Water, Wastewater and Environmental Engineering Topics - Assignment Example

A compilation of essays on water, wastewater and environmental engineering topics A compilation of essays on water, wastewater and environmental engineering topics QUESTION 1 A) In the process of water treatment removal of solid particles from raw water is done by the use of sedimentation tank. The efficiency of this tank is always made to achieve a rate of 70% in removal of these solids. In order to determine whether the tank has achieved the efficiency of that percentage, technicians normally use a test known as column test. This is done in order to know the efficiency at certain flow conditions. Efficiency of removal of solid is dependent on two factors. That is the time of retention (t) or the velocity (v), both of them are variable, meaning they can be manipulated in order to achieve the desired rate of efficiency. You can increase or lower the two factors at will, in order to achieve the right efficiency. Velocity is also known as hydraulic loading rate or it can be called known as surface overflow rate. To find out the value of velocity V0= design settling velocity. We use the following equation VO= ho/to. Of which to find out the value of t, we use the equation to= v1/Q. Q in the equation means the overflow rate while V1is the flow rate into the tank. In the velocity equation hois used to represent height of the holding tank. Figure 1.1 Figure 1.1 above shows an example of a sedimentation tank. From left there is the V1which is the flow rate into the tank, while on the right side there is the Q, which is the over flow rate. Height HO can be indicated as a location between mud wave and the water top. B 1 Rate of efficiency= height / mixed concentrates =2.4/ 200mg/l = 0.012 Hence time * settling rate= 80 minutes* 0.012 = 96% B2 Hydraulic loading rate in order to achieve an efficiency of 75%. Height=2.4 meters Solid concentration = 200mg/l Hence efficiency (75%) = height (2.4) / loading rate Hence 2.4 / 0.75 = 3.2 Finally 60 minutes divide by 3.2 = 18.75 meters per minute. B3 Design flow of the tank is 5000m3per day. Loading rate = 18 meters per minutes Hence in 1 hour = 18*60= 1080m per hour Hence in one day= 5000m3 per day. The above measurements are acceptable. Circular tank have a higher overflow rate, and the settling base is deep in enough. Hence this reduces the time required to settle. Hence the above rate are collect, and they are the best. QUESTION 2 Most available sources of water are either, wells, rivers, lakes and rain. And then there are special underground storage tanks known as Aquifers. They usually have a capacity to handle huge volumes and are fed from rain water sipping through the ground, or well-structured or defined underground channels of tributaries. In this part of the question the purpose is to determine what sort of treatment would be nice for aquifer water and also how to treat water in a reservoir. Starting with the water in the reservoir, the description is that, the water is located in an upland storage that is a reservoir and the water is said to be characterized by some unacceptable levels of color and taste. The water has a PH of 5.5 and the said location is a sheep farming area. Most water found in natural sources might be very unsuitable for husbandry or irrigation or home usage. Chances are that the water might be high in ions or certain metals. Likewise the water might have colors which can be deemed to be ordinary but they are not ordinary. Hence in all standards it is always important that if someone is not sure of their water they should at least use the services of water testing in order to avoid poor results in plant growth, animal care, and maintenance of recommended human health (Knappe, 2004). Water normally has a wide range of inherent qualities, but this is dependent on the location, type of soils and source of the water. Some of the qualities related to water include, corrosion, iron, PH, salinity, bacteria, taste, color and algae. This are some of the characteristics that water testing is supposed to determine, in order to reduce cases of water unfit for routine usage and farming activities. PH is used to describe the acidity and alkalinity of water. Acidity in water affects wide variety of things, ranging from, plants, the equipment’s used in irrigation, effect on drinking water and also determines how efficient a pesticide can be when mixed with water. PH is determined by the balance of either (+) hydrogen ions and (-) hydrogen ions in the water. That balance determines either the acidity or alkalinity in water. PH measurements run from 0 to 14. The determining number is 7. 7 in PH has a significant relevance, because when PH falls below 7 the water can be described as acidic, while a measurement of a make above 7 can be described as alkaline water. Research has proved that, numerous natural waters have got a PH value of around 5 to 8. This range is not bad for irrigation, because irrigation runs from 5.5 to 8.5. Though right for irrigation, such level of PH can cause alkaline water to have high bicarbonate concentration. When there are high levels of this carbonates in water, and then irrigation is done, it can cause a loss of calcium within the soil and also this can lead to loss of magnesium. This are elements that should always be present in the soil for proper growth. If the water leads to loss of this elements, then a farmer cannot have a good crop. PH determines a wide range of things. For instance acidic water in this case meaning PH of 4 and below means the soil might be acidic. Likewise water with a range of between 6.0 and 8.5 will reduce the effectiveness of pesticides if they are applied