Water Treatment Process

Overview of the Water Treatment Process

Water treatment in a typical water treatment plant is shown in the picture below. Based on the characteristics of the raw water and on other factors, this treatment process may vary considerably from place to place.

As water is pumped from the source (a well, spring, river, or lake), it is screened to remove debris. Then, at the water plant, various characteristics of the raw water are tested.
Next comes a variety of optional steps, only some of which are shown on the diagram above. The water may be prechlorinated to kill microorganisms, control odors and taste, and aid in coagulation and settling. The water may also be aerated, which removes carbon dioxide (CO2) and raises pH, oxidizes iron (Fe) and manganese (Mn), removes hydrogen sulfide (H2S), and removes organic contaminants. Potassium permanganate (KmnO4) may be added to the water in the collection tray of the aerator in order to remove iron and manganese from the water. Ozone may be added to the water to treat iron and manganese, remove algae, neutralize hydrogen sulfide (H2S), and aid in flocculation.

In most cases, the water then enters a flash mix chamber. Here, various chemicals are added and are mixed into the water. Coagulants cause fine particles to clump together into larger particles. Alkali are added to adjust the pH as well as to oxidize iron and manganese. Hexametaphosphate may be added to prevent corrosion of pipes.
After flowing out of the flash mix chamber, the water goes through a chamber which causes coagulation and flocculation to occur. Here, the fine particles of contaminants gather together into large clumps called floc. When the water flows on into the sedimentation basin, some of the floc settles out of the water and is removed. Next, the water is passed through filters which remove particles too small to settle out in the sedimentation basin.

Finally, chlorine is added to the water. The water may also be fluoridated to reduce tooth decay in the consumers. The water is left in the clear well for a period of time to allow the chlorine to kill bacteria in the water and to oxidize hydrogen sulfide. The water is now treated and ready to be distributed.

KOLESTEROL TINGGI? HAJAR PAKAI SELEDRI

Salah satu penyakit paling populer di zaman ini ialah kelebihan kolesterol atau hiperkolesterolemia. Ia ditakuti lantaran bisa mengganggu kesehatan jantung. Dengan berpantang makanan sumber kolesterol, kadar kolesterol darah ini bisa dikurangi. Kalaupun sudah kadung tinggi, bisa diturunkan dengan mengkonsumsi bahan alami seperti seledri, bawang putih, bawang prei, atau temulawak.
Seorang pria eksekutif muda tiba-tiba saja menolak ajakan rekan-rekannya menyantap tongseng ketika makan siang bersama di sebuah warung. Padahal sebelumnya, makanan lezat yang terbuat dari daging kambing ini termasuk favoritnya. Setelah diledek macam-macam, akhirnya dia buka kartu. "Gua kena kolesterol, nih!". Rupanya, dia menderita kelebihan kadar kolesterol alias hiperkolesterolemia. Ia lalu bercerita, seminggu sebelumnya hasil pemeriksaan kesehatannya menunjukkan kadar kolesterol dalam darahnya sudah menembus plafon sehat.
Dokter memang memberinya resep obat, tetapi - tahu sendiri - harganya mahal. Ia hanya menebus resep sekali saja. Sebagai gantinya ia bertanya sana-sini adakah bahan alami berkhasiat obat untuk melawan hiperkolesterolemia, selain mencoba melakukan olahraga dan diet secara teratur.
Celakanya, hiperkolesterolemia termasuk gangguan yang relatif baru diketahui dalam dunia kedokteran. Makanya, tidak dikenal obat tradisionalnya. Kalaupun kemudian diketahui obat alami untuk kondisi ini, sifatnya bukanlah warisan nenek moyang. Untunglah, beberapa penelitian sudah membuktikan adanya sejumlah bahan alami yang bisa dijadikan obat.
Beberapa tanaman yang telah diteliti dan memberi indikasi positif dalam penyembuhan hiperkolesterolemia di antaranya adalah tanaman yang biasa dipakai sebagai bahan sayur dan bumbu dapur. Umpamanya, bawang putih, bawang prei, seledri, temulawak, belimbing wuluh, kunyit, dan teh hijau.
Seperti diketahui, selain bisa dibuat oleh tubuh di dalam hati, kolesterol yang merupakan substansi lemak itu hanya ditemukan dalam bahan makanan hewani. Dua komponen penting dari kolesterol adalah LDL (low-density lipoprotein), yang disebut pula kolesterol "jahat", dan HDL (high-density lipoprotein) yang disebut kolesterol "baik".
Sebenarnya, kita hanya perlu sejumlah kecil kolesterol yaitu untuk membuat dan memelihara sel-sel saraf serta untuk membuat hormon. Kalau kadar kolesterol dalam pembuluh darah berlebihan, maka sebagian kolesterol itu akan mengendap. Hal ini memungkinkan terjadinya kalsifikasi atau pengapuran sehingga pembuluh darah tidak elastis lagi. Akibatnya, timbul tekanan darah tinggi.
Temulawak, rimpang yang juga banyak dipakai untuk ramuan jamu.

