Some sentences are wrong , I think you should correct it again like in single stack system you said human or animal excreta don't go from that pipe then from where it will go; you should explain that also otherwise it creates confusion. I have some information about this topic so I understood where you were wrong but for new person it will be a problem, he or she will learn wrong thing . But still thank you I learnt some new things also.
Madam we can or shall use additional pipes for collecting rheo plastic and gases separately..and safety warning against accumulation or retaining of stale and septic or infectious waste anywhere..
