To study the impact of lead on degradation of organic wastes under anaerobic condition and the use of compost as daily cover to reduce lead impact. Four laboratory-scale simulating landfill bioreactors were set up: 1) Synthetic organic wastes as control reactor; 2) Organic wastes spiked with lead during acid phase; 3) Organic wastes with compost as top cover and bottom liner with lead spiked during acid phase; 4) Organic wastes with compost as top cover and bottom cover liner. Aerobic compost was operated for 21 days for the use as top cover and bottom liner in anaerobic simulated bioreactors 3 and 4 while reactor 1 and reactor 2 were loaded only synthetic organic wastes. Anaerobic bioreactors were operated for 125 days with daily leachate recirculation and buffer neutralization since day 81. Lead was spiked in reactor 2 and reactor 3 on day 42 considered the most acidic condition with the most leaching out of lead that equals to 201 mg/l. The results showed that lead was toxic and not suitable for the growth of microorganisms during digestion and the retardation on stabilization process could be observed as indication from the lowest cumulative methane gas that equaled to 631 ml in reactor 2 including the observation of other indications from leachate and gas parameters in reactor 2 while the use of compost could reduce the impact of lead inhibition on landfill stabilization process as indication from less concentration of lead leaching during acid phase which gave the least concentration of 12 mg/l on day 75 including the observation of other parameters from leachate and gas in reactor 3. Moreover, compost use did not retard the stabilization process since cumulative methane production that equaled to 1497 ml, biogas production that equaled to 43695 ml and leachate nutrients in reactor 4 were higher than those from reactor 1(control reactor) which had 1230 ml cumulative methane gas and 34203 ml cumulative biogas production, respectively.