Coagulation and Flocculation Essay

1.0 Introduction In this lab, we are conducting two experiments on natural surface water. The first experiment is to conduct jar tests to estimate an optimum dosage of iron salt to remove suspended solids. The seconds experiment is to observe the rate of floc formation nad sedimentation. 2.0 Background Coagulation and Flocculation: Coagulation and flocculation are important part in water and wastewater treatment. Coagulation is the destabilization of particulate matter by physical or chemical processes. Flocculation is the formation of larger particles that will settle out of the solution. They are usually the first form of treatment of water and wastewater to remove suspended matter or color. Jar tests are used as a control test for plant operations. Aluminum or iron salts can be used to for coagulation of particles and to form flocs that can settle out. Coagulation and flocculation tests provide the optimum dosages to remove turbidity and color, along with secondary effects such as adjusting pH. Jar tests also provide information on the amount of energy needed to provide the coagulation and flocculation treatments, as well as settleability of the flocs, and clarity of the water. They can also be used to study basic processes, for instance, kinetics of reactions and removal of constituents. 3.0 Procedure Determination of Optimum Coagulant Dosage To determine the optimum coagulation dosage, a series of jar tests were conducted. First, 400 mL of clay and sodium bicarbonate amended DI water was measured and poured into a 500 mL Erlenmeyer flask using a graduated cylinder. The initial pH of that sample was then measured and recorded. The predetermined dose of coagulant was poured into a 100mL graduated cylinder and DI water was added to reach a total solution volume of 100 mL. A stir bar was added to the Erlenmeyer flask along with the coagulant dose. The flask was then placed on a magnetic stir plate was rapidly mixed for one minute. After a minute of rapid mixing, the speed was reduced to low and the solution underwent slow mixing for ten minutes. The flask was then removed from the magnetic plate and was allowed to settle. Samples were extracted from the top of the flask after five, ten, and fifteen minutes had elapsed using a 10 mL sampling syringe. Special care was taken to not disturb the sediment while sampling. The sample was transferred from the syringe to a vile, shaken, and placed in a Turbidimeter to determine the turbidity. The turbidity was recorded and the vile was emptied and rinsed between each sample. After fifteen minutes had elapsed and the last turbidity reading had been recorded, the pH of the sample was measured and recorded. The sample was then dumped into a specified waste container, the flask was rinsed with tap water and DI water, and the entire experiment was repeated using a new specified coagulant dose. 4.0 Results and Discussion After plotting turbidity against dosage from our results, we found that the optimum dosage of coagulant to be 1000 mg/L Fe2O3 as shown in Figure 1. Also, longer settling times produced lower levels of turbidity, with 15 minutes being most successful. Optimum pH for a coagulant is determined empirically from laboratory testing by keeping dosage constant and testing a pH range for optimal coagulation. Generally after adding Fe2O3, final pH decreased. Although we did not perform this in the lab, our samples had best success with a pH around 6.5 as seen in Table 1. Mixing speed is also important in coagulation and flocculation. Initially â€Å"flash mixing† is used, where high mixing speeds disperse the coagulant evenly throughout the container. Later, slower mixing speeds are used to promote particle collisions, which lead to larger floc formations. The lab is performed this way because higher speeds will help disperse the coagulant but will break up the flocs that form. By reducing the speed to slow after one minute, it allows for an even dispersion but also the formation of flocs.

