The microbial metabolic activity on carbohydrates and polymers impact the biodegradability of landfilled solid waste

Biological waste degradation is the main driving factor for landfill emissions. In a 2-year laboratory experiment simulating different landfill in-situ aeration scenarios, the microbial degradation of solid waste under different oxygen conditions (treatments) was investigated. Nine landfill simulation reactors were operated in triplicates under three distinct treatments. Three were kept anaerobic, three were aerated for 706 days after an initial anaerobic phase and three were aerated for 244 days in between two anaerobic phases. In total, 36 solid and 36 leachate samples were taken. Biolog® EcoPlates™ were used to assess the functional diversity of the microbial community. It was possible to directly relate the functional diversity to the biodegradability of MSW (municipal solid waste), measured as RI4 (respiration index after 4 days). The differences between the treatments in RI4 as well as in carbon and polymer degradation potential were small. Initially, a RI4 of about 6.5 to 8 mg O2 kg−1 DW was reduced to less than 1 mg O2 kg−1 DW within 114 days of treatment. After the termination of aeration, an increase 3 mg O2 kg−1 DW was observed. By calculating the integral of the Gompertz equation based on spline interpolation of the Biolog® EcoPlates™ results after 96 h two substrate groups mainly contributing to the biodegradability were identified: carbohydrates and polymers. The microbial activity of the respective microbial consortium could thus be related to the biodegradability with a multilinear regression model.

Biochemical Methane Potential and Kinetic Parameters of Goat Manure at Various Inoculum to Substrate Ratios

Anaerobic digestion is a proven technology for managing manure while harvesting natural gas and digestate as a biofertilizer. The biochemical methane potential (BMP), biodegradability, and kinetic parameters of goat manure (GM) were investigated at different inoculum to substrate ratios (ISRs). The cumulative biomethane yields at the ISRs of 0.0, 0.3, 0.5, 0.8, 1.1, 1.3, and 2.6 were 191.7, 214.3, 214.9, 225.9, 222.1, 222.8, and 229.9 mL gvs−1, respectively. The biomethane yield at all ISRs was significantly higher than control (0 ISR). Above the ISR of 0.0, the biomethane yield was similar among all ISRs. The biodegradability of GM at the ISRs of 0.3, 0.5, 0.8, 1.1, 1.3, and 2.6 varied between 73.3% and 78.7% and was statistically similar. In total, 90% of the yield was observed in 31 and 32 days in control and all other ISRs, respectively. The modified Gompertz equation fitted very well (R2 = 0.99) to the BMP of GM but predicted the lag phase (λ) of 3.2–5.2 days against observed 8–10 days among control and other ISRs.

Enhanced biogas production from anaerobic digestion of wastewater from the fruit juice industry by sonolysis: experiments and modelling

The aim of this study is to investigate the use of ultrasound pretreatment as potential technique to solubilize organic matter and fermentation of fruit juice effluents in anaerobic batch reactor. The efficacy of ultrasound pretreatment has been assessed at low frequency of 20 kHz and at different sonication times (20, 40 and 60 min). Compared with control, the amount of biogas produced increased by 47, 57 and 60% for sonication times of 20, 40 and 60 min, respectively. Methane content of the produced biogas was about 59% in the control and 64% in the case of effluent subjected to ultrasonic for 60 min. After 20 days of anaerobic digestion of the fruit juice effluents, the efficiency of COD increased by 9, 31 and 35% with respect to control for sonication times of 20, 40 and 60 min, respectively, corresponding to total sugars uptake efficiency of about 35, 51 and 54%, respectively. The modified Gompertz equation was used to describe the cumulative biogas production. A good agreement was found between simulated and experimental data.

