1. Which of these is used to remove odour?
a) Ultrafiltration
b) Pressure sand filter
c) Activated carbon
d) Nano filter
Explanation: Activated carbon filters are used to remove odour. This is also used to reduce COD by removing organics. The treatment process works on the principal of adsorption.
2. Reverse Osmosis is which type of treatment?
a) Primary treatment
b) Preliminary treatment
c) Secondary treatment
d) Tertiary treatment
Explanation: Reverse Osmosis is classified as tertiary treatment. This is mainly used to remove ions. This results in the reduction of total dissolved salts.
3. Which is usually prior to reverse osmosis?
a) Ultrafiltration
b) Activated carbon filter
c) Clarifier
d) Tube settler
Explanation: Ultrafiltration is usually prior to reverse osmosis. This is to remove the TSS present in the sample. Reverse osmosis reduces the total dissolved solids in the water sample.
4. What does zero discharge actually refer to?
a) There is zero discharge of ions
b) The reject is recycled from every part of the treatment plant
c) The reject is not rejected out. Influent equals effluent
d) 100 percent efficient plant
Explanation: Zero discharge usually refers to the treatment plant in which the reject from each part of the treatment plant is recycled. The reject is fed as the influent and once again treated. The removal efficiency of the pollutants is approximately 97-98%.
5. Primary sludge includes __________
a) Total suspended solids
b) Suspended solids
c) Removable solids
d) Settleable solids
Explanation: Sludge is mostly water with lesser amounts of solid material removed from liquid sewage. Primary sludge includes settleable solids removed during primary treatment in primary clarifiers.
6. Secondary sludge includes treated sewage sludge.
a) True
b) False
Explanation: Primary sludge includes settleable solids removed during primary treatment in primary clarifiers. Secondary sludge separated in secondary clarifiers includes treated sewage sludge from secondary treatment bioreactors.
7. Sludge treatment helps is reducing treatment costs.
a) True
b) False
Explanation: Reducing sludge weight and volume to reduce disposal costs is the aim of sludge treatment. The choice of a sludge treatment method depends on the volume of sludge generated, and comparison of treatment costs required for available disposal options
8.Which of the following methods are used in rural communities?
a) Aerobic digestion
b) Mechanical dewatering
c) Dewatering
d) Composting
Explanation: Air-drying and composting may be attractive to rural communities, while limited land availability may make aerobic digestion and mechanical dewatering preferable for cities, and economies of scale may encourage energy recovery alternatives in metropolitan areas.
9. From which of the following methods can toxic chemicals be removed?
a) Sorption
b) Adsorption
c) Absorption
d) Dewatering
Explanation: Coarse primary solids and secondary sewage sludge may include toxic chemicals removed from liquid sewage by sorption onto solid particles in clarifier sludge. Reducing sludge volume may increase the concentration of some of these toxic chemicals in the sludge
10.What is the term used for reuse of sewage sludge?
a) Compost
b) Solids
c) Biosolids
d) Sludge
Explanation: “Biosolids” is a term often used in engineering publications and public relations efforts by local water authorities when they want to put the focus on reuse of sewage sludge after the sludge has undergone suitable treatment processes.