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"Percobaan dilakukan untuk mengetahui pengaruh padat penebaran terhadap pertumbuhan dan performa benih ikan gurami (Osphronemus goramy, Lacepede 1801) dalam sistem resirkulasi air. Benih gurami (berat rata-rata 13,73 ± 0,93 g) ditebar dengan padat penebaran 4, 7, 10, 13, dan 16 ekor/20 l air. Pakan yang diberikan berupa pelet komersial dengan kandungan protein 38%. Pakan diberikan dua kali/hari sebanyak 3% berat tubuh ikan. Hasil percobaan selama 30 hari menunjukkan bahwa padat penebaran 4, 7, 10, 13, dan 16 ekor/20 l air masing-masing menghasilkan weight gain/WG (11,65; 10,24; 13,32; 10,03, dan 8,27 g), specific growth rate/SGR (2,07%; 1,93%; 1,83%; 1,87%; dan 1,57%), survival rate/sintasan (58,3%; 76,2%; 83,3%; 89,7%; dan 85,4%), dan feed conversion ratio/FCR (1,03; 1,31; 1,28; 1,0; dan 1,27). Hasil uji statistika Kruskal Wallis (p > 0,05) menunjukkan bahwa padat penebaran tidak berpengaruh terhadap WG, SGR, sintasan, dan FCR."

"A powerful flow visualization based on a laser-sheet and the quantification of the intensity of the lightfrom Mie scattering had been introduced and successfully used to evaluate the statistics and spatialcorrelations of gas distribution injected into a two-dimensional turbulent recirculation airflow, utilizing abackstep configuration. In the experiment the free stream velocity was, U, = 10 m/s and the step heightwas, H = 20 mm. The study focussed on the _fluctuation and the gas distribution in the recirculation zonein order to elucidate the gas-air moving characteristics. The results show that the distribution of injectedgas shows different trends depending on the location of injection. When the specific momentum ofinjection is increased the maximum fluctuation level of the gas concentration decreases. A reduction upto 30 % of the maximum RMS value of luminance intensity _fluctuation can be observed when increasingspecific momentum ratio of injection from 0. 04 to 0.3. Spatial correlations suggested that mixing betweeninjected gas and surrounding air was more rapid and better in case injection in the near reattachmentpoint due to higher turbulence in the region."

"Timbulan sampah meningkat sejalan dengan perkembangan aktivitas manusia. Hal ini memberikan masalah terhadap kemampuan lahan untuk menampung sampah. Timbulan sampah juga menghasilkan lindi yang mengandung senyawa organik berbahaya, seperti ammonia, nitrat, nitrit. Penelitian dilakukan dengan memodifikasi lysimeter dan menerapkan sistem pengisian sampah berkala selama tiga minggu, sehingga terdapat tiga lapisan sampah beda umur dalam lysimeter. Resirkulasi lindi diberikan ke dalam reaktor untuk mengetahui efeknya terhadap dekomposisi sampah dan kandungan ammonia, nitrat, nitrit. Akhirnya diketahui kesetimbangan nitrogen yang terjadi di dalam reaktor. Hasil pengamatan selama 150 hari membuktikan bahwa sistem pengisian sampah berlapis dan resirkulasi lindi ke dalam lysimeter akan mempercepat waktu dekomposisi sampah dan menurunkan kandungan ammonia, nitrat, nitrit dalam waktu yang relatif lebih cepat. Metode pengisian sampah 3 lapis membuktikan bahwa lapisan sampah teratas memiliki kandungan nitrogen yang terbesar. Dibuktikan pula bahwa hanya 17% nitogen terlarut dalam lindi, 21% berubah dalam fraksi gas atau cair (uncounted) dan tersisa 60,1% nitrogen yang ada di dalam sampah sebagai residu.

