Effects of Partial Saturation on Nitrogen Removal and Bacterial Community in Vertical-Flow Constructed Wetlands

The laboratory-scale pilot of constructed wetlands has been in operation for six months; (1) an unsaturated vertical flow constructed wetland (UVF-CW), this system was used to represent the classic vertical constructed wetlands, (2) a saturated vertical flow constructed wetland (SVF-CW), to evaluate the effects of the saturated condition on nitrogen removal and composition of the microbial community. The results showed that the saturation condition positiveley influenced the removal efficiencies of the nitrogen,, the aeverage removal rate of the total kjeldahl nitrogen increased from 56% in unsaturated vertical flow constructed wetland (UVF-CW) to 63% in saturated vertical flow constructed wetland ( SVF-CW). In addition, the microbial communities also was affected by the saturation condition, the relative abundances of nitrifying bacterium in UVF-CW are 13.8% (Nitrosomonas), 7.2% (Nitrosospira), 18.1% (Nitrospira) and 15.3% (Nitrobacter). In contrast, in SVF-CW, Nitrosomonas, Nitrosospira, Nitrospira and Nitrobacter only accounted for 6.8%, 5.6%, 7.4% and 10.6% respectively. However, the saturation condition seemed to increase denitrifying bacterium more than three times, in unsaturated vertical flow constructed wetland, only Pseudomonas (6.5%) and Paracoccus (4.85%) were detected, but in saturated vertical flow constructed wetland (SVF-CW), the abundance of Pseudomonas (13.08%) and Paracoccus (9.74%) were increased, and three other groups of denitrifying bacteria were also detected as Zoogloea (3.32%), Thauera (5.41%) and Thiobacillus (3).

Recommended Procedures to Assess Critical State Locus from Triaxial Tests in Cohesionless Remoulded Samples

The critical state theory is a robust conceptual framework for the characterisation of soil behaviour. In the laboratory, triaxial tests are used to assess the critical state locus. In the last decades, the equipment and testing procedures for soil characterisation, within the critical state framework, have advanced to obtain accurate and reliable results. This review paper summarises and describes a series of recommended laboratory procedures to assess the critical state locus in cohesionless soils. For this purpose, results obtained in the laboratory from different cohesionless soils and triaxial equipment configurations are compiled, analysed and discussed in detail. The procedures presented in this paper reinforce the use of triaxial cells with lubricated end platens and an embedded connection piston into the top-cap, together with the verification of the full saturation condition and the measurement end-of-test water content—preferable using the soil freezing technique. The experimental evidence and comparison between equipment configurations provide relevant insights about the laboratory procedures for obtaining a reliable characterisation of the critical state locus of cohesionless geomaterials. All the procedures recommended herein can be easily implemented in academic and commercial geotechnical laboratories.

Experimental Investigation of the Effect of Heat Spreading on Boiling of a Dielectric Liquid for Immersion Cooling of Electronics

This paper investigated the effect of heat spreading on the boiling of the Novec 649TM for two-phase immersion cooling of electronics. Reference pool boiling tests were performed by attaching a 25.4 by 25.4 mm square plate square copper plate to a same-sized heater, thus minimizing lateral heat spreading. Experimental measurements showed that the critical heat flux (CHF) happened at a heat flux of 17.4 ±0.8 W/cm2. Then, lateral heat spreading through the heat spreader was studied by attaching larger (47 mm by 47mm) spreaders with four different thicknesses to the copper plate. With an increase in the integrated heat spreader (IHS) thickness from 1 mm to 6 mm, the CHF increased by more than 60% at the saturation condition. One plate was a 1 mm-thick IHS removed from a commercial microprocessor. In this case, the CHF happens at 8.6 W/cm2 (50% lower compared to the reference case) in the saturation condition. At CHF, the boiling can be observed on the whole surface, with columns and slugs regime at the center and the fully developed nucleate boiling regime at the edges. This non-uniform boiling was more pronounced in sub-cooled conditions, in which the CHF occurred at the center while there were regions at the edges that had no boiling. Finally, the performance of a micro porous-coated IHS (with 3.15 mm thickness) was compared to the 6mm thick IHS. The thermal resistance was almost equal for powers above 200 W. This indicates that lateral heat spreading is a critical parameter for the thermal design of immersion cooling along with micro-porous coating.

Soybean Cultivation Technology Package on Tidal Swamp Lands in Indonesia

The main constraints of the tidal swamp lands in Indonesia for soybean growth are low soil pH, high Al saturation, and low nutrient availability of N, P, K, Ca, and Mg. The objectives of this research were to determine tolerance of several soybean varieties to Al saturation level, and to obtain a technological package for soybean cultivation which was suitable for farmers to adopt on tidal swamp lands. The research consisted of two stages of study. The first stage formulated of technology package, and the second stage evaluated feasibility of the technology package which was formulation from the first stage. The first stage studied the effect of dolomite application (20% - 30% of soil Al saturation) on four soybean varieties (Anjasmoro, Panderman, Dega 1, and Demas). The second stage studied the effect of three technological packages: existing technology; water- saturated soybean cultivation (WSC); and alternative technology which was formulated from the results of the first study. In the 30% of soil Al saturation condition, the alternative technology package (application of 50 kg urea + 75 kg SP36 + 50 kg KCl + 1500 kg organic fertilizers/ha + rhizobium biofertilizer “Agriosy” 0.25 kg/50 g seeds/ha) gave soybean yield of 1.78 - 2.72 t/ha for all of soybean varieties tested. The alternative technology package with Anjasmoro variety provided higher seed yields (2.62 t/ha) compared to the existing technology (2.07 t/ha) and WSC technology package (2.44 t/ha). The alternative technology package gave a profit of 11,595,000 IRD/ha with B/C values of 1.71 which was higer than the existing and WSC technology packages. The alternative technology package was more profitable than the existing technology (current farmer practice) and water-saturated soybean cultivation technology packages.

