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4R Waste Management

Diposting oleh On Sunday, December 22, 2013


Ada 4 istilah yg dipakai dalam pengelolaan limbah dan sering dikenal dg istilah "4R" yaitu :
  • Recycle
Adalah mendaur ulang limbah agar bisa digunakan utk proses produksi lain. Misalnya plastik bekas botol air mineral, botol makanan dan peralatan dari plastik dikumpulkan dan dibentuk ke dalam bijih (resin) dg pemanasan kemudian dicetak kembali dalam peralatan lain misalnya kantong plastik, gayung air, celengan dsb
  • Reuse
Adalah menggunakan kembali atas limbah yg dibuang, yaitu dengan mencari kemampuan lainnya dalam proses produksi atau proses2 lainnya yg menguntungkan. Misalnya arang kayu digunakan utk absorbant
  • Reduce
Adalah mengurangi penggunaan bahan atau peralatan.Misalnya mengurangi penggunaan kertas dgn membuat spasi penulisan yg lebih rapat, mengurangi batas2 margin
  • Reclaim / Recover
Adalah mendapatkan kembali unsur seperti awal sesudah dihancurkan atau mengubah sampah menjadi sumber daya (panas, listrik, bahan bakar). Misalnya sampah dikomposkan kemudian kompos digunakan utk pupuk tanaman.

Sumber lain menyebutkan ada "R" utk mengganti Reclaim / Recover yaitu :
  • Replace
Adalah mengganti barang yg hanya bisa dipakai 1 kali dengan barang yg lebih tahan lama.

Macam - macam pengolahan limbah adalah :
  • Pengolahan FISIK
Adalah pengolahan yg melibatkan sifat fisika dlm prosesnya, seperti solidifikasi (pemadatan), degradasi (penghancuran), sedimentasi (pengendapan), insenerasi (pembakaran), open dumping (penimbunan di ruang terbuka), recycle (daur ulang), sanitary landfill (penguburan di tanah dg pelapisan khusus).
  • Pengolahan KIMIA
Adalah pengolahan yg melibatkan sifat kimia dlm prosesnya, seperti stabilisasi (penyeimbangan ion / unsur kimianya), pelarutan, penyebaran daya racun (menggunakan semen), penetralan pH (menggunakan zat asam / basa / kapur), menghilangkan kesadahan air (menggunakan soda, zeolit).
  • Pengolahan BIOLOGI
Adalah pengolahan yg melibatkan mikroorganisme dlm prosesnya, seperti Bioremediasi (penggunaan bakteri utk mendegradasi limbah B3), Vitoremediasi (penggunaan tumbuhan utk mengabsorbsi / mengakumulasi bahan beracun dari tanah).

Referensi :
[1] http://www.museums.ca/Sustainable_Development/Chapter_8_Waste_Management/
[2] http://www.iisd.org/business/tools/bt_4r.aspx
[3] http://www.victorynews-media.com/opini/15/04/2013/
[4] Catatan kuliah dan penjelasan dosen

ARTIKEL TERKAIT :
1. Teknik Pengolahan Limbah Cair B3 
2. Cara Menurunkan Kadar BOD Limbah Cair 
3. Cara Menurunkan Kadar COD Limbah Cair

Junior High School

Diposting oleh On Sunday, December 22, 2013

Age 13 years, CV entered into Islamic Junior High School in Kunir Wonodadi Blitar. CV chose this school because CV has a dream can understand Islamic and applied them to life. His parents suggested that CV be a good child and be a care person. CV school there with his friends in village about 10 childrens. CV went to school by bike and left home at 6 am and arrived school at 6.45 am.
In 1st class, CV entered into heterogen classes which men and women in a class, should class is divided between women in one class and also men. CV into heterogen class because become one favorite classes. CV has characteristic diligent, ashamed and smart. CV always given pocket money by parents Rp. 500 and this must enough to buy food, drink and to kept if happen unexpected something. CV took this condition and done school happily. His father always bought complete literature book and CV spirit to solve every problem in exercise. His father said that will gave college fund and also his mother gave support accompany his study every night. Here CV received both 1st ranked in 1st and 2nd semester. CV showed that he could make his parents proud with his achievement. In final semester and would move to 2nd class, his father died. This disaster made CV deep sadness and couldn’t think about future life because his father that become family backbone. All of friends gave spirit for him and pray for his future live, CV could reach his dream and could make happy his parents such as dream of father during alive. Good bye CV father, I hope your kindness and your charity accepted by Alloh.

