The essence of the methane fermentation course is the phase nature of changes taking place during the process. The biodegradation degree of sewage sludge is determined by the effectiveness of the hydrolysis phase. Excess sludge, in the form of a flocculent suspension of microorganisms, subjected to the methane fermentation process show limited susceptibility to the biodegradation. Excess sludge is characterized by a significant content of volatile suspended solids equal about 65 ÷ 75%. Promising technological solution in terms of increasing the efficiency of fermentation process is the application of thermal modification of sludge with the use of dry ice. As a result of excess sludge disintegration by dry ice, denaturation of microbial cells with a mechanical support occurs. The crystallization process takes place and microorganisms of excess sludge undergo the so-called “thermal shock”. The aim of the study was to determine the effect of dry ice disintegration on the course of the methane fermentation process of the modified excess sludge. In the case of dry ice modification reagent in a granular form with a grain diameter of 0.6 mm was used. Dry ice was mixed with excess sludge in a volume ratio of 0.15/1, 0.25/1, 0.35/1, 0.45/1, 0.55/1, 0.65/1, 0.75/1, respectively. The methane fermentation process lasting for 8 and 28 days, respectively, was carried out in mesophilic conditions at 37°C. In the first series untreated sludge was used, and for the second and third series the following treatment parameters were applied: the dose of dry ice in a volume ratio to excess sludge equal 0.55/1, pretreatment time 12 hours. The increase of the excess sludge disintegration degree, as well as the increase of the digestion degree and biogas yield, was a confirmation of the supporting operation of the applied modification. The mixture of reactant and excess sludge in a volume ratio of 0.55/1 was considered the most favorable combination. In relation to not prepared sludge for the selected most favorable conditions of excess sludge modification, about 2.7 and 3-fold increase of TOC and SCOD values and a 2.8-fold increase in VFAs concentration were obtained respectively. In relation to the effects of the methane fermentation of non-prepared sludge, for modified sludge, about 33 percentage increase of the sludge digestion degree and about 31 percentage increase of the biogas yield was noticed.

The root-knot nematode Meloidogyne graminicola is an economically important pest in rice production. The identification of a nematode species is an important basis in nematode management to reduce yield losses by extracting nematode DNA as an early step in molecular identification. This study aimed to investigate the optimal extraction method and number of M. graminicola for nematode genomic analysis based on PCR (polymerase chain reaction) and Sanger sequencing. The DNA extraction methods used in this study were the CTAB, SDS, and commercial kit (GeneAidTM Tissue/Blood DNA Mini Kit). The results revealed that the three DNA extraction methods could be used to analyze the nematode genomics based on PCR and Sanger sequencing using one nematode, both in a second-stage juvenile and a female, equipped with the process of nematode destruction by freezing. This finding was shown by the amplification of all DNA templates with Mg-F3 and Mg-R2 primers through PCR with a size of 370 bp, while Sanger sequencing obtained 372 bp.

This study focuses on mapping the groundwater’s vulnerability to pollution in the region of Ouargla, located in the North-East of the northern Sahara, exposed to potential risks of alteration. By applying the methods (GOD, DRASTIC, and SINTACS), coupled with a Geographic Information System (GIS), we were able to identify a medium to high vulnerability trend. In light of the results recorded, the DRASTIC and SINTACS methods prove to be more suitable for our study region. This makes it possible to highlight the recharge zones and land use as being the most vulnerable in the territory studied. The GOD method presents a strong vulnerability trend over 77.02% of the study area. Such a result is directly related to the depth of the water table. It can therefore be argued that this method is far from being representative of the reality on the ground because of these very heterogeneous characteristics.

Phytolith-occluded carbon (PhytOC) is highly stable, and constitutes an important source of long-term C storage in agrosystems. This stored carbon is resistant to the processes of oxidation of carbon compounds. In our research phytolith content in barley (Estonia) and oat (Poland) grain and straw was assessed at field trials, with Si as a liquid immune stimulant OPTYSIL and compost fertilisation. We showed that cereals can produce relatively high amounts of phytoliths. PhytOC plays a key role in carbon sequestration, particularly for poor, sandy Polish and Estonian soils. The phytolith content was always higher in straw than in grain regardless of the type of cereals. The phytolith content in oat grains varied from 18.46 to 21.28 mg∙g−1 DM, and in straw 27.89–38.97 mg∙g−1 DM. The phytolith content in barley grain ranged from 17.24 to 19.86 mg∙g−1 DM, and in straw from 22.06 to 49.08 mg∙g−1 DM. Our results suggest that oat ecosystems can absorb from 14.94 to 41.73 kg e-CO2∙ha−1 and barley absorb from 0.32 to 1.60 kg e-CO2∙ha−1. The accumulation rate of PhytOC can be increased 3-fold in Polish conditions through foliar application of silicon, and 5-fold in Estonian conditions. In parallel, the compost fertilisation increased the phytolith content in cereals.