Performance of an Earthworm-Based Biological Wastewater-Treatment Plant for a Dairy Farm: Case Study

Abstract

Earthworms have been in existence for approximately 600 million years and have adapted to toxicity. They may help cleaning wastewater by devouring micro-organisms. Although the performance of earthworm-based wastewater-treatment technology is still under investigation, this study contributes some performance data to the investigation process. This study observes the performance in terms of removal efficiency of water quality constituents and energy requirements of an earthworm-based wastewater-treatment plant to treat the effluent from a dairy farm located at the California State University Fresno Agricultural Laboratory. Results show that the nitrogen-based water quality constituents, ammonium nitrogen (NH4), nitrate nitrogen (NO3-N), and total kjeldahl nitrogen (TKN), can be removed at higher removal efficiencies (above 90%). The removal efficiencies for biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) are found to be promising, but the removal efficiencies for other water quality constituents [e.g., calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P), etc.] are found to be poor. In terms of energy consumption, 55% of total energy requirement data show better performance than a baseline study. This study was conducted with a pilot treatment plant. Study findings recommend that additional caution and protocols should be maintained during water quality sampling and other types of data-collection processes.