Full waste water

The upper outlet for water from the condenser should be above the jacket so as to ensure that the condenser is full of water. If the rubber tube, which carries the waste water to the sink, tends to kink, a short copper spiral, made by winding a length of copper wire round a glass tube, may be slipped over the end attached to the condenser. 

Appendix D presents the U.S. EPA data on a full-scale treatment of aluminum forming waste-water by chromium reduction, chemical precipitation, and sedimentation clarification. Chromium reduction, as described in detail by Wang, Hung and Shammas,9 is an important step prior to... 

Frijters CTMJ, Vos RH, Scheffer G et al (2004) Decolorizing and detoxifying textile waste-water in a full-scale sequential anaerobic-aerobic system. In Guiot SR, vol 4. IWA Publishing, London, pp 2387-2390... 

Hollender J, Zimmermann SG, Koepke S, Krauss M, McArdell CS, Ort C, Singer H, von Gunten U, Siegrist H (2009) Elimination of organic micropollutants in a municipal waste-water treatment plant upgraded with a full-scale post-ozonation followed by sand filtration. Environ Sci Technol 43 7862-7869... 

This chapter provides an overview and guidance on the various applications of ozone in water and waste water treatment, where full-scale facilities exist and it has been demonstrated that ozonation is effective and economical. 

The subsequent parts on full-scale applications of ozone for water and waste water treatment are not arranged according to the water source, but describe the different and multiple tasks of ozone with regard to water constituents and treatment goals. Furthermore, attention is given to the appropriate combination of the ozonation process with preceding and subsequent treatment steps. 

Full-scale waste water ozone treatment facilities may roughly be defined as systems with a ozone generation capacity of more than 0.5 kg per hour. They can be found in various applications in all branches of industry, treating almost all types of waste waters. The operating conditions used in waste water ozonation are dependent on the type of industry and the kind of waste water. They can be grouped according to ... 

The discussion of full-scale ozonation systems for waste waters in the following sections is grouped according to the main removal goal of the application, analogous to that used in drinking water ozonation systems. 

The most frequently used contactors in full-scale waste water ozonation systems are bubble column reactors equipped with diffusers or venturi injectors, mostly operated in a reactor-in-series counter-current continuous mode. Many full-scale ozone reactors are operated at elevated pressure (2-6 barabs) in order to achieve a high ozone mass transfer rate, which in turn increases the process efficiency. 

Full-scale ozonation systems have been used to treat waste waters, such as landfill leachates, as well as waste waters from the textile, pharmaceutical and chemical industries (FTGAWA, 1997 Bohme, 1999). The main pollutants associated with these waters are refractory organics, which can be characterized as (Masten and Davies, 1994) ... 

Goals, technology and results of full-scale applications on some types of waste waters are discussed in more detail in the following sections. An overview of technological features, operating parameters and treatment costs of full-scale plants for waste water ozonation is given in Table 3-3. 

Table 3-3 Overview of technological features, operating parameters and treatment costs of full-scale plants for waste water ozonation. 

In full-scale applications very fast corrosion (formation of holes over the course of weeks, especially at improper welds) has been observed in off-gas piping, even when made from stainless steel. The problem is most evident when aerosols, for example containing chloride, escape from the reactor into the pipes where they form a very corrosive wet film. But corrosion may also occur in stainless steel pilot or full-scale reactors, especially when treating waste waters. Such reactors are best made of stainless steel because of the possibility to operate them at elevated pressures, e. g. 200-600 kPa, which can readily be achieved with commercially available ozone generators (Masschelein, 1994). 

Possiblities of explosive gas mixtures exist. In full-scale ground or waste water applications for example, volatile organic compounds could be contained in the off gas. These compounds escape from the reactor due to comparatively high temperatures and... 

The continuous-flow set-up can use either a reaction, similar to semi-batch, to remove the oxygen transferred or two reactors in series. The ozone or oxygen is removed from the liquid in the first reactor by stripping or vacuum degassing and then it flows into the absorber. After having passed through the absorber, the liquid can be recycled or discharged. More information on full-scale application of this method in municipal waste water treatment plants can be found in Redmon (1983) and ASCE (1991). 

Ozone is applied in three-phase systems where a selective ozone reaction, oxidation of residual compounds and/or enhancement of biodegradability is required. It can be used to treat drinking water and waste water, as well as gaseous or solid wastes. Especially in drinking water treatment full-scale applications are common, e. g. for particle removal and disinfection, while in waste water treatment sludge ozonation and the use of catalyst in AOP have been applied occasionally. Current research areas for three-phase ozonation include soil treatment and oxidative regeneration of adsorbers. Ozonation in water-solvent systems is seldom studied on the lab-scale and seems favorable only in special cases. In general, potential still exists for new developments and improvements in ozone applications for gas/watcr/solvent and gas/waler/solid systems. 

In the laboratory batch ozonation is easy to apply, whereas multi-stage continuous-flow systems are difficult to handle (Method 1). However, mainly due to large liquid flow rates the inverse situation is valid for many full-scale applications. Often three oxidation reactors in series are found in waste water ozonation (cf. Table A 3-3). The advantage of a multi-stage CFSTR system - or even a batch system - lies in their faster reaction rates compared to a single CSTR due to the reduced axial/longitudinal mixing. 

This example is divided into three parts. In (a), the development of a new, selfaspirating and radially discharging funnel-shaped nozzle is presented. In (b), a flotation cell with two spatially separated spaces is described. The inner chamber is used for contacting gas bubbles with flocks and the annular ring around it is needed for the tranquilization of liquid throughput. This facilitates the complete separation of the flocks from the biologically purified waste water. It is shown how the flotation kinetics can be determined in this continuously run cell and how this knowledge is used to scale-up a full-scale flotation plant. On the contrary, in (c), data from batch-wise performed experiments are used to evaluate the flotation kinetics and to scale-up continuously run full-scale flotation cells. 

Various methods for the removal of As from geothermal waste waters have been investigated at theoretical, laboratory, pilot plant and full plant scales. These include adsorption onto Fe-oxide floe and subsequent separation by dissolved air flotation (De Carlo and Thomas, 1985 Shannon et al., 1982) and co-precipitation with lime to form an As-rich calcium silicate (Rothbaum and Anderton, 1976). In both cases, effective removal was achieved only after oxidation of As" to As, For Fe-oxide floe treatment, competitive adsorption of silica inhibits As adsorption, particularly that of As" (Swedlund and Webster, 1999), suggesting that prior removal of silica would help optimise As removal efficiency. The use of ion selective chelating resins for As" removal from geothermal waters has also been successfully tried (Egawa et al, 1985). 

A range of chemical remediation processes is at various stages of development, both for in situ and ex situ applications. Many of these are based on the treatment of waste water or other hazardous waste. However, the range of processes that have been widely used at full scale is restricted. Major types include ... 

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