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Refuse generation will increase in line with development of human activities. This fact make a problem to land area that is no longer able to accommodate. Refuse generation will produce leachate that contains dangerous organic matter such as ammonia, nitrate, nitrite. This study done with modification reactor and implemented continued waste filling method. This research also implement leachate recirculation through the lysimeter. Leachate recirculation aims to know the effect towards refuse decomposition and concentration of ammonia, nitrate, nitrite in lysimeter. This observation results nitrogen balance in reactor. The result of 150 days observation proved that leachate recirculation make refuse decomposition becomes faster and decrease concentration of ammonia, nitrate, nitrite in short period. With continued filling method proved that 3rd refuse layer has more nitrogen compounds than the other layers. This study also prove that only 17% of nitrogen leaves the system via leachate, 21% transferred either into liquid or gas phase (uncounted), and only 60,1% nitrogen stays in refuse as residual nitrogen."

"Material lignoselulosa yang mengandung tiga kompenen utama, yaitu selulosa, hemiselulosa, dan lignin, diketahui sulit untuk didegradasi melalui proses biologis. Selulase telah terbukti mengkatalis degradasi selulosa dengan menggunakan hidrolisis enzimatik. Namun, penambahan selulosa diperkirakan bisa mempengaruhi kualitas air lindi yang dihasilkan. Tujuan dari penelitian ini adalah menganalisis efek penambahan enzim terhadap kualitas air lindi. Dua 1,5 meter bioreaktor disediakan untuk dua perlakuan, yaitu 1 resirkulasi air lindi dengan penambahan enzim, 2 hanya resirkulasi air lindi sebagai kontrol. Penambahan enzim selulase sebanyak 15 x 106 U/ton menghasilkan konsentrasi COD lebih rendah 29,100 mg/L dengan penambahan enzim dan 31,900 mg/L pada kontrol , TS 17,800 mg/L dan 22,100 mg/L , TDS 15,900 mg/L and 19,800 mg/L. Hal ini mungkin disebabkan oleh percepatan hidrolisis menggunakan proses enzimatik. Namun, nilai BOD lebih tinggi ketika penambahan enzim dilakukan 16,100 mg/L dan 11,600 mg/L disebabkan karena penambahan enzim mendorong pembentukan glukosa, sehingga meningkatkan nilai BOD. Nilai pH meningkat seiring waktu menuju netral, mengindikasikan landfill telah menuju fase metanogenik. Dari penelitian ini, bisa disimpulkan bahwa penambahan enzim pada landfill mempunyai dampah pada kualitas air lindi yang dihasilkan.

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Lignocellulose material which consist of three main component, including cellulose, hemicellulose, and lignin, was known hard to degrade using biological process. Cellulase has proven to catalyst the degradation of celullose by enzymatic hydrolysis. However, the addition of enzyme might affect leachate qualities that was emitted from landfill. The aim of this research is to analyses the effect of cellulase addition on leachate qualities. Two 1.5 m height bioreactors was provided for two different treatment including 1 leachate recirculation with cellulase addition 2 leachate recirculation only as control. The addition of cellulase at 15 x 106 U tonne was resulting lower concentration for COD 29,100 mg L in cellulase addition and 31,900 mg L in control, TS 17,800 mg L and 22,100 mg L, respectively, TDS 15,900 mg L and 19,800 mg L, respectively. This was likely caused by acceleration of hydrolysis using enzymatic process. However, BOD value higher when cellulase addition was conducted 16,100 and 11,600 mg L, respectively because the addition of cellulase was supported formation of glucose, therefore escalate BOD value. pH value was increasing over time towards neutral, indicates landfill has been headed toward methanogenic phase. From the experiment, it can be concluded that addition of cellulase has impacts towards leachate qualities."

