NOVELTY - Processing heavy metal-containing sewage involves taking sludge, washing surface layer with salt water, gravitationally settling, culturing for 30 days using culture medium including 250 mg/L sodium nitrate, 50 mg/L zinc sulfate, 50 mg/L magnesium sulfate heptahydrate, 1250 mg/L vitamin B and 100 mg/L sucrose with change of culture medium every 3 days to obtain greater than or equal to 90% purity phototactic bacteria enriched liquid, mixing with deionized water to obtain phototactic bacteria aqueous solution, mixing with heavy metal-containing sewage, standing for greater than or equal to 72 hours, irradiating for 24 hours and filtering.    USE - Method for processing heavy metal-containing sewage used for preparing cement or tiles (claimed).    ADVANTAGE - The method is simple and pollution-free, and has greater than 90% heavy metal removal efficiency.    DETAILED DESCRIPTION - Processing heavy metal-containing sewage comprises taking sludge, washing surface layer with salt water, gravitationally settling, culturing for 30 days using culture medium comprising 250 mg/L sodium nitrate, 200 mg/L sodium acetate, 1000 mg/L monosodium succinate, 50 mg/L zinc sulfate, 50 mg/L manganous sulfate, 50 mg/L magnesium sulfate heptahydrate, 1250 mg/L vitamin B and 100 mg/L sucrose with change of culture medium every 3 days to obtain greater than or equal to 90% purity phototactic bacteria enriched liquid, mixing with deionized water to obtain phototactic bacteria aqueous solution, mixing with heavy metal-containing sewage, standing for greater than or equal to 72 hours, irradiating for 24 hours, filtering, checking quality of clear liquid before discharging and evaporating turbid liquid at 60-80 degrees C until moisture content is less than 5% to obtain sewage treatment by-product. An INDEPENDENT CLAIM is included for preparation of tiles comprising taking kaolin, bentonite and palygorskite at weight ratio of 1:3:2 to obtain mixed clay, mixing with water until solids content is 30%, removing ferromagnetic impurities, mixing with sodium hydroxide or potassium hydroxide, placing in graphite crucible, heating at 110 degrees C for 2 hours, washing with distilled water until neutralized, drying, calcining at 300 degrees C for 30 minutes, crushing into 240-mesh to obtain modified clay, mixing 1-3 pts. wt. sewage treatment by-product/sandstone, 4 pts. wt. dolomite, 1.5 pts. wt. calcium fly ash, 12 pts. wt. apatite, 8 pts. wt. asbestos, 0.8 pt. wt. colemanite, 30 pts. wt. quartz sand, 4 pts. wt. nanosilicon carbide fiber, 10 pts. wt. crushed egg shell, 15pts. wt. starch, 15 pts. wt. tourmaline, 0.5 pt. wt. nanotitania and 20 pts. wt. modified clay, adding plasticizer and binder, stirring uniformly, compression molding into 2 mm particle diameter at 80 MPa, primary drying at 1350 degrees C with 15 degrees C/minute heating rate for 2 hours, secondary drying at 880 degrees C with 5 degrees C/minute heating rate for 2 hours, tertiary drying at 510 degrees C with 4 degrees C/minute heating rate for 1 hour, quaternary drying at 1160 degrees C with 8 degrees C/minute heating rate for 2.5 hours, quinary drying at 680 degrees C with 5 degrees C/minute heating rate for 1.5 hours until moisture content is 1.5%, cooling, edge grinding and packaging. Weight ratio of mixed clay and sodium hydroxide or potassium hydroxide is 1:1.