Masses of bacteria associated with fungal filaments to form mesh like structures in secondary treatment in sewage plants. What is it called?

Give the one word scientific term for the following . Masses of bacteria associated with fungal filaments to form mesh like structures.

'Secondary treatment is sewage water treatment is called biological'. Justify.

What is the key difference between primary and secondary sewage treatment ?

While eating peach or pear it is usually seen that some stone like structures get entangled in the teeth, what are these stone like structures called?

Read the following passage and answer the questions given. The production and improper disposal of waste are causes for a great deal of environmental pollution. Many toxic industrial wastes from manufacturing process require treatment and /or safe disposal. When materials are recycled, apart from saving on the coast of raw material, waste disposal coast are reduced. Some combustible materials like dried leaves etc can be burnt to get heat energy. Sewage treatment includes filtering, scudge settlement, degradation coagulation disinfection using chlorine etc. Certain microorganisms can degrade waste in the absence of oxygen-digestion. Sewage water is purified by: light, Fishes, Microorganisms, Aquatic plants