TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The method involves (a) pouring municipal sewage containing 80% of moisture into a spiral-ribbon pressurizing mixer, improving internal pressure to 1.5 MPa through vapor, heating the mixer until external temperature reaches to 180 degrees C and internal temperature reaches to 110 degrees C or more, adding the special treating solution to the mixture and agitating uniformly at 75 degrees C for 15 minutes to obtain gelatinous slurry, transferring the slurry into a sludge pump for first centrifugation, discharging the obtained upper wastewater into a heavy metal treatment tank, adding the special treating solution to the bottom slurry and agitating uniformly and centrifuging for second time, discharging the upper wastewater into the heavy metal treatment tank after the second centrifugation, adding the special treating solution to the obtained bottom slurry and centrifuging for third time, and starting the treatment for removing the heavy metal completely, (b)transferring the sludge obtained after three centrifugation into frame-plate presser or screw-type presser for squeezing, agitating the obtained slurry through a conveyer belt after moisture of the sludge reaches to 40%, inoculating the slurry with microorganism, and adding additives to the sludge, and agitating for uniformly distributing the microorganism into the sludge, (c), fermenting agitated sludge in a fermenting chamber at 50-60 degrees C for 6-10 days to obtain semi-finished organic fertilizer, (d) transferring the uniformly fermented sludge into a centrifuging granulator for granulating and pelleting in an abrator after the moisture of the sludge reaches to 25%, and spraying liquid bacteria during the granulating process, (e) cooling and packing the pellets to obtain finished product of organic fertilizer. The special treating solution is bacterium solution of Thiobacillus ferrooxidans or acid resistant Rhodotorula. The dosage of the bacteria is 10-15% of the sludge volume. The microorganism used for inoculating is engineered bacteria for treating sludge, and the dosage of the engineering bacteria is 1-2% of the sludge volume. The additive is chosen from pulverized coal ash or binder, and the dosage of the additive is 6-10% of the sludge volume. The liquid bacteria in step (d) are the bacteria in the special treating solution, and their dosage is 0.5-1% of the sludge volume. ACTIVITY - Fertilizer.