Modern Methods for Wastewater Purification

Nanocomposites are multi-phasic materials, in which at least one of the phases shows dimensions in the nano range (10–100 nm). Now-a-days nanocomposite materials have emerged as suitable alternatives to overcome limitations of different engineering materials. They are reported to be the materials of 21st century. Nanocomposite materials can be classified as polymer based and non polymer based. Among different nanocomposites, polymer-based nanocomposite (PNCs) have become a prominent area of current research and development. PNCs have lot of advantageous properties such as film forming ability, dimensional variability, and activated functionalities. The PNC prepared from inorganic materials (metals and metal oxide nano-particles) using  in situ  polymerization and composite formation shows excellent sorbent properties and are also suitable as catalysts, sensors, reducing agents, and bactericides.  Addition of nanoparticles in polymer matrix improves the polymer proper...

In many parts of the world, access to clean drinking water is far from certain. Filtration of large volumes of water, however, is slow and impractical. As a consequence, scientists have introduced a new water purification method based on magnetic nanoparticles coated with a so-called “ionic liquid” that simultaneously remove organic, inorganic, and microbial contaminants, as well as microplastics. The nanoparticles are then easily removed with magnets. The surfaces of the nanoparticles were coated with a layer of an ionic liquid. An ionic liquid is a salt that is in its molten state at room temperature, making it a liquid without use of a solvent. The ionic liquid used by the researchers were based on polyoxometallates (POMs)—metal atoms bound into a three-dimensional network by oxygen atoms.  In this case the metal of choice was tungsten because the polyoxotungstate anions can bind to heavy metals. As counterions, the researchers used bulky tetraalkylammonium cations w...

  Membrane technology has served as an advanced separation process of surfactant–stabilized emulsions and it is a simple process. However, the real necessity of membranes is in industrial fields for treating oily wastewater which remains limited. The big problem here is severe membrane fouling caused by surfactant adsorption and pore plugging by oil droplets along with degradation over long term application due to its polymeric based structure. In this matter, carbon-based membrane technology has been found out to be an attractive technique to glue the gap between membrane technology and existing oily wastewater treatment. One of the most concerning pollution sources worldwide is Oil contaminated wastewater. This kind of wastewater pollutants come from sources such as, oil refineries, petrochemical industries, crude oil production, metal processing, lubricants, car washing and cooling agents . It is hazardous industrial wastewater due to toxic substances like phenols, petroleum h...

  Source- Intechopen  Biochar, as an high efficiency, environmental friendly, and low-cost adsorbent, is usually used as soil conditioner, bio-fuel, and carbon sequestration regent. Recently, biochar has attracted much attention in wastewater treatment field. There are plenty of studies about application of biochar to adsorb pollutants in wastewater, because of its low-cost preparation, high surface area, large pore volume, plentiful functional groups, and environmental stability.  Furthermore, it can be reused due to their high treatment efficiency and resource recovery potential. As biochar can be used for adsorption of typical pollutants in livestock wastewater, it becomes a promising method to treat livestock wastewater. The preparation methods, including pyrolysis, hydrothermal carbonization, and gasification, were introduced. The applications of biochar to adsorb typical pollutants, such as organic pollutants, heavy metals, and nutrients, in livestock wastewater wer...

  Most of the organics in the sewage sludge were transformed into useful energy by the anaerobic fermentation of microorganism. Plenty of nitrogen, phosphate, potassium could be separated from the leachate produced in this fermentation which makes the recycling of sewage sludge much easier. This method could also help stabilize and decrease the amount of sewage sludge and make it harmless.  Here is a brief account on the mechanism of this process. The sewage sludge samples are taken in conical flasks; the flasks were sealed and kept in an airtight and anaerobic condition. Then the conical flasks were kept in thermostatic water bath box, controlling the temperature at 95°C to improve the efficiency of the anaerobic fermentation of the sewage sludge. The conical flasks were taken out and put into a container with oxygen at the 2th, 7th, 10th, 14th, 17th, 21th, and 28th day after the beginning of the anaerobic fermentation, respectively. When the flasks were taken out, a little o...

Alcanivorax borkumensis  is an  alkane -degrading marine  bacterium  which naturally propagates and becomes predominant in crude-oil-containing seawater when  nitrogen  and  phosphorus  nutrients are supplemented. In our fossil-fuel age, oil spills remain a major problem. From the  Exxon Valdez  to the recent  Prestige  disaster in Spain, several million tons of oil soils the world's seas every year, causing ecological catastrophe. Scientists developing cleanup strategies have looked to the microbes that thrive in the wake of such spills as one solution. Now, thanks to a detailed breakdown of one of the most effective of these oil-eaters, they are closer to having biologically based remedies for such environmental disasters. Alcanivorax borkumensis  is a rod-shaped bacteria that relies on oil to provide it with energy. Relatively rare in unpolluted seas it quickly com...

 INTRODUCTION:- Use of ozone for wastewater treatment:- The use of ozone to disinfect sewage is becoming increasingly important, especially when a high degree of treatment is required. Ozone is a strong disinfectant with a high oxidation potential and is one of the most effective ways of inactivating pathogens. In order to observe and evaluate the effect of this disinfectant on the physical, chemical and microbiological characteristics of wastewaters, we analyzed the effluent input and output of an ozone disinfection plant located in Almeria, southeast Spain. The ozone input rate is adjusted according to the residual ozone content in the effluent output. The effluent is currently reused to irrigate vegetable crops. Another objective of this study has therefore been to verify the adequacy of this water treated process for preparing water for this purpose. Among the results obtained, it is important to highlight the fact that the ozone disinfection treatment was sufficie...