"The majority of 0D/1D knock models available today are known for their poor accuracy and the great effort needed for their calibration. Alexander Fandakov presents a novel, extensively validated phenomenological knock model for the development of future engine concepts within a 0D/1D simulation environment that has one engine-specific calibration parameter. Benchmarks against the models commonly used in the automotive industry reveal the huge gain in knock boundary prediction accuracy achieved with the approach proposed in this work. Thus, the new knock model contributes substantially to the efficient design of spark ignition engines employing technologies such as full-load exhaust gas recirculation, water injection, variable compression ratio or lean combustion.Contents: Experimental Investigations and Thermodynamic Analysis Unburnt Mixture Auto-Ignition PredictionKnock Occurrence CriterionKnock Model Validation"

"Masalah pencemaran lingkungan sungai di kota DKI Jakarta, telah menunjukkan gejala yang cukup serius. Salah satu penyebab dari pencemaran tersebut adalah air buangan dari limbah perkantoran. Gedung The City Center (TCC),. merupakan gedung perkantoran yang terletak di Jakarta Pusat. Gedung ini telah mempunyai IPAL dengan sistim lumpur aktif dan telah berupaya menjaga kualitas air limbah buangan nya memenuhi baku mutu air limbah sesuai permen LHK RI No. 68/Menlhk/Setjen/kum.1/8/2016. Sejak tahun 2020, telah terjadi pandemi COVID-19 sehingga debit air olahan menurun hingga kurang dari 50% dari total desain kriteria debit. Oleh karena itu, perlu dilakukan pengaturan debit resirkulasi lumpur aktif . Tujuan dari penelitian ini mengevaluasi efisiensi penyisihan BOD dan COD dalam kurun waktu tahun 2017 hingga bulan Maret 2021, mengatur debit resirkulasi lumpur aktif pada masa pandemi COVID-19 dan mengevaluasi efisiensi penyisihan BOD dan COD. Data BOD dan COD pada kurun waktu 2017 hingga bulan Maret 2021 dikumpulkan dari data sekunder. Pengaturan debit resirkulasi lumpur dilakukan dari kondisi maksimum resirkulasi sampai dengan kondisi resirkulasi terendah yaitu pada 176 m3/hari, 206 m3/hari dan 236 m3/hari. Pada tiap variasi debit, dilakukan pengambilan sampel lumpur di tanki pengukuran, sampel air limbah influent di bak grit chamber dan sampel air limbah effluent di bak effluent. Pengambilan sampel dilakukan pada waktu tinggal 24 jam dan 48 jam. Sampel lumpur di tanki pengukuran diukur MLSS, sampel influent dan effluent dikur kadar BOD dan COD. Dari hasil penelitian diperoleh bahwa debit resirkulasi lumpur yang optimum terjadi pada 206 m3/hari dengan waktu tinggal 24 jam. Jumlah MLSS di tangki aerasi sebesar 4435.97 mg/L dan , Nilai Food to mass ratio (F/M ratio) sebesar 0.008374 kg BOD/kg. Pada kondisi optimum, effisiensi penyisihan BOD dan COD masing – masing sebesar 95.60% dan 96.73%. Pada kondisi pandemi COVID-19, dengan mengatur debit resirkulasi lumpur, efisiensi penyisihan BOD dan COD lebih tinggi dibanding tanpa pengaturan debit resirkulasi dengan efisiensi penyisihan rata –rata BOD dan COD masing masing 94% dan 93%

