Concentrations and environmental fate of Ra in cation-exchange regeneration brine waste disposed to septic tanks and accumulation in sludge, New Jersey Coastal Plain, USA

Concentrations of Ra in liquid and solid wastes generated from 15 softeners treating domestic well waters from New Jersey Coastal Plain aquifers (where combined Ra (²²⁶Ra plus ²²⁸Ra) concentrations commonly exceed 0.185 Bq L⁻¹) were determined. Softeners, when maintained, reduced combined Ra about 10-fold (<0.024 Bq L⁻¹). Combined Ra exceeded 0.185 Bq L⁻¹ at 1 non-maintained system. Combined Ra was enriched in regeneration brine waste (maximum, 81.2 Bq L⁻¹), but concentrations in septic-tank effluents receiving brine waste were less than in the untreated ground waters. The maximum combined Ra concentration in aquifer sands (40.7 Bq kg⁻¹ dry weight) was less than that in sludge from the septic tanks (range, 84–363 Bq kg⁻¹), indicating Ra accumulation in sludge from effluent. The combined Ra concentration in sludge from the homeowners' septic systems falls within the range reported for sludge samples from publicly owned treatment works within the region.