Design-support and performance estimation using HYDRUS/CW2D: a horizontal flow constructed wetland for polishing SBR...

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Computational Modeling

Background:

• The Balf, Hungary wastewater treatment plant (4,000 PE, 700 m³/d) utilizes sequencing batch reactor technology with tertiary phosphorus precipitation.
• Effluent quality generally met thresholds but exhibited winter peaks exceeding limits, necessitating advanced polishing.

Purpose of the Study:

• To simulate the performance of a horizontal flow constructed wetland for polishing wastewater effluent.
• To provide design-supportive data on wetland suitability and validate the HYDRUS/CW2D computational tool.

Main Methods:

• Utilized the HYDRUS/CW2D model package to simulate constructed wetland performance.
• Evaluated effluent quality parameters including NH4-N, COD, BOD5, total nitrogen, total inorganic nitrogen, and total phosphorus.

Main Results:

• The simulated wetland design met most effluent thresholds (COD, BOD5, total N, total inorganic N, total P).
• The model indicated the proposed wetland layout could not effectively manage peak ammonia nitrogen (NH4-N) loads.
• The HYDRUS/CW2D tool could not simulate COD and BOD5 removal under anaerobic conditions due to limitations in modeling these processes.

Conclusions:

• The HYDRUS/CW2D model can identify design weaknesses in constructed wetland systems, facilitating effective system design.
• While the wetland shows promise, design modifications are needed to address ammonia nitrogen peaks.
• Complex modeling tools require careful application due to potential uncertainties and high work demands in design processes.