Keadaan itu dapat membahayakan, terutama bila sampai menyebabkan pecahnya pembuluh darah. Apalagi pembuluh yang pecah adalah pembuluh darah di otak yang dapat menyebabkan kelumpuhan. Bila pengapuran terjadi di pembuluh darah jantung, organ vital ini akan kekurangan pasokan darah sehingga kekuatannya berkurang. Kalau aliran darah sampai tersendat, akan terjadi infark jantung yang membuat denyut jantung tidak teratur atau sama sekali tidak kuat. Akibatnya bisa fatal.
Mencegah penggumpalan darahUntuk mencegah agar tidak mencapai tahap yang fatal, mau tidak mau kadar kolesterol harus dinormalkan dengan menurunkan LDL dan meningkatkan HDL dalam darah. Penelitian menunjukkan, untuk setiap penurunan tingkatan kolesterol 1%, risiko penyakit jantung dikurangi sampai 2%.
Pada hewan percoban, sari bawang putih Allium sativum terbukti dapat menurunkan kadar kolesterol serum dan trigliserida dalam serum darah. Ia juga dapat menaikkan kadar HDL serta meningkatkan aktivitas fibrinolitik. Umbi bawang putih ini pun bisa mencegah terjadinya infiltrasi (penyusupan) lemak, menghambat atau mencegah agregasi platelet (bagian darah yang berperan dalam pembekuan darah), sehingga penggumpalan darah tidak terjadi. Semua ini mencegah terjadinya pengapuran dan akan mencegah terjadinya tekanan darah tinggi serta serangan jantung (koroner). Maka tak salah kalau bawang putih juga dikatakan bersifat antiarteriosklerosis. Percobaan pada manusia lebih berarti untuk pencegahan.
Seluruh bagian tanaman bawang putih mengandung minyak atsiri. Kandungan senyawa itu lebih banyak terdapat di dalam daunnya ketimbang pada umbinya. Sayangnya, bawang putih mengeluarkan aroma menyengat. Untuk menghilangkannya telah dicoba dengan mencampurnya dengan minyak atsiri sirih. Juga telah dicoba dengan menggunakan campuran daun beluntas. Secara in vitro, daun beluntas bisa menghilangkan bau bawang putih, tetapi tidak mempengaruhi potensi bawang putih.
Diperlukan dua siung bawang putih atau sekitar 4 g setiap kali mengkonsumsinya. Umbi putih dengan rasa menyengat ini dikunyah hingga halus baru ditelan. Setelah itu minum air hangat secukupnya. Ini dilakukan sebanyak tiga kali dalam sehari.
Penelitian menggunakan seledri Apium graveolens L. menunjukkan hasil positif pada tikus putih. Kadar kolesterol darah hewan percobaan yang diberi rebusan daun seledri ternyata menurun.
Rasa dan aroma bawang putih memang menyengat, tapi demi kesehatan, jangan dipersoalkan.

