. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. was reduced from l40 mg/1 to 5 mg/1. The concentrations of both lime and alum were also reduced, with alum being effec- tive at about 20 mg/l and lime at 40 mg/l. The effect of iron added to the RGP in terms of reduction in required dosage for coagulation can also be seen in Figure 49. Al- though only 1 mg/l was added to the pond daily, the concen- tration of total iron in the pond tended to increase gradually. The growth studies indicated that as a necessary addition to the algal ponds iron will provide a dual benefit, Sh
. Removal of nitrate by an algal system. Water; Nitrates; Water; Algae. was reduced from l40 mg/1 to 5 mg/1. The concentrations of both lime and alum were also reduced, with alum being effec- tive at about 20 mg/l and lime at 40 mg/l. The effect of iron added to the RGP in terms of reduction in required dosage for coagulation can also be seen in Figure 49. Al- though only 1 mg/l was added to the pond daily, the concen- tration of total iron in the pond tended to increase gradually. The growth studies indicated that as a necessary addition to the algal ponds iron will provide a dual benefit, Shown in Table 12 is the effect of adding lime, alum, and iron on the cost of removing 90 percent of the algae from one million gallons of plant effluent. (This does not include the cost of the FeCl^ needed for algal growth.) Figures in the table show that the cost of these chemicals for separation of algae may be extremely low and that ferric sulfate was the cheapest of the primary floccu- lents tested. Additions of 1 to 5 mg/l of this compound would probably have little effect on the algae's potential market value. lOOn r--:^:==:&"-^' -A—--A. BEFORE FeCl3 ADDITION --- AFTER o LIME A ALUM a Feg (504)3 SAMPLE DATA BEFORE AFTER DATE .JAN. 9,| 11,1970 pH VOLATILE SOLIDS 175 265 mg/l TEMPERATURE 10* C I *0 80 120 i?0 CONCENTRATION OF COAGULANT (mg/l) 200 FIGURE 50-CONCENTRATIONS OF LIME, AUUM AND FERRIC SULPHATE REQUIRED FOR 90% ALGAE REMOVAL - BEFORE AND AFTER ADDITION OF FERRIC CHLORIDE TO RAPID GROWTH POND -82-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original California. Dept. of Water Resources; Brown, Randall L. Sacramento]; For sale by the Supt. of Docs. , U. S. Govt. Print. Off. , Washington
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Keywords: ., bookcentury1900, booksubje, booksubjectalgae, booksubjectnitrates
