Tag: microbes in waste treatment and biogas

Answer is B.
Windmills, like waterwheels, were among the original prime movers that replaced animal muscle as a source of power. They were used for centuries in various parts of the world, converting the energy of the wind into mechanical energy for grinding grain, pumping water, and draining lowland areas.
Kinetic energy of the wind is transformed into mechanical energy of the turning windmill. This can be used to turn a generator to generate electricity. The original energy to cause the wind to blow came from the sun. Uneven heating of the earth's surface causes wind.
Hence, the statement is false.

Answer is B.

Biogas is characterized based on its chemical composition and the physical characteristics which result from it. It is primarily a mixture of methane (${ CH } _{ 4 }$) and inert carbonic gas (${ CO } _{ 2 }$). However the name 'biogas' gathers a large variety of gases resulting from specific treatment processes, starting from various organic waste - industries, animal or domestic origin waste, etc . 
Hence, the statement is false.

Fuel-grade ethanol is one energy source that has great potential for being generated from biomass. The gas obtained by the fermentation of biomass is called biogas.

Biogas is a type of secondary energy because biomass (primary energy) is used to produce biogas by anaerobic digestion into more efficient and higher value fuel.Biogas is also called gobargas as made by waste remains of plants and animals.

Major gases released from biomass are methane ($CH _4$), carbon dioxide ($CO _2$), hydrogen ($H _2$) and hydrogen sulphide ($H _2S$).

The activated sludge have to settle quickly so that it can be pumped back to the aeration tank. So, the correct option is 'be rapidly pumped back from sedimentation tank to aeration tank'

The primary treatment involves physical removal of particles from the sewage through filtration and sedimentation. These are removed initially by sequential filtration which removes the floating debris and then grit is removed by sedimentation. 

Wastewater treatment generates a large quantity of activated sludge during secondary treatment which is used as a inoculum and a small part of it is pumped back to the large aeration tanks whereas the remaining part of that sludge is treated by anaerobic sludge digesters anaerobically. During this digestion, bacteria produces a mixture of gases called biogas. 

Activated sludge should have the ability to settle quickly so that it can be rapidly pumped back from sedimentation tank to the aeration tank, where it can start the process of decomposition of the organic matter again. Activated sludge has filamentous bacteria that are capable of performing the aerobic digestion of organic waste is the sewage water.