A Circular Economy Approach to Restoring Soil Substrate Damaged by Sewage Sludge Using Amendments

Aijie Wang^*
*Correspondence: Aijie Wang, Department of Environmental Science & Engineering, Harbin Institute of Technology, Harbin, P.R. China, Email:

Editorial

Gaining and sustaining acceptable physical and chemical conditions in reclamation projects intended at obtaining tree cover entails combining the reclamation process with agrotechnical procedures typical of the early management of biological reclamation. Reclamation with sewage sludge combinations may be beneficial in recovering formerly arable wasteland, where herbaceous or woody plants may enhance soil conditions for agricultural plants. As pollution has become a serious worry in recent years, the accumulation of potentially hazardous elements (PTEs) in plants has gained attention. Priority pollutants include arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) [1].

The usage of an artificial soil substrate in a mining waste reclamation area was investigated, as well as the influence on plant metabolic activities. The association between the plants' biochemical characteristics and the qualities of plant growth medium obtained from post-flotation coal waste, sewage sludge, crushed stone and fly ash on the surface of the mine waste disposal area was investigated. On the material, trees and bushes were planted and left to grow for eight years. The study indicated that the applied plants and the naturally existing Taraxacum officinale were acceptable for physio-biochemical assessment, derelict area identification and reclamation.

Cistus salviifolius, a plant that can thrive in polluted soil, has apparently demonstrated reasonably high Pb, Zn and Cu tolerance and may be regarded a promising species for phytostabilisation. PTEs were transferred from green to senesced Cupressus sempervirens leaves. Plantago major roots, which are suited for phytoextraction from soil and phytostabilisation, aid in the investigation of the efficacy of bioaccumulation for PTE contamination. Furthermore, the soil–plant interactions that control the migration of PTEs from soil to plant might be beneficial in soil reclamation. Some plants, such as flax and hemp, may extract significant amounts of PTEs from the soil through their root systems. Mining, in particular, contributes to a rise in PTEs in soil and plants [2].

This is especially critical when they are translocated from the soil to crops and subsequently accumulate in them, posing substantial human health risks even at low concentrations due to their bioaccumulation abilities. Diverse and prolific vegetation is critical to the success of soil reclamation. Metal detoxification systems in plants have received a lot of attention. Furthermore, it is recognised that photosynthetic pigments in plants, such as chlorophyll and carotenoids, protect photosynthetic organisms under stress circumstances and proline is a stress signal in crops. However, measures to combat the risks posed by metal stressors, such as antioxidant systems, have largely gone unnoticed in the field of reclamation [3].

We used industrial and municipal garbage in our study and we enhanced reclamation materials based on their physical features. Wastewater treatment plants are an integral part of a circular economy. Sewage sludge is created in wastewater treatment plants by a number of physical, chemical and biological processes. Innovative sewage sludge processing methods increase the efficiency of the entire treatment process and turn sludge into a useful raw material for other businesses. Wastewater sludge should be treated as a material and energy resource. In this approach, sewage sludge is employed as a raw material for further processing. Sludge from sewage treatment plants may be a source of organic materials.

Plants used for cleanup can grow spontaneously on sewage sludge substrate in abandoned places. Sewage sludge can be utilised in the reclamation of polluted regions and as an immobilising agent for phytostabilisation. Plants grown on experimental plots have been demonstrated to have adequate water to support appropriate growth or to suffer from water constraint due to other circumstances. Wastes like sewage sludge, post-flotation lime and mineral wool contain nutrients for plants and soil microbes and can be used to improve soil quality. The multiple roles of vegetation cover in degraded regions that are required in the reclamation process are well understood [4].

Chlorophyll can represent the nutritional state of plants by indicating vegetative stress and external disturbance. Drought stress frequently causes changes in the chlorophyll content/components of plants, resulting in weakened photosynthetic machinery. Drought causes a decrease in chlorophyll content, while water stress causes a significant rise in Pro content. In this study, total porosity was related to both chlorophyll and Pro content, while bulk density was associated to total phenolic content. The present set of quantifiable criteria for assessing the quality of reclamation works and categorization criteria for emerging soils and habitats should be enhanced by the addition of a reliable index showing deterioration of post-mining sites [5].

Conclusion

The metabolic activity of plants is presented in this study to completely understand their influence on substrate soils (mobility, bioavailability and ecotoxicity). The interpretation of the data points to future study topics, such as determining the concentration of reinforcing components. The physiological and biochemical characteristics of plants are closely related to the soil or substrate in which they develop. The findings may give fresh insights into abiotic postmine plant development constraints such as salinity stress, including oxidative stress, as well as the influence of stress variables (in terms of biochemical activity) and serve as a baseline reference for sensible restoration of mining regions.

Acknowledgement

None.

Conflict of Interest

No potential conflict of interest was reported by the authors.

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