This paper presents a new way to design a broadband harvester for harvesting high energy over a low-frequency range of 10–15 Hz. The design comprises a cantilever beam with two parallel grooves to form three dissimilar length parallel branches, each with an unequal concentrated tip mass. The piezoelectric material covers the whole length on both sides of the beam to form a bimorph. Appropriate geometry and mass magnitudes are obtained by a parametric study using the Finite Element Method. The design was simulated in COMSOL Multiphysics to study its response. The first three bending modes were utilized in energy harvesting, resulting in three power peaks at their respective fundamental frequencies. The adequate load resistance determined was 5.62 kΩ, at which maximum power can be harvested. The proposed harvester was compared to two other harvesters presented in the literature for validation: First, an optimized conventional harvester while the proposed harvester is operating at adequate load resistance. Second, a multimodal harvester, while the proposed harvester is operating at a 10 kΩ load. The suggested harvester proved to be more efficient by harvesting sufficiently higher broadband energy and is applicable in a wide range of vibration environments because of its adaptability in design.

The use of biochar biofilters as a sustainable solution for industrial water remediation has become popular. This review presents a summary of existing works on the use of biochar filters for industrial effluent. Factors like design, hydraulic performance, and mechanical durability have been explored. For filter design, key reactor parameters like empty bed contact time (EBCT), hydraulic load ratio (HLR), bed depth, and media configuration were reviewed. The parameters were found to have a significant effect on pressure drop, clogging mechanisms, and backwash requirements. Similarly, the mechanical properties of biochar media, like density, hardness, and attrition resistance, were affected by head loss, media lifespan, and regeneration capability. Case studies like textile pharmaceutical industries and stormwater effluents revealed reductions in colour, heavy metals, and refractory organics. Practical design workframes are provided for scaling systems from laboratory columns to pilot and full-scale levels. EBCT-based sizing, media selection, parallel module operation, and breakthrough monitoring are emphasized for multiscale designs. Regeneration techniques were evaluated in relation to lifecycle durability and end-of-life handling. It was shown that biochar biofilters are suitable for effluent polishing with appropriate hydraulic design, especially when EBCT exceeds 15 minutes. The main remaining challenges that were identified are the control of long-term fouling, standardization of filter-grade biochar, and balancing adsorption capacity with permeability. In future studies, automated fouling control, standardized specifications for filter-grade biochar, and composite media designs that balance adsorption efficiency with hydraulic permeability should be explored.