AEROBIC TREATMENT OF METAL-CUTTING-FLUID WASTE-WATER

Two separate sets of aerobic treatment experiments were conducted using two-stage chemostats. The first set involved the aerobic treatment of effluent collected from the anaerobic reactor, which was treating a simulated metal-cutting-fluid wastewater (anaerobic/aerobic treatment), while the second set involved the straight aerobic treatment of the wastewater (straight aerobic treatment). Both anaerobic and aerobic experiments were conducted such that practically all biodegradable organics in either anaerobic or aerobic environment were degraded. Experimental results on the reduction of chemical oxygen demand (COD) indicated the following: (1) the anaerobic/aerobic treatment reduced the COD in the simulated wastewater by a total of 88%, 65% anaerobically, and 23% aerobically and (2) the straight aerobic treatment also reduced the COD in the simulated wastewater by 88%. Although both treatment schemes showed the same COD reduction, it is not known whether the organic compositions of the effluents are similar. Results also revealed that almost all of the organic nitrogen in the simulated wastewater was also degraded, indicating that nitrogen-containing organic compounds in the wastewater such as alkanolamines and amino acids were biodegradable either anaerobically or aerobically.