Biological Nutrient Removal Theories and Design

Résumé du document

Flocculation Method: Add 1 ml of 100 g/l zinc sulfate solution to a 100 ml waste water sample and mix vigorously with a magnetic stirrer for 1 minute. Adjust the pH to approximately 10.5 with a 6 M sodium hydroxide solution. Settle quiescently for a few minutes. Withdraw the clear supernatant with a pipette and pass through a 0.45 µm membrane filter. Measure the COD on the filtrate.

Extraits

[...] Exception: Some wastes containing sufficientn the RAS. In situations whether most wastewater is pumped to the plant and the temperatures are favorable, P removal will take place without a serious attempt at reducing nitrates. When high percentage removal of both N and P is required, the plant should be biased towards nitrogen removal, since augmenting P removal with chemicals is much less costly and easier to control. Importance of Nitrate for P Removal VFAs as well as other easily degradable materials are responsible for the first high rate of denitrification. [...]

[...] CODinf Total truly sol. CODinf is determined by flocculating with Zn(OH)2 at pH 10.5 and filtering with a 0.45 µm filter. Non-readily sol. CODinf is determined by performing the above test with the effluent of a 24 hr fill-and-draw activated sludge system (MCRT > 3 days). Flocculation Method Add 1 mL of a 100 g/L zinc sulfate solution to a 100 mL wastewater sample and mix vigorously with a magnetic stirrer for 1 min. Adjust the pH to approx with 6 M sodium hydroxide solution. [...]

[...] pH Optimal nitrification pH: 7.2 [...]

[...] Incineration Separate the primary and secondary sludges. No problem. Heat treatment It may return unwanted (nondegradable) compounds Operator Skills Greater operatort the necessary skills are easily learned and applied. A retraining program for the operators should be part of any retrofit project. Case Histories: The York River, Virginia, Wastewater Treatment Plant Simultaneousf 7.4 hrs; primary sludge gravity thickeners, secondary sludge dissolveds, and belt filter presses; no supernatant recycle from the anaerobic digesters but the recycle of the filtrate from the belt presses and the supernatants from the thickeners. [...]

[...] Biological Phosphorus Removal (BPR) Return sludge Influent Anaerobic Aerobic To clarifier Conc. Time Sol. BOD Orthophosphorus Phosphate Release and Uptake - Secondary Release Biological Phosphorus Removal (BPR) Phosphorus Removal Mechanism Entirely by disposal of sludge containing larger portions of phosphorus in the biomass than conventional activated sludge Phosphate Release and Uptake - Secondary Release: Design Implications For fairly fresh, weak sewage, any effort at acid fermentation in the anaerobic basin (by increasing HRT in the anaerobic zone) is counterproductive. For strong, partially fermented sewage, a longer anaerobic retention time may be useful. [...]