Three chemical treatment processes are listed here. Micro-aeration breaks down high hydrocarbon content components from wastewater, which leads to easily biodegradable organic generation. At a dissolved oxygen (DO) concentration from 0.2 to 0.3 mg/L, the hydrolysis of wastewater organics is enhanced.
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How does chemical wastewater treatment work?
This chemical wastewater treatment process works in a similar fashion as chemical oxidation. Sludge is treated with a large amount of a given oxidant, such as chlorine. The introduction of the oxidant slows down the rate of biological growth within the sludge and also helps deodorize the mixture. The water is then removed from the sludge.
How can hydrocarbon polluted wastewater be remediated?
The remediation of hydrocarbon polluted wastewater can be achieved by three methods, which are phytoremediation, bioremediation and chemical remediation. Phytoremediation entails the use of plants to reduce the volume, mobility and toxicity of contaminants in soil and water.
How to remove organic compounds from wastewater?
Chemical, physical and biological methods have been used to remove the organic compounds from the wastewater, and biological method has been paid much attention owing to its economic and ecologic superiority. The biodegradation rate and biodegradation degree of the organic substance partly depended on the characters of the substance.
What chemicals are used in wastewater treatment?
'Chemical treatment' is an umbrella term that refers to a number of different ways of treating wastewater, and the chemicals used in wastewater treatment vary from method to method. For example, sodium hypochlorite, hydrochloric acid and magnesium hydroxide are used in different chemical treatments.
How does chemical water treatment work?
Specialized chemicals such as chlorine, hydrogen peroxide, sodium chlorite, and sodium hypochlorite (bleach) act as agents that disinfect, sanitize, and assist in the purification of wastewater at treatment facilities.
What is chemical treatment in wastewater treatment?
Chemical wastewater treatment forces contaminants that are dissolved in wastewater to separate more easily through the targeted addition of specific substances. During precipitation, a previously dissolved substance is turned into a dissoluble substance that can be filtered from the liquid.
Is chemical treatment method the best way to treat wastewater?
Chemical. Chlorine is the chemical most often used in treating sewage and other types of wastewater. The process is called chlorination. This is the most effective means of destroying a variety of viruses and bacteria.
Which is the method of treating organic material in wastewater?
Biological Water Treatment Microorganisms metabolize organic matter in the wastewater in biological treatment. It can be divided into three categories: Aerobic processes: Bacteria decomposes the organic matter and converts it into carbon dioxide that can be used by plants. Oxygen is used in this process.
What is a chemical treatment?
Chemical treatment (of hazardous waste) refers to the treatment methods that are used to effect the complete breakdown of hazardous waste into non-toxic gases or, more frequently, to modify the chemical properties of the waste, for example, through reduction of water solubility or neutralisation of acidity or ...
How are chemicals removed from wastewater?
New research shows that wastewater treatment plants that employ a combination of purifying techniques followed by reverse osmosis – a process by which water is forced through a barrier that only water can pass – do a good job of removing chemicals that may elicit health effects.
How does wastewater treatment work?
There are two basic stages in the treat- ment of wastes, primary and secondary, which are outlined here. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.
How is the operation of a chemical sewage treatment plant?
The sewage enters the aeration compartment where it is digested by aerobic bacteria and micro-organisms, whose existence is aided by atmospheric oxygen which is pumped in. The sewage then flows into the settling compartment where the activated sludge is settled out.
What are the 3 stages of wastewater treatment?
There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment.
What are organics in wastewater?
Organics - A determination of the concentration of carbon-based (i.e., organic) compounds aimed at establishing the relative “strength” of wastewater (e.g., Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), and Oil and Grease (O&G)).
What are the options in dealing with the organic and inorganic contaminants in wastewater?
Primary treatment involves physical separation of floatable and settleable solids. Secondary treatment involves biological removal of dissolved solids. Tertiary treatment involves physical, chemical, and biological treatment.
How is carbon removed from wastewater?
