A bench-scale rock-plant filter investigation.

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Ecological Engineering

Background:

• Rock filters are used for wastewater treatment.
• Vegetation can enhance filter performance.
• Nutrient removal efficiency is a key performance indicator.

Purpose of the Study:

• To evaluate the effectiveness of Sagittaria Iancifolia and Scirpus validus in planted rock filters for wastewater treatment.
• To compare nutrient removal in vegetated versus unvegetated rock filters.
• To analyze the relationship between BOD5 loading rates and removal efficiency.

Main Methods:

• Bench-scale rock filters (0.6 m gravel) were used.
• Two filters were planted (S. Iancifolia, S. validus), one was a control.
• Eight BOD5 loading combinations (4.63-30.96 g/day/m²) were tested over 80 days.

Main Results:

• Removal percentages averaged 69% (Scirpus), 57% (Sagittaria), and 47% (control).
• Little correlation found between BOD5 loading rate and removal percentages.
• Total Kjeldahl nitrogen removal was higher in vegetated systems, with Scirpus outperforming Sagittaria.

Conclusions:

• Planted rock filters, especially with Scirpus validus, demonstrate superior nutrient removal compared to unvegetated systems.
• Limited correlation between BOD5 loading and removal suggests other factors influence efficiency in short-term studies.
• Further research is needed to optimize detention times and loading rates for maximum treatment efficacy.