on crops. Drinking water will normally range at a PH of 5. Such a PH will not be bad for the health nor cause heath related complications. In the question the PH of this upland reservoir is not bad for use; the water has a PH of 5.5. This is an acceptable level for drinking and other sections of usage such as irrigation, husbandry and the sheep will not have any problems. In fact, it is always recommended that water needs to be maintained at a PH scale of 5.5 to a PH scale of 7. At this range water is taken to have a couple of benefits such as-: I. There will be a maintenance of nutrient balance. II. There will be no formation of scale in the equipment used in the irrigation processes. III. The rate is good for chemical disinfection that is effective. If an individual has a problem with, the level of PH, there are solutions available to tackle acidity or alkalinity of water respectively. The two factors are variable. Meaning we can be able to manipulate to our liking. To solve the PH issue, one can either add a substance of alkaline, or a substance of acid into the target system. This can be done depending on the systems an individual is using for circulation. If a person is using automatic systems, the balancing substances can be injected into a pipeline. If the individual is using manual systems, the substances can be mixed into a tank and it will do a trick. For instance, if it is a huge water reservoir the substances depending on the PH can be added into the water in large volumes too (Robinson, 1990). Most public water industries will know what to add to their water in order to treat it. An individual should always seek for assistance from the department of water on what to add into the water. When an individual decides to add an acid into the water, an example of such include sulphuric acid which can reduce the PH, while a substance such as lime will trigger the increase in PH of water. In the case with our upland reservoir example, the water body can be treated from the source. A farmer may decide to add the acid or the alkaline into the water, using the recommended scales and weight. The water in the reservoir has a PH of 5.5, by all standards that is not a bad range, it is a good range, the water is able to harbor the benefits earlier mentioned. But the water has other undesirable qualities. The qualities as mentioned in the question include, color and taste that is not acceptable. It should be noted that, PH alone cannot determine the usability of water. Color and the taste are equally important. In our case, the upland reservoir has taste and color levels that are not acceptable. This is a sheep farming area, hence we can as well assume that the animals are not enthusiastic when it comes to drinking of the water. The causes of bad taste and bad color vary, and there are a couple of factors which can cause such a situation. The two situations are caused by suspended elements on the water. These elements include algae, wastes, pollutants of chemical nature, bacteria and also other sorts of matter. Color in the water is caused by specifically substances of organic nature. This organic substances may be a release from vegetation such algae and tannins. Other factors that color water include manganese or iron which has been dissolved into the water. Clay as much as it is a soil can also make water have a look of murkiness. Bad taste that is inherent within this water can be caused by high concentrations of either sodium, chloride, iron or even algae. In order to treat this water from the reservoir, we can use a variety of good remedies. This include algae removal if any, aeration and chlorination can also assist. Study should be taken to know where there might be source of rotten vegetation, or if there is waste disposal near the holding place. Pipelines too need to be regularly flashed. And there should be adoption of carbon filters (Ohgaki, 2008). Carbon filters are good with filtering of impurities of organic nature. The filter in normally preceded by a carbon filter. These filters need to activate so that the filter can be able to attract and retain those impurities. As this happens, the water gets better in color and taste. Chlorination is also an important aspect to try. In part two of the question, we are presented with a system of pumping that is responsible for delivering water from the ground that is anaerobic. The water source is an aquifer that has chalk characteristics. Suspicions are that the water might be harboring some organisms of pathogenic nature it also has vast amounts of iron and manganese. The two water sources are very different, one is in the open, and it is an open reservoir and water can be treated from the source depending on the problem while the other one is an aquifer source. This is underground natural holding tank. Water from such a source cannot not be treated from the source. Iron is bad news for pipes and sprinklers. When the water is high on this element, over a long term it causes the blockage of this pipes and added to it is the fact it can cause the discolor of leaves. Biologically though not relevant material for this question, it can cause problems with photosynthesis in plants. The water in question is from an aquifer, down there, there is always low oxygen supply. Low oxygen supply is a catalyst for high concentrations of iron. When the iron is dissolved this can lead to growth of bacterium related to iron mostly in water from the underground. Such a scenario would not be available with the upland reservoir discussed above. In order to treat water that has significant quantities of iron, we need aeration. When iron in water is oxidized the result is that we get particles of solid