In the traditional wastewater treatment process, activated sludge is commonly used for the removal of carbon, and it involves complex steps with anaerobic, aerobic, or anoxic conditions during 5–8 h of treatment and it also produces a high volume of sludge.
How to control pH in wastewater?
What is a wastewater chemical control system? 1 The chemical dosing system measures, controls, and regulates pH levels with the automatic injection of chemicals. 2 Water disinfection systems allow you to safely store rainwater and recycled water. Available in both chemical treatment and ultraviolet units. 3 Keep discharge at the right pH level with pH control systems, designed to automatically stop your company from breaching regulations.
What is added to sludge to slow down biological growth?
A big quantity of chlorine — or hydrogen peroxide — is added to the sludge. This slows down the biological growth, and also deodorises the substance. Then, the water can be taken out, and safely rerouted to the environment.
What is the chemical reaction that causes sodium ions to be released into the water?
Positively charged ions are added to the mix by putting sodium chloride salt into the hard water. This causes a chemical reaction where sodium ions are released into the water, breaking up the calcium and magnesium ions that have caused the hardness of the water.
What is precipitation reagent?
A precipitation reagent is added, and the disparate particles take a solid form. These solids can then be filtered out. When choosing a precipitation reagent, people either go with calcium, or a sodium hydroxide water treatment process is used.
What is a chemical dosing system?
The chemical dosing system measures, controls, and regulates pH levels with the automatic injection of chemicals. Water disinfection systems allow you to safely store rainwater and recycled water. Available in both chemical treatment and ultraviolet units.
When will Cleanawater be available?
Cleanawater on 1 July 2020. For many businesses, wastewater treatment is a necessity. Governments have strict laws and regulations to prevent contaminated runoff flowing into the environment, and causing ecological harm. Thankfully, there is a range of different chemical processes and technological solutions which make treating wastewater safe, ...
What are the pollutants that are metabolized in wastewater?
On the other hand, the persistent organic pollutants, such as PAHs, PCBs, and DDT, are very slowly metabolized or otherwise degraded.
What are the environmental hazards of organic waste?
Environmental hazards of organic wastewater. High mount of hydrophilic organic pollutants, such as organic matters, oil could consume a large amount of soluble oxygen. The acute toxicity and high quantity of oxygen demand could worsen the water quality and lead to great damage to the aquatic ecological system.
What are the most toxic substances in wastewater?
Since they are persistent, long way transported and toxic, these organic pollutants draw more attentions. The classic poisonous substances in organic wastewater are as follow: Water organic matter. Water organic matter is the genetic name of the organic compounds in the sediment and wastewater.
What is hydrogen peroxide used for?
Hydrogen peroxide has been used in the industrial effluent treatment for detoxification of cyanide, nitrite and hypochlorite, for the destruction of phenol aromatics, formaldehyde, removal of sulfite, thiosulfate and sulfide compounds.
What are PAHs in the aquatic system?
PAHs are recalcitrant organic pollutants consisting of two or more fused benzene rings in linear, angular, or cluster arrangements. PAHs occur in oil, coal, and tar deposits, and PAHs in the aquatic system could come from accidently leaking, atmosphere deposition and contaminated sediment release.
What are PCBs used for?
PCBs. PCBs are biphenyl combined with 2 to 10 chlorine atoms. PCBs are widely used as dielectric and coolant fluids, for example in transformers, capacitors, and electric motors, and various kinds of PCBs could be found the wastewater of this factories [ 3 ].
What is ozone used for?
Ozone can be used for treatment of effluents from various industries relating to pulp and paper production (bleaching and secondary effluents), Shale oil processing, production and usage of pesticides, dye manufacture, textile dyeing, production of antioxidants for rubber, pharmaceutical production etc.
How effective is biological treatment?
The biological treatment is effective in removing up to 95% of the BOD. Large tanks are required in order to eliminate the entire BOD, which is not feasible. The biological treatment systems are unable to handle “shock loads” efficiently.
What is a bioreactor made of?
The bioreactors are commonly made of stainless steel, usually cylindrical in shape and range in size from liters to cubic meters. The bioreactors are classified as batch, plug, or continuous flow reactors (e.g., continuous stirred-tank bioreactor).