Di dalam daun seledri terkandung senyawa glukosida, apiin, dan apoil yang memberi aroma khas. Namun, senyawa apa yang berkhasiat menurunkan kadar kolesterol darah belum terungkap.
Bila daun ini dipilih sebagai obat, diperlukan sebatang seledri yang direbus dengan 1 gelas minum air hingga mendidih. Setelah dingin, minumlah air rebusan itu. Dalam sehari cukup minum satu kali.
Terbukti pada hewan percobaanBegitu pula ekstrak temulawak Curcuma xanthorrhiza dan kunyit Curcuma domestica. Keduanya dapat menurunkan kadar kolesterol darah hewan percobaan. Dengan dosis 6 ml, 8 ml, dan 10 ml, rimpang temulawak dapat menurunkan kadar kolesterol total dan trigliserida darah kelinci yang mengalami hiperlipidemia. Pada dosis 10 mg, 15 mg, dan 20 mg kurkuminoid temulawak menurunkan kadar kolesterol total dan trigliserida. Khusus pada dosis 20 mg, pengaruh yang diberikan berupa peningkatan HDL-kolesterol darah. Sementara, kunyit mempunyai sifat menurunkan kadar kolesterol pada tikus. Ini berkat kurkumin yang terkandung di dalamnya.
Daun bawang prei (Allium porrum L., A. fistulosum L.) termasuk yang telah diteliti kemampuannya dalam menurunkan hiperkolesterolemia. Dalam penelitian itu, digunakan tikus yang diberi ekstrak daun bawang prei yang jumlahnya setara dengan 10 g bawang daun/kg BB (berat badan)/hari selama 60 hari. Hasilnya ternyata meningkatkan kadar trigliserida dan kolesterol darah tikus. Tapi pada tikus yang dietnya diberi sukrosa, pemberian ekstrak dengan jumlah dan jangka waktu sama ternyata dapat menurunkan kadar trigliserida dan kolesterol darah.
Buah belimbing wuluh Averrhoa bilimbi L. yang biasa digunakan sebagai bagian dari bumbu masak atau sayur, terbukti pula menurunkan kadar kolesterol darah. Dari penelitian terbukti, air perasan belimbing wuluh dengan volume 1 ml, 1,5 ml, 2 ml, dan 2,5 ml secara oral pada tikus putih dapat menurunkan kadar kolesterol dalam serum darahnya.
Sementara pada dosis tertentu, 0,54 g/200 g BB, teh hijau ternyata mampu menurunkan kadar kolesterol total, kolesterol LDL, trigliserida, dan berat badan tikus putih. Tapi teh hijau tidak mempengaruhi kadar kolesterol HDL.
Tikus yang dietnya diberi sukrosa bawang prei, kadar kolesterol darahnya turun.

Sayangnya, takaran optimal empat bahan obat terakhir untuk menurunkan kadar kolesterol pada manusia belum diketahui. Ini lantaran penelitian belum sampai pada penerapannya bagi manusia. Data empiris pun masih belum ditemukan. Untuk memanfaatkannya, memang perlu percobaan. Yang pasti, semua tanaman tadi dalam penelitian tidak menunjukkan sifat toksik (beracun), sehingga relatif aman untuk dicoba dalam upaya menurunkan kadar kolesterol darah.
Bagaimanapun pengobatan merupakan langkah baik untuk menurunkan kadar kolesterol darah yang telanjur tinggi. Namun, tindakan pencegahan tetap lebih baik. Beberapa patokan sederhana untuk mencegah hiperkolesterolemia di antaranya menambah kadar serat dapat larut dalam diet dengan makan buah-buah, sayuran, kekacangan, dan bebijian; memilih lauk produk daging putih atau ikan; menyingkirkan kulit sebelum memasak ayam; memilih daging tak berlemak dan membuang semua lemak yang ada, serta mengkonsumsi dalam porsi sedang.
Juga membatasi jumlah kacang tanah yang dikonsumsi; membatasi penggunaan mentega, margarin, keju, dan minyak goreng dari kelapa atau kelapa sawit, sebaliknya gunakan minyak bunga matahari, kedelai, kanola, atau minyak zaitun; memilih produk-produk makanan dan minuman yang tanpa atau rendah lemak; dan bila kelebihan bobot badan, sebaiknya lakukan penurunan bobot badan dan olahraga. (Drs. B. Dzulkarnain)

