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refractory effluents | |||
difficult-to-treat effluents; difficult-to-treat sewage (напр., из-за высокой концентрации и имеющихся загрязнений или специфических примесей); hard-to-treat effluents; stubborn effluents | |||
stubborn sewage | |||
difficult sewage; refractory effluent | |||
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difficult sewage |