1 usage of water, 4 reasons for water contamination
You already finished the chapters about usage and application of water and about treatment of fresh water. Now, it comes to the focus on waste water. This topic deals with the question: How does it come to waste water load?
Detergents cause waste water load. This assertion is
right. Detergents contain surfactants, chlorine and phosphate. Phosphate leads to eutrophication of waters.
wrong. They remove the soil and have no further effect.
wrong. Due to reaction with soil the detegent will be exhausted and won`t occur in the waste water.
Soil from laundry causes waste water load. This assertion is
wrong. Soil is something which is "biological" and never harmful to the environment.
right. Soil, especially from work wear and mats, can contain mineral oils and heavy metals.
wrong
Fresh water might contain contaminants. This assertion is
right. E.g. river water contains microbial contaminants and/or sand.
wrong
Right. Steam may contain heavy metals.
Another origin for contaminations in washing process is steam. This assertion is
right. Steam may contain heavy metals
wrong. Steam is lighter than water, that is why contaminants always remain in physically heavier water.
wrong
AOX-formation is a problem caused by washing powder only. This assertion is
wrong. AOX-formation is caused by the reaction of organic compounds with chlorine id chlorine is applied as bleaching agent in the washing process.
right. That is, washing powder containing enzymes will react with the soil of the laundry and accumulate AOX