Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Identify different stages in the treatment of sewage.
Disinfection and secondary treatment
Primary treatment and secondary treatment
Primary treatment and disinfection
Primary treatment, secondary treatment and disinfection
Primary treatment, secondary treatment and disinfection
Sewage treatment is a multi-stage process designed to remove contaminants from wastewater before discharge into the environment. It involves physical removal of solids (Primary), biological decomposition of organic matter (Secondary), and final pathogen elimination (Disinfection).
CPHEEO Manual on Sewerage and Sewage Treatment Systems
Sewage treatment is a multi-stage process designed to remove contaminants from wastewater before discharge into the environment. It involves physical removal of solids (Primary), biological decomposition of organic matter (Secondary), and final pathogen elimination (Disinfection).
BODtтАЛ=L0тАЛ(1тИТeтИТkt) тАФ First-order kinetic model for biochemical oxygen demand representing remaining organic matter at time t.
Primary treatment relies on gravity (sedimentation) to remove suspended solids. Secondary treatment utilizes microorganisms in aerobic environments (e.g., Activated Sludge Process) to break down dissolved organic matter measured by BOD. Disinfection (typically chlorination or UV) is the final stage to kill pathogenic organisms to meet public health standards.
Primary treatment removes 50-70% of suspended solids and 25-40% of BOD.
Secondary treatment is biological, focused on reducing the carbonaceous BOD (CBOD).
Tertiary or advanced treatment may follow disinfection if nutrient removal (N and P) is required.
The sequence is essential: removal of large solids must precede biological stages to prevent pipe clogging and process inefficiency.
Prevention of waterborne diseases through pathogen reduction.
Mitigation of eutrophication in receiving water bodies by removing nutrients.
Protection of aquatic ecosystems from deoxygenation caused by high organic loads.
High capital investment and recurring operational energy costs.
Complexity in managing sludge handling and safe disposal.
Sensitivity of biological processes to toxic industrial inflows.
Municipal wastewater management systems.
Industrial effluent pretreatment units.
Water reuse systems for irrigation and industrial cooling.
The sequence must be strictly maintained as Primary тЖТ Secondary тЖТ Disinfection.
Option D is the most comprehensive as it covers the full scope of standard treatment processes.
Options A, B, and C are incomplete because they omit at least one critical phase necessary for meeting environmental discharge standards.
D is correct тАФ The sewage treatment process follows a sequential path of physical, biological, and chemical/physical disinfection stages to ensure safe effluent disposal.
Remember that tertiary treatment is not a standard requirement for all plants but is essential when discharge standards require nutrient removal or high-quality reuse.
Get instant step-by-step AI explanations, full shift Previous Year Papers (SSC GD, RRB, SSC JE), and regional rank analysis on the official Examoogle App.
Free Download тАв 100K+ Aspirants