From a consideration of the work of Raschig and Rideal, it appeared that the most efficient proportions of available chlorine and ammonia would be two parts by weight of the former to one part of the latter and this ratio was maintained during the run on the experimental plant. Lower ratios of chlorine to ammonia were contra-indicated by the laboratory experiments, which showed that the efficiency was not increased thereby whilst higher ratios were left for future consideration.
The results obtained on the experimental plant, together with those obtained on the main plant, where 24 million gallons per day were treated with bleach only, are given in Tables XXVI, XXVII and XXVIII. The two periods given represent the spring flood condition and that immediately preceding it; these are respectively the worst and best water periods. The results in both cases are from samples examined approximately two hours after the application of the chemicals.
The cost data were calculated on the current New York prices of bleach and ammonia.
TABLE XXVI.--COMPARISON OF HYPOCHLORITE AND CHLORAMINE TREATMENT
-----+------------------+----------------------+---------------------------- | RAW WATER. | TREATED WITH HYPO- | TREATED WITH HYPOCHLORITE | | CHLORITE ALONE. | AND AMMONIA. +------------+-----+-----------+-----+----+------------+-----+----+---- 1916 | Bacteria | | Bacteria | | | Bacteria | | | | per cubic | | per cubic | | | per cubic | | | |centimeter. | _B. |centimeter.| _B. | |centimeter. | _B. | | +-----+------+coli_+-----+-----+coli_| +------------+coli_| | |Agar | Agar |Index|Agar |Agar |Index| (1)|Agar |Agar |Index| (1)| (2) | 1 | 3 | per | 1 | 3 | per | | 1 | 3 | per | | | day | days | 100 | day |days | 100 | | day | days | 100 | | | at | at | cc. | at | at | cc. | | at | at | cc. | | | 37° | 20° | | 37° | 20° | | | 37° | 20° | | | | C. | C. | | C. | C. | | | C. | C. | | | -----+-----+------+-----+-----+-----+-----+----+-----+------+-----+----+---- Mar. | 44| 238| 35.7| 4 | 12 |<0.14|0.90| 4 | 12 |0.14 |0.22|0.11 15-31| | | | | | | | | | | | April|3,099|14,408|195.5| 32 | 56 | 0.50|1.10| 33 |246 |0.74 |0.25|0.13 1-19 | | | | | | | | | | | | -----+-----+------+-----+-----+-----+-----+----+-----+------+-----+----+---- Legend: (1) Available chlorine parts per million. (2) Ammonia, parts per million.