Issue 02/2023 (February)

In many countries, the structure of the gas market is undergoing significant changes, driven mainly by the decarbonization of Energy sources (renewable gases), the development of global and local gas trade (including primarily LNG), the activities of regulatory institutions (liberalization of markets, TPA principle), or, finally, the challenges of renewable energy storage (hydrogen and synthetic methane). The above-mentioned processes lead to an increase in the number of distributed entry points in the gas network, accompanied by a significant diversification of gas quality. The article reviews modern technologies related to the management of gas networks under diversified gas quality conditions, and solutions supporting the introduction of renewable gases into the pipeline systems. Examples of biomethane and hydrogen injection plants are presented, the experience of selected countries in integrating LNG and pipeline gas is discussed, and modern techniques for software-based gas quality tracking systems in the networks are presented.

W ostatnich latach odnotowano dynamiczny rozwój przemysłu biometanowego w Europie. Zwiększa się liczba instalacji biometanowych,a produkcja biometanu wynosi już około 3,5 mld m3. W Polsce brakuje instalacji biometanowych, co więcej, nic nie wskazuje na to, żeby w najbliższym czasie nastąpił ich gwałtowny rozwój.Rozporządzenie Systemowe dotyczące funkcjonowania systemu gazowego miało być pierwszym krokiem w kierunku umożliwienia rozwoju rynku biometanowego w Polsce, jednakże niektóre zapisy wymagają zmiany lub doprecyzowania, by Rozporządzeniespełniło związane z nim oczekiwania.

Flourishing petroleum industry is the main cause of environmental pollution. According to the estimates, annually from 3 up to 6 million metric tons of crude oil are released into the world’s water reservoirs due to oil seepage and spills. Supertanker accidents and oil rig disasters are the cause of major oil spills in the ocean, the oil slick while floating on the water surface can spread out by wind and currents to disrupt the ecosystem at long distances from the source of the spill. To limit the scale of environmental damage some oil spill clean-up techniques have been implemented, like for example skimming – physical separationof oil from water, use of sorbents such as, for example, volcanic ash and shavings of polyester-derived plastic to absorboil hydrocarbons or application of surfactants to disperse oil plume in a water column and thus make it available for bacterialdegradation. Recently, more attention is being paid to bioremediation process employing indigenous and exogenous hydrocarbondegrading bacteria to remove spilled oil fractions. This approach seems most promising and beneficial as ecosystemclean-up and recultivation method, since based on activity of naturally occurring microorganisms it is safer, more sustainableand providing diminished human impact on environment in comparison with other techniques.

Groundwater, the main source of the drinking water supply, due to its composition, often requires treatment using aeration and filtration processes. The effectiveness of the process is determined by a number of operational parameters of individual unit processes, which should be controlled and, in the case of the treated water quality deterioration, properly verified. In the article, based on the performer studies, it is shown that the evaluation of iron and manganese compounds removal during groundwater treatment can be carried out on the basis of large-laboratory and technical scale studies.

The paper presents a sensor network for the measurements of air pollution on the campus of Wrocław University of Science and Technology. Sensor devices for the measurement of the PM2.5, using Plantower low-cost PMS A003 optical sensors, aredescribed. The structure of the network located on the main campus and peripheral campuses is also presented. The operation of the system for informing the academic community and residents of Wrocław about air quality is described, and examples of the results of tests carried out with the sensor devices are presented. During episodes of elevated PM2.5 concentrations, sensor signals were consistent with measurements from regulatory monitoring stations, and the devices showed high reproducibility between units. In the future, the network may be supplemented with new sensors for measuring gaseous pollutants such as ozone.

Modern municipal waste management should be in line with the circular economy (CE) assumptions – an economic model based on refuse,rethink, reduce, reuse, repair, refurbish, remanufacture, repurpose, recycle and recover. The implementation of CE principles is a challenge for every city. The city of Łódź served as an example of considerations in this regard, where there is still room for taking actions within the circular economy,which will also allow for improving the municipal waste management system. In the years 2015-2020, a significant increase in the municipal waste accumulation index was observed – both in the city of Łódź and in the entire Łódź Voivodeship. One of the most difficult challenges seems to be the functioning of an effective selective municipal waste collection system. Nearly 60% of all municipal waste collected in Łódź is mixed (residual) waste, although the share of selectively collected waste is increasing. It also seems difficult to achieve the required level of preparation for the reuse and recycling of municipal waste, but it is a problem for the whole country.

Heat recovery from gray wastewater is an attractive energy source that increases the efficiency of the domestic hot water preparation system. The temperature effectiveness of heat recovery in horizontal heat exchangers depends on the operating conditions described by the temperature, size, proportion and simultaneity flows of drain water and utility. Operating characteristics of a horizontal plate heat exchanger for heat recovery from gray wastewater were tested for two variants of hydraulic connection, variable proportions of streams on the hot and cold sides of the exchanger, and different temperatures of gray wastewater. Extended operating characteristics of the heat exchanger were prepared, enabling the estimation of energy results in a wide range of operating conditions of the heat exchanger. The tests were carried out in simulated laboratory working conditions typical for a shower. The test flows were 50, 100 and 150% of the design flow rate from the shower, and the hot water temperature varied from 30 to 50°C, reflecting the baths of users with different preferences. The results of the temperature effectiveness obtained in the tests were compared with the values presented in the literature for other drain water heat recovery units, both in vertical and horizontal applications.