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activated sludge plant controller Applications

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    Real-time Control System for Wastewater Treatment Plants

    Wastewater treatment plants (WWTP) are subject to large variation in flow and load, not to speak of uncertainties on the composition of the incoming wastewater. On top of that, the activated sludge treatment process, as used by the vast majority of treatment plants, is difficult to control due to the complex behaviour of the biological process. Nevertheless WWTPs are run 24/7, with operators and management challenged to meet ever tightening environmental regulations.

    In order to meet the operational demands of modern-day plants, a new control system was developed. Proprietary control algorithms were introduced based on a large set of data from nutrient measurements in various WWTPs. The customer`s benefits are twofold: (1) achieving optimum effuent quality and, at th same time, (2) lowering energy needs and dosing of commidity chemicals.

    By AppliTek NV based in Nazareth, BELGIUM.

  • Filamentous Bulking Control with Hydrogen Peroxide

    Basis of Control with Hydrogen Peroxide Hydrogen peroxide may be used to correct a serious filamentous bulking situation or, preferably, to prevent one from occurring until adjustments can be made to remove the cause. When applied to the return activated sludge, hydrogen peroxide supplies dissolved oxygen which helps restore the microbial activity necessary for effective operation, while selectively oxidizing the filaments which retard settling. The effective dose of hydrogen peroxide is a function of time and concentration, and varies from plant to plant. To correct a serious bulking problem, immediate results may be obtained by adding 100 - 200 mg/L H2O2 to the biosolids recycle line. Once control of bulking is obtained, the dose may be reduced to 25 - 50 mg/L H2O2 to prevent re-occurrence. Practical Considerations Filamentous bulking of municipal activated sludge is not a normal occurrence, and suggests more fundamental problems may be at work (e.g., low dissolved oxygen, high sulfide input, heavy organic loading, nutrient imbalance, improper sludge age, or rapid changes in influent characteristics). Consequently, the use of chemicals such as hydrogen peroxide to control bulking should be pursued in concurrently with more fundamental corrective measures.

    By USP Technologies based in Atlanta, GEORGIA (US) (USA).

  • Headworks Odor and Corrosion Control Using Hydrogen Peroxide

    Hydrogen Peroxide typically controls odors and corrosion at treatment plant headworks by direct oxidation of hydrogen sulfide (H2S) within the wastewater. In the direct oxidation mode, H2O2 is applied to the wastewater 5-30 minutes prior to the point where the odors are being released, generally as the wastewater line enters the plant boundary. The efficiency of hydrogen peroxide treatment depends upon the available reaction time, the level of iron in the wastewater (reaction catalyst), wastewater pH and temperature, and the initial and target levels of H2S odor. Under optimal conditions, effective dose ratios are 1.2 - 1.5 parts H2O2 per part dissolved sulfide, and can be reliably estimated through beaker tests. H2O2 + H2S → S0 + 2H2O Frequently, control of odors through the primary clarifiers is wanted. In such case, the mechanism of control is both direct oxidation of H2S (as it rises from the solids blanket), and prevention of odor generation (by supplying dissolved oxygen). Control is typically achieved with a booster dose of 1-2 mg/L H2O2 added to the clarifier influent. Higher doses or alternate modes of addition may be required in cases where: 1) hydraulic retention times are > 2-3 hours; 2) solids blanket depths are > 1-2 feet; 3) soluble BOD levels are > 200-300 mg/L; or 4) waste activated sludge is co-settled with the primary solids. 2H2O2 → O2 + 2H2O

    By USP Technologies based in Atlanta, GEORGIA (US) (USA).

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