The water contains inorganic nutrients the bacteria need, and is perfused by streams of air bubbles which provide the CO2.

水中含有细菌所需的无机营养素，并被提供二氧化碳的气泡流所灌注。

But sewage is still rife with dangerous contaminants, including billions of pathogens and microorganisms, trace chemicals, and excess inorganic nutrients that can pollute rivers and lakes.

但污水中仍然充斥着危险的污染物，包括数十亿的病原体和微生物、微量化学物质和过量的无机营养物质，这些都可能污染河流和湖泊。