Bench-Scale Evaluation of Hydrothermal Processing Technology for Conversion of Wastewater Solids to Fuels.

Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of hydrothermal treatment for handling municipal wastewater sludge. HTL tests were conducted at 300 to 350 °C and 20 MPa on three different feeds: primary sludge, secondary sludge, and digested solids. Corresponding CHG tests were conducted at 350 °C and 20 MPa on the HTL aqueous phase output using a ruthenium-based catalyst. Biocrude yields ranged from 25 to 37%. Biocrude composition and quality were comparable to biocrudes generated from algae feeds. Subsequent hydrotreating of biocrude resulted in a product with comparable physical and chemical properties to crude oil. CHG product gas methane yields on a carbon basis ranged from 47 to 64%. Siloxane concentrations in the CHG product gas were below engine limits. The HTL-CHG process resulted in a chemical oxygen demand (COD) reduction of > 99.9% and a reduction in residual solids for disposal of 94 to 99%.

Laparoscopic cholecystectomy: an initial community experience.

The initial 950 consecutive laparoscopic cholecystectomies performed in one city at four hospitals by 30 general surgeons are reported, covering a period from April 4, 1990 to April 3, 1991. There were two operative deaths (0.2%), three common bile duct lacerations (0.3%), two subhepatic abscesses, two bowel perforations, and three bile leaks, two requiring laparotomy. Seven episodes of bleeding occurred, of which five required laparotomy, but none involved a major vessel. Sixty-five procedures were converted to open (6.7%). The mean operative time was 85.4 min. Intraoperative cholangiography was adequately completed in 49.8% and not attempted in 30.3%. Thirteen patients (2.7%) were found to have common duct stones. The pathologic diagnoses were chronic cholecystitis in 784 patients (82.5%), acute cholecystitis in 145 (15.3%), and cancer of the gallbladder in one (0.1%). Hospital stays ranged from 4 h to 31 days (mean 49.5 h). This procedure can be learned and performed safely in a community setting.