Soil aquifer treatment using advanced primary effluent.

Area of Science:

• Environmental Engineering
• Water Resource Management
• Wastewater Treatment Technologies

Background:

• Soil aquifer treatment (SAT) is a viable wastewater reuse method, especially in developing nations.
• Primary effluent (PE) poses clogging challenges in SAT due to high suspended solids.
• Effective pre-treatment is crucial for enhancing SAT performance and reliability.

Purpose of the Study:

• To evaluate the impact of sedimentation (SED), coagulation (COAG), and horizontal roughing filtration (HRF) as pre-treatment methods for PE in SAT systems.
• To assess the reduction in clogging and improvement in water quality achieved by different pre-treatment options.
• To identify the most effective pre-treatment strategy for optimizing SAT performance.

Main Methods:

• Laboratory-scale batch and soil column experiments were conducted.
• Primary effluent (PE) was subjected to three pre-treatment methods: sedimentation (SED), coagulation (COAG), and horizontal roughing filtration (HRF).
• Performance was evaluated based on head loss development, clogging effects, and removal efficiencies of dissolved organic carbon (DOC) and nitrogen.

Main Results:

• Sedimentation and coagulation pre-treatments significantly reduced head loss and clogging.
• Head loss in soil columns was reduced by 85% with PE + COAG and 72% with PE + SED compared to PE alone.
• Overall DOC removal efficiencies were 34% (PE only), 44% (PE + SED), 51% (PE + COAG), and 43.5% (PE + HRF).

Conclusions:

• Coagulation pre-treatment demonstrated superior performance in removing suspended solids, DOC, and nitrogen, making it the most effective option for PE in SAT.
• Sedimentation offers a cost-effective alternative, particularly in areas with available land for sedimentation basins.
• Pre-treatment is essential for overcoming the limitations of SAT with primary effluent and promoting wider adoption of wastewater reuse.