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The problem of river environmental pollution in the city of DKI Jakarta, has shown quite serious symptoms. One of the causes of this pollution is wastewater from office waste. The City Center (TCC) building. is an office building located in Central Jakarta. This building already has an WWTP with an activated sludge system and has made efforts to maintain the quality of its wastewater discharge to meet the wastewater quality standards according to the Indonesian LHK Regulation No. 68/Menlhk/Setjen/kum.1/8/2016. Since 2020, there has been a COVID-19 pandemic so that the treated water discharge has decreased to less than 50% of the total design discharge criteria. Therefore, it is necessary to regulate the activated sludge recirculation discharge. The purpose of this study were evaluate the efficiency of BOD and COD removal from 2017 to March 2021, setting the activated sludge recirculation discharge during the COVID-19 pandemic and evaluate of removal efficiency of BOD and COD . BOD and COD data for the period of 2017 up to March 2021 were collected from secondary data. Sludge recirculation discharge settings are carried out from the maximum recirculation conditions to the lowest recirculation conditions at 176 m3/day, 206 m3/day and 236 m3/day. For each discharge variation, a sample of sludge was taken in the measurement tank, a sample of the influent wastewater taken in the grit chamber and a sample of the effluent wastewater taken in the effluent tank. Sampling were carried out at detention time of 24 hours and 48 hours. Sludge samples in the measurement tank were measured MLSS, influent and effluent samples measured oncentration of BOD and COD. The results of the study showed that the optimum sludge recirculation discharge occurred at 206 m3/day with detention time of 24 hours. The amount of MLSS in the aeration tank is 4435.97 mg/L and the value of Food to mass ratio (F/M ratio) is 0.008374 kg BOD/kg. Under optimal conditions, the removal efficiency of BOD and COD is 95.60% and 96.73%, respectively. In the COVID-19 pandemic conditions, by setting the sludge recirculation discharge, the removal efficiency of BOD and COD were higher than without the setting of recirculation discharge with an average removal efficiency of 94% for BOD and 93% for COD respectively.

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"Kenaikan timbulan sampah menyebabkan terbatasnya lahan TPA dan permasalahan pengelolaan pada lindi. Hal ini dapat diatasi dengan penerapan bioreaktor landfill yang dapat mempercepat dekomposisi sampah yang sekaligus dapat menurunkan kandungan pencemar yang ada dalam lindi. Pada penelitian ini berfokus pada kemampuan sampah bioreaktor lysimeter yang terdekomposisi berumur 3 tahun tanpa resirkulasi lindi dalam mengolah air lindi yang berasal dari TPA Cipayung. Parameter yang diukur di dalam penelitian ini adalah karakteristik sampah dan parameter kimia air lindi. Uji karakteristik sampah yang dilakukan adalah analisis ultimate yang berupa kandungan unsur karbon (C), hidrogen (H), oksigen (O), nitrogen (N), total sulfur (S), dan fosfor (P), rasio C/N, serta analisis proximate yang berupa uji kadar kelembaban, dan kadar abu, serta nilai kalori sampah. Sedangkan untuk parameter kimia lindi berupa tingkat penyisihan BOD, COD, TSS, nitrit, nitrat, dan pH. Berdasarkan simulasi pengolahan yang telah dilakukan, data analisis ultimate yang mengalami penurunan adalah unsur C dengan hasil akhir 1,38% dan N adalah 0,16%, sedangkan unsur H dan O mengalami peningkatan dengan kadar akhir sebesar 1,98% dan 12,16%. Peningkatan juga terjadi pada data analisis proximate, dimana kadar kelembaban akhir sebesar 3,4%, sedangkan kadar abu dalam sampah adalah 85,1%. Berdasarkan data analisis ultimate, nilai kalor akhir pada sampah adalah 550,599 kkal/kg dengan rasio C/N sebesar 8,625. Sedangkan untuk pengolahan lindi, sampah bioreaktor memiliki efisiensi rata-rata tingkat penyisihan lindi pada parameter BOD, COD, TSS, dan nitrit sebesar 89,26%, dan penurunan pH efluen mendekati rentang pH netral sebesar 7,2-7,8, sedangkan kenaikan konsentrasi terjadi pada parameter nitrat hingga kenaikan rata-rata sebesar 249,99%.

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Increasing in solid waste generation causing limited area of landfill and leachate management problems. These can be solved by applying the bioreactor landfill to accelerate waste decomposition that also can reduce pollutants content in the leachate. This study focused on the ability of 3-year-old decomposed waste in bioreactor lysimeter without leachate recirculation for treating the leachate from Cipayung landfill. Parameters measured in this study are the waste characteristics and leachate chemical parameters.Characteristics of waste includes ultimate analysis of element content of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), total sulphur (S) and phosphorus (P), ratio of C / N, and proximate analysis in the form of moisture content, ash content, and calorific value of the waste.As for chemical parameters of the leachate includes removal efficiencies of BOD, COD, TSS, nitrite, change of pH, and rate of nitrate increase.

