Abstract: To reduce the accumulation of undesirable solid material within an anaerobic digester, new slurry for digesting is injected into the digester at locations extending across the horizontal width at one end, parallel to a zone of floating solids in a concentration of solid material between ten and twelve percent, with a momentum of at least 0.1 pound-foot per second. Liquid is taken out of the digester across a trough extending across the width of the digester. Bubbles are broken above the liquid level of the digester by a sieve or surfactant or combination of the two.