Chemically enhanced primary treatment (CEPT) is a wastewater treatment method that provides as smart alternative to the conventional primary treatment. It can also be used as a proficient preliminary step of the biological secondary treatment processes. CEPT embraces coagulation and flocculation, and it accomplishes remarkable increases in the pollutants removal from the influent (Ødegaard, 1989; Rashed et al., 1997; Ayoub et al., 2013; Rashed et al., 2013a; Rashed et al., 2013b). Chemical precipitation is the technique of CEPT process, the main idea of chemical precipitation that it converts soluble substances to insoluble particles, which can be flocculated and separated from the liquid. Removal efficiencies depend on mixing times, mixing …show more content…
In comparison, well designed and operated primary settling tanks without addition of coagulants may remove between 50-70% of TSS, 25-40% of BOD5 and 5-10% of phosphorus (Rashed et al., 1997; Metcalf & Eddy, 2003; Mahvi et al., 2005; Sarparastzadeh et al., 2007; Rashed et al., 2013b; Barbosa et al., 2016; Barghpeyma and Farahbod, 2016).The main problem of CEPT is the chemicals costs, which considered to be an additional burden on the operating costs of wastewater treatment (Xu et al., 2009). On the other hand, water treatment sludge contains a significant amount of coagulant when it can be recovered to be more economical for CEPT as well as safe disposal of water treatment sludge (Rashed et al., 1997; Xu et al., 2009; Evuti and Lawal, 2011; Allerdings et al., 2015; Roccaro et al., 2015; Ayoub and Abdelfattah, …show more content…
(2007) proved that recovered coagulant is very effective in removing COD from municipal wastewater treatment plant by about 66.8% and phosphorus removal rate reaches to 98.9% and a slight total nitrogen removal about 29.9%. On the other hand, Xu et al. (2009) investigated effect of the recovered alum from water treatment sludge in CEPT of sewage as a coagulant. The obtained results reveal that pollutants removal efficiencies form CEPT using the recovered alum are similar to that of the fresh alum. Removal efficiencies of COD and turbidity reach up to 53% and 96% respectively with the recovered
Due to the Water Pollution Control Act of 1970, there are stringent standards that need to be considered when depositing wastewater from the process. It was not possible to show the path that the wastewater would take after leaving the system, however, the pollution standards were considered. The water that was produced in the reaction were present in streams with other components such as CO2, butadiene, and maleic anhydride. Due to this exposure, the separated water will be sent to a waste water treatment plant where it will undergo many steps to ensure that the pollutants have been properly removed (Plant Design Book
Stephenson, R., & Blackburn, J. J. (1998). The Industrial Wastewater Systems Handbook. New York: Lewis Publishers.
Wei Y., Van Houten R. T., Borger A. R., Eikelboom D, H., Fan Y., 2003. Minimization of excess sludge production for biological wastewater treatment. Water Research 37, 4453-44671.
There are several types of treatment methods present but biological treatment methods have gained much traction in the recent years due to their low operation costs, comparatively benign effects on the environment and their ease of handling and maintenance. Biological wastewater treatment methods can be subcategorized into dispersed growth systems and attached growth systems. Biofilms fall under the latter category (Sehar & Naz, 2016)
One sustainable solution that has been proposed by the scientific community is bioremediation. Bioremediation is the application of microorganisms or biological enzymes to treat or remove contaminants. (“In Situ Bioremediation,” para. 1) Bioremediation is a lower cost and more effective option than removing contaminated soil offsite as a preventative measure, before the contaminants reach groundwater. When contaminants reach ground water bioremediation is still an excellent option, but it takes a longer period of time to remove the contaminants. Bioremediation is a sustainable option because it uses naturally occurring microbes that degrade contaminants naturally. This is most evident in the Exxon Valdez spill, where bioremediation was applied and was a major factor in restoring the environment. One of the most beneficial aspects of bioremediation is that this solution is ready for use today. From the time that the microbes are applied to the contaminants it can take anywhere from 65 days to several hundred days. Factors that can influence the time it takes to render the contaminants ineffective are seasonal temperatures, which contaminants where spilled, and the depth and area of contamination. The cost of bioremediation is another appealing aspect to this option because the cost is relatively low. There is no construction cost and the machinery cost is low. The cost of aerobic
Ultrafiltration is a water purification process that can be used for the removal of particulates and macromolecules from raw water to produce potable and drinking water. They have been used to either replace existing secondary (coagulation, flocculation, sedimentation) and tertiary filtration (sand filtration and chlorination) systems employed in water treatment plants. When treating water with high suspended solids, UF is often integrated into the process, utilizing primary (screening, flocculation and filtration) and some secondary treatments as pre-treatment stages. Ultrafiltration processes are currently preferred over traditional treatment methods for the following reasons:
