BY HARDOLPH WASTENEYS. 
129 
APPENDIX VIII. 
MONTHLY AVERAGES OF PER CENTAGE REDUCTION IN ORGANIC 
MATTER, COLOUR AND BACTERIA, EFFECTED 
BY PLAIN SAND FILTRATION. 
1905. 
(1904) 
December 
(start) 
(1905) 
January 
February 
March 
April 
May 
June 
July 
Average from, 
23/12/04 to 
12/7/05 
‘Temperature. 
| 
Effluent. 
| 
aks Oxygen Con- Colour. a 
oa,2| Ammonia. sumed at (Lovibond = ~ 
a8 90deg. Fahr. Scale.) o_s 
BSc : 5 o oes 
— oS a eS 
Bee Si wea) PE eos 
sae) ¢ | Seg | 6 gee 
efo| & | | #| 2] @ |] s 388 
eas 2 ~ tal 3 < 
ass = 3 
2.1 | 100 | 31.8) 23.8 | 26.2 | nil nil 
2.0| 71 | 48.8|26.1136.3| 71.5] 48.1 
1.9 | 76.7] 58.8 | 34.5 | 40.2 | 98.2) 65.9 99.1 
2.0 | 11.7] 57.0 | 38.4 | 38.7 | 55.9] 33.2 | 96.0 
2.1 | 82.8] 42.7 | 41.2 | 37.2 |/100.0} 61.1 
2.4°| 75.3} 51.4 | 30.7 | 30.0 | 88.7] 67.4 98.2 
2.1 | 97.6] 44.5 | 30.0 | 18.4 | 85.7) 69.7 | 96.0 
2.3 |100.0) 57.8 | 31.6 | 32.7 | 92.0 67.0 99.0 
2.0 | 66.0 | 51.2 | 33.0 | 35.2 | 77.8 | 52.7 | 98.5 
APPENDIX IX. 
AVERAGE PER CENTAGE REDUCTION IN ORGANIC MATTER, 
COLOUR AND BACTERIA, EFFECTED BY THE VARIOUS TYPES 
OF FILTERS USED IN CONNECTION WITH THE EXPERIMENTAL 
PURIFICATION OF THE LAGOON WATER. 
Type of Filter. 
Morry Filter (sand & gravel) 
Plain Sand Filter 
Sand and Ashes 
Machine Filter (Coagulants 
used) 
Combination of Morry Fil- 
ter and Plain Sand Filter 
Intermittent Plain Sand 
Filter 
Period for which 
average reduction 
is calculated. 
Sans 
6 |% 
183 
bo 
—_ (o2) —_ 
-~I =) lad 
oS 
to 
gas Average Percentage of Reduction. 
1 Se Oxygen. | etn. 
£28 ne ‘Consumed. sobs Pes 
eax 34 a | | Lovibond Rope 
w Mei so | 2 “% | Tintometer| ~5 0 
oso| €§ I il | aaa epee |iecscrt 
o.o & z FI & 3° | . oe = apes 
@a8) S| sele se Bol si / sees 
ass) < ca ial Meh oc 2 4 
2.1} 54| 40] 39{ 93 | 67 | 91.8 
2.0) 53 | 33 | 36 | 93 66 | 98.5 
2.1] 53.5 | 40 | 39 | 97 | 70 peas 
104.0] 766.| 57, | 40) b=) 
| 
2.2) 59 | 35 | 42 | 100 | 68 | 97.3 
2.1 58 | 43 | 43 | 997 66 | 74.2 
