Water Purification In The Coming Decades Environmental Sciences Essay

piddle Purification In The Coming Decades Environmental Sciences EssayThis oblige was written by six academicians related to a work for The Center of ripe(p) Materials for the Purification of wet with Systems (NSF STC WaterCAMPWS, University of Illinois, USA). They ar working for various departments which atomic number 18 equal for this research at different universities. The WaterCAMPWS works for saucy technologies for peeing word. (1)This condition focuses on new technology for disinfection, decontamination, re-use and desalinization modes to improve weewee quality. It describes the vastness of peeing and peeing puzzles, moreover it gives information near the body of water preaching systems apply today and will be used in the future. It to a fault makes comparisons to identify the advantages and the disadvantages of water treatment systems. It is suitable for anyone who wants to be informed approximately water purification techniques. A person who has the technical infrastructure approximately water and water treatment can understand more considerably this name. While reading rough(a)what generation difficulties may be encountered to understand this article exactly in general language of the article was clear.At the number 1 part of the article authors mention the importance of the water, pollutants water problem and new water treatment technologies. Water problem is explained clearly by using remarkable numbers simply they do not give the consider and sources slightly numbers. In addition to the situation at the article, developed and evolution countries argon provided the examples of the water situations to make the water problem more understandable.Water is needed for living organisms to survive and at that place is life on the farming thanks to water.(2) According to the World Health Organisation (WHO) water may contain bacteria, hang particles, parasites, viruses, organic chemicals, loaded down(p) metals and sol vents above the al small(a)ed amount for example, Escherichia coli and white arsenic direct limit is should be less than 10 g/l (WHO piece of writing, 2008) (2-3) The elimination of unwanted significants, chemicals, contaminants, impurities, micro-organisms is called water purification which is a cleaning performance. (4) middling water demand is rising day by day because of increase in population, water shortage and users competition. (5) If people accessed clean potable water easily, it would be a completely positive effect on health. Unfortunately, WHO report in 2007 shows that 1.1 billion people cannot reach the clean water and 1.8 jillion people die dehydration from diarrheal because of safe water problem each year. Hearth problems, brain stokes, HIV/AIDS, acute respiratory diseases, degenerative lung diseases are some health problems which are caused by diarrheal.(3) The recent water treatment activities are not safe, sustainable and sufficient enough but they can be develop such as energy cost-effective systems, renewable purification.(2) New generation water treatment systems, which are base on such as disinfection, flocculation, sedimentation and decontamination technologies, should be developed to channelise bacterial, viral and parasitic pathogens more effectively.(9)At the beginning of 4000 B.C. people assay to make insobriety water better in taste and smell. few treatment regularitys were developed such as smooth filtration, disinfection by sunniness and boiling after 1500 B.C. (9) At 1600s desalination experiments began and around 1800s the first water purification ready was built in Scotland. During the twentieth century, people focused on drinking water quality peculiarly removing the pathogens. In 1914 The U.S. Public Health Service prepared standards somewhat drinking water and which were revised by the Public Health Service in 1925, 1946 and 1962. (9-3)Disinfection is the process of the deactivating or destroying of path ogenic microorganisms present in water. (10) In the paper, drawn-out information about disinfection methods and the comparison between germicides were written. Authors give information about how the disinfection processes can control the viruses but I think this is un incumbent lucubrate about the subject. Using sunlight (solar) was the first application of disinfection. (10) The close normal disinfection methods are free chlorine and chlorine related chemicals because of cost and wanton accessibility, they eliminate the living materials by oxidation of cell wall compounds. unembellished chlorine (Cl2) is so effective method but chlorine is a very dangerous chemical and it pretends toxic disinfection by-product DBPs for example trihalomethanes. (11) The method of using solid calcium hypochlorite (Ca(ClO)2.4H2O 65% chlorine) as a disinfectant has a lot of limitations such as corrosion and taste problems. some other disinfectant is sodium hypochlorite (NaClO) solution (5-15 % chlorine) which cannot be stored easily. (11) Viruses, yeast, spores, bacteria, and molds can be killed by ozone disinfection method. Ozonation method is more effective than chlorine method and it does not produce any danger by-products. (10) There are some disadvantages of this method for example, it is not easy technology, misfortunate dosages are not enough to kill pathogens and it is costly. (11) ultraviolet radiation light (UV) can be used for inactivating pathogens by photochemical reactions in the RNA and DNA which is the result of light absorption. (10) It is effectively and for this method the rival time is short, there are not toxic or non-toxic by-products but it cannot use water which includes suspended material. The new method is use chlorine with UV and ozone which is very effective method to eliminate bacteria, protozoa cysts and some vital pathogens. The solar photocatalysis disinfection which means killing of pathogens by using the photocatalysis of TiO2 is the future method for water disinfection.(12) The use of nanoscale science in the water treatment systems, which includes nanocatalysts, nanostructure tissue layers, bioactive nanoparticles, nanoparticles filtration, nanosorbants, is the futuristic disinfection method. Nanoparticles which work large surface areas will be the beat materials for water purification systems in the near term. Today, the major challenges of nanomaterials are the integration of water purification process, cost effective and design problems. (5)In the article another method is described called, the water decontamination which is the process of eliminating the harmful substances (chemicals, organisms, heavy metals, radioactive materials) from the water. In this section of article, authors try to explain some problems about measuring and detection of compounds concentrations, modelling, and remediation strategies. Reverse osmosis, synthetic resins, activated carbon, sand filtration are the some methods to rem ove contaminants from the water.