Vermicomposting as an advanced biological treatment for industrial waste from the leather industry

Abstract

The leather industry (tanneries) generates high amounts of toxic wastes, including solid and liquid effluents that are rich in organic matter and mineral content. Vermicomposting was studied as an alternative method of treating the wastes from tanneries. Vermicompost was produced from the following tannery residues: tanned chips of wet-blue leather, sludge from a liquid residue treatment station, and a mixture of both. Five hundred earthworms (Eisenia fetida) were added to each barrel. During the following 135 days the following parameters were evaluated: pH, total organic carbon (TOC), organic matter (OM), cation exchange capacity (CEC), C:N ratio, and chromium content as Cr (III) and Cr (VI). The results for pH, TOC and OM contents showed decreases in their values during the composting process, whereas values for CEC and total nitrogen rose, indicating that the vermicompost reached maturity. For chromium, at 135 days, all values of Cr (VI) were below the detectable level. Therefore, the Cr (VI) content had probably been biologically transformed into Cr (III), confirming the use of this technique as an advanced biological treatment. The study reinforces the idea that vermicomposting could be introduced as an effective technology for the treatment of industrial tannery waste and the production of agricultural inputs.

Sustainable approach to biotransform industrial sludge into organic fertilizer via vermicomposting: a mini‐review

“…In addition, Nunes et al . reported that vermicomposting was able to reduce or eliminate the toxicity of industrial waste . On the other hand, most of the bioavailable portions of heavy metals could effectively be decreased by the vermicomposting process.…”

“…On the other hand, Nunes et al . employed vermicomposting on tannery sludge mixed with cattle manure and sawdust as bulking materials to obtain a more beneficial product . They observed decreases in pH, total organic carbon, C:N ratio and organic matter while the total nitrogen and cation exchange capacity increased at the end of the vermicomposting process.…”

Vermicompostagem como tecnologia aplicada à valorização e reaproveitamento dos resíduos de curtume: um estudo químico e agronômico com vistas à produção orgânica de pimentão em ambiente protegido

“…Estes insumos poderiam ser aplicados ao solo para a produção de plantas de interesse econômico, melhorando sua qualidade e respectiva produtividade (Nunes et al, 2016;Vig et al, 2011;Ramesh et al, 2006Ramesh et al, , 2009). …”

“…Assim, espera-se reduzi-lo ao seu estado trivalente, que é nutriente e desejável às práticas agrícolas e a nutrição -humana e vegetal -desde que em quantidade ótima (Nunes et al, 2016;Ramesh et al, 2009;Khan, 2001 …”

“…Mesmo assim, outros estudos utilizaram vermicompostos com composições química e nutricional distintas e, mesmo assim, apresentaram resultados satisfatórios (Nunes et al, 2016;Kenyangi e Blok, 2013;Vig et al, 2011;Kaur et al, 2010;Bachman e Metzger, 2008).…”