Superstition Essay

English Composition Dr. Linfoot 30 September 2010 Worried Sick Believe it or not most of us are affected by some form of anxiety in our everyday life. Weather it is being shy when talking in front of a large audience or worrying about a big paper you have to write for your English class. These are both common forms of anxiety related issues. Though neither is very severe both can be attributed to a manifestation of anxiety. It is believed that it is normal for everyone to experience a mild amount of anxiety during their lifetime. Common mild anxiety can be attributed to the stresses of everyday life. Anxiety diagnosis is at an all time high and is the number one mental health problem throughout the world. Anxiety affects more than twenty million people worldwide. The physical effects of anxiety and its disorders can range from being very mild such as being stressed out, all the way to severe and debilitating. Anxiety disorders can become so chronic and debilitating, that just getting out of bed in the morning can be difficult for a person suffering from a form of an anxiety disorder. Anxiety does not discriminate it affects every race, ethnicity, gender and social class. Nobody is immune to it. A man who fears suffering is already suffering from what he fears† (qtd. In Root 1). Anxiety is an uncontrollable persistent feeling of dread, fear and worry. Anxiety can be attributed to a stressful or traumatic event that took place previously in a persons life. The early warning signs and symptoms of anxiety related disorders start with worrying excessively about minor matters. Mo re severe symptoms include muscle aches, tension and spasms along with shortness of breath and heart palpitations. People diagnosed with anxiety related disorders often experience other mental health problems such as depression. Depression caused by anxiety is often coupled with some form of substance abuse. Women are also statistically at a greater risk of developing an anxiety related disorder. There are six scientifically classified categories of adult anxiety related disorders. The most common anxiety disorder is known as generalized anxiety disorder. General anxiety disorder is usually developed before the age of twenty. Symptoms of this disorder include persistent uncontrollable worrying that lasts longer than six months at a time. Eighty percent of people with this form of anxiety are also diagnosed with depression as well. Panic disorder is another form of anxiety. Panic disorder is also known as panic attacks. During a panic attack a person feels an intense feeling of panic and apprehension. Panic attacks happen often but sporadically and usually do not last longer than ten minutes. It is medically unknown what triggers panic attacks in people. Anxiety researchers suggest â€Å"These attacks are typically experienced out of the blue, and are not precipitated by a situational trigger†(Crits et al. 16). The most diverse category of anxiety disorders are phobias. Phobias are inexplicable and illogical fears of a particular object, class of objects, or situation. People suffering from phobias worry about what will happen when they come in contact with that particular object, class of objects or situation. Phobias can range from the fear of heights, to the fear of a certain animals. Social anxiety disorder is also known as social phobia. People with this disorder fear social situations or interactions where they are the center of attention. They fear embarrassing themselves in front of others thus increasing their own anxiety levels. In a social setting people suffering from social anxiety disorder tend to sweat and become visibly flustered. People with this disorder try and avoid these social situations all together and are usually always self conscious type people. I think one way or the other we all have our own manifestation of social anxiety, I know I do. Presently there is a handful mainstream television shows dedicated to documenting people living with obsessive compulsive disorder. Obsessive compulsive disorder is type of anxiety disorder where a person experiences repeated involuntary obsessions and compulsions. Involuntary obsessions and compulsions such as distracting ritualistic thoughts and behaviors. People suffering from obsessive compulsive disorder often spend hours a day performing their individual rituals. In a small number of cases people only suffer from a compulsion and not an obsession or vice versa. It is believed that obsessive compulsive disorder can be linked to superstition. Like superstition people with obsessive compulsive disorder tend to perform certain rituals in hopes of preventing bad things from happening to them. If left untreated obsessive compulsive disorder is known to be the most physically debilitating of all known anxiety disorders. Today post traumatic stress disorder is the most highly publicized form of all anxiety disorders. There are numerous service members coming back from both the present wars and being diagnosed with this disorder. Post traumatic stress disorder occurs as a result of experiencing a highly traumatic event such as combat, death, rape, abuse and so on. People suffering from post traumatic stress disorder often have flashbacks of that traumatic event. Flashbacks can often be triggered by something that reminds them of that traumatic event. People diagnosed with post traumatic stress disorder often feel helpless from preventing the same traumatic event from occurring again. Without treatment people diagnosed with anxiety disorders often have difficulty ever leading a normal life again. There are a handful of treatment methods used by different doctors to treat anxiety disorders, but not all have been proven to be effective. Medications and psychotherapies are the two different categories of treatment methods for anxiety disorders that have proven to be most effective. The main form of psychotherapy used to treat anxiety disorders is cognitive behavioral therapy. Cognitive behavioral therapy uses either individual or group therapy sessions to gradually expose a patent to his or her fears, obsessions or anxiety provoking situations. It may take several sessions for a patient to see any progression toward their goal of overcoming their anxiety disorder. By the end of the scheduled treatment therapists ultimate goal is to try and prove to the patient that their dysfunctional thought processes are unrealistic. Cognitive behavioral therapy is a slow process but has been proven to be the most effective form f psychotherapy used to treat anxiety disorders. Medication is only used in treating anxiety disorders if the patient showed little or no progress with therapy. There are several different brands of medications doctors can prescribe to treat anxiety disorders. But all brands commonly fall into three classes. The first class of medication prescribed by doctors is called selective serotonin reuptake inhibitors or SSRIs. Selective serotonin reuptake inhibitors have proven to be very effective. The medication helps raise the patients level of serotonin in the brain. With continued use of selective serotonin reuptake inhibitors the patients overall sense of anxiety is reduced, and sense of well being is highly elevated. If selective serotonin reuptake inhibitors do not work for a patient, doctors then prescribe Benzodiazepines. Benzodiazepines enhance the effects of natural neurotransmitters in the brain that calm and relax a person. Benzodiazepines produce a calm, almost sedative state. Benzodiazepines are highly effective but patients can become tolerable of the drug, therefore the drug is only used for less than two weeks at a time. The third category of medication is called Monoamine oxidase inhibitors or MAOIs. Monoamine oxidase inhibitors are used by sufferers of anxiety disorders but only used in a medical setting. Monoamine oxidase inhibitors are not intended for daily use. Monoamine oxidase inhibitors are highly potent drugs and it is easy for a patient to overdose. Monoamine oxidase inhibitors require a strict diet and do not interact well with other drugs. Because of these restrictions and dangers monoamine oxidase inhibitors are not commonly used today. To me anxiety disorders are very similar to viruses like the common cold. Everybody gets them from time to time and they can be treated, but you are never completely cured from them. All the therapy and medication in the world will not help a person completely get over their anxiety disorder. But thankfully there is always help available. During the last forty years there has been significant progress in the diagnosis and treatment of anxiety disorders. Today doctors are now far better able to diagnose and treat anxiety disorders. The number of people diagnosed with anxiety disorders has been skyrocketing over the last few decades. I am curious to know if the umber has been climbing because of better diagnosis methods, meaning in the past people went untreated. Or could it be because people are just fearful of where the world is possibly headed? Only time and more research will be able to tell. Even a small amount of anxiety if left untreated can build up and develop into a full blown disorder. Anxiety and its disorders need to be taken seriously. They are very serious illnesses and should always be addressed. Like I stated before, a small amount of anxiety from time to time is normal. It is how you deal with your anxiety that is most important. Works cited Crits, K. , Greg, J. , Efran, J. , Greunberg, A. , Felgoise, S. , Hayes, S. , . . . Lackie, B. (2007). Anxiety Disorders : A Practitioner's Guide to Comparative Treatments (Gosch & R. DiTomasso, Eds. ). New York, NY: Springer Publishing Company, Incorporated. Retrieved from http://site. ebrary. com/lib/excelsior/docDetail. action? docID=10176162 Root, B. (2000). Understanding Panic and Other Anxiety Disorders (B. Root, Ed. ). MS: University Press of Mississippi. Retrieved from http://site. ebrary. com/lib/excelsior/docDetail. action? docID=10157894