Ключевые слова: above, aerial, background, biology, bird, circle, city, cityscape, clean, cleaning, construction, dirty, down, drone, ecology, environment, environmental, europe, eye, facility, factory, flow, green, industrial, industry, management, plant, pollution, purification, purified, purity, recycle, recycling, river, sewage, sewer, sludge, storage, system, tank, technology, texture, top, treatment, urban, view, waste, wastewater, water, winter,