Helminth eggs inactivation efficiency by sludge co-composting under arid climates

Int J Environ Health Res. 2021 Jul;31(5):530-537. doi: 10.1080/09603123.2019.1671960. Epub 2019 Sep 26.

Abstract

Primary sludge (PS) from the wastewater treatment plants is constituted of organic matter and other nutrients that could be reused as soil fertilizers. However, primary sludge amendment is hampered due to the presence of pathogens that could be responsible for several infections in various ways depending on the prevalence of the human sources. This study investigates helminth eggs (HE) removal and inactivation efficiency by co-composting. So, PS was mixed with date palm waste as a bulking material at a 1:1 volume ratio. The C/N ratio decreased from 25:1 to 12:1 and temperatures above 50ºC were observed since 33 days. The initial concentration of HE eggs in the PS is 135.9 per 10 g DR. Microscopic examination of the PS, according to the Bailenger method, showed the presence of nematodes and Cestodes represented by: Ascaris lombricoïde, Ancylostomes duodenale, Trichuris trichiura, Capilaria spp, Hymenolepis nana, Taenia saginata, and Ascaris lombricoïde. After 60 days of co-composting, the charge of parasites was reduced to 18 eggs per 10 g per DR. The viability of ascaris eggs was examined using a light microscope and the percentage of the embryonated eggs was determined. No viable eggs were observed in the final compost. The result corroborates the WHO guidelines for the application of the composted sewage sludge safely for agriculture purposes.

Keywords: Ascaris; Primary dewatered sludge; agriculture; co-composting; helminth eggs; inactivation.

MeSH terms

  • Animals
  • Composting / methods*
  • Desert Climate
  • Helminths* / isolation & purification
  • Morocco
  • Ovum*
  • Sewage / parasitology*

Substances

  • Sewage