Ключевые слова: 3d, blue, city, clean, color, colorful, construction, dirty, drain, drainage, drop, ecology, environment, environmental, factory, flow, flowing, green, icon, illustration, industrial, industry, isolated, liquid, minimal, minimalism, nature, pipe, pipeline, plant, pollution, purification, purity, recycle, recycling, render, rendering, river, sewage, sign, sludge, symbol, system, tank, toxic, treatment, tube, waste, wastewater, water,