Clogging index: A tool to quantify filter bed clogging in horizontal subsurface flow macrophyte-assisted vermifilter

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Bioremediation

Background:

• Horizontal subsurface flow macrophyte-assisted vermifilters (HSSF-MAVF) are effective for wastewater treatment.
• Filter bed clogging is a significant operational challenge affecting HSSF-MAVF performance.
• Quantifying clogging is crucial for maintaining treatment efficiency and system longevity.

Purpose of the Study:

• To develop a mathematical index for quantifying filter bed clogging in HSSF-MAVF systems.
• To simulate porosity reduction caused by suspended solids, biofilm, and plant growth.
• To validate the developed clogging index (CI) using experimental data.

Main Methods:

• Conducted experiments using HSSF-MAVF with synthetic dairy wastewater.
• Varied hydraulic loading rates (HLR), chemical oxygen demand (COD), and total suspended solids (TSS).
• Developed and validated a clogging index (CI) against experimental observations.

Main Results:

• The developed CI accurately replicated the clogging phenomenon with a 2-8% error range.
• Established CI thresholds for unclogged (<25), partially clogged (25-40), and clogged (>40) filter beds.
• Higher CI values correlated with a 5-15% reduction in COD removal efficiency.

Conclusions:

• The CI effectively quantifies HSSF-MAVF clogging and its impact on performance.
• The index helps understand the contributions of biofilm, suspended solids, and plant roots to clogging.
• The CI facilitates optimizing operational conditions to extend HSSF-MAVF service life.