Abstract: A method utilizing the phenomenon of plug flow for removing solids from liquid. Liquid with suspended solids, such as paper mill effluent, is passed through a conduit under conditions of plug flow. This produces a moving plug containing the suspended particles, with the liquid along the wall of the conduit being relatively free of suspended particles. The wall is made liquid permeable, and liquid is forced through the wall as the liquid moves along the conduit. Preferably the wall is made relatively impermeable to a substantial portion of the suspended solids to assure that relatively pure liquid flows through the wall, leaving the solids concentrated in the remaining liquid flowing through the conduit. Liquid with concentrated solids is recirculated.

Abstract: An improved mold construction is disclosed which is particularly useful in the manufacture of molded pulp products. The mold construction includes a rigid foraminous base member shaped to define the desired product, and a support frame having a first groove adapted to receive the marginal edge of the base member and a second groove which releasably receives a retainer member. The frame support is manipulatable to allow insertion and removal of the marginal edge of the base member into and from the first groove when the retainer member is removed from the second groove, but may not be so manipulated when the retainer member is inserted within the second groove. In one embodiment, the retainer member is separable from the support frame, while in an alternative embodiment the retainer member is formed integral with the support frame.

Abstract: A method and apparatus are disclosed for making a molded pulp product such as a plate or the like which has an upper liquid impervious layer integrally secured thereon. The pulp product is formed on a foraminous mold and, together with the mold, is heated to the softening temperature of a liquid impervious thermoplastic sheet material which is caused to be cut to size by engagement with a cutting edge on the mold whereafter the severed portion is drawn by suction and bonded to a selected surface area of the pulp product.