Direct dosage of reactivated carbon from waterworks into the activated sludge tank for removal of organic micropollutants.

The thermal reactivation of granular activated carbon is a substantial ecological and economic benefit in the process of drinking water treatment. A significant amount of abraded carbon, which is similar to powdered activated carbon (PAC), is produced that can be brought to application at wastewater treatment plant level for the removal of micropollutants in a powdered activated carbon-activated sludge (PAC-AS) system. This excess carbon derived as a by-product from the reactivation process in a waterworks was applied directly into the activated sludge tank and has been elevated in this study by monitoring the removal efficiencies for benzotriazole, carbamazepine, diclofenac, metoprolol and sulfamethoxazole in the effluent of a semi-technical wastewater treatment plant of 39 m3. A simulation-derived sampling strategy was applied to optimize the recovery rates of the micropollutants. Flow-proportional, 72-hour composite sampling was considered best. The elimination rates obtained for a 10 g PAC·m-3 dosage were 73% for benzotriazole, 59% for carbamazepine, 60% for diclofenac, 67% for metoprolol and 48% for sulfamethoxazole. The obtained results underline the importance of appropriate sampling strategies, which can be derived from hydraulic modeling.

Symptomatic arachnoid cyst at the clivus drained stereotactically through the vertex.

A 40-year-old man had an acute ischemic event affecting the pons. He had no cardiac illness or vasculities and was not diabetic or hypertensive. The contrast-enhanced computed tomographic scan disclosed nothing abnormal, and a vertebral angiogram showed an avascular mass markedly displacing the basilar artery and pons posteriorly and toward the right. A magnetic resonance image clearly delineated a homogeneous arachnoid cyst containing cerebrospinal fluid. To avoid manipulating posterior fossa arteries, after the recent pontine stroke, this arachnoid cyst with unusually favorable anatomical landmarks was approached stereotactically through the vertex. Fenestration and drainage of the cyst was accomplished under local anesthesia and benzodiazepine sedation with low morbidity. The procedure was well tolerated, and the patient returned to gainful employment shortly afterward. He remains asymptomatic at 3 years' follow-up. The successful outcome of this case suggests that in carefully selected symptomatic arachnoid cysts, stereotactic interventions could become a useful surgical alternative. Stereotaxis may also be helpful in other cumbersome surgical cases in which a second port for contrast injection or simple manipulation would be advantageous.