The Lake Tahoe Water Reclamation Plant

Tertiary treatment of wastewater at Lake Tahoe consists of coagulation and filtration of secondary effluent through separation beds and adsorption of remaining organics on activated carbon. Separation bed medium is hydraulically graded from coarse at top to fine at bottom. Carbon from the countercurrent column operation is regenerated thermally. Early operating results show plant effluent biochemical oxygen demand less than 1 mg/l, chemical oxygen demand 3-16 mg/l, suspended solids less than 0.5 mg/l, phosphates 0.1-1.0 mg/l, coliforms less than 2.2/100 ml, and odor undetectable. Fixed costs are $46/mil gal (1.2¢/cu m) and operating costs $98/mil gal (2.6¢/cu m).