 A way to reduce excess sludge production and enhance mineralization is to retain the sludge completely in a treatment plant, which can be achieved by a membrane separation process. There the sludge concentration is expected to stabilize at the level at which energy supplied is fully utilized for maintenance purpose. Another way to enhance mineralization and reduce the sludge production is to exploit the organism in the process that predate on bacteria (sludge), by promoting their growth in an extra “grazing stage”. During energy transfer from bacteria to higher trophic level organisms, energy is lost due to inefficient biomass conversion and thus the predator may make a large contribution to biomass replacement. A long sludge retention period in membrane bioreactors (MBR) is very suitable for the abundant growth of these higher organisms. This predatory population in the system can be exploited to enhance mineralization and reduce sludge production.  High metazoa density lead...

  Microflora of wastewater is very much vast just like the composition of pollutants. Large amount of microorganisms are found in domestic sewage along with human and animal excreta. Among the microbes determined in sewage and in the air collected at a wastewater treatment plant they contain both saprophytes, potential pathogens and pathogens of the genera  Clostridium ,  Enterobacter , Bacillus ,  Escherichia ,  Klebsiella ,  Mycobacterium ,  Pseudomonas ,  Serratia ,  Staphylococcus ,  Salmonella , as well as filamentous fungi from genus , Penicillium and Aspergillus . Microorganisms which are transferred from sewage to air in the form of mainly bioaerosol are prone to some conditions which can increase their growth and development. Some amount die rapidly mainly due to desiccation, exposure to excessively high or low temperatures or are killed by solar radiation. But a few microorganisms have some specific mechanisms which enable t...

  Ultraviolet light is another disinfection method for destroying disease-causing organisms in wastewater effluent in onsite wastewater treatment systems. The UV light destroys the genetic material of microorganisms which prevents them from reproducing. Wastewater must pass through an advanced pretreatment component which is designed to remove most of the organic matter and suspended solids before it passes through the UV disinfection unit. Wastewater flows parallel to the UV light in a thin film to increase contact time.   For the UV light to be effective, the UV radiation must come in direct contact with the microorganisms in the wastewater stream. Constituents allow a hiding place for the pathogenic organisms and shield them from the UV light. If the UV light does not come in direct contact with the constituents of concern, then it is useless. Turbidity, suspended solids, and flow rate of the wastewater must be kept at low levels to ensure proper treatment. Proper...

 ION EXCHANGE:- Ion exchange is a process in which ions of a particular species in solution are replaced by ions with a similar charge but of different species attached to an insoluble resin. In essence, ion exchange is a sorption process and can also be considered a reversible chemical reaction. The common appli cations of ion exchange are water softening (removal of "hardness" ions such as CA2+ and Mg2+) and nitrate removal in advanced wastewater treatment operations. These ion exchange resins are either naturally occurring inorganic zeolites or synthetically produced organic resins. The synthetic organic resins are the predominant type used today because their characteristics can be tailored to specific applications. An organic ion exchange resin consists of an organic or inorganic network structure with attached functional groups that can exchange their mobile ions for ions of similar charge from the surrounding medium. Each resin has a distinct number of mob...

Aerobic digestion is a process in sewage treatment designed to reduce the volume of sewage sludge and make it suitable [1] for subsequent use. [2] More recently, technology has been developed that allows the treatment and reduction of other [3] organic waste, such as food, cardboard and horticultural waste. It is a bacterial process occurring in the presence of oxygen. Bacteria rapidly consume organic matter and convert it into carbon dioxide, water and a range of lower molecular weight organic compounds. As there is no new supply of organic material from sewage, the activated sludge biota begin to die and are used as food by saprotrophic bacteria. This stage of the process is known as endogenous respiration and it is process that reduces the solid concentration in the sludge.   PROCESS:- Aerobic digestion is typically used in an activated sludge treatment plant. Waste activated sludge and primary sludge are combined, where appropriate, and passed to a thickener where the so...

 Anaerobic digestion is widely considered as an environmentally friendly technology for various organic waste including sewage sludge. Although the implementation of anaerobic digestion as an alternative treatment method for sewage sludge can be seen in many countries, its status in Malaysia is not clear. This study reviewed the current state of sewage sludge treatment in Malaysia and discussed the challenges to promote anaerobic digestion in sewage sludge treatment. Other than the common constraints faced, namely technical, political and economic, the characteristics of sewage sludge in Malaysia are considered to be a factor regarding feasibility. Anaerobic co-digestion is the simultaneous anaerobic digestion of two or more substrates which is a promising possible option to overcome the disadvantages of mono-digestion, and improve the economic viability due to higher methane production. There are a variety of biomasses as co-substrates in Malaysia. However, the anaer...

 An aerated lagoon is a suspended-growth process in waste water treatment unit. The aerated lagoon water treatment system consists of a large earthen lagoon or basin that is equipped with mechanical aerators to maintain an aerobic environment and to prevent settling of the suspend biomass. It is provided with inlet at one end and outlet at the other end to enable the wastewater to flow through and to retain for the specified detention time. Initially, the population of microorganisms in an aerated lagoon is much lower than that in an ASP because there is no sludge recycle. Therefore, a significantly longer residence time is required to achieve the same effluent quality. However, this longer residence time may be an advantage when complex organic chemicals are to be degraded. Also, the microorganisms in aerated lagoons are more resistant to process upsets caused by feed variations than those in ASP because of the larger tank volumes and longer residence times used. Th...