1,656 research outputs found
A pilot-scale trial comparing mesophilic and thermophilic digestion for the stabilisation of source segregated kitchen waste
No full textSource segregated food waste was collected from domestic properties and its composition determined together with the average weight produced per household, which was 2.91 kg per week. The waste was fed over a trial period lasting 58 weeks to an identical pair of 1.5 m3 anaerobic digesters, one at a mesophilic (36.5 oC) and the other at a thermophilic temperature (56 oC). The digesters were monitored daily for gas production, solids destruction and regularly for digestate characteristics including alkalinity, pH, volatile fatty acid (VFA) and ammonia concentrations. Both digesters showed high VFA and ammonia concentrations but in the mesophilic digester the pH remained stable at around 7.4, buffered by a high alkalinity of 13,000 mg l-1; whereas in the thermophilic digester VFA levels reached 45,000 mg l-1 causing a drop in pH and digester instability. In the mesophilic digester volatile solids (VS) destruction and specific gas yield were favourable, with 67% of the organic solids being converted to biogas at a methane content of 58% giving a biogas yield of 0.63 m3 kg-1 VS added. Digestion under thermophilic conditions showed potentially better VS destruction at 70% VS and a biogas yield of 0.67 m3 kg-1 VS added, but the shifts in alkalinity and the high VFA concentrations required a reduced loading to be applied. The maximum beneficial loading that could be achieved in the mesophilic digester was 4.0 kg VS m-3 d-1
Attenuation of Mecoprop by a low organic carbon landfill liner material: a comparison between batch and column tests
No full textA pilot-scale comparison of mesophilic and thermophilic digestion of source segregated domestic food waste
No full textSource segregated food waste was collected from domestic properties and its composition determined together with the average weight produced per household, which was 2.91 kg per week. The waste was fed over a trial period lasting 58 weeks to an identical pair of 1.5 m3 anaerobic digesters, one at a mesophilic (36.5°C) and the other at a thermophilic temperature (56°C). The digesters were monitored daily for gas production, solids destruction and regularly for digestate characteristics including alkalinity, pH, volatile fatty acid (VFA) and ammonia concentrations. Both digesters showed high VFA and ammonia concentrations but in the mesophilic digester the pH remained stable at around 7.4, buffered by a high alkalinity of 13,000 mg l-1; whereas in the thermophilic digester VFA levels reached 45,000 mg l-1 causing a drop in pH and digester instability. In the mesophilic digester volatile solids (VS) destruction and specific gas yield were favourable, with 67% of the organic solids being converted to biogas at a methane content of 58% giving a biogas yield of 0.63 m3 kg-1 VSadded. Digestion under thermophilic conditions showed potentially better VS destruction at 70% VS and a biogas yield of 0.67 m3 kg-1 VSadded, but the shifts in alkalinity and the high VFA concentrations required a reduced loading to be applied. The maximum beneficial loading that could be achieved in the mesophilic digester was 4.0 kg VS m-3 d-1
Assessing the potential for attenuation of organic substances within mineral landfill liners
No full textDevelopment of TD Website and Repository
No full textSEAFDEC, an Inter-Governmental Organization plays an important role in promotion of sustainable development of fisheries and aquaculture in the Southeast Asian Region for more than four decades. Cooperation with other regional and international organizations have been recognized through several important events such as Millennium Conference in 2001 and ASEAN-SEAFDEC Conference in 2011. Since 1990s, internet have been introduced worldwide, where information technology becomes important as a part of human life including education, economic, social and politicsand so on. Development of high speed internet creates a new communication system and support living style including works and activities such as public relations, multi-media production, publication etc., especially information dissemination and website which are technologies for communication between internal and external organization as well as in developing management system for efficiencies. The objective of this paper is to enhance SEAFDEC visibility by developing the information and dissemination system which developed new TD website in 2017.
In this regards, TD established Southeast Asian Fisheries Development Center, Training Department Institutional Repository (STIR), which is the official digital repository of scholarly, research and technical information of the Department to download all information materials using open source software named the DSpace.
