Ключевые слова: aerial view, aerobic, agency, background, birds eye view, cesspit, cesspool, clean, crude, digestion, dirty, drinking, effluent, environment, filter, from above, high angle view, industrial, industry, looking down, odours, oxidation, plant, pump, pumping, purification, purify, purifying, quality, septic tank, sewage, sludge, station, surface, tanks, treatment, urban, waste, water, works,