Rashid Abbas Khan

Biomass feedstocks are converted into engineered carbon-based fertilizers whose pores and surface chemistry control nutrient release, rhizosphere interactions, and plant uptake, improving soil health and sustainability.

Nanotechnology is increasingly contributing to decarbonization, food security, and resource-efficient production. This chapter, per the authors, provides an overview of the environmental and life-cycle aspects of nanomaterials used in lithium-ion batteries and agricultural systems. It discusses how nanostructured electrodes, separators, electrolytes, and conductive additives can improve ion transport, interfacial contact, mechanical stability, and battery cycle life. In agriculture, the chapter examines nanosensors, nanocarriers, nano-fertilizers, and nano-pesticides for improving nutrient-use efficiency, reducing agrochemical losses, and supporting precision farming. It also highlights key sustainability concerns, including raw-material extraction, energy-intensive synthesis, environmental release, toxicity, occupational exposure, and end-of-life management. The chapter emphasizes life-cycle assessment, safer-by-design approaches, exposure assessment, and circular economy strategies.

Abiotic stressors, including drought, salinity, and heavy metal contamination, pose escalating threats to global food security, challenges further exacerbated by climate change and progressive soil degradation. As a strategic geochemical amendment, biochar is increasingly proposed to enhance soil resilience and agricultural sustainability, directly supporting sustainable development goal (SDG) 2 (Zero Hunger) and SDG 13 (Climate Action). This review critically evaluates biochar in stress mitigation, focusing on production principles, soil physicochemical adjustments, and changes in the soil‐plant microbiome and soil–plant–microbe interactions. Specifically, we synthesize data demonstrating biochar's multifaceted efficacy: regulating ion homeostasis to reduce Na ⁺ uptake by 20%–40% under saline conditions, enhancing water use efficiency by 15%–30% in arid environments, and immobilizing heavy metals to reduce cadmium (Cd) accumulation by 25%–50%. These synergistic soil–plant interactions further contribute to SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land). However, significant challenges remain regarding feedstock variability, dosage optimization, and long‐term field stability. Furthermore, performance discrepancies under combined multi‐stress scenarios underscore the urgent need for standardized biochar formulations. Integrating biochar into precision frameworks offers a promising geobiochemical frontier for modulating multi‐stress crop resilience and shifting soil–plant–microbe dynamics toward climate‐adaptive landscapes. Such advancements are essential for ensuring global food security for a projected population of 9.7 billion by 2050.

The water sector faces an urgent mandate to shift from energy-intensive wastewater treatment toward decentralized, resource-recovering systems that address the global water-energy nexus. Microbial Electrochemical Technologies (METs) have emerged as a transformative engineered solution capable of simultaneously remediating complex pollutant streams while recovering high-value energy carriers. This review provides a comprehensive analysis of the state-of-the-art in METs, explicitly bridging the interface of biochemistry and molecular-scale nanochemistry. We synthesize fundamental extracellular electron transfer (EET) kinetics with recent breakthroughs in green-synthesized nanomaterials, quantum dots, and advanced nanostructured electrode architectures (including carbon nanotubes and 3D graphene composites) engineered to accelerate electrocatalytic remediation. By critically evaluating performance indicators, such as power density, Coulombic efficiency, and nanomaterial-driven pollutant degradation kinetics, this work assesses the feasibility of integrating nano-enhanced METs with existing infrastructure like anaerobic digestion. Furthermore, we address critical barriers to industrial-scale deployment, specifically evaluating the environmental fate, safety risks, and regulatory frameworks governing nanomaterial usage in water reuse. To bridge the gap between laboratory discovery and societal impact, we highlight the pivotal role of “Industry 4.0” tools, including artificial intelligence (AI) and digital twins, in optimizing real-time reactor performance. This review concludes by outlining a strategic roadmap that aligns nano-engineered METs with circular bioeconomy principles, offering a sustainable blueprint for global climate adaptation and resilient water governance.

Microalgae is a disruptive technology for Carbon Capture and Utilization in a circular bioeconomy, showing volumetric productivity and CO2 fixation rates much higher than terrestrial plants. These organisms act as efficient biological carbon sinks due to specialized Carbon Concentrating Mechanisms that enhance inorganic carbon concentration at RuBisCO to maximize the Calvin–Benson cycle. Reported sequestration rates among microalgal strains range from 0.06 to 2.57 g L−1 d−1, with Haematococcus sp. at the upper end. Genetic and metabolic engineering improved performance, Chlamydomonas reinhardtii manipulation increased carbon fixation by 35%, while transgenic Chlorella sorokiniana achieved 88.5% carbon capture. Coupling microalgal systems with wastewater treatment enables nutrient recovery, removing up to 93% nitrates and 83% phosphates, yielding 3.21 g L−1 biomass. Optimal growth occurs at ~2000 lux and up to 35 °C. Although 5 vol% CO2 enhances biomass, 9 vol% can cause culture collapse. High PBR capital costs and energy-intensive harvesting remain major commercialization barriers.