nature that can be filtered. The simple formula for iron treatment is oxidizing, then process goes through sedimentation and finally the water undergoes filtration process. In the case of the water in question that is from the aquifer, pumps are used to deliver the water to the destination. Hence the solution is to inject air at the intake side of the pump, which will cause the formation of some solid particles that will eventually settle in a sedimentation tank. The outflow will then further be filtered and final segments of iron will be removed. Figure 1.2 The other option is as shown in the figure 1.2 above. Pump the water from the aquifer, then construct a cascade wall, which will lead to aeration of the water, then iron will settle in the settling tank, and finally the storage tank will have water that has iron to acceptable levels. This kind of treatment is not singular to iron alone, even manganese will react the same during oxidation, hence in the storage tank, and we are facing a situation of a tank which does not have major concentrations of iron or manganese (Bhattacharya, 2011). The water from the aquifer is also suspected to have some pathogenic organisms. These organisms can at times cause specific disease outbreaks. And because it is a health hazard such a situation needs to be solved through treatment. The treatment procedure for such a situation is pretreatment, then we coagulate, then undertake flocculation and finally sedimentation. Pretreatment is removal of microorganisms through the use of micro strainers. The strainers assist in removing of algae, and even protozoans. The pathogens can also be done away with, by use of very strong compound of oxidation. This compounds include, either chlorine, or ozone. This compounds normally act as disinfectants and they make the pathogens inactive. But in order to fully deactivate the pathogens, concentrations of compounds must be right and contact time needs to be sufficient. In the case of the question above, this can be done at the sedimentation before the water goes into the storage. Hence in the question the two sources of water are different and each harbor characteristics of unique water problems. Likewise the treatment is different. It is possible to treat water inside the reservoir but impossible to treat the water inside an aquifer. For the diagnostics it is recommended that an individual should always take or seek the assistance of water testing when in doubt about the quality and source of their water. Surrounding soil can be able to determine what is contained in the water, hence soil testing is necessary and also the growth and look of crops can be to determine when there is a problem with water (Bhattacharya, 2011) QUESTION 3 The process whereby there is a boom in the growth of algae in water means that the water has a quality in it that is favorable to growth of algae. This boom in growth of algae is caused by adding of excessive nutrients to the water. This condition is known as eutrophication. The growth of this nutrient hungry algae can be noticed in different forms. It can manifest itself as a thick foam that forms on the water or as green carpet on the water. From the description eutrophication can be viewed as an advantage to the water because it adds nutrients, but the reality is reverse. Eutrophication means that the water is of a quality that is not acceptable by all standards. This condition mainly manifests itself due to the activities that human beings undertake. They are activities that direct effluents into the natural water bodies. When humans undertake their activities, this can lead to the release of either, waste from the industries, or domestic water waste and finally runaway water from farms that has fertilizer in it which is rich in nitrogen. Eutrophication is a condition that causes some numerous effects this includes but not totally-: I. It results in a boom of algae, water with algae is not always a good sight. II. It causes a condition known as, hypoxia. This is a situation where, the dissolved oxygen into the water is always at the minimal. III. With reduced dissolved oxygen, this will lead to death of those animals that survive only inside the water. Hence we will be facing a situation of fish kills. IV. The water is likely to have poor quality of color and taste and also, it will lead to bad smell on the water. V. It can lead to loss of bio-diversity related to certain species and this is leading to loss of species which have commercial value. (Ansari, 2011) VI. In humans this is leading to certain impacts which are negative, some types of phytoplankton are leading to some sufferings which are severe, such as the usual diarrhea, paralysis or memory loss and even death at certain severe cases. This are all worst case scenarios. The effects of eutrophication are felt widely and not just on the water body. When fish die, apart from poisoning, it also means that this leads to the demise of specie diversities. Let us narrow down to the effects on industries. It means that, fishing will cease to be competitive, due to low stock. Likewise, we cannot engage in water sports on waters that smell, meaning and recreational ideas will be killed, then finally it shows the demise of tourism industry. Which is normally connected to water and what it harbors within. The sources of these nutrients are also diverse in nature. However, research has revealed that much of these nutrients came from waste water. Waste water has a huge amount of nitrogen and phosphorous if it is untreated. Statistically waste water is said to have, a milligram figure of (25 to 40) in nitrogen and a milligram figure of (6 to 10) in phosphorous. Therefore it is normally wise to