Ключевые слова: above, aerial, background, circle, city, clean, construction, dirty, down, drone, ecology, environment, environmental, factory, fly, green, industrial, industry, outdoors, over, plant, pollution, processing, purification, purified, purity, recycle, recycled, recycling, sewage, sewer, sha tin, sludge, storage, tank, technology, top, top down, treatment, view, waste, wastewater, water,