When was vermifiltration introduced?
The introduction of earthworms to the filtration systems, termed vermifiltration systems, was advocated by José Toha in 1992 [ 21 ]. Vermifilter is widely used to treat wastewater, and appeared to have high treatment efficiency, including synchronous stabilization of wastewater and sludge [ 22, 23, 24 ].
What is the process of aeration?
Aeration has been used to remove trace organic volatile compounds (VOCs) in water. It has also been employed to transfer a substance, such as oxygen, from air or a gas phase into water in a process called “gas adsor ption” or “oxidation”, i.e., to oxidize iron and/or manganese.
What are some examples of bioremediation?
Example of bioremediation: fish bone char has been shown to bioremediate small amounts of cadmium, copper, and zinc. The bioremediation of wastewater can be achieved by autotrophs or heterotrophs.
Is chlorine a disinfectant?
Chlorine. Chlorine is one of the oldest disinfection agents used, which is one of the safest and most reliable. It has extremely good properties, which conform to the aspects of the ideal disinfectant. Effective chlorine disinfection depends upon its chemical form in wastewater.
Does temperature affect substrate removal?
The higher temperatures increase the biological activity and metabolism, which result in increasing the substrate removal rate. However, the increased metabolism at the higher temperatures may lead to problems of oxygen limitations. 4.2. Bacterial kinetics.
What is chemical treatment?
Chemical treatment of water and wastewater. In addition or in complement to physical or biological treatments, chemical-based technologies are used to process water to a safe, potable product or to mitigate the release of contaminants in receiving waterbodies along with wastewater discharges. Different chemical processes are used ...
What is the most common application of ion exchange in drinking water treatment?
The softening of water is the most common application of ion exchange in drinking water treatment. This treatment step consists of the removal, from the aqueous phase, of the calcium and magnesium ions through the replacement by sodium ions released by the ion exchanger solid.
What is coagulation and flocculation?
Chemical coagulation and flocculation is used to promote the removal of finely divided solids by forming more readily settleable flocs, prior to filtration or sedimentation. The conventional process sequence of coagulation/flocculation/sedimentation is essential in pre-treatments for most water purification systems and wastewater treatment systems. Chemicals such as lime (Ca (OH)2, most commonly used for drinking water treatment), soda ash (Na 2 CO 3) and organic polyelectrolytes (starch, polysaccharide gums or synthetic polyelectrolytes) are used in drinking water processing to produce quick-forming, dense and rapid-settling flocs in order to enhance the removal efficiency of suspended solids. When treating wastewater, this chemical treatment step enhances the efficiency of removal of suspended solids, BOD5 (five-day biological oxygen demand) and phosphorus as compared to sedimentation performed without coagulation. As summarized in Table 17.2, enhanced and more consistent removals are obtained with chemically enhanced sedimentation than plain sedimentation. However, it tends to result in a larger quantity of primary solids, also known as primary sludge which is often more difficult to dewater. It also entails higher operational costs and demands greater attention on the part of the operator than plain sedimentation. Coagulants such as alum (Al2 (SO 4) 3 -14H 2O), iron salts (ferric chloride (FeCl3 6H 2O), ferric sulfate (Fe2 (SO 4) 3) and ferrous sulfate (FeSO 4 7H 2 O)), lime (Ca (OH) 2) and organic polyelectrolytes are used as flocculation aids during wastewater treatment.
What are the factors that determine the design of a water treatment plant?
Numerous factors have to be considered in the design of water treatment facilities, including site selection, process selection criteria, quantity of wastewater to be expected, water characteristics, variability in flow and quality of influent water, discharge limits (wastewater) or water quality requirements (drinking water) set by local regulatory agencies, testing and monitoring requirements, maintenance, safety as well as waste treatment and disposal. Treatment processes are selected according to influent-effluent constraints as well as technical and economic considerations. The choice of technology and design may be influenced during the planning stages by sustainability issues such as the cost to design and build treatment plants as well as the ongoing cost to operate, maintain, rehabilitate and replace infrastructure. The following sections briefly present some important considerations and design guidelines for chemical unit operations used in water and wastewater treatment.
