Evaluation of the Use of Sewage Sludge Biochar as a Soil Amendment—A Review

Abstract

In recent decades, minimization and recycling/reuse policies were introduced to reduce the quantities of generated waste and for alternative waste recovery. Organic wastes represent 46% of total global solid waste. Possible uses of organic wastes include using it as fertilizer and amendment for soil, for energy recovery and for the production of chemical substances. Sewage sludge disposal and reuse are identified as future problems concerning waste. The total amount of sludge generated in the entire world has increased dramatically, and this tendency is expected to increase significantly in the years to come. In most developed countries, special attention is given to sewage sludge treatment in order to improve the quality and safety of using it on the ground surface. Sewage sludge pyrolysis is considered an acceptable method, from an economic and ecological perspective, for the beneficial reuse of sewage sludge. This method has many advantages because, during the pyrolysis process, the sludge volume is reduced by 80%, pathogenic agents and hazardous compounds from sewage sludge are eliminated, metals are immobilized in solid residue and organic and inorganic fractions are immobilized in a stabilized form of pyrolytic residues (biochar). The biochar generated by sewage sludge pyrolysis does not contain pathogenic agents and is rich in carbon and nutrients.

Enhanced Adsorptive Removal of Tetracycline by Phosphomolybdic Acid-Modified Low-Temperature Sludge Biochar

“… We conducted further peak fitting and calculation of the Mo 3d fine spectrum of PMABC-200. The characteristic peaks at 232.7 and 235.7 eV corresponded to MoO 3 , whereas those at 231.9 and 234.8 eV corresponded to MoO 4 . − As presented in Table S1, the content of oxygen-containing functional groups (such as C–OH, C–O–C, and CO) on the surface of PMABC-200 was higher than that of BC-200, with the exception of the O–CO group. The total content of the oxygen-containing groups on the surface of PMABC-200 (41.5%) was greater than that of BC-200 (39.4%), indicating that new oxygen-containing groups were generated on PMABC-200 through the modification with phosphomolybdic acid oxidation.…”

“…Compared with the current utilization method for sewage sludge, pyrolysis offers numerous advantages. Along with other benefits, pyrolysis reduces the volume of solid residue and effectively stabilizes heavy metals present in the sludge by subjecting it to an inert gas atmosphere . Sludge pyrolysis has recently garnered considerable research interest. , Sewage sludge is known to be a good feedstock material for pyrolysis as it is rich in organic matter and various types of waste biomass. , Biochar (BC) is the solid product of pyrolysis and is regarded as an efficient and inexpensive adsorbent owing to its simple and cheap preparation and good adsorbability .…”

Pyrolysis—A tool in the wastewater solids handling portfolio, not a silver bullet: Benefits, drawbacks, and future directions

“…Others have noted negative impacts on ryegrass, although the reason for the poor performance (the crop, feed material, or both) could not be determined (Jeffery et al, 2011). Variables impacting biosolid‐derived biochar impacts on crops can include pyrolysis feed material, pyrolysis temperature, soil characteristics, and land application rates, among other factors (Goldan et al, 2022; Jeffery et al, 2011). The widely differing results presented in the literature highlight the need for additional and long‐term studies to better understand the influence of the factors noted above on the performance of biosolid‐derived biochars for crop production and identify suitable outlets for these materials.…”

“Green” nZVI-Biochar as Fenton Catalyst: Perspective of Closing-the-Loop in Wastewater Treatment

“…Sewage sludge pyrolysis is considered an acceptable method from economic and ecological perspectives for the beneficial reuse of sewage sludge. This method has many advantages such as reducing sludge volume by 80%, the removal of pathogenic agents and hazardous compounds from SS, metals being immobilized in a solid residue, thus reducing their leaching, and organic and inorganic fractions being immobilized in a stabilized form of pyrolytic residues (biochar) [ 10 ]. There are many benefits of biochar (BC) production: energy production, sustainable waste recycling, carbon sequestration, improvement in soil quality, plant development, and mitigating greenhouse gas (GHG) emissions [ 6 , 11 , 12 ].…”