The increasing amount of electronic waste (e-waste) has placed significant burdens on society and the environment, particularly with regards to waste printed circuit boards (WPCBs), which are essential in electronics manufacturing. As natural resources become scarce, it is crucial to effectively recycle and reclaim WPCBs due to their high value and large output. Comminuting printed circuit boards is a crucial step in enabling the recovery of valuable materials, and this review provides an in-depth analysis of WPCB comminution. It explores the structure, types, and composition of the WPCBs, including their mechanical properties. The review thoroughly surveys conventional mechanical comminution machinery and also discusses emerging technologies such as innovative pretreatment approaches, electrodynamic disintegration, high voltage electrical pulses, and abrasive waterjet cutting. The literature has been critically examined to identify research gaps and inconsistencies, and future directions for increased efficiency and sustainability are proposed.

In recent years, the environmental impacts of plastic production and consumption have become increasingly significant, particularly due to their petroleum-based origins and the substantial waste management challenges they pose. Currently, global plastic waste production has reached 413.8 million metric tons across 192 countries, contributing notably to greenhouse gas emissions. Bioplastics have emerged as eco-friendly alternatives, with bioplastic carrier bags composed of 20% starch, 10% additives, and 70% polybutylene adipate terephthalate (PBAT) being the focus of this research. This study aimed to evaluate the biodegradation of these bioplastic bags under industrial composting conditions, addressing the gap in the existing literature that often lacks real-world applicability. A large-scale composting experiment was conducted using 37.5 tons of manure/wood and 50 tons of biopolymer bags over 12 weeks. Results showed that compost temperatures peaked at 70 °C and remained above 50 °C, pH levels stabilized at 8.16, and electrical conductivity was recorded at 1251 μs cm⁻¹. Significant changes were observed in key metrics, such as the carbon-to-nitrogen ratio and organic matter content. Disintegration tests revealed that 95% of the bags disintegrated by the 12th week, though ecotoxicity tests indicated varying germination inhibition rates. Advanced analytical methods (Fourier transform infrared spectroscopy, gas chromatography coupled with mass spectrometry) highlighted morphological and chemical transformations in the bags. This research enhances understanding of bioplastic degradation in real-world composting environments and suggests potential improvements to existing standards, promoting sustainable waste management solutions.

Natural rutile is a widely available titanium mineral which shows great potential as a photocatalyst for environmental remediation when processed correctly. Industries invest large sums in the transformation of the rutile mineral into pure, synthetic nano titania. Still, the present study proves that bare natural rutile with trace element content can also be applied as a photocatalyst, without harsh chemical interventions, simply by processing via nano grinding. Samples with different mean primary particle size values were obtained by wet stirred media milling, their compositional and structural properties were investigated, and their photocatalytic properties were evaluated under both visible- and UV-light illumination for the degradation of phenol and ibuprofen. By changing the grain size and the particle size distribution, and due to the doping effect of impurities present in the mineral, the band gap values of the samples and their photocatalytic activities changed as well. The nano milled rutile exhibited visible light photocatalytic activity, with a 33% degradation efficiency in the case of both phenol and ibuprofen, after 22 h of irradiation. The present study not only highlights the photocatalytic degradation of a pharmaceutical by natural rutile mineral, but its findings also suggest that ground nano rutile can function as an environmentally friendly photocatalyst, as it not only avoids the use of harmful chemicals typically employed in TiO₂ synthesis but also offers a simpler, more cost-effective alternative for producing photocatalytic materials.

The two most common used mechanical test in the aggregate industry for quality control are the resistance to wear (micro-Deval) and resistance to fragmentation (Los Angeles) tests. The quality of aggregates strongly depends on the textural, structural, and mineralogical features of the crushed material. These rock properties were experimentally studied on andesite samples from Tállya quarry. The mineralogical and chemical composition of samples were determined, textural observations were made on thin sections. The alteration was quantified using the chemical composition and mineralogical data. Micro-Deval and Los Angeles tests were conducted on the samples. The micro-Deval indices and the Los Angeles values showed similar trends, although the different type of stresses. The results showed that the examined mechanical properties of the Tállya andesites are complexly influenced by the textural and structural features, mineralogical composition, and alteration, however alteration has one of the most significant effects.