In 2nd class, CV must done dependent person after left his father. CV started keeping 2 male goats, CV hunted grass in the field. CV had opportunity after he leaving school. CV lived with his mother which still contain his brother and also with his sister. After 2 month since his father died, his brother was born. This was a happiness and also sadness, happiness because had brother and sadness because confuse about live cost, but Alloh said that coming brother brought live fortune. CV always went home from school at 2 pm and then he must hunted grass until 6 pm. CV’s goat increased always over 12 goats and this was a cost of family live. CV never upset on this live state and done with happiness. During school CV always economize due to money deficit. If rest time, CV still exist in the class not brave leave place because had not money to buy food. So every rest time, CV used that time to solve exercise book and reading book until end of rest time. CV ate at home and after that went to the field. Here CV received both 1st ranked in 1st and 2nd semester. Effort and pray that was done by him got a same achievement. Routinitas time per day after hunted grass at 6 pm and maghrib pray, CV went to the bedroom and woke up 2 am CV for isya' pray, reading Al quran, tahajjud pray then study lesson. This routinitas he was done until 3rd in senior high school. CV gave his mother and also his father (alm) good award although low economical in cost live. Disaster again was motor cycle accident when he with his mother from market. CV took mandible and arm fractura and must be operated for normalize condition whereas his mother only unconscious. This accident happen while holiday so CV no absences and Alhamdulillah still gave live from Alloh, thank to Alloh on this gift fortunate.

In 3rd class, CV school with injury in his arm and operation. CV must drove bike went to school and still spirit and never say die. In this class, CV still must sunat because his friend already sunat since elementary school but CV long ago always crash time with disastrous time such as his father died and motor cycle accident. Here CV chose as team 11 which team as duty school in olympic. Because it, CV must went to school 5.30 am to attend private lesson from teacher about solving of olympic problem. CV get award 1st championship science in Islamic junior high school and also championship in Kediri residence degree. Here CV received both 1st ranked in 1st and 2nd semester and received a good mark in final exam.

Sistem Pendingin (Refrigeration) pada AC

Diposting oleh On Saturday, December 21, 2013

Sistem Refrigerasi adalah sistem pendinginan yg aplikasinya biasa kita lihat pada Air Conditioner (AC). Siklusnya terbilang cukup komplek dan menggunakan prinsip teknik kimia yaitu transfer panas dan massa. 

"Refrigeration system is a cooling system which general application at Air Conditioner (AC). The cycle system is quite complex and using chemical engineering principles such as heat and mass transfer."

Refrigerant adalah bahan yg dipakai utk refrigerasi yg mempunyai sifat pendingin contohnya yg terkenal Freon / CFC (Chloro Fluoro Carbon), dimana akhir2 ini penggunaannya mulai dibatasi karena kerugiannya lebih besar dari keuntungannya yaitu merusak lapisan ozon shg sinar UV masuk ke bumi dan bumi menjadi panas. Contoh lain refrigerant adalah udara, karbondioksida dan ammonia. Selain itu terdapat juga refrigerant yg ada di pasaran seperti dibawah ini :

"Refrigerant are substances that used for refrigeration and have cool properties such as Freon / CFC (Chloro Fluoro Carbon), where lately using of this substance is limited because of disadvantages greater than advantages such as damaging ozone layer so that UV rays entering into earth and earth become hot. Other examples of refrigerant are air, carbon dioxyde and ammonia. Below example of general refrigerant :"


Sistem Kerja Refrigerasi
Dalam sistem ini terjadi beberapa perubahan fase (gas ke liquid dan liquid ke gas / kabut) dan kondisi (tekanan dan suhu). Istilah Sistem adalah yg mengacu pada sesuatu didalam rangkaian alat dan Lingkungan adalah sesuatu di luar alat.

