298 



The Country Gentlcmaiis Magazine 



and 1869 injunctions were granted by 

 the Court of Chancery to prevent the 

 Local Board of Merthyr Tydfil from discharg- 

 ing the sewage of that town into the river Taff, 

 and in 1870 the Board purchased 70 or 80 acres 

 of land below the village of Troedyrhiw, of 

 which about 20 acres have been converted into 

 a filter on the plan suggested by the Commis- 

 sioners. The soil consists of a deep bed of 

 gravel (probably the former river bed of the 

 Taff, which is embanked on the east side and 

 raised above the valley) composed of rounded 

 pebble of the old red sandstone and coal 

 measure formations interspersed with some loam 

 and beds of sand, forming an extremely porous 

 subsoil with a vegetable mould upon the surface. 

 The land has been pipe-drained at a depth of 7 

 feet, and the pipes are concentrated at the lowest 

 corner, where the effluent water is discharged 

 into an open drain which leads to the river 

 Taff, at some distance down the valley. 

 The area is laid out in square beds, 

 intersected by roads and paths, along which 

 are constructed the main carriers which re- 

 ceive the sewage from the outfall sewer and 

 distribute it over the beds. The sewage before 

 entering the farm is screened through a bed of 

 slag which arrests the coarser matters. The 

 system which is adopted in applying the sewage 

 is called the intermittent — that is, the land 

 being divided into four portions, the sewage is 

 turned on to each in succession of six hours at 

 a. time, leaving an interval of eighteen hours for 

 rest and aeration of the soil. The surface of 

 land was cultivated to a depth of from 16 to 18 

 inches, and was laid up in ridges in order that 

 the sewage might run down the furrows, while 

 the ridges were planted with cabbages and 

 •other vegetables. The sewage was originally 

 received from Merthyr Tydfil in a very diluted 

 condition ; and this dilution was increased by 

 percolation of water from the river, so that the 

 quantity of effluent water was nearly double that 

 of the sewage supplied. The average quantity 

 of the latter was about 900,000 gallons/^r diein. 



The Committee paid both a summer and a 

 winter visit to the farm, and completed a variety 

 of analyses. They declare the general result of 

 the process to be that suspended matters are 

 removed, and that the ammonia and nitrogenous 

 organic matters held in solution are almost 

 completely oxidized, so that they escape in the 

 effluent water as nitrates and nitrates. The 

 sewage is therefore satisfactorily purified, but 

 the process cannot be looked upon as one of 

 utilization. 



In Section 5 were given the results of the 

 continued observation of the application of 

 sewage to Breton's Farm, at Romford ; and 

 during the last year the Committee have added 

 to the data formerly ascertained particulars of 

 the crops grown on the farm during the twelve 

 months from March 25, 1871, to March 24, 1872. 

 To make this inquiry more complete, and of 

 greater practical utility, the Committee made an 

 alteration in the form of the analysis of the 

 sewage and affluent water, so as to determine 

 the total nitrogen. The facts were expressed 

 in six tables, which it would be impossible here 

 to reproduce ; but the result to be deduced from 

 the grand totals is that of every 100 parts of 

 nitrogen distributed over the farm during the 

 year, 10.09 parts were found in the effluent 

 water, 39.50 parts were recovered in the crops, 

 and 50.41 parts (or in round numbers one half) 

 were unaccounted for. Of this half the greater 

 part must have remained in the soil ; and as 

 the average composition of the soil previously 

 to the application of the sewage was deter- 

 mined by the Committee, it is their intention to 

 determine also the proportion of this missing 

 nitrogen which does actually remain in the soil 

 at various depths. The two main facts at pre- 

 sent ascertained at Breton's Farm are, that only 

 10 per cent, of the total nitrogen applied to the 

 land escaped in the effluent water (of which 10 

 per cent., only a fractional quantity, is in an or- 

 ganic form), and that 40 per cent, was recovered 

 in the crops grown. 



