Turbidity and algae are removed from raw waters by screens, gravel filters and slow sand or rapid gravity filters. The difference between slow and rapid sand filtration is not the speed of filtration, but in the underlying concept of the treatment process. Slow sand filtration is essentially a biological process whereas rapid sand filtration is a physical treatment process.
Screens
Screens are effective for the removal of particulate material and debris from raw waters and are used on many surface water intakes. Coarse screens will remove weeds and debris while band screens or micro strainers will remove smaller particles including fish and may be effective in removing large algae. Micro strainers are used as a pre-treatment to reduce solids loading before slow sand filters or chemical
…show more content…
They may also be used to remove turbidity, algae and iron and manganese from raw waters. Granular activated carbon medium is used to remove organic compounds and filters incorporating an alkaline medium are used to increase the pH value of acidic water. Rapid gravity sand filters usually consist of rectangular tanks containing silica sand (size range 0.5 to 1.0 mm) to a depth of between 0.6 and 1.0 m. The water flows downwards and solids become concentrated in the upper layers of the bed. Treated water is collected via nozzles in the floor of the filter. The accumulated solids are removed periodically by backwashing with treated water, usually preceded by scouring of the sand with air. Frequency of backwashing depends on loading rate and raw water quality and is typically every 24 hours. Backwashing can be initiated automatically after a predetermined head loss has been reached or may be carried out manually. A dilute sludge that requires disposal is produced which may be discharged to sewer, soak-away or, after treatment, to a watercourse provided that any required discharge consent is
In Regina Calcaterra’s memoir, Etched in Sand, the speaker is Regina as a ten-year-old female, who was being abused, and forced to grow up much faster than most, other children her age. She wrote this book to reach her siblings, and show her love for them; but she also was looking to reach out to children who were/are being abused, are in foster care, and who are homeless. The book was set in The Hamptons of Long Island, during the 1970s and 1980s. Regina and her four other sibling were being abused by their mother, who was hooked on drugs and alcohol, and was all around a very irresponsible person. This group of siblings, were moving quite often because their mother either did not remember to pay the bill, or they were sleeping in the back
The Effect of Solute Concentration on the Rate of Osmosis Aim: To test and observe how the concentration gradient between a potato and water & sugar solution will affect the rate of osmosis. Introduction: Osmosis is defined as, diffusion, or net movement, of free water molecules from high to low concentration through a semi-permeable membrane. When a substance, such as sugar (which we will be using in the experiment we are about to analyse), dissolves in water, it attracts free water molecules to itself, and in doing so, stops them from moving freely. The effect of this, is that the concentration of (free) water molecules in that environment goes down. There are less free water molecules, and therefore less water molecules to pass across a semi-permeable membrane, through which sugar molecules and other molecules attached to them are too big to diffuse across with ease.
The American Dream has been a fantasy for many people around the world. It has
The first encounter with Helga Crane, Nella Larsen’s protagonist in the novel Quicksand, introduces the heroine unwinding after a day of work in a dimly lit room. Alone. Or, is she? Although no one else is present in the room, Helga is accompanied by her own thoughts, feelings, and her worrisome perceptions of the world around her. Helga’s anxieties and fears are perhaps some of her most challenging adversaries. And while there are human character antagonists that will soon play a significant role in the novel and in the story of Helga Crane, such as her friends, coworkers, relatives, and ultimately even her own children, there are also enemies that Helga confronts who never say a word. These quiet yet taxing antagonists appear throughout the novel in many different forms. Physical and cultural settings, racial oppression, religious and educational institutions, even the concepts of marriage and childbirth emerge as massive obstacles for Crane. These problems are a substantial source of Helga’s apprehensions and eventually lead to her tragic demise.
Comment on class result with respect to differences in filter types, differences in filter assemblies, and overall on the confidence you would have in using this type of sterilisation process in preparation of pharmaceutical products. List the factors that may cause contamination during filtration. (20 marks)
when to do it etc. This should lead me to good results at the end of
Trickling Filters and Membrane Bioreactors are focused on in this paper. Trickling Filters: Trickling Filter (TF) reactors consist of a vertical column packed with biofilm supporting media.
The bacteria and wastewater is mixed in an aeration tank and therefore the contaminants are removed by action of sorption and series of breakdown by the bacteria.
These items are removed by a bar screen that the waste water flows through.... ... middle of paper ... ... Youtube.com (accessed 03/08/2014). Richardson, S. Water Analysis. Journal of Analytical Chemistry.
Investigating the Effect of Drop Height on the Depth of Sand Aim: To investigate the depth of the sand depending on the height at which the ball is dropped from. Variables: Independent variable chosen: The height at which the ball is dropped Dependent variable chosen: The depth of the sand after removing the fallen ball from it. Constant variables and how they will be controlled: Variable How we will keep it constant Amount of sand We leave the sand in the bucket and make sure that none spills over. Type of sand Use the same one for each trials Ball Use the same ball for each trial, with the same size, volume, material and brand.
Desalination refers to the removal of salt. It is typically used in the context of saline water, particularly seawater. Desalination is an intricate process and there are multiple methods of approaching desalination; however, the most popular technique is reverse osmosis. There are various factors that must be considered when desalinating water, such as pressure and concentration. Desalinating water has been used for many purposes, whether it be providing drinking water for communities, a steady source of water for agricultural irrigation, or a decent quality steam for the pharmaceutical industry. In today’s world, desalination is becoming more widely practiced in a large scale.
The Sand Cone Model describes business improvement as a process which should be based on improving specific competitive dimensions in a different order (Meredith & Shafer, 2013). For instance, a business which is struggling with quality outputs should place an emphasis on improving the quality of its outputs first. Businesses that produce high quality outputs are successful over the long term. Matthew 7:24-25 (ESV) states, “Everyone then who hears these words of mine and does them will be like a wise man who built his house on the rock. And the rain fell, and the floods came, and the winds blew and beat on that house, but it did not fall, because it had been founded on the rock.” When a business builds its foundation on
The process of disposing waste, producing food, and purifying bodies of water is useful today. For example, communities that live in the desert, like in the southwestern United States and in the Middle East, can use this process to farm and survive. They can use the newly purified water for their crops or for their own consumption. In addition, when algae purifies water, it releases oxygen.
The terms secondary and primary treatment have been used to basically describe a degree of treatment; for example, biological wastewater treatment and settling. Tertiary treatment has been regarded as different from secondary and is the advanced one. It comprises of the use of sand filters to separate the solid particles from the wastewater. Tertiary treatment has also been regarded as the treatment involved to remove plant nutrients, primarily nitrogen and phosphorous.
Chemicals and impurities removed from water may not be disposed properly thus polluting the environment. A sheet volume of discarded filters may add up to landfill mass. The system itself may take up large amount of spaces and cause lots of noises and destructions. There may also be chemical or wastewater spills if not handled properly.