Wastewater purification

Environmental applications of CNTs include the purification of air, water, soil, etc., by using various properties of CNTs. For instance, properties such as high surface area, chemical stability and low density of CNTs make them suitable for applications such as adsorption of heavy ions, salts, etc., for wastewater purification [202]. CNT-based filters can be designed for such applications. 

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Vinyl chloride can be completely oxidized to CO2 and HCl using potassium permanganate [7722-64-7] in an aqueous solution at pH 10. This reaction can be used for wastewater purification, as can ozonolysis, peroxide oxidation, and uv irradiation (42). The aqueous phase oxidation of vinyl chloride with chlorine yields chloroacetaldehyde (43). 

FIG. 22-25 Hydr othermal-oxidation process (also called supercritical water oxidation) for wastewater purification. (Cowtesy Eco-Waste Technologies.)... 

Pillared clays (MELS) are aLso covered in this review. MELS have three-dimensional network structure like zeolites, and, unlike clays, which have two-dimensional layered structures, pillared cationic and anionic clays have been studied. Phthalocyanins intercalated in anionic clays have given interesting results for wastewater purification (Vaccari, 1998). 

Retaining of different ions from solutions is a very important target for wastewaters purification and for recovery of different ionic expensive species from solutions. 

In the recent years, many researchers have devoted attention to the development of membrane science and technology. Different important types of membranes, such as these for nanofiltration, ultrafiltration, microfiltration, separation of gases and inorganic membranes, facilitated or liquid membranes, catalytic and conducting membranes, and their applications and processes, such as wastewater purification and bio-processing have been developed [303], In fact, almost 40 % of the sales from membrane production market are for purifying wastewaters. 

FIGURE 8.6 Bubble foam separation method for wastewater purification. 

Before the application of Chemical Leasing (ChL) the service company supplied chemicals and materials (iron chloride FeCI3, sodium hydroxide NaOH, filter packs) for wastewater purification. However, the level of water decon-... 

The service provider has developed and installed the improved wastewater purification process at the user s facilities and currently supplies the minimised amounts of required chemicals (FeCI3, NaOH) on the basis of Chemical Leasing. The company also takes care of the user s personnel training in the new process operation, the residual solid wastes transportation and disposal. 

The service recipient has performed all up-scaling activities required for the improved wastewater process installation and currently effectively performs wastewater purification using the chemicals supplied on the basis of Chemical Leasing. 

Payment according to the Chemical Leasing agreement between the parties is based on the amount (cubic meters) of purified water. The process optimisation provided the reduction of 1 m3 wastewater purification cost from the initial value of about 27 Euro to 13 Euro established according to the Chemical Leasing agreement. 

Economic benefits More than 50% decrease of wastewater purification cost and required chemicals consumption mutually profitable for participating companies. 

Quality and organisational benefits The implementation of the advanced wastewater purification process is profitable for the service provider only in the case of Chemical Leasing application since the amount of supplied chemicals is significantly reduced. 

Environmental benefits The installation of the new wastewater purification process provided the reduction of impurities contents in the glue production effluents to a level below the sanitary standards. Furthermore, the amount of environmentally hazardous chemicals (FeCl3, NaOH) used for wastewater purification is significantly reduced. 

Role in the project Service provider of industrial wastewater purification including the supply of chemicals, equipment, personnel training and residual wastes disposal... 

Role in the project User (service recipient) of chemicals and equipment for wastewater purification... 

What were the key benefits expected leading to your participation in the project 1. implementation of new equipment, chemicals and process for the purification of glue production wastewater 2. more than 50% decrease of wastewater purification cost and required chemicals consumption mutually profitable for participating companies ... 

Reasons The application of Chemical Leasing business model provided more than 50% decrease of wastewater purification costand required chemicals consumption thus providing a mutual profit for both participating companies. Small enterprises also can collect wastes for cyclic purification (for example once per week). ... 

Wastewater purification L Activated carbon Equilibrium Steam stripping... 

Aluminosilicate zeolites are recognized as excellent ionic exchangers [98,101,104,134,142-145], Using zeolites, mainly clinoptilolite, chabazite, and phillipsite, different process have been developed for the treatment of municipal wastewater, purification of radioactive wastewater, for the processing of agricultural wastewater with high chemical oxygen demand, animal nourishment, aquaculture, and the removal of heavy metals from wastewater [104],... 

The use of catalysts, furthermore, is required in the processes of wastewater purification by reducing treatments. Catalysts also find also application as complementary technologies to other wastewater treatment methods, such as in the control of odour, VOC, N2O and NOx emissions from wet oxidation treatments (for example, in the wet oxidation of industrial sludges), and of odours and VOC emitted from biological processes (aerobic and anaerobic). Although usually commercial catalysts are used in these cases, there are often unpredicted effects in treating complex mixtures and thus more specific catalysts would be preferable. The same is valid for catalysts used to convert stripped VOC from contaminated groundwater. 

Stankovic, V. (2007). Metal removal from effluents by electrowinning and a new design concept in wastewater purification technology. Chem. Biochem. Eng. Q., 21, 33-45. 

Fig. 3) [54,85] and reasonable exchange rates, K, ranging between 10"3-10 1 1 meq"1 min"1 [86]. For these reasons, on the basis of laboratory and pilot plant experiments performed by Ames and co-workers [e.g., 87], uses in wastewater purification were proposed since the beginning of the 1960s. Relevant applications have been reviewed in the recent literature [3,82,83,88,89]. Only the main (and most successful) uses will be presented here. 

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