"Working Refrigeration System
In this system there are phase changing (gas to liquid and liquid to gas / vapor) and condition (pressure and temperature). The means of System is something inside equipment series and environment is something outside of equipment."




Mula2 udara panas di lingkungan / ruangan masuk ke Evaporator (fase gas) karena tekanan udara lingkungan lebih besar daripada sistem, tekanan sistem lebih kecil karena sebelum evaporator ada katup ekspansi. Bersamaan dg itu refrigerant (fase liquid) mengalir dari katup ekspansi ke evaporator shg terjadi kontak antara udara panas dg refrigerant (transfer panas). Karena terjadi transfer panas maka suhu turun dan gas menjadi sejuk shg dengan dipasangnya kipas didepan evaporator maka udara sejuk inilah yg dihembuskan ke ruangan (intinya : udara panas lingkungan + refrigerant sistem shg menjadi sejuk dan dihembuskan oleh kipas ke lingkungan lagi). Kemudian gas refrigerant mengalir masuk ke Kompresor utk dinaikkan tekanannya shg suhu juga ikut naik kemudian masuk ke Kondensor yg biasanya dilengkapi kipas utk menghembuskan udara dan disinilah terjadi perubahan fase dari gas menjadi liquid (transfer panas dan massa). Kemudian masuk ke Katup Ekspansi yg memperkecil tekanan begitu juga suhunya (liquid dingin suhu rendah) shg terjadi penguapan dan fase berubah dari liquid ke uap sebelum masuk evaporator. Siklus ini berlangsung terus menerus dan selama tidak bocor, refrigerant akan tetap utuh karena hanya mengalami siklus tanpa bereaksi.

"Firstly, hot air in the environment / room entrance to the evaporator (gas phase) because environment air pressure is greater than system pressure, pressure of system is smaller than environment because of there is expansion valve before evaporator. Along with, refrigerant (liquid phase) blows from expansion valve to the evaporator so that contact between hot air with refrigerant (heat transfer). Because of there is heat transfer so that reduce temperature and cooling air with fan in front of evaporator that is exhaled to the room / environment (simplely : hot air from environment + refrigerant system become cool and exhaled by fan to the room). Then refrigerant system blowing into compressor for raise pressure and temperature too, then entering to the condenser which completed by fan to blowing air and here happen phase changing from gas to liquid (heat and mass transfer). Then entering to expansion valve to minimize pressure and temperature (cool liquid with low temperature) so that happen evaporation and phase changing from liquid to vapor before entering evaporator. This cycle is continue running and during not leak, refrigerant will whole due to only cycle run without chemical reaction ."

Pada pipa masuk ke evaporator dan pipa keluar katup ekspansi terdapat pipa kapiler yg dihubungkan dg tabung sensor panas (thermostat) utk membaca suhu evaporator shg udara yg keluar bisa diatur sesuai kebutuhan dan tidak terjadi pembekuan. Termostat terdiri atas saklar otomatis yang bekerja berdasarkan prinsip beda koefisien muai panjang yaitu bimetal. Bimetal adalah dua buah logam atau paduan logam yang memiliki beda koefisien muai panjang dan direkatkan satu sama lain dengan jalan mengeling atau mengelas. 

"At the inlet pipe to the evaporator and pipe out of expansion valve there is capillary tube that connected with hot sensor (thermostat) to read evaporator temperature so out air can be adjusted as necessity and not freezing. Thermostat consist of an automotic switch which working principle using difference coefficient of expansion length  that is bimetallic . Bimetallic is two metal or metal alloy have difference coefficient of expansion length and joined with welding."