Why is disinfection of water important?
Disinfection of drinking water is performed in order to control the outbreak of diseases.
What is adsorption in water treatment?
Adsorption is used in drinking water treatment mainly to remove compounds that cause objectionable taste, odor or color. In wastewater treatment, it usually follows biological treatment or tertiary treatment, if any, and contributes to the removal of dissolved organic matter although particulate matter may also be removed. Different types of granular material (such as activated carbon, activated alumina, synthetic polymers and silica-based materials) are used as adsorbents. Activated carbon is the absorbent that is by far the most widely used in water treatment because of the higher cost of the other options. Activated carbon used in water treatment is of two sizes centered around 0.1 mm (200-mesh) diameter particles – larger particles are referred to as granular activated carbon (GAC) and smaller as powdered activated carbon (PAC). Activated carbon can efficiently adsorb these target compounds because it has numerous capillaries and the surface available for physical adsorption is large (700–1600 m 2 /g for GAC and 1400–2200 m 2 /g for PAC) compared to other potential adsorbents. PAC treatment can easily be added to existing plants while GAC systems have a higher capital cost. However, GAC systems are capable of accomplishing higher levels of removal and their operating costs (mostly the cost of replacing spent activated carbon) are lower than systems using PAC.
How much does drinking water reduce cardiovascular disease?
For example, a report of the Safe Drinking Water Committee of the National Academy of Sciences published in 1977 ( NAS, 1977) indicated that optimal conditioning of drinking water (especially its hardness characteristics) may reduce the cardiovascular disease mortality rate by as much as 15% in the USA.
What are the processes of removing hydrocarbons from wastewater?
The removal of hydrocarbons from wastewater before discharge into receiving water bodies from wastewater effluents entails a variety of processes, with the most common processes being phytoremediation, bioremediation and chemical remediation .
What are the three methods of remediation of hydrocarbons?
The remediation of hydrocarbon polluted wastewater can be achieved by three methods, which are phytoremediation, bioremediation and chemical remediation. Phytoremediation entails the use of plants to reduce the volume, mobility and toxicity of contaminants in soil and water.
What are the three processes of hydrocarbon pollution?
The three main processes for hydrocarbon remediation in polluted waters are phytoremediation, bioremediation and chemical remediation.
What is chemical remediation?
In the case of chemical remediation, it involves the use of chemicals for the treatment of contaminated sites. Substances, such as dispersants and solidifiers are used in chemical remediation. This study was aimed at reviewing the sources, impacts and remediation processes for hydrocarbon polluted wastewater effluents.
Why are microorganisms limited in the amount of growth and remediation that occur due to the amount of available
Because the microorganisms are limited in the amount of growth and remediation that occur due to the amount of available nitrogen and phosphorus, the addition of supplemental nutrients in the proper concentrations , enhances the hydrocarbon degrading of microorganisms.
What is the source of hydrocarbon pollution in water bodies?
Another source of hydrocarbon pollution in receiving water bodies is pesticides.
What is the threat of hydrocarbons?
The discharge of polluted hydrocarbon wastewater into receiving water bodies poses threat to animals through inhalation, ingestion and absorption. Sea birds, which spend most of their time close to water bodies, are the most vulnerable to the effect of hydrocarbon pollution in water ( Alonso-Alvarez et al ., 2007 ).
What are the pollutants in wastewater?
There are several contaminants in wastewater, with organic pollutants playing the major role. Many kinds of organic compounds, such as PCBs, pesticides, herbicides, phenols, polycylic aromatic hydrocarbons (PAHs), aliphatic and hetercyclic compounds are included in the wastewater, and industrial and agricultural production as well as the people living could be the source of organic wastewater endangering the safety of the water resource [1]. The wastewater of the farmland may contain high concentration of pesticides or herbicides; the wastewater of the coke plant may contain various PAHs; the wastewater of the chemical industry may contain various heterogeneity compounds, such as PCB, PBDE; the wastewater discharged by the food industry contains complex organic pollutants with high concentration of SS and BOD; and the municipal sewage contains different type of organic pollutants, such as oil, food, some dissolved organics and some surfactants. These organic pollutants in water can harm the environment and also pose health risks for humans.
