Water Renew systems: wastewater polishing using renewable energy crops

Area of Science:

• Environmental Science
• Agronomy
• Soil Science

Background:

• Short rotation coppice (SRC) plantations are increasingly used for biomass production.
• Treated wastewater effluent is a potential irrigation source for SRC, but its impact on soil and water quality requires investigation.

Purpose of the Study:

• To assess the impact of irrigating SRC with secondary treated effluent on soil water macronutrient concentrations.
• To evaluate the potential risk to groundwater quality from this irrigation practice during the establishment year.

Main Methods:

• Drip irrigation of Salix viminalis, Populus trichocarpa, and Eucalyptus gunnii plots with treated effluent.
• Fortnightly soil water sampling at 30 cm and 60 cm depths using suction cups.
• Analysis of soil water for nitrogen (N), phosphorus (P), and potassium (K) concentrations.

Main Results:

• Willow and eucalyptus plots received significantly higher effluent volumes (over 900 mm) than poplar and unplanted plots.
• Elevated N and K concentrations in soil water were observed, particularly in eucalyptus plots, but P was not measurable.
• No significant effect of tree presence or species on overall soil water chemistry was detected.
• Groundwater chemistry remained unaffected by the irrigation treatment.

Conclusions:

• Intensive irrigation of SRC with treated effluent during the establishment phase poses minimal risk to groundwater quality.
• Willow and eucalyptus demonstrated a higher capacity to absorb effluent compared to poplar, without adverse effects on soil water chemistry.
• SRC plantations irrigated with treated effluent can be a viable sustainable practice for biomass production and wastewater management.