Two in-series UV reactors are disinfecting water for a small system (not potable use). The microorganism of concern is Ecoli dispersing to the water source from a close-by composite facility. Due to the seasonal fluctuation in the number of residences, the water demand for the treatment fluctuates. To make sure that these two UV reactors are capable of treating water all the time, the water flow rate and concentration of Ecoli were monitored for a full year (the results are presented in the table below). A. Determine whether this system can provide at least 3 log reduction of target microorganism through the year. B. In order to increase the performance and reliability of the system, a consulting company suggested rearranging these two UV reactors to parallel mode for the month of June and July. Evaluate this suggestion by comparing the total log reduction of the system for in-series and parallel UV reactor configurations. C. For the risk assessment of this system, assume 10% failure for each UV reactor. When the UV reactor fails, it provides 1/3 of its normal log inactivation. Calculate the probable number of days in June and July that the system fails the compliance for both in-series and parallel configuration. *Assume constant influent background water quality for UV reactors through the year. *N0, N1, and N2 are the target microorganism concentration 

Date	No - CFU/ml	N1 - CFU/ml	N2 - CFU/ml	Q (L/min)
January	30,000,000.00	5954	1	130
February	30,000,000.00	5954	1	130
March	30,000,000.00	3285	0	110
April	30,000,000.00	35462	42	190
May	30,000,000.00	86531	250	220
June	30,000,000.00	934052	29082	300
July	30,000,000.00	934052	29082	300
August	30,000,000.00	116499	452	230
September	30,000,000.00	86531	250	220
October	30,000,000.00	10792	4	150
November	30,000,000.00	8016	2	140
December	30,000,000.00	19562	13	170