Ключевые слова: aerated, bacterium, big, biology, biomass, circle, clean, dirty, ecology, engineering, environmental, excremental, factory, garbage, global, industrial, industry, natural, outside, pipe, plant, pollute, pollution, processing, protection, purification, purified, purity, recycle, recycling, reduce, reflection, sedimentation, settling, sewage, sludge, smell, treatment, unhygienic, view, waste, wastewater, water,