Removal of EDTA from low pH printed-circuit board wastewater in a fluidized zero valent iron reactor

Fluidized zero valent iron (ZVI) process was adopted to reduce ethylenediaminetetraacetic acid (EDTA) from low pH printed-circuit board (PCB) wastewater for two reasons: (1) low pH of the wastewater favoring the ZVI reaction; (2) higher ZVI utilization for fluidized process due to abrasive motion of the ZVI. The results showed that the degradation of EDTA was greatly enhanced under acidic pH, longer hydraulic detention time (HRT) and presence of dissolved oxygen (DO). Without addition of oxygen, 65% of EDTA was removed with capacity of 7.33 mg EDTA/g ZVI at pH 2, ZVI dosage of 424 g/L and HRT 10 min. With 6.8 mg/L of DO, 83% of EDTA was reduced with capacity of 19.01 mg EDTA/g ZVI for the same experimental condition. The presence of oxygen/ZVI initiated a Fenton type reaction to reduce EDTA. The end product after EDTA degradation was analyzed by high performance liquid chromoagraphy (HPLC), where propionic acid (C(2)H(5)COOH) was observed, indicating EDTA (oxidation number for carbon is 2) was oxidized to propionic acid (oxidation number for carbon is 3). Nitrogen species was also measured and the nitrogen in EDTA was converted to ammonium instead of nitrate and nitrite.

Coonrad-Morrey total elbow arthroplasty for tumours of the distal humerus and elbow

We reviewed 20 patients who had undergone a Coonrad-Morrey total elbow arthroplasty after resection of a primary or metastatic tumour from the elbow or distal humerus between 1980 and 2002. Eighteen patients underwent reconstruction for palliative treatment with restoration of function after intralesional surgery and two after excision of a primary bone tumour. The mean follow-up was 30 months (1 to 192).

Five patients (25%) were alive at the final follow-up; 14 (70%) had died of their disease and one of unrelated causes. Local control was achieved in 15 patients (75%). The mean Mayo Elbow Performance Score improved from 22 (5 to 45) to 75 points (55 to 95). Four reconstructions (20%) failed and required revision. Seven patients (35%) had early complications, the most frequent being nerve injury (25%). There were no infections or wound complications although 18 patients (90%) had radiotherapy, chemotherapy or both.

The Coonrad-Morrey total elbow arthroplasty provides good relief from pain and a good functional outcome after resection of tumours of the elbow. The rates of complications involving local recurrence of tumour (25%) and nerve injury (25%) are of concern.