Artificial Wetlands as a Low-cost Treatment Alternative for Complex Organic Wastewaters: Phase I and II

1. Purpose and Objectives: The objective of the research is to investigate the use of Artificial Wetlands Filter Systems (AWF) to remove complex organics and nitrogen species in domestic (septic tanks) and industrial wastewaters at both the pilot and demonstration scale of operation. This is a three-phase study.

2. Funding: $140,000

3. Partners: Southwest Center for Environmental and Research Policy (SCERP), New Mexico State University

4. Description and Background: Removing compounds from wastewater can be a very expensive procedure. Therefore, a study concentrating on low-cost approaches (removing compounds) needed to be conducted. Thus far, one of the best approaches for treating wastewater at low-cost is an Artificial Wetlands Filter (AWF). AWF systems can achieve tertiary wastewater standards for many domestic wastewater components such as biological oxygen demand and total suspended solids. To achieve this low-cost alternative wastewater treatment approach, a study was conducted to determine whether AWF could actually remove compounds from wastewater. Preliminary studies have indicated they can.

5. Methodology: In order to accomplish the goals of the research, AWF systems will be investigated at both the demonstration and pilot scale of operation. Several demonstration facilities within the NMSU area have agreed to participate in this study. One facility is in place operating and others are planned. In addition, construction, operation, and testing of a demonstration facility at the Universidad Autonoma de Ciudad Juárez is proposed as part of this work. These systems will be evaluated, particularly for nitrogen removal, by monitoring influent and effluent characteristics using a mass balance approach. These systems will be monitored through a full season of use to determine the temperature and decreased plant activity impacts on system performance. This will aid in the design understanding of these systems, not only in the Southwest, but throughout the U.S. The pilot level investigations will be pursued in the Southwest Technology Development Institute’s experimental greenhouse located on the campus of NMSU. At the pilot scale of operation, these systems will be optimized for specific target substrate (chlorinated aromatics) removal to develop full scale system control strategies.

6. Results: The first phase aimed to explore whether AWF had the capacity to remove aromatic organic compounds as represented by benzoic acid and evaluate its potential for biodegradation of more recalcitrant molecules. Initial results indicated excellent (99%) removal of benzoic acid at concentrations up to 40 mg/l. The second phase of the study concentrated on the AWF’s capacity to remove chloroaromatic organic compounds as represented by tri- and pentachlorophenol. Initial results indicate that the system could indeed remove the compounds. However, shallow reactor configurations had to be replaced with deep configuration reactors so that removal of compounds can be more effective. The third phase is still ongoing and results have not been provided.

7. Status: The first two phases of the project have been completed. The third phase, being conducted in Juárez, MX, is ongoing. The 1st step involves the removal of heavy solids and the second step will remove organics and suspended solids. The treated wastewater will be used in a local park for irrigation of trees. Depending on effluent quality, the water will also be used to irrigate grass.

8. U.S. Contacts: Dr. Walter H. Zackritz II, Southwest Technology Development Institute, NMSU Dr. Leon Lundie, Department of Biology, NMSU Ing. Mauricio Mercado Perez, Universidad Autonoma de Ciudad Juárez