Assessment of organic carbon contamination in the unsaturated zone: a case of Yogyakarta City, Indonesia

In 1997, groundwater pollution was caused by a diesel leak at the Yogyakarta City Railway Station. People in the south of the railway station discovered the presence of diesel in dug wells in 2001. The existing diesel is still found in dug wells even though the pollutant source had been removed. The current source of pollution comes from diesel residues trapped in the unsaturated zone. Understanding the distribution and concentration of diesel in the unsaturated zone is the goal of this study. In this study, diesel concentration was measured based on Total Organic Carbon (TOC) levels. The research was conducted through shallow core and deep core drillings. Shallow core drilling was done at 14 points with a depth of 50 cm, and deep core drilling was done at nine drilling points with a depth of 15-17 m. 14 shallow core drilling samples were taken from a depth of 30 and 50 cm and nine deep core drilling samples were taken from a depth of 4-5 m and 10-11 m. The lithology logs in both drills were tested for diesel odour and TOC levels using the Soli TOC tool. Based on the test results, the smell of diesel was found at a depth of 10 to 15 m. TOC levels in the unsaturated zone ranged from 340 to 90,870 mg/L. TOC levels >30,000 mg/L were dominant at shallow depths even though they did not smell like diesel. At a location close to the source of the diesel tank leak at a depth of 4-5 m, the measured TOC level was 30,100 mg/L. The results showed that there were zones of high TOC levels associated with diesel odour layers. The zones existed because of the infiltration and percolation processes that had carried surface water and diesel pollutants and eventually moved horizontally following groundwater flow.

Imaging with Neutrons

By exploiting the penetration, attenuation, and scattering properties of neutrons, images of matter in two or three dimensions reveal information unobtainable using other probes. Despite the limitation in brilliance of neutron sources, several neutron-based imaging techniques are essential to different aspects of modern geoscience. Typical examples include the evaluation of porosity in rocks and sediments, mapping of light elements in solids, noninvasive probing of cultural heritage objects, investigations of thick engineering components, and the exploration of diffusion and percolation processes of fluids within porous matrices, organo-inorganic composites, and living organisms. Techniques under development include simultaneous neutron and X-ray tomography in heterogeneous media, Bragg-edge imaging, and the possibility of porosimetry from dark-field imaging.

Material Characterization and Substrate Suitability Assessment of Chicken Manure for Dry Batch Anaerobic Digestion Processes

Chicken manure is an agricultural residue material with a high biomass potential. The energetical utilization of this feedstock via anaerobic digestion is an interesting waste treatment option. One waste treatment technology most appropriate for the treatment of stackable (non-free-flowing) dry organic waste materials is the dry batch anaerobic digestion process. The aim of this study was to evaluate the substrate suitability of chicken manure from various sources as feedstock for percolation processes. Chicken manure samples from different housing forms were investigated for their chemical and physical material properties, such as feedstock composition, permeability under compaction and material compressibility. The permeability under compaction of chicken manure ranged from impermeable to sufficiently permeable depending on the type of chicken housing, manure age and bedding material used. Porous materials, such as straw and woodchips, were successfully tested as substrate additives with the ability to enhance material mixture properties to yield superior permeability and allow sufficient percolation. In dry anaerobic batch digestion trials at lab scale, the biogas generation of chicken manure with and without any structure material addition was investigated. Digestion trials were carried out without solid inoculum addition and secondary methanization of volatile components. The specific methane yield of dry chicken manure was measured and found to be 120 to 145 mL/g volatile solids (VS) and 70 to 75 mL/g fresh matter (FM), which represents approximately 70% of the methane potential based on fresh mass of common energy crops, such as corn silage.

Особенности влияния состава и кристаллической структуры на поведение электрофизических свойств сплавов системы Ni-=SUB=-(1-x)-=/SUB=-W-=SUB=-x-=/SUB=- при низких температурах

The problem of establishing the correlation between, on the one hand, the chemical and phase compositions of Ni_1– x W_ x alloys (0 ≤ x ≤ 0.5) and, on the other hand, the character of the temperature dependences of the electrical resistivity, is considered. Based on the experimental ρ( T ) curves, the concentration dependences of are reconstructed in the wide temperature range (50 K ≤ T ≤ 273 K). The ρ( x ) curves have features related to a change in the crystal structures of the alloys (concentration fcc–bcc phase transition), their magnetic structures and percolation processes occurring in the two-phase fcc + bcc medium.