treat the waste water first before disposing it into a water body. The other contributor of nitrogen and phosphorous is rain. Rain is advantageous anywhere in the world, but due to the activities that human undertake, it has led to release of nitrogen and phosphorous gases into the air. In the air when there is pollution, nitrogen is normally 20 times more than phosphorous concentration. Main contributors of nitrogen and phosphorous into the atmosphere include vehicles that are faulty in filtration and industries. As rain drops, it collects the gases and particles on the way, and this will be directed to the waters. The figure below, i.e. figure 1.3 shows the contributors of nutrients into the lakes and other water bodies, which potentially lead to eutrophication due to buildup of nutrients. Figure 1.3 The figure shows, the main contributors of nutrients as being, erosion problems, industries waste waters, agriculture due to usage of fertilizers high in the compounds. And finally rain effects, as explained earlier, rain is only a victim of air pollution. In waste water nitrogen is normally four times higher than phosphorous, but this source is the highest in adding water nutrients (Kohl, 2006). Economically it is easier and cheap to remove phosphorous nutrients from water than nitrogen nutrients from the water. Hence most regulatory authorities for water bodies always aim at removing as much phosphorous as possible. This should not be confused that nitrogen and phosphorous is a harmful compound in the water. In right quantities, nitrogen and phosphorous assist in the growth of aquatic plants and also the compounds assist in maintenance of habitats. Therefore problems with nitrogen arise only when there is excess concentration of this compounds in the water. Algae loves such an environment and this triggers the eutrophication. Excessive nitrogen and phosphorous will not only affect those water bodies in the open, but waste water can find itself sipping into the ground and this subsequently affects water in the ground. Different places and countries have recognized the impact of waste water in the pollution of water bodies. The question in this section seeks to understand the effects and causes of waste water which I have explained above and also the ways in which they affect the water bodies. In 2007 among the major things the planets environment federation, discussed on the importance of removing nutrients from the waste waters from industries. Waste water has led to dead zone on numerous places around the world killing a lot of habitats. Hence for waste water to be described as satisfactorily disposed, there must be a process of enough water treatment in order to avoid a situation of contamination. The process of waste water treating involves the use of technologies necessary to improve water quality. The process will involve, collecting the wasted water in a super tank, it is in this super tank, that numerous treatments are undertaken in order to lid off the compounds from the water. This water cannot be treated at the same time, since we are looking into very huge volumes of water. Hence treatment is normally undertaken in motion. This means that treatment will normally be undertaken as a continuous flow (Judd, 2002). But in the continuous flow, there are certain aspects that still need to be batched. Waste water treatment involves a number of different options. In total there are three different options, that is either physical, biological or chemical treatment. One system can harbor all the three treatment options in order to fully do away with nitrogen and phosphorous. All the three options involve the following. Physical treatment- when using the following process, there is no involvement of any chemical or biological options. This process will involve use of screening, screening assists in removing of huge particles or elements. Sedimentation in physical treatment uses pure gravity in order to allow the huge parts to sink, therefore this will involve holding water for a short while in order to allow this gravitational phenomenon to take place. Physical treatment is common, and it is normally undertaken at the beginning of waste water treatment. It is a common sense procedure since large particles will normally need to be removed before further treatment. After this procedure, we embark on another physical process known as aeration. This will involve addition of air into waste water in order that when it is mixed with another water body, it would reduce oxygen concentration. The next physical process is filtering. Filtration causes the removal of solid substances from the waste water. Sand filters for instance can assist to do away with sand particles from the water before moving on to the next point. Skimming taken literally is also part of physical processes, hence oil parts are allowed to float then they are skimmed off the water. Chemical treatment- whenever there is the use of the word chemical, there is normally expectation of reactions. Hence in chemical treatment reactions take place, which lead to the improvement of water quality. The most favored from of chemical reaction is the usage of chlorine. The chemical is an oxidizing agent. The reaction assists in killing of bacterium. When the organisms are demised, this will have the effect of reducing the rate of decomposing waste waters. The other form of chemical treatment is use of neutralization process. In neutralization we either add an alkaline or an acid, so that we can hit a PH of 7. This is the neutral mark between alkalinity and acidity. Coagulation is another example of chemical reaction. By coagulating this will make formation of insoluble substances that