Informasi lebih lanjut bisa ditelusuri di antaranya dalam kepustakaan berikut:
Dirghantara, E. 1994. Efek Ekstrak Sari Seduhan Daun Teh Hijau (Camellia sinensis O. Kuntze.) terhadap Kadar Kolesterol dan Trigliserida Tikus Putih yang Diberi Diet Kuning Telur dan Sukrosa. Jurusan Farmasi, FMIPA UI. Jakarta.
Gunawan, N., 1988. Pengaruh Campuran Ekstrak Bawang Putih dan Daun Beluntas terhadap Kadar Kolesterol Serum Darah Tikus Putih. Fak. Farmasi, UGM. Yogyakarta.
Hutagalung, J.S., 1986. Penelitian Pendahuluan Pengaruh Perasan Belimbing Asam (Averrhoa bilimbi L.) terhadap Kadar Kolesterol dalam Serum Darah Tikus. Jurusan Biologi, FMIPA Unair. Surabaya.
Idris, N. S., 1990. Penelitian Pendahuluan Pengaruh Pemberian Rebusan Daun Seledri (Apium greaveolens L) terhadap Kadar Kolesterol Darah Tikus Putih. Jurusan Biologi, Unas. Jakarta.
Pramadhia B., 1988. Pengaruh Kurkuminoid dari Temulawak (Curcuma xanthorrhiza Roxb.) terhadap Kolesterol Total, Trigliserida, HDL-kolesterol Darah Kelinci dalam Keadaan Hiperlipidemia. Jurusan Farmasi, FMIPA Unpad. Bandung.
Perry, L. M., Metger, Y., 1980. Medicinal Plants of East Asia and Southeast Asia. The MIT Press. Cambridge, Massachusetts, London.
Yusuf, A., 1988. Pengaruh Ekstrak Eter Bawang Prei (Allium porrum L.) terhadap Kadar Glukosa, Triasilgliserol, dan Kolesterol Plasma Darah Tikus yang Diberi

Water/Wastewater Treatment..Nature way

Hello, I'm Sper3099. I would like to introduce you to a subject called water and wastewater treatment. In water and wastewater, there are many concepts to learn so I thought I would start out with the way nature treats water - the hydrologic cycle.
The hydrologic cycle follows water as it evaporates from the earth's surface, forms clouds, and then falls back to the earth's surface as rain.


Evaporation and Rainfall
Water evaporates into the air due to the sun's warming the water and changing it into a gas. The water escapes from plants as they breathe (a process called transpiration) or evaporates from surface water. After evaporating the moisture disperses into the atmosphere and forms particles which are collected in clouds.
Fog is an example of a cloud next to the earth's surface. As you drive through fog, you can tell that there is water in the air because droplets collect on the windshield as a result of the water's attraction (affinity) to the glass.
Water must collect together before it can fall out of the air. If clouds are in a dusty region, water will collect on the dust in the air and cause precipitation. For example, in times of war there is often a greater than usual amount of rainfall because explosions on the ground throw dust up into the atmosphere.
Dust particles form the centers of raindrops, but these drops usually fall only when the clouds are cooled. As air cools, it becomes supersaturated, meaning that the air has more water in it than it can hold. Clouds cool and become supersaturated when they gain in elevation or come in contact with a cold front. When clouds are forced over mountains they become extremely supersaturated and enormous amounts of precipitation can occur. On one of the Hawaiian Islands, approximately 500 inches of rain may fall every year.



















Purification in the Sky

Evaporating water can carry contaminants such as bacteria into the air with it. However, the bacteria are killed by two substances: ultraviolet light and ozone. As a result, the rain falling out of the clouds is usually pure until it nears the earth's surface.
Although we cannot see ultraviolet light, also known as UV light, it causes sunburn in humans. Greater than usual amounts of UV light can kill both plants and animals. Luckily, most UV light penetrates into clouds to kill bacteria.
The same ozone which prevents most UV light from reaching the earth's surface is also a potent killer of bacteria. Ozone kills microorganisms in the atmosphere about 30,000 times faster than chlorine can kill microorganisms in water.
Whereas UV light shines down on the atmosphere in an endless stream from the sun, ozone must be produced. Energy from cloud movement causes ions (charged particles) to separate and the ionic charge released produces lightning. When lightning occurs, ozone and a soluble form of nitrogen are made.
Ozone production occurs primarily during warm weather. In cold weather, there is no need for the ions to separate as much. Thus, there are very few static charges in the clouds to create ozone. But the UV light and the cold temperatures still kill microorganisms.

