Methods of Sewage Waste disposal | |
Methods of sewage disposal are of two types:
Mathematically; HRT, tD = (Volume/Discharge) ------- days/hours/sec (units) | |
Flow Through Velocity or Horizontal Velocity and Settling Velocity Settling path of a solids particle in a tank Surface Loading Rate or Overflow Rate is the volume of water/wastewater applied per unit surface area of the treatment basin and is normally expressed in units of m3/m2-d or gal/ft2-d. Mathematically;
SLR = (Flow, Q/Area, As) {Numerically; SLR = HRT}
 Weir Loading Rate or Weir Overflow Rate is the quantity of wastewater flowing over a unit weir length of the tank in a unit time. It is expressed in units of m3/m-d or gal/ft-d. Mathematically; WLR = (Flow, Q/Total Length of Weir, L) PROBLEM: A treatment unit is 1.5 ft wide, 20 ft long and has a depth of 2.0 ft. if the wastewater flow rate through the tank is 0.5 ft3/sec. Calculate; detention time, overflow rate and weir loading rate. Organic Loading is the total quantity of organic matter in terms of BOD or COD that is applied per day over the unit surface area of per unit volume of the treatment basin or tank. Mathematically; OLR = (applied kg of BOD per day)/(volume of the basin) It is expressed as kg-BOD/m3-d or kg-COD/m3-d PROBLEM: A treatment basin has a diameter of 20 ft and a depth of 2.5 ft. Calculate the organic loading rate for an effluent of 10.0 MGD having 220 mg/L of BOD. Food-Microorganisms (F/M) Ratio is the relationship between the available food (F) and the microorganism (M) present in a biological treatment system. F/M = [(Q*So)/(V*X)] ----------- it is expressed in unit of sec-1 or d-1 etc. Since, HRT tD = V/Q, therefore, F/M = [So/(tD*X)] PROBLEM: If the wastewater with BOD concentration of 200 mg/L is treated in a tank having 5 hours HRT and containing 4000 mg/L MLVSS, calculate its F/M ratio. Mean Cell Residence Time or Solid Retention Time or Sludge Age; is the average time in days for which biomass are retained in the biological reactors | |
Arches An arch is an opening spanned by a collection of wedge shaped pieces ( voussoirs ) which stay in position by pressing in on one another. The joints between the pieces appear to radiate from some central point lying within the opening, and sometimes from points which lie outside, so every type of arch has a characteristic curvature. The simplest and visually most natural shape for an arch is the semicircle but many other designs have been used. How an Arch "Works" The central voussoir ( keystone ) is traditionally the last to be set into position to "lock" the whole thing into a strong and stable structure. A keystone is not always necessary, however; there may be a joint at the apex instead, as is common in Gothic arches. Gravity tries to pull the keystone downwards, but the thrust is carried on either side by the voussoirs immediately flanking it. These in turn have their total thrust carried through the whole semicircle of pieces in a sideways direc...
Comments
Post a Comment