Inexpensive Organic Materials and Their Applications towards Heavy Metal Attenuation in Waters from Southern Peru

Abstract

There is interest in using locally available, low cost organic materials to attenuate heavy metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn found in surface waters in Peru and other developing regions. Here we mesh Spanish language publications, archived theses, and prior globally available literature to provide a tabulated synthesis of organic materials that hold promise for this application in the developing world. In total, nearly 200 materials were grouped into source categories such as algae and seashells, bacteria and fungi, terrestrial plant-derived materials, and other agricultural and processing materials. This curation was complemented by an assessment of removal potential that can serve as a resource for future studies. We also identified a subset of Peruvian materials that hold particular promise for further investigation, including seashell-based mixed media, fungal blends, lignocellulose-based substrates including sawdust, corn and rice husks, and food residuals including peels from potatoes and avocadoes. Many studies reported percent removal and/or lacked consistent protocols for solid to liquid ratios and defined aqueous concentrations, which limits direct application. However, they hold value as an initial screening methodology informed by local knowledge and insights that could enable adoption for agriculture and other non-potable water reuse applications. While underlying removal mechanisms were presumed to rely on sorptive processes, this should be confirmed in promising materials with subsequent experimentation to quantify active sites and capacities by generating sorption isotherms with a focus on environmental conditions and specific contaminated water properties (pH, temperature, ionic strength, etc.). These organics also hold promise for the pairing of sorption to indirect microbial respiratory processes such as biogenic sulfide complexation. Conversely, there is a need to quantify unwanted contaminant release that could include soluble organic matter and nutrients. In addition to local availability and treatment efficacy, social, technical, economic, and environmental applicability of those materials for large-scale application must be considered to further refine material selection.

Occurrence of Chemical Contaminants in Peruvian Produce: A Food-Safety Perspective

“…Thus, it is increasingly important to advocate and push for more compliant wastewater treatment practices. For example, low-cost materials of biological origin (e.g., biochar and agricultural byproducts) have been shown as adsorbents that effectively remove pesticides and heavy metals in water, and could be explored as remediation options [ 128 , 129 , 130 ].…”

Hydrologic Analysis of an Intensively Irrigated Area in Southern Peru Using a Crop-Field Scale Framework

“…Drip irrigation technologies maintain higher levels of moisture in the root zone, meeting the crop's growth requirements with lower volumes of water stored in the soil surface which, in turn, is able to slow down soil moisture evaporation and reduce the rate of seepage processes. However, the benefit of flood irrigation is that it can be used to help manage salt build-up in the soil, while this kind of salt amelioration would not be achieved by drip irrigation [105]. The application of mulch (i.e., a thick layer of organic material that covers the soil surface, in order to decrease evaporation rates) is another strategy to increase irrigation efficiency [106].…”

Biochar Capacity to Mitigate Acidity and Adsorb Metals—Laboratory Tests for Acid Sulfate Soil Drainage Water

“…These problems call for a new, environmentally, and economically sustainable way of mitigating acidity and metal export. Common methods used to treat metal-polluted water generally require centralized facilities and trained people, as well as use various chemicals and generate waste (Abdullah et.al, 2019, Garcia-Chevesich et al, 2020. A potential solution could be water purification via adsorption using biochar-filled reactors in ditch drains.…”