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Biotechnological Energy Conversion Technology: New Advances in Biosolids Management and Wastewater Treatment

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A4: Bio-Energy".

Deadline for manuscript submissions: closed (5 March 2026) | Viewed by 895

Special Issue Editors


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Guest Editor
Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Interests: biosolids management; wastewater treatment; thermal treatment processes; waste-to-energy; resource recovery from wastewater; contaminant’s fate during thermal treatment
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Guest Editor
Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
Interests: chemical looping; biogas decarbonisation to hydrogen and carbonanomaterials; thermal treatment processes; wastes transformation to energy and materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Water and energy are pivotal in human sustenance and economic development. It is hard to imagine life without them. Therefore, it is not surprising to see increasing demands for water and energy, reflected by the huge volume of research and innovation in water management and energy production in recent decades. Wastewater and biosolid (stabilised sewage sludge) generation are rapidly increasing thanks to rising populations, urbanisation, and industrialisation. In particular, the increasing volume of biosolids is being met with stringent regulations due to emerging concerns regarding contaminants, odours, greenhouse gas emissions, and nutrient leaching, among other issues. The global regulatory landscape is rapidly changing, and the water industry is faced with uncertainties, relying on scientists, engineers, technologists, and researchers alike to proffer sustainable solutions. Consequently, advances have been made in the development of innovative bio-technological processes, including, but not limited to, thermal hydrolysis, anaerobic digestion, thermal and hydrothermal treatments, and oxidation and immobilisation techniques.

This Special Issue will present and consolidate recent advances in biotechnological conversion technologies, focusing on wastewater treatment and biosolid management, particularly for energy production, volume reduction, resource recovery (carbon, nutrients), contaminant destruction, and char/agri-ash generation.

Topics of interest include, but are not limited to, the following:

  • The removal, degradation, transformation, and destruction of contaminants of emerging concern that are typical of wastewater and biosolid streams, such as per- and polyfluoroalkyl substances (PFASs), microplastics, pharmaceuticals and personal care products, hormones, and pathogens;
  • Thermal treatments, such as pyrolysis, gasification, incineration, hydrothermal carbonisation/liquefaction, and the supercritical water oxidation of biosolids for material and energy production;
  • Circular resource recovery of nutrients and materials from wastewater;
  • Sewage sludge stabilisation methods to create biosolids via thermal hydrolysis, anaerobic digestion, dewatering, and thermal drying;
  • In situ applications of biosolid-derived char in wastewater treatment, biomethane generation, biogas upgrading, and gaseous pollutant removal;
  • Energy production from biogas, biochar, syngas, and bio-oil obtained from the biological–thermal treatment of wastewater sludges;

Any other topic that demonstrates bio-technological solutions to wastewater treatment and biosolid management for energy and material production.

Dr. Ibrahim Gbolahan Hakeem
Prof. Dr. Kalpit Shah
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • volume reduction
  • advanced thermal conversion
  • contaminants of emerging concerns
  • circular resource recovery
  • odour and greenhouse gas emissions
  • sludge-to-energy treatment
  • biomethane generation
  • biochar for energy and environmental applications

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Published Papers (1 paper)

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Research

17 pages, 2505 KB  
Article
Valorisation of Orange Peel into Biochar Using Pyrolysis for Phenolic Contaminant Removal from Water: Experimental and Quantum Chemical Insights
by Lalit Kumar, Kalpit Shah, V. Ezhilselvi, Adhithiya Venkatachalapati Thulasiraman and Ibrahim Gbolahan Hakeem
Energies 2026, 19(6), 1407; https://doi.org/10.3390/en19061407 - 11 Mar 2026
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Abstract
This study investigates orange peel valorisation through KOH pre-treatment and high-temperature pyrolysis (800 °C) to develop a highly porous activated char for the efficient removal of phenolic compounds, specifically 2,4-dinitrophenol (DNP) and aminophenol (AP), from water. The main objective of the study is [...] Read more.
This study investigates orange peel valorisation through KOH pre-treatment and high-temperature pyrolysis (800 °C) to develop a highly porous activated char for the efficient removal of phenolic compounds, specifically 2,4-dinitrophenol (DNP) and aminophenol (AP), from water. The main objective of the study is to synthesise high-surface area activated char from orange peel and investigate its performance for the adsorption of DNP and AP from water. The synthesised adsorbent exhibited a Brunauer–Emmett–Teller (BET) specific surface area of 965 m2/g, contributing to its excellent phenol adsorption efficiency. Batch adsorption experiments were performed, and a maximum removal efficiency of 99% and 92% was observed at pH 4 and 7 with initial concentration 50 mg/L, contact time 60 min, and adsorbent dosage 0.6 g/L, for DNP and AP, respectively. The adsorption process was described by the Langmuir isotherm model (R2 = 0.99), indicating monolayer adsorption and followed pseudo-second-order kinetics, achieving a maximum adsorption capacity of 366 mg/g for DNP and 341 mg/g for AP. Furthermore, DFT analysis revealed that DNP possesses a lower HOMO-LUMO energy gap (−0.54 eV), favouring a stronger adsorption interaction, whereas AP exhibited a relatively higher energy gap (−0.27 eV), corresponding to its comparatively lower adsorption capacity. Overall, the findings demonstrates that a single step chemical-thermal conversion of orange peel into biochar-based adsorbent offers a sustainable pathway for the removal of phenolic compounds from water. Full article
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