Bacterial Contamination

In temperate conditions ozone and UV light cleanse the cloud of bacterial contamination. But once rain begins to fall, the rain drops start picking up contaminants, such as bacteria and dust, from the air. The bacterial contamination is all around us. For proof, expose some agar to air and you will see that it grows microorganisms. Agar is a gelatin-like food designed to grow only certain groups of organisms.
Some of the falling rainwater evaporates back into the air due to the saturation of the soil and the warmth of the earth. Other water is retained by the vegetation or trickles down through the soil. This groundwater is cleaned by filtering slowly through the earth's crust. Still other water runs across the earth's surface and ends up in rivers and streams.
As water runs across the earth's surface, it picks up any contaminants it comes in contact with, including bacteria and organic matter such as ammonia. Surface areas have high bacterial counts and bacteria are easily washed into rivers and streams. Some of these contaminants are harmful to humans. For example, TB is a disease which can be transmitted through food, animals, water, and soil.
But many of the bacteria which enter surface waters are not harmful. Instead, they eat the organic matter that is suspended in the water and start using up oxygen dissolved in the water. This action raises the biological oxygen demand (BOD) of surface waters. This is also how the natural world starts the process of water treatment.

Natural Water Treatment

By the time rain water reaches streams, it has picked up microorganisms, organic matter (such as ammonia), and materials of various sizes (such as dirt and rocks). Natural processes remove each type of contaminant from the water.
The materials suspended in the water come in sizes ranging from tiny particles of mud to large rocks. Over time, the materials and sediments within the water tend to settle selectively by velocity, as shown in the illustration below. Quickly moving water can carry large objects with it, but the largest rocks will soon fall to the bottom of the stream and stay there. As a stream leaves rapids and begins to move more slowly, smaller objects, such as pebbles, settle to the bottom. Even slower water drops sand. Finally, when the stream reaches a basin or pond where the water moves very slowly, sediments settle to the bottom and form mud.
The removal of organic matter begins in these impoundments of still water. Here, microorganisms begin to eat the organic matter. In the process, they use up oxygen in the water.
As water leaves these impoundments, it often flows over rocks, increasing the amount of water surface coming in contact with the air. The increased surface area enables the water to pick up oxygen to replace the oxygen used by the microorganisms. Carbon dioxide, a waste product from the microorganisms, is also released here. As the carbon dioxide is driven off, pH readings rise in the water.
Contaminants are also removed as the water flows over rocks in streams. In a living stream, rocks develop a slick coating because of the microorganisms that attach to them. So a living stream can be determined by the presence of slick rocks and plant growth.
In a healthy stream, the microorganisms are able to convert ammonia into nitrates. Plants in the stream absorb the nitrates which they in turn use for food.
So ammonia and sediments are both removed from the water during the natural flow of a stream. But microorganisms remain in the water until it flows to the ocean. There, salt kills most of the freshwater microorganisms.

Buffers

As I mentioned above, whenever carbon dioxide is released into water or removed from water, the pH of the water changes. Most of the living things in the stream, including the microorganisms which digest organic matter, are sensitive to the stream's pH. Changing pH can kill many of these organisms.
But in a natural system, the pH of the water does not usually change dramatically. Buffers in the water prevent it from becoming very acidic or basic. A buffer can best be described as an acid and a base mixed together. As the pH of the water begins to change, the buffer neutralizes the change. As a result, the microorganisms survive.
Buffer: A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH. Any of certain combinations of chemicals used to stabilize the pH values or alkalinities of solutions.
Buffer Capacity: A measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water or wastewater for offering a resistance to changes in pH.

Taken From: College Chemistry, 1980 LC 79-88562 page 427:
Mixtures of weak acids and their salts or mixtures of weak bases and their salts are called buffer solutions. They resist a change in hydrogen-ion concentration upon the addition of small amounts of acids or bases.