Low Impact Process Research Articles

Moisture Sorption of Wood Surfaces Modified by One-Sided Carbonization as an Alternative to Traditional Façade Coatings

Surface carbonization, or charring, of wooden cladding boards is a promising, low impact process that can substitute inorganic coatings. The char surface is inert and hydrophobic and possibly a long-lasting solution for exterior uses. To determine the performance of surface-charred wood, several sorption experiments were established. Sapwood of two hardwoods (aspen, birch) and two softwoods (pine, spruce) were used as the experimental material, modified by contact charring and gas flame charring, including surfaces coated with oil for further protection. The results showed that flame charring modification is equal to a double layer of acrylic paint on primer in terms of permeability on all wood species, with higher moisture exclusion efficiency at high relative humidity. Contact charring modification presented much improved properties in comparison to both flame charring and acrylic paint in all implemented sorption experiments, but the dimensional stability was poor with strong cupping in wetting. However, hardwoods and especially birch exhibited less dimensional distortion than the other investigated species, and oiling further reduced the cupping. The contact charring modification produced more repeatable results with less impact from substrate and all wood species benefitted, whereas the flame charring modification is more dependent on inherent properties of the wood species, and does not seem to suit aspen as well as birch, and pine as well as spruce, although oiling affected the observed results.

Odors Emitted from Biological Waste and Wastewater Treatment Plants: A Mini-Review

In recent decades, a new generation of waste treatment plants based on biological treatments (mainly anaerobic digestion and/or composting) has arisen all over the world. These plants have been progressively substituted for incineration facilities and landfills. Although these plants have evident benefits in terms of their environmental impact and higher recovery of material and energy, the release into atmosphere of malodorous compounds and its mitigation is one of the main challenges that these plants face. In this review, the methodology to determine odors, the main causes of having undesirable gaseous emissions, and the characterization of odors are reviewed. Finally, another important topic of odor abatement technologies is treated, especially those related to biological low-impact processes. In conclusion, odor control is the main challenge for a sustainable implementation of modern waste treatment plants.

The synergistic effect of peracetic acid activated by graphene oxide quantum dots in the inactivation of E. coli and organic dye removal with LED reactor light

This study presents a low-impact process that uses the synergy of peracetic acid (PAA) and graphene oxide quantum GQDs to degrade poorly biodegradable organic compounds and potentially substitute chlorination in wastewater treatment. The role of GQDs in GQDs/PAA activity and the effect of GQDs loading were examined. The results showed that increasing GQDs loading in the GQDs/PAA system greatly improved the photodegradation efficiency. Conversely, increasing the PAA concentration slightly enhanced efficiency due to few active sites being available. GQDs acted as catalysts and radical scavenging experiments confirmed that the degradation occurred via generation of hydroxyl (•OH) and peroxy (CH3C(=O)OO•)) radicals. A probable degradation mechanism of the organic dye was presented based on the reaction by-products detected after HPLC-MS studies. The E. coli inactivation mechanism was elucidated by monitoring the morphological changes of E. coli using scanning microscopy. The proposed antimicrobial mechanism includes the initial diffusion of PAA through the cell membrane which caused damage and induced cellular matter leakage, resulting in cell death. Bacterial regrowth studies confirmed GQDs/PAA were able to bypass the natural mechanisms of microorganisms that enables them to repair any damages in their DNA.

The attractive concept of simplicity in environmental impact assessment: Perceptions of outcomes in southeastern Brazil

Pressures are mounting for the simplification of environmental impact assessment (EIA). This phenomenon is drawing increasing scholarly attention, but studies have not gone far beyond speculating what could happen as a result of recently implemented or proposed regulatory changes. This paper takes a more longitudinal look at simplified EIAs. The main objective was to analyze the perceived outcomes of a number of simplified EIA processes, using Brazil as the empirical context. More specifically, this paper aimed at understanding: 1) how simplified EIAs have been conceptualized and implemented in southeastern Brazil; and 2) how developers and civil servants in that region perceive the outcomes of simplified EIAs. This study adopted a sequential mixed method research approach. Data was collected through literature reviews, 261 telephone-based interviews and 10 face-to-face interviews. Degrees of EIA simplification can vary significantly within and across jurisdictions. In any case, simplification is often framed as a win-win solution to EIA ineffectiveness, through which regulatory and procedural changes are made to ease the process, while, at the same time, maintaining or providing better environmental protection. This approach is more frequently applied to potentially low-impact processes. Chi-square tests of the data collected through telephone interviews in the Brazilian state of Minas Gerais indicated that developers tend to perceive EIA processes as difficult and slow regardless of how simplified it is. Most civil servants, who were directly involved in the implementation of simplified EIAs in state environmental agencies, argued that simplified EIAs are driven mostly by environmental agencies, as these institutions have long been unable to cope with an ever-increasing load of license applications. Policy outcomes of simplified EIAs in the territory are not sufficiently monitored by state agencies. Civil servants revealed concerns about the potential long term effects of EIA simplification on the ground, as they have had limited resources for audits and inspections.

Low Impact Methanol Production from Sulfur Rich Coal Gasification

In economy nowadays, methanol is already a key compound widely employed as building block for producing intermediates or synthetic hydrocarbons, solvent, energy storage medium, and fuel. In recent times, methanol has been employed in a number of innovative applications. It is a clean and sustainable energy resource that can be produced starting from different sources traditional or renewable: natural gas, coal, biomass, landfill gas and power plant/industrial emissions. In this work is proposed an innovative low impact process for methanol production starting from coal gasification. The most important features, instead the traditional ones, are the lower emissions of CO2 (about 2.5%) and the surplus production of methanol (about 1.7%) without any addiction of primary sources. Moreover, it is demonstrated that a coal charges with a high sulfur content means a higher reduction of CO2 emissions. The key idea is the application of AG2STM technology that is a completely new effective route of processing acid gases: H2S and CO2 are converted into syngas (CO and H2) by means of a regenerative thermal reactor.

Direct light-induced polymerization of cobalt-based redox shuttles: an ultrafast way towards stable dye-sensitized solar cells.

The photopolymerization of Co(II)/Co(III) complexes for dye-sensitized solar cells (DSSCs) by means of a fast, inexpensive, in situ and inhibition-free process has been examined. We have succeeded in fabricating high-performance DSSCs able to retain a light-to-electricity power conversion efficiency exceeding 6.5% (8.5% at low intensity) after 1800 h of mixed (light on/off, temperature high/low) accelerated aging tests, thus revealing a possible way for the stabilization of these record-holding redox pairs.

Controlled DI Water Gasification System for Advanced Semiconductor Cleaning Processes

Driven by continually shrinking feature sizes and adoption of ever more fragile materials in IC manufacturing, it has become crucial to develop effective and low impact processes that are benign to features on wafers. Recently, there is increasing interest in using gasified DI water in photolithography, wet etch & clean, mask clean and CMP applications. In this paper, we describe the design and development of an automated in-line CO2 gasification system using Entegris all PFA hollow fiber membrane-based contactors. The paper addresses key system design features to enable a responsive and seamless process with minimum system downtime. Capacity and control data demonstrating the versatility and robustness of the system will also be presented.