Environmental Engineering FOURTH EDITION

184 ENVIRONMENTAL ENGINEEFtING Return activated sludge Waste activated to C02, H20, some stable compounds, and more microorganis ...

Wastewater Treatment 185 Table 9-3. Loadings and Efficiencies of Activated Sludge Systems Loading: F/M Aeration period BOD remov ...

186 WIRONMENEL ENGINEERING Influent * * Influent Aeration Short aeration (sorption) Aeration d Influent Return sludge Return slu ...

Wastewater Treatment 187 Air header Diffused Aeration Figure 9-15. Activated systems with diffused aeration. (Photo courtesy of ...

(21’6) .paw aieiisqns 30 ssem iad pampoid sursyw2!ioo~~p 30 SSBW :ppj = pue ‘ss io ‘srnsyw8~00~~~ 30 SSBW = x ‘ailriisqns 30 SSB ...

Wastewater Treatment 189 I I I I I I 0 50 100 150 200 250 300 Solid loading kg/d-rn2 Figure 9-17. Allowable solids loading for f ...

190 ENVIRONMENTAL ENGINEERING Q +W+Q V X Figure 9-18. A biological reactor without microorganism recycle. completely mixed the i ...

Wastewater Treatment 191 In a steady-state system, (dX/dt) = 0, and Xo = 0 is assumed. Substituting Eq. (9.15) into Eq. (9.18), ...

192 ENVIRONMENTALENGINEERING and since X =- 0 (9.22b) Note that in this case 0, # t. Substrate removal can be considered in term ...

Wastewater Treatment 193 Using a mass balance in terms of microorganisms Net rate of change Rate of Rate of Rate of in microorga ...

194 ENVIRONMENTAL ENGINEERING case that X = 4OOOmgL The hydraulic retention is then obtained by rearranging Eq. (9.30): t= 0.5 ...

Wastewater Treatment 195 where X, = the expected return suspended solids concentration (in m&), X = MLSS (ma), H = height of ...

196 ENVIRONMENTAL ENGINEERING I 02 'I \ Figure 9-20. Schematic diagram of an oxidation pond and photograph of an aeration lagoon ...

Wastewater Treatment 197 BOD may also be removed by activated carbon adsorption, which has the added advantage of removing some ...

198 ENVIRONMENTAL ENGINEERING Phosphate may be removed chemically or biologically. The most popular chem- ical methods use lime, ...

Wastewater Treatment 199 The production of Al(OH)3 is The total sludge production is then AlPO4 + Al(OH)3 = 21.3 + 24 = 45 mg - ...

200 ENVIRONMENTAL ENGINEERZNG wastewater treatment systems. Such land treatment systems have been used in Europe for many years ...

Wastewater Treatment 201 Figure 9-22. An aerial view of a secondary wastewater treatment plant. (Courtesy of Envirex.) Figure 9- ...

202 ENVIRONMENTAL ENGINEERING sense to entrust unqualified operators with multimillion dollar facilities. Wastewater treatment r ...

Wastewater Treatment 203 BOD Suspended solids Phosphorus Waste (ma) (SS, mgw (ma) Chemical industry 40,OOO^0 0 Pickle cannery 0 ...