New Approach for Mining Site Reclamation Using Alternative Substrate Based on Phosphate Industry By-Product and Sludge Mixture

Yao Kohou Donatien Guéablé,Lhoussaine Moughli,Haitam Moulay,Mohamed El Gharouss,Mohamed Hafidi,Khalil El Mejahed,Youssef Bezrhoud

doi:10.3390/su131910751

Yao Kohou Donatien Guéablé, Lhoussaine Moughli + Show 5 more

Open Access

https://doi.org/10.3390/su131910751

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Abstract

Mining soils are generally characterized by soils having a coarse texture and low fertility, which makes revegetation a very difficult and delicate operation, especially in arid and semi-arid zones. The main objective of this work is to evaluate different substrates that can both contribute to the successful reclamation of phosphate mining soils and the valorization of phosphate by-product and sewage sludge. The study was carried out in pots under a greenhouse on Italian ryegrass (Lolium multiflorum). The experimental design is a randomized complete block with ten treatments, four repetitions from five substrates: phosphogypsum (PG), phosphate sludge (PS), sewage sludge (SS), topsoil from mining (TS) and phosphate waste rocks (PWR); this corresponds to soil after rock phosphate extraction. Nitrogen fertilization was applied to treatments after soil depletion in treatments not receiving sludge. An aerial biomass measurement and nutrient analysis were carried out for the three cuts. The results showed that a proportion of 65% of PG enriched the substrate in phosphorus by improving the crop yield. The addition of 5% of SS contributed to a significant improvement of ryegrass aerial biomass. In the absence of SS application, the addition of nitrogen is required to maintain crop growth. For large-scale application, TS can be mixed with PS, SS and PG for mine site reclamation.

Highlights

Taking advantage of a favorable geological context, Morocco is a country of a very long mining tradition which constitutes an important vector of economic and social development
Significant differences between different treatments during the three cuts were expressed with their standard error using ANOVA and mean comparison
The electrical conductivity (EC) measurements, revealed that, PG and sewage sludge (SS) had the highest values compared to phosphate waste rocks (PWR), phosphate sludge (PS) and topsoil from mining (TS)

Summary

Introduction

Taking advantage of a favorable geological context, Morocco is a country of a very long mining tradition which constitutes an important vector of economic and social development. Mining in Morocco is characterized by the dominance of phosphates of which. According to [3], Morocco geographically concentrates 77% of the global phosphate rock reserves, with two thirds of the world reserves that are located in four sedimentary Moroccan basins. The exploitation of phosphate mines generates large quantities of by-products such as: phosphogypsum (PG), phosphate sludge (PS) and phosphate waste rocks (PWR) that remain accumulated and not recovered [6,7]. Wastewater treatment generates large amounts of sewage sludge (SS), the amount of which is rapidly increasing with urbanization and industrial development

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