In this paper, author considers the importance of information technology for introducing SEAFDEC/TD activities and improving access to SEAFDEC/TD technical/scientific articles was expressed via the website. In this regards, the author introduced for developing of the TD website and Repository to increase public relation and increase TD’s visibility as well as point out constrains of its development that requires the strengthening and cooperation within the Training Department of SEAFDEC
Quantifying the effect of settlement and gas on solute flow and transport through treated municipal solid waste
No full textThe effect of degradation and settlement on transport properties of mechanically and biologically treated (MBT) waste was examined by applying three different tracers to two waste columns (~ 0.5 m diameter) in a series of closed-loop experiments. One column was allowed to biodegrade and the other was bio-suppressed. Permeability and drainable porosity were reduced by settlement, in line with previous results.A dual-porosity model performed well against the data and suggested that more preferential flow occurred early on in the un-degraded column. Diffusion timescales were found to be between 0.8 and 6 days. Volumetric water contents of the mobile region were found to be small in the bio-suppressed cell (~ 0.01) and even smaller values were found in the degrading waste, possibly due to displacement by gas.Once either settlement or gas production had disrupted this pattern into a more even flow, subsequent compression made little difference to the diffusion time-scale. This may indicate that transport was thereafter dominated by other aspects of the waste structure such as the distribution of low-permeability objects. The presence of gas in the degrading waste reduced the volumetric water content through displacement. The model indicated that the gas was primarily located in the more mobile porosity fraction. Primary compression of the degrading waste tended to squeeze this gas out of the waste in preference to water
Provisional analysis of the effect of compression on transport in degrading municipal solid waste
No full textOn Rota-Baxter Nijenhuis TD algebra
No full textThere was a long standing problem of G. C. Rota regarding the classi- fication of all linear operators on associative algebras that satisfy algebraic identities. Initially, only very few of such operators were known, for example, the derivative operator, average operator, difference operator and Rota-Baxter operator. Recently, in a paper by L. Guo, W. Sit and R. Zhang, the authors revisited Rota’s problem by concentrating on two classes of operators; differ- ential type operators and Rota-Baxter type operators. One of the Rota-Baxter type operators they found is the Rota-Baxter Nijenhuis TD (RBNTD) oper- ator which puts together the terms of the well-known Rota-Baxter operator, Nijenhuis operator and Leroux’ TD operator. In this dissertation, we initiate a systematic study of the RBNTD operator, extending the previous works on the Rota-Baxter, Nijenhuis and TD operators. After giving basic properties and examples, we construct free commutative and then free (non-commutative) RBNTD algebras. We then use free RBNTD algebras to obtain an extension of the renowned dendriform algebra with five binary operations.Ph. D.Includes bibliographical referencesMonica AggarwalVita
Large Time Step and DC Stable TD-EFIE Discretized with Implicit Runge-Kutta Methods
No full textThe time domain-electric field integral equation (TD-EFIE) and its differentiated version are widely used to simulate the transient scattering of a time dependent electromagnetic field by a perfect electric conductor (PEC). The time discretization of the TD-EFIE can be achieved by a space-time Galerkin approach or, as it is considered in this contribution, by a convolution quadrature using implicit Runge-Kutta methods. The solution is then computed using the marching-on-in-time (MOT) algorithm. The differentiated TD-EFIE has two problems: 1) the system matrix suffers from ill-conditioning when the time step increases (low frequency breakdown) and 2) it suffers from the DC instability, i.e., the formulation allows for the existence of spurious solenoidal currents that grow slowly in the solution. In this article, we show that 1) and 2) can be alleviated by leveraging quasi-Helmholtz projectors to separate the Helmholtz components of the induced current and rescale them independently. The efficacy of the approach is demonstrated by numerical examples including benchmarks and real-life applications.Numerical Analysi
“Dear Author": A Transparent SoTL Peer Review
No full textThis epistolary article is written as an extended SoTL peer review. It contains two sections: my preparatory work as peer reviewer and my actual review. In the first section, I remind myself of the function and processes of the SoTL peer review, what the author expects from a SoTL peer reviewer, and how I see my role as a peer reviewer in SoTL. In the second section, I write my review, focusing on three common feedback areas in SoTL: how the author brings in existing scholarship, how the author describes their SoTL project, and how the author demonstrates its importance. My review concludes with some advice for navigating the potentially conflicting reviews that are not unusual in SoTL
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