Empirical Characterization of Particle Size Distribution Spatial Dynamics for Detection of Helminth Eggs in Waste Stabilization Ponds (WSP)

Abstract

This study assesses the seasonal particle size distribution (PSD) dynamics inside a WSP (Buguruni, Tanzania) to understand the settling dynamics of wastewater particles with a specific focus on helminth eggs. Results indicate that particles coming into the pond are mainly supracolloidal and settleables, at 52.9% and 45.6%, respectively, in the dry season and 48.9% and 49.9%, respectively, in the wet season. Inflow PSD is a unimodal distribution that splits into settling and suspended PSDs, with an indication of particle breakage as shown by the increased volume of smaller particles, and hence the appearance of a bimodal distribution for the suspended particles. Up to 61.5% and 45.2% of particles that fall within the size range of helminths eggs are suspended during the dry and wet seasons, respectively, and have the potential to be carried in the effluent, causing contamination.

Keywords

• waste stabilization ponds
• WSP
• particle size distribution
• helminths