What is adsorption in wastewater?
Adsorption is the process by which a solid adsorbent can attach a component dissolved in water to its surface and form an attachment via physical or chemical bonds, thus removing the component from the fluid phase. Adsorption is used extensively in industrial processes for many purposes of separation and purification. The removal of metals, coloured and colourless organic pollutants from industrial wastewater are considered an important application of adsorption processes using suitable adsorbents.
What is activated carbon used for?
Activated carbon is by far the most common adsorbent used in wastewater treatment. Since, during adsorption, the pollutant is removed by accumulation at the interface between the activated carbon (absorbent) and the wastewater (liquid phase) the adsorbing capacity of activated carbon is always associated with very high surface area per unit volume. Activated carbon can be manufactured from carbonaceous material, including coal (bituminous, subbituminous, and lignite), peat, wood, or nutshells (i.e., coconut). The manufacturing process consists of two phases, carbonization and activation. The carbonization process includes drying and then heating to separate by-products, including tars and other hydrocarbons, from the raw material, as well as to drive off any gases generated. The carbonization process is completed by heating the material at 400–600°C in an oxygen-deficient atmosphere that cannot support combustion. Powdered activated carbon is made up of crushed or ground carbon particles, 95–100% of which will pass through a designated mesh sieve or sieves. Granular activated carbon can be either in the granular form or extruded. It is designated by sizes such as 8×20, 20×40, or 8×30 for liquid phase applications and 4×6, 4×8 or 4×10 for vapor phase applications.
What is oxidation ditch?
The oxidation ditch is a circular basin through which the wastewater flows. Activated sludge is added to the oxidation ditch so that the microorganisms will digest the organic pollutants in the water. This mixture of raw wastewater and returned sludge is known as mixed liquor. The rotating biological contactors could add oxygen into the flowing mixed liquor, and they could also increase surface area and create waves and movement within the ditches. Once the organic pollutant has been removed from the wastewater, the mixed liquor flows out of the oxidation ditch. Sludge is removed in the secondary settling tank, and part of the sludge is pumped to a sludge pumping room where the sludge is thickened with the help of aerator pumps [14]. Some of the sludge is returned to the oxidation ditch while the rest of the sludge is sent to waste.
What are the advantages of anaerobic and aerobic reactors?
The advantages of the combined system are as follow: 1) the anaerobic process could get rid of the organic matters and suspended solid from the wastewater, reduce the organic load of the aerobic degradation as well as the production of aerobic sludge, and finally reduce the volume of the reactors; 2) wastewater pretreated by anaerobic technology is more stable, indicating that anaerobic process could reduce the load fluctuation of the wastewater, and therefore decrease the oxygen requirement of the aerobic degradation; 3) the anaerobic process could modify the biochemical property of the wastewater, making the following aerobic process more efficient. Investigation showed that the wastewater from aerobic-anaerobic combined reactor are more stable and ready for degradation, indicating that this technical have a huge potential for application. The classic aerobic-anaerobic reactors include A/O reactor, A2/O reactor, oxidation ditch, constructed wetland.
What is anaerobic biofilter?
Anaerobic biofilter, so called anaerobic fixed film reactors , is a kind of high efficient anaerobic treatment equipment developed in 1960 s. These reactors use inert support materials to provide a surface for the growth of anaerobic bacteria and to reduce turbulence to allow unattached populations to be retained in the system (Fig 4). The organic matter of wastewater is degraded in the system, and produce methane gas, which will be released from the pool from the top [13].
What is a membrane bioreactor?
Membrane bioreactor (MBR) is the combination of a membrane process like microfiltration or ultrafiltration with a suspended growth bioreactor , and is now widely used for municipal and industrial wastewater treatment. The scheme of the reactor is showed in Fig. 2 [11].