Srikakulam city has been a developing place due to the steady increase in city population, which in turn resulted in the increase of domestic sewage generated, but still there is no sewage treatment plant. So it is required to construct a sewage treatment plant with sufficient capacity to treat the generated sewage. Sewage water treatment has challenges to treat the excess sludge and disposal of sludge. Sewage/Wastewater treatment operations are done by various methods in order to reduce, its water and organic content, and the ultimate
Pharmaceutical waste seems to be one of the dominant elements that are prevalent in our waters, and other aspects of the environment. These aforementioned elements are largely becoming a concern in today’s society because its effects have proven to be harmful towards our environment, and all of its existing forms of life. Through various ways, whether controllable or uncontrollable, pharmaceutical waste slowly and increasingly multiplies its presence within the environment. Additionally, it eventually trickles down into our waterways and causes a large array of damages. Some of the most common ways that this waste gets into the water includes: disposal through the drainage systems, farming fertilization methods and the maintenance of treatment plants. These methods are self-explanatory through their brief discussions, but it helps decipher whether the disposal of these dangerous wastes are intentional or not.
One of the greatest environmental issues that the world faces is throwing away thrash and products that contain hazardous chemicals that affect the environment negatively. The most common way people throw away their trash is by dumping chemicals down the drains. Many communities, wastewater treatments plants, and private septic systems contain a biological process that breaks down sewage when it goes through. When chemicals go down...
Horan, N. J.: Biological wastewater treatment systems: theory and operation. Thomson Press ( India) Ltd; 1990. 124-132 p
On the top of that, chemical precipitation is also one of the techniques that can be applied to liquid waste stream that contained hazardous compounds. It is very effectively in removing or eliminating the heavy metals that dissolved in the waste stream. The solubility of the heavy metal can be decreased by properly adjusting the pH value. For examples, lime is commonly used to the precipitate the metals ion into insoluble metal
It also decreases the amount of sludge, which needs to be disposed. Electrocoagulation is a technology that removes components from wastewater by applying a strong electric field that produces a series of oxidation and reduction reactions. By decomposing the electrodes, the metallic ions produced are subject to fast hydrolysis and the products of the hydrolysis neutralize the charge of the suspended particles driving them to a fast coagulation and sedimentation. Electrodes consist of iron and aluminium have special coagulation properties and are very efficient in decolouring industrial wastewater. In recent years, the EC has been successfully tested to decolourization of dye-containing solutions. Applied electrodes in EC process are usually iron or aluminium. The dye in coloured wastewater is coagulated by iron and aluminium hydrates or hydroxides produced from the sacrificial anode. EC technology, compared with other techniques, enjoys some advantages like plain equipment, easy functionality, short resistance time, no need of chemicals, low sludge production, sludge stability, suitable sedimentation of sludge, dewatering and environmental compatibility. EC process is being used for the removal of ions, organic matters, colloidal and suspended particles, dyes, oil and heavy metals from aqueous
Improvement and upgrading of wastewater treatment processes and also the need to reduce the environmental factors make the use of tertiary wastewater treatment important.
Firstly the air and oxygen is provided to the excrement of the sewage or the industrial waste water that reduce the organic content quantity in the sewage and produce the biological mass. This waste water and biological mass both are mixed with each other and called" mixed liquor ".this is also called the primary treatment. The sufficient primary treatment is done with the waste water. After this excess mixed liquor is poured in the setting chamber and treats it with the supernatant results liquid lying above a solid residue. Solid residue is called sludge and it discharge in the aeration system and the new waste water enters the tank. This process is called fractional process and the sludge is called "return operative sludge"and the sludge present in huge amount is called "excess operative sludge" or "useless operative sludge" removed by the treatment of decomposition. This decomposition process may be occurs in the presence or absence of oxygen.
Many detergents are resistant to the action of biological agents and thus are not biodegradable. Their elimination from municipal wastewaters by the usual treatments is a problem.