Compost Microbiologically Controlled (CMC) has proved to be a viable process to manufacture compost from sewage sludge previously treated with fly ash from biomass plants to reduce its heavy metals’ and organic contaminants´ content.

<p style="text-align: justify;"> A total decontamination level of pathogens was achieved, according the microbiological requirements of Spanish law (absence of Salmonella and E. coli). The compost obtained meets the legal criteria for this organic fertilizer in terms of nutrients composition: Humidity &lt; 40%, Total Organic Matter &gt;35%, and C/N &lt; 20.</p> <p style="text-align: justify;"> The fertilizer manufactured was A Class quality (the best), regarding its level of heavy metals, lowest than the minimum level established in RD 506/2013 for fertilizing products coming from Sewage Sludge from Waste Water Treatment Plants (WWTP). Its germination capacity was excellent, with absence of weeds.</p> <p style="text-align: justify;"> The compost was applied as base fertilizer, at 2 t/ha dose, in a corn trial developed in CTAEX experimental farm.</p> <p style="text-align: center;"> &nbsp;</p> <p style="text-align: center;"> <img alt="" src="https://www.ctaex.com/icirbus/ficheros/imagenes/2018_01/17-03-compost-final2.jpg" style="width: 306px; height: 234px;" /></p>