1,720,954 research outputs found
Recovery Amonium Dan Fosfat Pada Limbah Urin Menggunakan Elektrodialisis Dengan Anoda Magnesium
Get PDFLimbah urin menyumbang sejumlah besar nutrien dalam air limbah yakni sebesar 70-80% nitrogen dan 50% fosfor padahal urin hanya mewakili 1% volume dari total volume limbah domestik. Pemisahan urin dari air limbah memiliki banyak keuntungan diantaranya ialah menekan biaya dan tenaga yang dibutuhkan untuk transportasi dan pengolahan air limbah domestik. Selain itu, recovery nutrien yang terkandung dalam urin seperti amonium dan fosfat berpotensi besar menjadi sumber nutrien yang berkelanjutan di saat kebutuhan akan nutrien terus meningkat mengingat fosfor merupakan sumber daya yang tidak dapat diperbarui yang diperkirakan akan habis dalam 45-100 tahun yang akan datang. Sedangkan nitrogen melimpah di atmosfer (78%) dalam kondisi sangat stabil dan tidak reaktif sehingga pemanfaatan dalam bentuk reaktif memerlukan energi fosil yang besar. Recovery amonium dan fosfat dalam limbah limbah urin dalam bentuk struvite telah banyak diteliti sebelumnya karena struvite atau MAP (Magnesium Ammonium Phosphate) merupakan slow release fertilizer yang memiliki efisiensi tinggi dengan mengendalikan laju pelepasan unsur hara. Namun recovery fosfat dalam bentuk struvite dari urin memerlukan tambahan magnesium (Mg) karena ketersediaan Mg yang kecil pada urin.
Oleh karena itu, dalam penelitian ini dilakukan recovery nutrien yaitu amonium dan fosfat pada limbah urin dengan proses elektrodialisis untuk memperoleh efisiensi penyisihan yang tinggi. Penelitian ini dilakukan dalam skala laboratorium menggunakan reaktor elektrodialisis dengan tiga kompartemen yang dipisahkan oleh Anion Exchange Membrane (AEM) dan Cation Exchange Membrane (CEM). Elektroda yang digunakan ialah magnesium sebagai anoda dan stainless steel sebagai katoda. Volume limbah urin yang diolah adalah 2L dengan sistem batch. Bahan uji yang digunakan adalah limbah urin sintetis yang diformulasikan di Laboratorium Departemen Teknik Lingkungan. Variabel yang ditetapkan adalah pH dan arus listrik dalam proses elektrodialisis yang ditentukan pada penelitian pendahuluan. Parameter yang akan diteliti adalah pH, COD, konsentrasi amonium, konsentrasi fosfat dan konsentrasi magnesium.
Karakteristik imbah urin yang digunakan untuk penelitian ini memiliki pH 6,7-9,1, COD 840-1260 mg/L, 1112-2438 mg NH4-N/L, 454-609 mg PO4-P/L, dan 50 mg Mg/L. Pada penelitian yang telah dilakukan, didapatkan penyisihan NH4+ terbesar yaitu 42,35% (2,445 gram) dari penerapan variasi pH 8,5 dan kuat arus listrik 300 mA. Sedangkan penyisihan PO43- terbesar didapatkan dari penerapan pH 8,5 dan kuat arus 450 mA yaitu sebesar 28,48% (1,057 gram). Struvite yang dihasilkan dari proses elektrokimia pada kisaran pH 7,5-9,3 memiliki kemurnian tinggi (lebih dari 90%) dengan bentuk struvite yaitu memanjang, dengan pola berbentuk jarum, serta bertepi halus dan tajam. Analisis EDX menghasilkan grafik mikroanalis yang dapat menunjukkan unsur dominan dalam presipitat.
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Urine wastewater contributes a large number of nutrients in wastewater, which is 70-80% nitrogen and 50% phosphorus whereas urine only represents 1% by volume of the total volume of domestic waste. Separation of urine from wastewater has many advantages including reduced the costs and labor required for transportation and domestic wastewater treatment. In addition, the recovery of nutrients contained in urine such as ammonium and phosphate has great potential to become a sustainable source of nutrients when the need of nutrients continues to increase considering that phosphorus is a non-renewable resource that is expected to be exhausted in the next 45-100 years. While nitrogen is abundant in the atmosphere (78%) in a very stable and unreactive condition so that its use in reactive form requires a large amount of fossil energy. The recovery of ammonium and phosphate in urine wastewater in the form of struvite has been studied previously because struvite or MAP (Magnesium Ammonium Phosphate) is a slow release fertilizer that has high efficiency by controlling the rate of nutrient release. However, recovery of phosphate in the form of struvite from urine requires additional magnesium (Mg) because of the low concentration of Mg in the urine.
Therefore, in this study, the recovery of nutrients, namely ammonium and phosphate in urine wastewater, was carried out by electrodialysis to obtain high removal efficiency. This research was conducted on a laboratory scale using an electrodialysis reactor with three compartments separated by an Anion Exchange Membrane (AEM) and a Cation Exchange Membrane (CEM). The electrodes used were magnesium as anode and stainless steel as cathode. The volume of processed urine wastewater is 2L in batch system. The material used in this research is synthetic urine which is formulated in the Laboratory of the Department of Environmental Engineering. The variables determined were pH and electric current in the electrodialysis process determined in the preliminary study. The parameters to be studied are pH, COD, ammonium concentration, phosphate concentration and magnesium concentration.
The urine wastewater characteristics used in this study had a pH of 6,7-9,1, COD 840-1260 mg/L, 1112-2438 mg NH4-N/L, 454-609 mg PO4-P/L, and 50 mg Mg. /L. In the research that has been done, it was found that the largest NH4+ removal was 42,35% (2,445 grams) from the application of a pH variation of 8,5 and an electric current of 300 mA. Meanwhile, the largest PO43- removal was obtained from the application of pH 8,5 and an electric current of 450 mA, which was 28.48% (1,057 grams). Struvite produced from an electrochemical process at a pH range of 7,5-9,3 has a high purity (more than 90%) with a struvite shape that is elongated, with a needle-shaped pattern, and has smooth and sharp edges. EDX analysis produces a microanalyst graph that can show the dominant element in the precipitate
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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