Investigations of An Aggregate Resource for Constructed Wetland Use near the City of Valladolid, Yucatan, Mexico

Subsurface flow constructed wetlands are an important, efficient solution to treating sewage along the Caribbean coast of Quintana Roo, Mexico, and are necessary to sustain the tourism industry in this region. The interior of the region is also experiencing increasing environmental pressures from tourism. Here constructed wetlands have not yet been implemented and aggregate resources need to be identified to enable installation.

Limestone from a quarry located on a topographic high (20° 41.440” N, 88° 14.691) on highway 180 west of the city of Valladolid was investigated for feasible use for constructed wetlands. Thin section analyses of samples indicate the rocks to be biopelsparites / grainstones with 10-15% porosity. X-ray diffraction was conducted on crushed powders of which identified calcite as the only mineral present above detection limits (approximately 1%). Most samples have insoluble residues below detection limit. A few samples have poorly crystalline Fe-oxides. SEM investigation from selected samples shows calcite has a high purity with respect to chemical composition and there is an abundance of irregular grains and pore spaces.

Several factors make rocks attractive for aggregate use in constructed wetlands. The quarry is located on a major road and thus is accessible and meets economic requirements. The quarry is on a topographic high such that local groundwater environment will not be directly impacted by mining. No environmentally suspect minerals were detected in the limestone. Pure calcite aggregate is also fortunate in that modeling wetlands systems is more straightforward. Geochemical processes such as dissolution and sorption of pollutants can be predicted.

Basic resource investigations such as this study are needed to aggressively pursue constructed wetland system installations in area. Only through these low cost technologies for wastewater treatment can the immediate needs of environmental health protection and a sustainable tourism be met.