Effects of Saturation Levels on the Ultrasonic Pulse Velocities and Mechanical Properties of Concrete

The main objective of this research is to investigate the effect of water content in concrete on the velocities of ultrasonic waves (P- and S-waves) and mechanical properties (elastic modulus and compressive strength) of concrete. For this study, concrete specimens (100 mm × 200 mm cylinders) were fabricated with three different water-to-binder ratios (0.52, 0.35, and 0.26). These cylinders were then submerged in water to be saturated in different degrees from 25% to 100% with an interval of 25% saturation. Another set of cylinders was also oven-dried to represent the dry condition. The dynamic properties of concrete were then assessed using a measurement of elastic wave accordance with ASTM C597-16 and using resonance tests following ASTM C215-19, before and after immersion in water. The static properties of saturated concrete were also assessed by the uniaxial compressive testing according to ASTM C39/C39M-20 and ASTM C469/C469M-14. It was observed that the saturation level of concrete affected the two ultrasonic wave velocities and the two static mechanical properties of concrete in various ways. The relationship between P-wave velocity and compressive strength of concrete was highly sensitive to saturation condition of concrete. In contrast, S-wave velocity of concrete was closely correlated with compressive strength of concrete, which was much less sensitive to water saturation level compared to P-wave velocity of concrete. Finally, it was noticed that water saturation condition only little affects the relationship between the dynamic and elastic moduli of elasticity of concrete studies in this study.

Purifikasi Alami Sungai Bedadung Hilir Menggunakan Pemodelan Streeter-Phelps

Latar Belakang: Sungai Bedadung hilir berada di Kabupaten Jember dan merupakan bagian sungai utama di DAS Bedadung. Sungai ini berperan penting bagi kehidupan masyarakat Jember. Kegiatan pengunaan lahan mengubah fungsi sungai menjadi saluran pembuang limbah. Limbah organik masuk ke badan air Sungai Bedadung dan menurunkan oksigen terlarut di perairan.Metode: Penelitian ini merupakan penelitian deskriptif. Data primer diperoleh dengan melakukan pengukuran debit dan kualitas air (Temperatur, DO dan BOD) sungai di lima titik pantau. Data tersebut kemudian diolah dan digunakan sebagai input variabel persamaan Streeter-Phelps.Hasil: Berdasarkan penelitian yang dilakukan laju deoksigenasi dan reoksigenasi Sungai Bedadung hilir tertinggi berada pada BDG02 masing-masing 7.997 mg/L.hari dan 19.168 mg/L/hari. Purifikasi alami yang dimodelkan dengan persamaan Streeter-Phelps, pada BDG02 tidak menunjukkan tren penurunan oksigen terlarut, sedangkan empat titik yang lain cenderung turun, mencapai kondisi kritis dan saturai di waktu yang berbeda. Hasil pembuktian model menunjukkan terjadi perbedaan nilai DO model terhadap kondisi lapangan (DO aktual).Simpulan: Aplikasi pemodelan Streeter-Phelps untuk menganalisis purifikasi alami Sungai Bedadung tidak dapat menunjukkan kesesuaian dengan kondisi lapang, karena proses deoksigenasi dan reoksigenasi di sepanjang sungai selalu berbeda dengan model bergantung pada tambahan pencemar dan hidraulik sungai. ABSTRACTTitle :Background: Bedadung Downstream, at Jember Region, is the primary river of Bedadung basin. The river has its meaningful advantages to public activities. Change of land uses the stream functions to a big drainage channel. Organic pollutants entrance to the water body and decrease the concentration of dissolved oxygen.Methods: This research was descriptive. The primary data was obtained by measuring stream flows and water quality (Temperature, DO, and BOD) at five observed stations. The data were processed and used as variable inputs to the Streeter-Phelps equation.Results: Based on the research conducted, BDG02 had the highest values of deoxygenation and reoxygenation rates, which were 7.997 mg/L.day and 19.168 mg/L.day respectively. DOmod at BDG02 tends to line up, whereas DOmod at four stations had a tendency to declined to critical conditions and rise to the saturation condition at different times. DO sag model was different from actual DO, which measured directly in the water body.Conclusions: The use of the Streeter-Phelps equation to analyze the self-purification of Bedadung downstream wasn’t appropriate with the field conditions. Deoxygenation and reoxygenation process in the river body was typically difference with the model applied, which were affected by organic pollutants and stream hydraulics.