55. Container of claim 53, wherein the inwards-facing surfaces of the pipe-side-walls are smooth and uninterrupted lengthwise of the treatment-trough, whereby substantially no pockets of water can collect, and be retained.
56 . Container of claim 53 , wherein: the container includes an inlet chamber, which contains the inlet-port; the treatment-pipe is sealingly attached to the inlet chamber, and is in liquid-transfer-communication therewith. 57 . Container of claim 56 , wherein the inlet chamber includes a deposition-sump, which is so arranged, as to its depth and location in the inlet chamber, that a portion of the water comprising the minimum-standing-body and residing in the inlet chamber remains still enough to enable sediment present In the water to settle out into the deposition-sump.
58 . Container of claim 53 , wherein: the container includes an outlet chamber, and the outlet chamber contains the outlet-port; the treatment-pipe is sealingly attached to the outlet- chamber, and is in liquid-transfer-communication therewith.
59 . Container of claim 53 , wherein the treatment-troughs comprise two treatment-pipes, and the container includes a middle chamber, sealingly connected between the two treatment-pipes.
60 . Container of claim 38 , wherein the treatment-pipe includes a body of a filter medium, which is so structured as to promote the attachment of microbes thereto.
61 . Container of claim 3 8 , wherein: the arrangement of the container is such that the waste- water remains in the container, on an average flow basis, for at least half a day.
62 . The com bination of a container o f claim 61 with a dwelling having N bedrooms, wherein the volume of the minimum-standing-body of water retained in the container is N times 500 liters.
63 . Apparatus of claim 3 8 , wherein the wastewater co m prises sewage-water from a human habitation.
64 . Apparatus o f claim 63 , wherein the apparatus is so sized and arranged as to be suitable for treating the sewage effluent from a single domestic dwelling, or from a small number of domestic dwellings.