A sludge drying bed comprising: (a) a front wall, a back wall and two side walls; (b) a floor which slopes downwards from the back wall to the front wall along the longitudinal axis of the bed and inwards from each of the side walls to a trough line centred along said longitudinal axis of the sludge drying bed, (c) an openable roof comprising of a breathable, waterproof, black membrane cover fixed in two pitched frames each frame sloping downwards towards the side walls or sloping towards the front and back wall, (d) means for introducing sludge into the sludge drying bed, comprising of valve controlled inlet pipe, (e) means for allowing the discharge of water from the sludge comprising a sluice door located in the front wall of the sludge drying bed, having three sluice door plates and slots for said sluice door plates which comprise one solid blanking plate and the remaining two interchangeable drainage plates each containing ten horizontal slots; wherein the sluice door can be in a closed position by using the solid blanking plate when filling the sludge drying bed and settling the sludge, and the solid blanking plate can be slided up in the vertical direction, therefore removing it from the sluice door, so that the decanted water can be released from the sludge, the water being released through the horizontal slots in the drainage plate which is positioned directly behind the slot of the removed solid blanking plate wherein the first drainage plate can be at certain intervals replaced with the second drainage plate to allow the release of water from multiple levels of the sludge contained in the sludge drying bed; and (f) a sump in the floor of the sludge drying bed to the front of the sluice door. (a) a front wall, a back wall and two side walls; (b) a floor which slopes downwards from the back wall to the front wall along the longitudinal axis of the bed and inwards from each of the side walls to a trough line centred along said longitudinal axis of the sludge drying bed, (c) an openable roof comprising of a breathable, waterproof, black membrane cover fixed in two pitched frames each frame sloping downwards towards the side walls or sloping towards the front and back wall, (d) means for introducing sludge into the sludge drying bed, comprising of valve controlled inlet pipe, (e) means for allowing the discharge of water from the sludge comprising a sluice door located in the front wall of the sludge drying bed, having three sluice door plates and slots for said sluice door plates which comprise one solid blanking plate and the remaining two interchangeable drainage plates each containing ten horizontal slots; wherein the sluice door can be in a closed position by using the solid blanking plate when filling the sludge drying bed and settling the sludge, and the solid blanking plate can be slided up in the vertical direction, therefore removing it from the sluice door, so that the decanted water can be released from the sludge, the water being released through the horizontal slots in the drainage plate which is positioned directly behind the slot of the removed solid blanking plate wherein the first drainage plate can be at certain intervals replaced with the second drainage plate to allow the release of water from multiple levels of the sludge contained in the sludge drying bed; and (f) a sump in the floor of the sludge drying bed to the front of the sluice door.