(13) The best treatment method which supplies the most purified water is not clear. The determination of contaminant type and concentration are as meaning(a) as the decontamination technology. The advanced laboratory technology is necessary for measuring of low concentration of toxic compound for example Hydride times Atomic Absorption Spectrophometery and UV-Spectrophometry can be used to analyse arsenic. (13) Chromatography and spate spectroscopy which have the drawbacks such as cost, sensitivity and business care are the old but the most common technologies. Catalytic DNA is the recent system for testing heavy metals in the water and the traditional methods for this are X-Ray Fluorescence, some chemical tests and Inductively Coupled Plasma.(13) The biosensoring technology is defined as the usage nanoscale or microscale biologic sensors to detect contaminants with gamey sensitivity. The proficient information about biosensors is necessary t o determine the toxicity of water treatment process.(14)highly treated water can be called reclaimed water which is the low cost alternative of potable water. If we consider the amount of consumed water per day, remained water on the Earth and the growth of population, the reuse of reclaimed water is abruptly necessary. Some of the uses of reclaimed water are irrigation, industrial activities and groundwater recharge.(15) Since historical times wastewater has been used but it became attractive two or iii decades ago. (16) There are several methods for reclaimed water, such as chlorination, filtration and biological systems which have been used since early 1800s. (15) Authors give information about some recent methods such as membrane bioreactors and filtration. For the biological treatment ultrafiltration and microfiltration technologies have been understood to provide high quality purified water. (17) Today activated liquid ecstasy process, which is another biological treatment method, are designed for high performance. (18) The membrane bioreactor (MBR) method is relatively new treatment technology which is based on liquid-solid separation and its applications are becoming acceptable day by day for small scale with high quality of water. (17-18) Membrane bioreactor process has some advantages compared to the activated sludge process such as more succinct reactor, smaller footprint for high concentration, higher mixed liquor suspended solids concentration (for MBR process average concentration 8-12 g/l). The most important drawback of MBR method is some terms such as fuse issues should be developed. (18) The cleaning of membrane and dynamic effects such as aeration loss, saline solution intrusion and backflush loss are the two parameters which affects the performance of MBR technology. The improvements about material characteristics, permanent fouling, cost and membrane cleaning process should be through with(p) for this process. The average annual gro wth rate 10.9 % is estimated for the global MBR market. (19) Reverse osmosis (RO) is a liquid membrane method which removes dissolved materials. The combination of MBR and RO is highly efficient which provides 67% water recycling at the lowest cost. (20)Desalination is a method that separates the salt from water. The oldest process to remove salt from water is boiling. thermal distillation method and natural the hydrologic cycle work same federal agency and in the early 1900s, membrane system was developed. There are triplet types of thermal methods namely multi-stage flash distillation, multi-effect distillation and vapour compression distillation. (21) The advantages of desalination by distillation are low operating and maintenance cost, minimal environmental effect and the highly purified water production, the disadvantages are high level knowledge and large capacity plants.(22) Electrodialysis, Electrodialysis reversal and swipe osmosis are the three main membrane processes for desalination. (21) Simple systematic structure, removing organic and inorganic contaminants and high production/capacity ratio are the advantages on the other hand the necessity of pre-treatment step, the difficulty of cleaning membrane and decreasing in flow rate are the drawbacks of membrane processes. (22) Total number of desalination plant is nearly 1400 (80% Membrane desalination, 20% Thermal desalination). Reverse osmosis desalination process includes four parts pre-treatment, high-pressure pumps, membrane systems and post-treatment. (21) Hybrid desalination method can be defined as the comparison of thermal and membrane desalination process which generates power. The advantages of this process are using less energy, low cost of construction and high plant efficiency. Nowadays the RO and simple intercrossed multistage flash configuration are very popular. The advantages of integrated systems are well(p) thermal efficiency and high quality purified water. (23) The Afforda ble Desalination collaboration process is newly design of reverse osmosis process which demonstrates the water with a good design. (21) Carbon nanotubes have the specific electrical, chemical and mechanical features. In the future, nanotubes will allow us to desalinate cheaply but there are some challenges, we have to face about this method like capital cost and difficult mechanism. Carbon nanotubes, Biomimetic membranes and forward osmosis are neighboring generation systems for desalination. (8-21) In this section of the article the figure about reverse osmosis and activate desalination (figure 5) makes understandable the processes. The information in the book related to entropy and energy calculation is the high-level information about the subject.This article contains extensive knowledge about the water treatment systems. Authors clearly reason out solutions of water treatment systems. I have some knowledge about water purification before preparing this report but while writing I learned lots of information about new water treatment techniques from article and references. This research was made in 2008, it is a technological subject because of this when research is carried out is very important. Some current water treatment techniques need intensive energy and chemicals. We should improve the not besides water treatment systems but also monitoring, measuring, modelling and management systems to drop out safe and clean water to everybody. As a result, we need new, sustainable, environmental and inexpensive purification methods.Science and technology for water purification in the coming decades by M.A. Shannon, P.W. Bohn, M. Elimelech, J.G. Giorgiadis, B.J. Marinas, A.M. Hayes, Nature 452 (2008) 301-310