Based on the simulation of leachate treatment has been done, ultimate analysis data that decreased was element C with final results 1.38% and N was 0.16%, while the final results of element H and O increased by 1.98% and 12,16%. Escalation also occurred in proximate analysis data, which the final moisture content was 3.4%, while the ash content in the waste was 85.1%.Based on data from ultimate analysis, final result of calorific value of waste was 550.599 kcal/kg with C/N ratio was 8.625.As for the results of leachate treatment, bioreactor landfill has average efficiency rate of leachate removal on the BOD, COD, TSS, and nitrite parameters at rate 89,26%, and a decrease of pH occured in leachate effluent with pH range 7,2 to 7,8, while the increase occured in average of nitrates concentrations reached 249,99%."

"Indonesia dikenal sebagai negara maritim dengan luas laut mencapai 7,9 juta km2, namun Indonesia diproyeksikan akan mengalami krisis air bersih pada tahun 2025. Microbial Desalination Cell (MDC) merupakan teknologi yang dikembangkan untuk mengurangi konsentrasi garam pada air laut sehingga dapat digunakan untuk kebutuhan masyarakat. Pada penelitian ini, substrat yang digunakan berasal dari model limbah tahu. Untuk meningkatkan kinerja MDC, maka desain reaktor dimodifikasi, dimana membran IEM akan disusun bertumpuk dua pasang dan pada akhir siklus desalinasi akan dilakukan proses resirkulasi anolit-katolit untuk mempertahankan nilai pH. Variasi yang dilakukan yaitu laju alir resirkulasi 0,5 dan 5 mL/ menit, jenis oksidator berupa KMnO4 0,1 M (katolit) dan aerasi katoda (tanpa katolit) dengan laju alir 100 mL/ menit, serta perbandingan volume anolit dan volume penyangga fosfat berturut-turut sebesar 1:1; 1:0,75; 1:0,5 dan 1:0,25. Hasil yang diperoleh yaitu oksidator KMnO4 0,1 M dapat digantikan dengan aerasi katoda pada laju alir 100 ml/menit dengan perbedaan TDR sebesar 1,061 g/jam, laju alir resirkulasi optimum untuk sistem 2-stacked MDC yaitu 0,5 ml/menit dengan TDR sebesar 2,447 g/jam, dan perbandingan penyangga:substrat optimum sebesar 0,5:1 dengan perolehan TDR sebesar 5,202 g/jam.

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Indonesia has been known as maritime country with the extemtion of sea is 7.9 million km2, but Indonesia is predicted to undergo water crisis pHenomena in 2025. Microbial Desalination Cell (MDC) is a developed technology for reducing salt concentration of seawater, so it could be used for people daily needs. In this research, the substrate comes from tofu wastewater model. For increasing MDC performance, there are modification in reactor design, whereas the IEM membrane would be arranged in two stacked design, yet in the end of of desalination cycle there would be a recirculation through anolyte-catholyte to maintain pH level. The variations are flow rate of recirculation 0,5 and 5 mL/ min, types of oxidator in the form of KMnO4 0,1 M (catholyte) and cathode aeration (without catholyte) with flowrate of 100 mL/ min, and the ratio of anolyte and buffer pHospHate volume respectively as 1:1; 1:0,75; 1:0,5 and 1:0,25. The result showed that KMnO₄ 0,1 M could be replaced with air cathode 100 ml/min which has different value of TDR reached 1.061 g/h, optimum recirculation flowarate for 2-stacked MDC was 0.5 ml/min that reached 2.447 g/h of TDR, and the optimum ratio of buffer phosphate:substrate was 0.5:1 that reached 5.202 g/h of TDR."