Prinsip kerja dari bimetal adalah apabila dipanaskan akan melengkung. Melengkungnya logam ini disebabkan oleh perbedaan koefisien muai kedua plat logam. Apabila suhu sudah mencapai nilai tertentu sesuai setting yang telah ditentukan sebelumnya, kontak akan terputus karena logam yang ada pada bimetal membengkok. Beberapa saat kemudian apabila suhu turun maka arus akan mengalir kembali karena logam pada bimetal kembali ke posisi semula yang mengakibatkan arus terhubung.

"Working principle of bimetallic is warped when heated. Curved metal is caused by difference coefficient of expansion length between metal. When temperature reach certain value according to predetermined setting, switch will disconnect due to metal at bimetallic is curve. A few moment later when temperature drop and the current will flow back due to metal in bimetallic back to original position  and resulting in the flow connected."



Komponen - komponen pada sistem refrigerasi
  • Evaporator
Alat ini berfungsi menguapkan cairan yg semula liquid menjadi uap / gas. Terdapat coil utk sistem pemanasnya. Disini antara refrigerant dari katup ekspansi dan udara panas dari lingkungan terjadi kontak dan dilengkapi kipas utk menghembuskan ke udara keluar shg udara lingkungan menjadi dingin. Disini tekanan lebih rendah dari tekanan atmosfer dan juga suhu lebih rendah dari lingkungan karena adanya refrigerant. Karena disini dipanasi, refrigerant yg semula liquid berubah menjadi gas.

"This equipment has function to vaporize from liquid to gas / vapor. There is coil for heating system. Here between refrigerant from expansion valve and hot air from environment are contacted and completed by fan for blowing to the room and cool air. Here pressure is lower than atmosferic and also temperature because of refrigerant. Because of heated, refrigerant changing from liquid to gas."
  • Kompresor/Compressor
Kompresor bekerja tidak boleh dalam fasa liquid karena akan menganggu sistem alat, maka refrigerant berfase gas. Disini terjadi penaikan tekanan dan suhu.

"Compressor work not be permitted in liquid phase because will disturb equipment system, so refrigerant has gas phase. Here occur raising the pressure and temperature."
  • Kondensor/Condenser
Gas refrigerant tekanan dan suhu tinggi diubah fasenya dari gas menjadi liquid, disini tekanan tetap tinggi sedangkan suhu turun. Kondensor dilengkapi kipas utk membantu pendinginan.

"Refrigerant gas has high pressure and temperature and converted phase from gas to liquid, here pressure still high and temperature drop. Condenser is completed by fan to help cooling."
  • Katup Ekspansi/Expantion Valve
Gas refrigerant tekanan tinggi diubah menjadi bertekanan rendah shg terjadi pengupan pada liquid dan dihembuskan ke evaporator. Disini karena tekanan evaporator rendah maka udara luar dapat masuk utk kontak dg refrigerant.

"High pressure of refrigerant gas is converted to low pressure so that occur evaporation at liquid and exhaled into the evaporator. Here because of low presssure so outside air can entrance to cantact with refrigerant."

Kutip Artikel ini sebagai Referensi (Citation):
Feriyanto, Y.E. (2020). Sistem Pendingin (Refrigeration) pada AC, Best Practice Experience in Power Plant. www.caesarvery.com. Surabaya

Referensi :
[1] http : //web.mit.edu/2.972/www/reports/compression_refrigeration_system.html
[2] http : //www.hawsepipe.net/chiefhelp/AC&R/Refrigeration.htm
[3] http : //m-edukasi.net/online/2008/sistemac/komponen.html
[4] http : //cvastro.com/cara-kerja-sistem-ac-ruangan.html

ARTIKEL TERKAIT
1. Macam - Macam Kompresor (Compressor) 
2. Isotermal, Isobaris, Isokhoris dan Adiabatis 
3. Cooling Tower