1. Soil as a Wastewater Treatment Medium By J.G. Mexal Department of Agronomy & Horticulture New Mexico State University

2. Soil as a Treatment Slow Rate Land Application System “Slow rate land application for wastewater treatment is a proven technology for municipal and other organic wastewaters. Used for over one hundred years, it has evolved from a ‘disposal’ method to one that can be used to recycle wastewater onto agricultural crops, forests, or park lands.” EPA 1992

3. Soil as a Treatment Who Does It?

4. Soil as a Treatment Site Characteristics

5. Soil as a Treatment Wastewater Loading Rates/ Tyler & Assoc.

6. Soil as a Treatment Wastewater Infiltration A = Restaurant B = Septic C = Gray D = Tap

7. Soil as a Treatment Wastewater Composition / Metcalf & Eddy

8. Soil as a Treatment Survival of Human Parasites

9. Soil as a Treatment Land Application Performance

10. Soil as a Treatment Wastewater Treatment Options

12. Wastewater Treatment Options/ PSC

13. Soil as a Treatment Conceptual Mass Balance Diagram

14. Soil as a Treatment Water Characteristics--Ojinaga

15. Soil as a Treatment Species Selection--Ojinaga / 2 yrs

16. Soil as a Treatment Groundwater Quality/ Ojinaga

17. Land Application System/West Mesa Pipes H20H20 H20H20 Wastewater (H 2 0, OM, N, Salts) N,P,Ca,Mg,K N2N2 Soil Matrix/Precipitant P,Ca,Mg P Ca Mg Cl Na Cl PP P Na Ca Mg P P P Cl Caliche CO 2

18. Soil as a Treatment Limitations of SRLA System Percolate < 10 mg NO 3 - -N Balance water- vs N-loading Salt loading limits plant productivity Growing season limits water use

19. Soil as a Treatment Conclusions A functioning soil-plant ecosystem is an effective wastewater treatment and water reuse system. Arid environments create unique situations that preclude ‘off-the-shelf’ adoption. SRLA systems can be economical, sustainable treatment systems.