Numerous studies are ongoing to understand the long-term effects of using evaporation ponds, in both traditional ways and in highly-managed, controlled settings. In countries surrounding the Mediterranean, for instance, where evaporation ponds are used by olive oil producers, there is some indication that when olive mill wastewater is disposed of in shallow and unprotected evaporation ponds, a threat may exist in terms of soil and water pollution. Although documentation is not yet adequately available, analysis has found profound changes in the concentration of soil phenols at downsite locations due to subsurface migration of olive mill wastewater.
Another critical concern is the removal of viruses and other organic material that may exist in evaporation ponds or lagoons used for wastewater (sewer) treatment in municipal settings. One of the most common uses of evaporation ponds today, the efficacy of their use is universally acknowledged, particularly when treated effluent is used for irrigation. Research has confirmed that “sunlight-mediated mechanisms” are dependent on the specific virus characteristics as well as on pond water chemistry and other factors. Again, studies are ongoing and testing is robust to ensure that public safety is not compromised. Additional research is planned to determine in greater detail what interactions occur between viruses and other organisms or particles, and to develop a workable model for virus treatment and removal. Results of such research will be important for future design purposes, and it will “inform future editions of the WHO Guidelines for Wastewater Use in Agriculture,” according to an abstract submitted by researchers affiliated with the University of South Florida.
