Ключевые слова: background, canal, chemical, city, construction, corrosion, danger, dirty, disaster, drain, drainage, dump, ecology, environment, environmental, flow, flowing, fluid, garbage, green, industrial, industry, influence, life, liquid, natural, nature, old, plant, polluting, pollution, pond, problem, production, river, rust, sewage, sewer, sewerage, stream, substance, system, technology, toxic, treatment, unhygienic, urban, waste, wastewater, water,