Sequential extraction of heavy metals during composting of sewage sludge

Composting sewage sludge with green waste from tree pruning

“…Also, the EPA 3051 uses only concentrated nitric acid, or alternatively, concentrated nitric acid and concentrated hydrochloric acid, leading to a pseudo-total content and not the total content. Amir et al (2005) found a reduction in the overall levels of Zn, Pb, and Cu in compost, the amount of potentially bioavailable metals was less than 2 %, because metals were in more stable forms bound to humic substances present in compost.…”

“…In the sludge, 60 % of total N was found in organic form and 40 % in mineral form (N-NO 3 -+ N-NH 4 + ), while for the compost of both piles, the distribution was 20 % in mineral form and 80 % in organic form. Amir et al (2005) and Corrêa et al (2006) indicated that the mineral-N released during organic matter decomposition was immobilised in organic forms of slow release into the soil, thereby reducing the risks of contamination of the groundwater with nitrates.…”

Biomass of Fish By-Products as a Component of Compost for Agricultural Use

“…The mineralization of organic substances and decrease in the pH of the environment may be accompanied by the release of mobile forms of metals which, upon having undergone biosorption, can create organic complexes with newly created humic substances [18]. Values of pH between 6.7 and 9.0 ensure a proper course of microbiological processes, whereas optimal pH falls into the range of 5.5 to 8.0 [19].…”

Aplicação do método de mineralização de nitrogênio com lixiviação para solo tratado com lodo de esgoto e composto orgânico

“…Ao mesmo tempo, o processo de compostagem propicia um produto com melhores características físicas, facilitando sua aplicação ao solo, bem como nutricionais Amir et al, 2005), além de aumentar o pool de matéria orgânica do solo, pela incorporação de substâncias húmicas de difícil degradação, mesmo em solos sob condições tropicais . Por sua vez, o uso de resíduo vegetal oriundo da poda de árvore urbana como material estruturante no processo de compostagem com o lodo destina adequadamente o enorme volume gerado, que sobrecarrega aterros sanitários e ao mesmo tempo gera um composto orgânico enriquecido em substâncias húmicas (D´Orazio et al, 2005), originárias de seu conteúdo em lignina.…”