Parasitological study of waste‐water sludge

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Abstract
A parasitological study was made of different stages of‐ treatment and post‐treatment sludge from a wastewater treatment plant: during treatment, after storage and during composting. Out of 157 samples, 69 % were positive for Nematode eggs and/or Cestode eggs. Anaerobic digestion of sludge had little effect on helminth egg recovery but lime and ferric chloride treatment reduced the number of eggs found in sludge samples Samples of sludge stored for 1 or 2–3 years were all positive but after 4 years of storage, no more helminth eggs were found. After 120 days composting helminth eggs were still recovered. Although compost and stored sludge were positive, no Ascaris eggs tested showed any indication of viability.