Cloth Depth Filtration of Primary Domestic Wastewater

With over 20 years treating tertiary wastewaters, cloth depth filtration (CDF) has demonstrated the capacity to accept high solids loadings while offering reuse quality effluent. To verify whether CDF is suitable for primary treatment, a six month pilot study was conducted at the Rock River Water Reclamation District (RRWRD), Illinois in 2014. In that study, CDF removed 80-90% of the primary TSS which ranged from 104 to 526 mg/L, attaining 50 kg/m2-day (~10 lbs/ft2-day) at an 8.0 m/hr (3.25 gpm/ft2) hydraulic loading rate. By comparison, the primary clarifiers provided ~66% TSS removal. Additionally, CDF demonstrated 54-64% BOD5 removal while the primary clarifiers attained 44% removal. These results indicate CDF, while occupying less than 10% of the footprint of a conventional primary settling basin, can produce higher quality effluent. The observed filtration performance and operational requirements promises CDF to achieve significant energy and capital cost savings.