Sludge systems

Process water streams from vinyl chloride manufacture are typically steam-stripped to remove volatile organics, neutralized, and then treated in an activated sludge system to remove any nonvolatile organics. If fluidized-bed oxychlorination is used, the process wastewater may also contain suspended catalyst fines and dissolved metals. The former can easily be removed by sedimentation, and the latter by precipitation. Depending on the specific catalyst formulation and outfall limitations, tertiary treatment may be needed to reduce dissolved metals to acceptable levels. 

Sedimentation Tanks These tanks are an integral part of any activated-sludge system. It is essential to separate the suspended solids from the treated liquid if a high-quality effluent is to be produced. Circular sedimentation tanks with various types of hydraulic sludge collectors have become the standard secondary sedimentation system. Square tanks have been used with common-wall construc tion for compact design with multiple tanks. Most secondary sedimentation tanks use center-feed inlets and peripheral-weir outlets. Recently, efforts have been made to employ peripheral inlets with submerged-orifice flow controllers and either center-weir outlets or peripheral-weir outlets adjacent to the peripheral-inlet channel. 

Designs activated sludge systems. Also provides data data for flow modeling and permits. 

In wastewater treatment with an activated sludge system... 

The oxygen requirements for an activated sludge system with aeration and agitation for complete mixing are shown by mathematical model as the rate of oxygen transferred is... 

Activated Sludge System Including Deep Shaft Process... 

The deep shaft biological treatment process,87 which is one of the activated sludge systems, has been successfully applied to a paper mill wastewater treatment in Japan (see Case Study III, Section 21.6.3). 

A description is given of a unique solution for the problems of overloaded conventional activated sludge systems. A high-rate dissolved air flotation (DAF) clarifier is applied in series between the... 

The primary distinguishing feature of the improved activated sludge treatment system is that high-rate DAF is the secondary clarifier for separation of suspended solids from the activated sludge aeration basin effluent, as opposed to secondary sedimentation alone in a conventional activated sludge system. 

Section 27.3 introduces the improved activated sludge systems involving the use of either a DAF clarifier or a dissolved air flotation-filtration (DAFF) clarifier as the secondary flotation clarification unit. 

FIGURE 27.12 Improved activated sludge system with the installation of a secondary flotation clarifier (example). Note 1MGD = 0.0438 m3/s lppm-lmg/L 1 TPD = 37.8 kg/h. 

For example, the mean hydraulic retention time for the entire improved activated sludge system can be expressed as... 

A typical overloaded conventional complete-mix activated sludge treatment plant (shown in Figure 27.11) has been described in Section 27.3.3. The same conventional treatment plant can be improved by the addition of a secondary flotation clarifier (shown in Figure 27.12). Some advantages of the improved activated sludge system are mathematically presented below. 

The comparable conventional activated sludge system (Figure 27.11), on the other hand, generates 0.0396 MGD of waste sludge with a concentration of 12,500 mg/L. The sludge treatment cost of an improved system will, therefore, be reduced to one half due to a reduction in sludge flow and an... 

Beer, C. and Wang, L.K., Activated sludge systems using nitrate respiration design considerations, Journal WPCF, 50 (9), 2120-2131, 1978. 

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