will be removable from the waste water. Some types of coagulating agents include lime, specific iron elements and other specific metals. Use of activated carbon is neither physical nor chemical in nature. It contains active parts on the base which attract some organic material which when settled is the removed from the waste water. Biological treatment- this affair involves the use of microorganisms to speed up decomposition in the waste water. The product mainly used is bacteria. When decomposition occurs we get, sludge’s, or even release of lurking gases. The target and goal of treating waste water is to remove a large amount solid as possible before a release into the lakes or oceans. Hence with biological option, as much as possible organic solid is removed which would lead to decaying and formation of nitrates (Arceivala, 2007). When all the devices are brought together to perform waste water treatment, they will undertake all the three processes above. But the treatments that the machines are subjected to, can be broken down into 6 types of treatments. This includes-: Preliminary treatment Primary treatment Secondary treatment Disinfestation Sludge treatment Tertiary treatment Preliminary treatment- these equipment’s normally cut or remove. It can either be removal of solids, greases or even the oils. Primary treatment- solids which have sunk or settled are removed during this treatment. The treatment targets is to allow solids to sink and floating oils to manifest themselves. Secondary treatment- in secondary treatment. This is equivalent to decomposition of certain parts of the waste water forming solids. Disinfestation- chlorine is normally used widely to kill pathogens and control of smell and color of waste water. Other used chemicals in this section include ozone. Treatment of sludge- when water has been ridden off the sludge, this sludge is normally treated into order to prepare it for safe disposal. In this section, the process aims at removing some water from the sludge, and also fasten decay some of the components in the sludge. Tertiary treatment- when there is no use of either physical or biological treatment of water, what happens is that, the process that takes place is a more extensive or advanced treatment. This for example involves flocculation. Figure 1.4 The figure 1.4 above shows all the processes that I have explained above. In each of the above illustrated processes the target is to make the water safe enough to mix with any of the other waters that it will be released to. Nitrogen like mentioned earlier is expensive to remove hence, when removing nitrogen from the waste water, a couple of processes are undertaken. Among the processes there is ammonification, this is converting the nitrogen in waste water into ammonia through hydrolysis. When the water reaches the point of treatment, most of the nitrogen will have normally been converted into ammonia. Then after ammonification, the next point is nitrification. This is the process of converting ammonia to nitrate nitrogen. Here bacteria is used, and it converts the ammonia to something nitrite. Then another bacteria known as nitrobacteria finishes the process by converting nitrite to nitrate after which a bacteria is used to break, the nitrate into two parts (Tyagi 2004). Nitrate is written as N03- . Hence the nitrate is broken down by bacteria into nitrate oxide N2O and the nitrogen gas N2. With the gas, it is able to escape into the air, and as this happens, sludge climbs on top of the water. Hence the treatment of waste water can be summarized as follows-: I. Removal of particles and huge solids from the waste water, by passing the water through huge filters II. Transfer of the water into a settlement tank, where sinking of solid particles and debris can occur. III. The third stage is biological treating. Here stone filters that harbor bacteria and other tiny organisms remove pollutants of organic nature from the water. IV. Then the water, goes through another settlement tank process whereby, remaining particles and sludge can sink. Also at this stage sludge is normally treated further before it is taken to the outside environment. Modern methods are calling for the right treatment of waste water such we are able to achieve, the right levels of untreated water. Better yet the new methods are insisting on a process known as wastewater resource recovery. This is the utilization of the waste water, by practically making use of all the components it has to offer. The ideal situation is whereby a good technology has identified that waste can give out biogas which can be utilized to generate electricity. This is practically the new and the future of waste water. Instead of releasing the water, the water could be reused. Countries such as Sweden have achieved 100% usage of waste water. Hence new technologies should aim not at releasing the water but achieving a certain recovery. Figure 1.5 Figure 1.5 above shows the ideal situation with latest technology. References Ansari, A. A. (2011). Eutrophication: Causes, consequences and control. Dordrecht: Springer. Arceivala, S. J., &Asolekar, S. R. (2007). Wastewater treatment for pollution control and reuse. New Delhi: Tata McGraw-Hill Publishing Compagny Limited. 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B., AWWA Research Foundation.,& American Water Works Association. (1990). Sequestering methods of iron and manganese treatment. Denver, CO: AWWA Research Foundation. Tyagi, K. D., &Surampalli, R. Y. (2004). Advances in water and wastewater treatment. Reston: American Society of Civil Engineers. Vesilind, P. A. (2003). Wastewater treatment plant design. Alexandria, Va: Water Environment Federation. Read More