Improving the quality of organic compost of sewage sludge using grass cultivation followed by composting

• Published in: Journal of environmental management Vol. 314; p. 115076
• Main Authors: Cardoso, Paulo Henrique Silveira, Gonçalves, Paula Wellen Barbosa, Alves, Gustavo de Oliveira, Pegoraro, Rodinei Facco, Fernandes, Luiz Arnaldo, Frazão, Leidivan Almeida, Sampaio, Regynaldo Arruda
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.07.2022
• Subjects: Biodegradation; Biosolid; Composting; Lead; Metals, Heavy - chemistry; Organic fertilizer; Poaceae; Sewage - chemistry; Soil - chemistry; Waste recycling; Waste treatment; Biodegradation; Organic fertilizer; Waste treatment; Biosolid; Waste recycling
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.115076

Composting is one of the main processes of stabilization of sewage sludge and its association with cultivation in this residue has a great potential to produce stabilized organic fertilizer and, or substrate for plant development. The aim of this work was to evaluate the physical, chemical, and microbial attributes of sewage sludge (SS) aerated and cultivated with Pennisetum purpureum or Urochloa brizantha and, later, composted. The study was installed in a 2x2+2 factorial scheme, with four replications. The factors consisted of cultivation of P. purpureum or U. brizantha in SS for 90 days, with or without intermittent aeration for 60 days. The control treatments were SS without cultivation, with the presence or absence of aeration. After 90 days of cultivation, the grass was cut, crushed, and incorporated into the SS for composting for 60 days. The composted sewage sludge showed an increase of 26, 24, 17, 123, 19, 32, and 7.7% in the levels of P, Ca, Cu, Fe, Mn, Zn, and Pb; and a reduction of 22, 5.2, 26, 30, 8.8, and 70% in the levels of C, N, K, Mg, Ni, and Na, respectively. The levels of Cu, Ni, Zn, and Pb remained below the maximum limit allowed by environmental resolution. The degradation of SS decreased the particle diameter, increasing the bulk density and total porosity, improving the physical properties of the compost. The SS cultivation and composting, regardless of the grass, led to a reduction in pH, basal and accumulated respiration, nitrification index, and C/N ratio and an increase in the CEC/C ratio, showing adequate maturation of the compost produced. Thus, the SS cultivation and composting with grasses were effective for producing matured and quality organic compost with low risk of environmental contamination. [Display omitted] •Pennisetum purpureum and Urochloa brizantha were grown in sewage sludge (SS).•P. purpureum and U. brizantha biomass were crushed and used for SS composting.•Cultivation and composting improved SS physical, chemical, and microbial attributes.•There was an increase of 26, 17, 19, and 32% in the P, Cu, Mn, and Zn concentration.•Cultivation and composting of SS promoted greater maturation of the organic matter.