Wednesday, March 4, 2020

METHODS OF SEWAGE WASTE DISPOSAL - Methods of sewage disposal are of two types: Dry or conservatory system and Water carriage system. Detention Time (Hydraulic Retention Time, HRT) is the length of time a particle or a unit volume of water/wastewater remains in a reactor/basin/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. 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. 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. It is expressed as kg-BOD/ m3-d or kg-COD/ m3-d. Food-Microorganisms (F/M) Ratio is the relationship between the available food (F) and the microorganism (M) present in a biological treatment system. 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.

Image result for images Sewage Waste disposal
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Image result for images Sewage Waste disposal
Methods of Sewage Waste Disposal
By: Haseeb Jamal 




Image result for images Sewage Waste disposalMethods of sewage disposal are of two types:
1.        Dry or conservatory system
2.        Water carriage system (99.9)
Detention Time
Detention Time (Hydraulic Retention Time, HRT) is the length of time a particle or a unit volume of water/wastewater remains in a reactor/basin/tank.
Mathematically;
HRT, tD = (Volume/Discharge) ------- days/hours/sec (units)
Flow Through Velocity or Horizontal Velocity and Settling Velocity
Velocity
Settling path of a solids particle in a tank
Surface Loading Rate
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}
OverFlow Rate
Weir Loading Rate
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.
Haseeb Jamal. I am a Civil Engineer, graduated from University of Engineering and Technology, PeshawarPakistan in 2010. I also have a PG-Diploma in Disaster Management and MS in Urban Infrastructure Engineering (In Progress). My expertise include civil related softwares like AutoCAD, SAP2000, MS Project, Primavera, MS Office and GIS. My technical skills include project management, monitoring and evaluation, structural assessment, disaster risk management, Quantity survey, land survey, material testing, site management and technical writing. I am trained in writing project progress reports as well as proposals and concept papers. I have also received advanced training on surveying, proposal writing, Monitoring and Evaluation of projects as well as organizations.
I have worked as Project Engineer at National Research and Development Foundation, Peshawar and CENCON Associates. I also worked with Spectra Engineering Solutions as Senior Civil Engineer in monitoring of World Bank and UNDP funded projects all over Khyber Pakhtunkhwa and FATA. Currently, I am working as Deputy Manager Development at NayaTel, Peshawar.

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