November 19, 1914:  Operation of Sewage Disposal Plants. By Francis E. Daniels. "A man in charge of a sewage disposal plant should know what each unit of his works is doing every day. A skilled observer may detect faults and short-comings with some degree of certainty by mere inspection; and if the output is bad and a heavy pollution is occurring or a local nuisance is resulting, it is not at all difficult to recognize the trouble. If the break-down has been sudden and due to a wash-out, a broken bed or wall or some other equally obvious cause, an expert is not needed to diagnose the case. But suppose the output of a plant or of some of its units is gradually falling below the requirements. In that case the gradual decline cannot be detected by observation and in order that one may know what is actually happening, tests are made....Careful attention paid to tank effluents will delay for years the expenditure of thousands of dollars for the removal, washing and replacing of the stone in contact beds. Poor effluents discharged upon sand beds cause clogging quickly, which results in undue expense for frequent cleaning and often the sand filter effluent is seriously impaired.   more