# Sustainable Environmental Technologies: Recent Development, Opportunities, and Key Challenges
## 3 Waste-To-Energy Conversion
[25] investigated the use of biochar in immobilizing potentially hazardous elements (PTEs) in agricultural soils. Their study demonstrated that biochar effectively reduced the mobility and bioavailability of heavy metals such as Pb, Cd, Cu, and Ni in soils, leading to a lower uptake of these metals by plants. This enhanced biochar adsorption potential is due to its high surface area, porosity, pH, aromatic structure, and several functional groups, which mostly rely on the feedstock type and pyrolysis temperature. Thus, this study shows that agriculture waste-based biochar can be an effective option for soil remediation and sustainable agriculture. Biochar has also been effectively applied in the treatment of polluted water and wastewater. [PERSON] et al. [22] reviewed the possible application of various feedstock-based raw and modified biochar in the remediation of geogenic pollutants such as fluoride (F\({}^{-}\)) and uranium (U) from aqueous solutions. The data showed that cellulose- and hemicellulose-rich feedstocks, including agricultural residues, grasses, softwood, and manure-based biochars, were successful in removing U and F\({}^{-}\) at low-to-medium pyrolysis temperatures. While metal oxide, hydroxide, and alkali modification promoted F-adsorption, acidic and magnetic modification favored U adsorption. Similarly, [PERSON] et al. [26] investigated the effectiveness of plant-based waste materials as adsorbents for removing nitrogen-based chemicals from water. The results demonstrated that in comparison to animal biomass and chitosan, vegetal biomass and pineapple crowns were more effective in eliminating organic pollutants from water bodies. Therefore, the use of these plant-based biomasses is a practical and affordable solution to lessen the amount of waste that ends up in sanitary landfills and dumps while also addressing environmental pollution. The performance of the denitfying bacterial strain _Pseudomonas_ sp. in a laboratory-scale sequencing batch reactor was examined in another study conducted by [PERSON] et al. [27]. The findings imply that microorganisms can improve total nitrogen (TN) elimination by bioaugmentation. A metal-organic framework (MOF) was developed by [PERSON] et al. [28] as an effective sorbent for environmentally friendly oil-water separation. Similar to this, an MOF was used by [PERSON] et al. [29] to remove methyl orange from water, showing the versatility of MOFs in water treatment. Phytoremediation, a process that uses plants to remove contaminants from the environment without creating secondary pollution, is another low-cost, sustainable, and effective option compared to conventional procedures based on chemical extraction. In another study conducted by [PERSON] and [PERSON] [30], the phytotoxicity and accumulation of antibiotics in two different types of plants were examined. The researchers found that water lettuce had a higher accumulation of antibiotics in its tissues compared to parrot feather plants, indicating its great potential for removing xenobiotics from contaminated environments. These plants possess a natural ability to adapt and thrive in harsh, polluted conditions, making them valuable tools for environmental cleanup. Overall, these studies offer insightful information on the technical developments in the production of sustainable materials for the removal of pollutants from water and soils. The integration of plant-based solutions, microbial bioaugmentation, and MOFs highlights the growing potential of sustainable, low-cost methods for addressing environmental contamination.