This study aimed to determine the effect of the low-temperature conditioning of excess dairy sewage sludge using solidified carbon dioxide on the efficiency of methane fermentation. An increase in the solidified carbon dioxide to excess dairy sewage sludge volumetric ratio above 0.3 had no significant effect on chemical oxygen demand concentration in the dissolved phase. The highest chemical oxygen demand values, ranging from 490.6 ± 12.9 to 510.5 ± 28.5 mg·dm⁻³, were determined at solidified carbon dioxide to excess dairy sewage sludge ratio ranging from 0.3 to 0.5. The low-temperature conditioning caused ammonia nitrogen concentration to increase from 155.2 ± 10.2 to 185.9 ± 11.1 mg·dm⁻³ and orthophosphates concentration to increase from 198.5 ± 23.1 to 300.6 ± 35.9 mg·dm⁻³ in the dissolved phase. The highest unitary amount of biogas, reaching 630.2 ± 45.5 cm³·g o.d.m.⁻¹, was produced in the variant with the solidified carbon dioxide to excess dairy sewage sludge volumetric ratio of 0.3. Methane content of the biogas produced was at 68.7 ± 1.5%. Increased solidified carbon dioxide dose did not lead to any significant changes in biogas and methane production. The efficiency of biogas production from unconditioned excess dairy sewage sludge was lower by 43.0 ± 3.2%. The analysis demonstrated that the low-temperature conditioning is an energetic viable technology aiding the methane fermentation process.

The development of a sustainable bioenergy market is currently largely fueled by energy crops, whose ever-increasing production competes with the global food and feed supply. Consequently, non-food crops need to be considered as alternatives for energy biomass production. Such alternatives include microalgal biomass, as well as energy crops grown on non-agricultural land. The aim of the present study was to evaluate how co-digestion of microalgal biomass with giant miscanthus silage affects feedstock properties, the biogas production process, biogas yields, methane fractions and the digestate profile. Combining giant miscanthus silage with microbial biomass was found to produce better C/N ratios than using either substrate alone. The highest biogas and methane production rates—628.00 ± 20.05 cm³/gVS and 3045.56 ± 274.06 cm³ CH₄/d—were obtained with 40% microalgae in the feedstock. In all variants, the bulk of the microbial community consisted of bacteria (EUB338) and archaea (ARC915).

Acid whey is a by-product of the dairy industry that should be utilized or appropriately neutralized. Anaerobic processes represent a group of prospective methods for whey processing, and a key priority in their development is to improve their technological and economical effectiveness. The present study aimed to determine the effect of ultrasonic disintegration (UD) of acid whey on the course and effectiveness of methane fermentation. The study results demonstrated that extending the UD duration resulted in increased concentrations of dissolved forms of COD and TOC, efficiency of organic matter biodegradation, and CH₄ production. The best effects were achieved at 900 s US, including CH₄ production of 0.203 ± 0.01 dm³/gCOD_in. and CH₄ content accounting for 70.9 ± 2.8%. Organic compounds were removed with the following efficiencies: COD—78.7 ± 2.1%, TOC—80.2 ± 1.3%, and BOD₅—84.1 ± 1.6%. The highest net energy gain of 5.763 Wh was achieved upon UD of 300 s. Extension of UD time had no significant effect on the improvement in the energetic effectiveness of anaerobic digestion. A strong positive correlation was found between COD and TOC concentrations in the dissolved phase and CH₄ production yield.

Water supply pumping stations are among the main energy-consuming elements in the water supply system. The energy optimization of a pumping station can significantly affect the energy consumption of a water utility. This article deals with the energy optimization of water pumping stations. The work assumes several variants of optimization of water supply pumping stations through changes in the water supply system, pressure changes in the pumping station, and modification of the number of pumps. After analyzing the network, conducting field tests, and creating a model of the water supply network, the network was calibrated in order to reproduce the existing water network as accurately as possible. Then, a variant analysis was performed, and the best optimization method for the pumping station was selected. In two variants, there was a decrease in electricity consumption; in three there, was an increase; in one, there was no change. By connecting the DMA zones and modifying the pressure in the pumping station, the energy consumption of the pumping stations was reduced. On this basis, it was found that it is possible to optimize the water pumping station by modifying the pumping station and work related to the network layout.

A properly conducted vermicomposting process is an environmentally friendly technology used to transform selected organic waste into vermicompost. This organic fertilizer is increasingly used in agriculture and horticulture as an alternative to mineral fertilizers. Research has investigated the use of vermicompost made from the waste mass of sugar beet pulp as a soil additive in the cultivation of peas (Pisum sativum L.). Experimentally, five treatments consisted of: a heavy clay soil as control (SL); the same soil with 10, 25, and 50% substitution of vermicompost, (V10, V25, and V50, respectively); and a standard peat-based horticulture substrate (GS) for comparison. Analyzed pea characteristics and the content of macro and microelements in their biomass were most favorably influenced by 25 and 50% vermicompost addition, and the values obtained were similar to those in the GS treatment. The lowest values of analyzed traits for P. sativum were found in the SL group. Thus, appropriate addition of vermicompost in the construction of plant growing substrates can reduce the use of inorganic fertilizers and be an alternative to peat in the medium, contributing to reduced use of this valuable environmental resource.