Wastewater Purification with Nutrient and Carbon Recovery in a Mobile Resource Container

Water reuse from wastewater treatment plants can significantly reduce freshwater demand. Additionally municipal sewage and some industrial wastewaters could be used as sources of nutrients and carbon more effectively than they are used today. Biological treatments have attracted the most attention in wastewater purification, whereas, so far, only a little attention has been paid to the physico-chemical technologies. These technologies could, however, have great potential to recover nutrients when purifying wastewater. In this study, the main emphasis was to study the possibilities to utilize existing physico-chemical unit operations for wastewater purification and nutrients as well as carbon recovery. Unit operations were selected so that they could produce exploitable circular economy products from wastewaters and be assembled in a mobile container for carrying out recovery anywhere that is suitable. The results showed that in a mobile container, solids could be successfully separated from the studied wastewaters by flocculation-assisted solid/liquid separation and then processed into hydrochar by hydrothermal carbonization. Phosphate was precipitated using lime milk as calcium phosphate, and ammonium nitrogen was captured from the wastewater using membrane contactor technology resulting in ammonium sulphate for fertilizer use. Additionally, reverse osmosis retained residual impurities well, producing good quality water for reuse. The techno-economic feasibility seems promising.

Mapping the irrecoverable carbon in Earth’s ecosystems

Avoiding catastrophic climate change requires rapid decarbonization and improved ecosystem stewardship at a planetary scale. The carbon released through the burning of fossil fuels would take millennia to regenerate on Earth. Though the timeframe of carbon recovery for ecosystems such as peatlands, mangroves and old-growth forests is shorter (centuries), this timeframe still exceeds the time we have remaining to avoid the worst impacts of global warming. There are some natural places that we cannot afford to lose due to their irreplaceable carbon reserves. Here we map ‘irrecoverable carbon’ globally to identify ecosystem carbon that remains within human purview to manage and, if lost, could not be recovered by mid-century, by when we need to reach net-zero emissions to avoid the worst climate impacts. Since 2010, agriculture, logging and wildfire have caused emissions of at least 4.0 Gt of irrecoverable carbon. The world’s remaining 139.1 ± 443.6 Gt of irrecoverable carbon faces risks from land-use conversion and climate change. These risks can be reduced through proactive protection and adaptive management. Currently, 23.0% of irrecoverable carbon is within protected areas and 33.6% is managed by Indigenous peoples and local communities. Half of Earth’s irrecoverable carbon is concentrated on just 3.3% of its land, highlighting opportunities for targeted efforts to increase global climate security.

Biodegradation of p-xylene – A comparison for three Cold-active Pseudomonas strains

p-xylene is considered a recalcitrant compound despite the similar aromatic structure with BTE (Benzene, toluene, ethylbenzene). This study evaluated the biodegradation potential of p-xylene by three cold-active Pseudomonas strains (named Pseudomonas putida S2TR-01, Pseudomonas S2TR-20, and Pseudomonas S2TR-09). The catabolic genes (xylM, xylA and xylE) and their regulatory genes (xylR and xylS) were investigated for the p-xylene metabolism. The biodegradation results showed that only strain S2TR-09 was able to degrade 200 mg/L of p-xylene after 60 h at 15 °C. The gene expression study indicated that xylE (encoding catechol 2, 3-dioxygenase) represents the bottleneck for p-xylene biodegradation and lack of its expression leads to the accumulation of intermediates and inhibits biomass production as well as carbon recovery. The activity of xylene monooxygenase and catechol 2,3 dioxygenase was significantly high in P. azotoformans S2TR-09 (0.5 and 0.08 U/mg) in the presence of p-xylene. The expression of ring cleavage enzyme, its encoding genes (xylE), and its activator (xylS) enabled to link the differences in p-xylene metabolism and can be used as a novel biomarker for efficient p-xylene biodegradation in contaminated sites.

Optimization of production technologyof continuous cast rail steel for increasing its purity by non-metallic inclusions

The purpose of the work was to examine the reasons for formation of non-deformable non-metallic inclusions in rail steel and ways to reduce the rejection of finished rails due to the defects revealed during ultrasonic testing. The study was conducted at the steelmaking plant of JSC “Ural Steel”. In the central laboratory of the combine, a chemical analysis of non-metallic inclusions was carried out in the samples of finished rails produced from blanks manufactured by JSC “Ural Steel” and rejected at the ultrasonic test unit during the rail production at the “Aktobe Rail and Section Works” LLP. Non-metallic inclusions by their composition are represented by aluminium oxides. The most probable reasons for their formation have been determined as following: the use of aluminium containing ferroalloys and interaction of the melt components with refractory materials and casting powder. The authors made analysis of the ferroalloys used in production of rail steel. Industrial trials of the manufacturing process of continuously cast blanks from rail steel were carried out, where FS65 ferrosilicon, which contains aluminium, was replaced with silicon carbide. An increasing degree of silicon and carbon recovery in trial heats was noted. Evaluation of contamination with non-metallic inclusions and mechanical properties of the rail steel manufactured using the experimental technology showed that the service characteristics of the rail steel meet requirements of the state standard GOST R 51685 – 2013. The full-scale experiment has confirmed that the technology of alloying E76F rail steel with silicon carbide at JSC “Ural Steel” is technically feasible. The yield of 100-meter rails was increased by 17 % on a trial batch produced from JSC “Ural Steel” continuously cast blanks.