Citation:

Martín-Hernández, E., Gerardo J. Ruiz-Mercado, AND M. Martín. Model-driven spatial evaluation of nutrient recovery from livestock leachate for struvite production. JOURNAL OF ENVIRONMENTAL MANAGEMENT. Elsevier Science Ltd, New York, NY, 271:110967, (2020). https://doi.org/10.1016/j.jenvman.2020.110967

Impact/Purpose:

Nutrient releases from organic waste disposal result in severe environmental and public health issues such as water and soil contamination, including eutrophication, harmful algal blooms (HABs), and dead zones (hypoxia). Thus, adequate management strategies for organic waste and the recovery of nutrients as valuable products are necessary to achieve a more comprehensive and permanent solution for nutrient pollution, resource depletion, and reduce the human impact on the environment. This journal article describes a thermodynamic feasibility evaluation model to inform decision-makers, the technical feasibility for optimal nutrient recovery as a valuable product (struvite) from livestock waste. In the long-term, this manuscript aims to propose a realistic feasibility tool for improving the management of nutrients from their source which has broad-scale implications for the environment in the United States, with interest for Regions, states, communities, and the public looking for feasible solutions to address quality of life challenges, ecological impairments, and economic impacts caused by inefficient management of organic waste, nutrient pollution, and HABs.

Description:

Nutrient pollution is one of the major worldwide water quality problems, resulting in environmental and public health issues. Agricultural activities are the main source of nutrient release emissions, and the livestock industry has been proven to be directly related to the presence of high concentrations of phosphorus in the soil, which potentially can reach waterbodies by runoff. To mitigate the phosphorus pollution of aquatic systems, the implementation of nutrient recovery processes allows the capture of phosphorus, preventing its release into the environment. Particularly, the use of struvite precipitation produces a phosphorus-based mineral that is easy to transport, enabling redistribution of phosphorus to deficient locations. However, livestock leachate presents some characteristics that hinder struvite precipitation, preventing extrapolation of the results obtained from wastewater studies to cattle waste. Consideration of these elements is essential to determine the optimal operating conditions for struvite formation, and for predicting the amount of struvite recovered. In this work, a detailed thermodynamic model for precipitates formation from cattle waste is used to develop surrogate models to predict the formation of struvite and calcium precipitates from cattle waste. The variability in the organic waste composition, and how it affects the production of struvite, is captured through a probability framework based on the Monte Carlo method embedded in the model. Consistent with the developed surrogate models, the potential of struvite production to reduce the phosphorus releases from the cattle industry to watersheds in the United States has been assessed. Also, the more vulnerable locations to nutrient pollution were determined using the techno-ecological synergy sustainability metric (TES) by evaluating the spatial distribution and balance of phosphorus from agricultural activities. Although only struvite formation from cattle operations is considered, reductions between 22% and 36% of the total phosphorus releases from the agricultural sector, including manure releases and fertilizer application, can be achieved.

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