Dynamics of Diaporthe ampelina conidia released from grape canes that overwintered in the vineyard

Phomopsis cane and leaf spot (PCLS) is an important disease of grapevines, which is mainly caused by Diaporthe ampelina. Dispersal dynamics of D. ampelina spores were investigated in two vineyards, one in North Italy and one in Montenegro, by using spore samplers that collected alpha and beta conidia from rain water running off from PCLS-affected canes. The canes were collected from each vineyard, deployed and overwintered in the corresponding vineyards. In each of three years (2016, 2017, and 2018), conidial dispersal was investigated during one (Montenegro) or two (Italy) growing seasons following the deployment of the PCLS-affected canes. In the first growing season following cane deployment in both vineyards, alpha conidia were mostly found in runoff water after grapevine bud break, especially in April and May, and beta conidia were regularly found in numbers comparable to alpha conidia, most frequently from June to September. In Italy, high numbers of alpha and beta conidia were also collected during the second growing season following cane deployment. The dispersal dynamics of alpha conidia over time were described by a Gompertz equation using hydrothermal time (i.e., the accumulated effect of temperature on the maturation rate of pycnidia on days in which the number of hours of wetness was ≥ 6 or 9 h), with R2 and concordance correlation coefficient >0.9. Rain (≥ 0.2 mm) was a good predictor of conidial dispersal, with an overall accuracy of 0.97. These results increase our understanding of D. ampelina spore dispersal and should be integrated into warning systems for PCLS management.

Growth of Stegophiura nodosa (Echinodermata, Ophiuroidea) in the Pechora Sea

The brittle star Stegophiura nodosa is one of the most abundant ophiuroid species living in Arctic seas and serves as a food resource for demersal fish. The study of autecological and biological patterns of S. nodosa is important for understanding the species reaction to environmental change. The growth features and growth rate of this brittle star from the Pechora Sea were estimated using the Gompertz equation as the basic mathematical model and compared with Bertalanffy equation parameters. Individual age was evaluated by counting the ring-shaped growth marks in the calcite structure of the animal's vertebral ossicle, where each visible ring was considered to be an annual growth mark. The calculations indicated: the theoretical limiting radius of the brittle star's ossicle (R∞) averages 318 ± 18 μm, and the exponential deceleration of the specific growth rate (g) is found to be 0.46 ± 0.02. The initial hidden growth marks were found to vary from 1–3, and the maximum lifespan of S. nodosa in the Pechora Sea (SE of the Barents Sea) is evaluated to be 9–10 years.

Correspondence between formulations of Avrami and Gompertz equations for untreated tumor growth kinetics

The classical and modified equations of Kolmogorov-Johnson-Mehl-Avrami are compared with the equations of conventional Gompertz andMontijano-Bergues-Bory-Gompertz, in the frame of growth kinetics of tumors. For this, different analytical and numerical criteria are usedto demonstrate the similarity between them, in particular the distance of Hausdorff. The results show that these equations are similar fromthe mathematical point of view and the parameters of the Gompertz equation are explicitly related to those of the Avrami equation. It isconcluded that Modified Kolmogorov-Johnson-Mehl-Avrami and Montijano-Bergues-Bory-Gompertz equations can be used to describe thegrowth kinetics of unperturbed tumors.

Effect of NaOH on biogas production under SSAD conditions along with kinetics studies

Indonesia is a large rice producing country where from these activities it produces waste in the form of rice husk. Rice husk cannot be degraded by itself due to the lignin content contained in the rice husk. Therefore, treatment is carried out to destroy the lignin content and use it as alternative energy in the form of biogas. The study was conducted at a laboratory scale at room temperature, preliminary treatment using 3% NaOH under the SSAD conditions of 27.5% TS and then biogas production was measured once every two days for 90 days. Furthermore, the results of biogas production were observed between biogas with NaOH and without NaOH and carried out a study of the kinetics. The result is that biogas production with NaOH is higher, reaching 59.2 mL/grTS whereas without NaOH at 14.7 mL/grTS. The results of kinetic studies using mathematical modeling through the Gompertz equation, the variable with NaOH is known to have a maximum biogas production of 63.9 mL/grTS, a daily biogas production rate of 0.97 mL/grTS.day and the initial formation of biogas significantly on the 8th day.