Ключевые слова: chemical, clean, conduit, danger, dirt, dirty, ecology, environment, environmental, factory, flow, garbage, ground, industrial, industry, natural, nature, pipe, plant, pollute, polluted, polluting, pollution, reflection, river, sanitary, sedimentation, sewage, sewer, sludge, smell, stream, toxic, trash, treatment, unhygienic, waste, wastewater, water,