Identification of potential sewer mining locations: a Monte-Carlo based approach.

Rapid urbanization affecting demand patterns, coupled with potential water shortages due to supply side impacts of climatic changes, has led to the emergence of new technologies for water and wastewater reuse. Sewer mining (SM) is a novel decentralized option that could potentially provide non-potable water for urban uses, including for example the irrigation of urban green spaces, providing a mid-scale solution to effective wastewater reuse. SM is based on extracting wastewater from local sewers and treatment at the point of demand and entails in some cases the return of treatment residuals back to the sewer system. Several challenges are currently in the way of such applications in Europe, including public perception, inadequate regulatory frameworks and engineering issues. In this paper we consider some of these engineering challenges, looking at the sewer network as a system where multiple physical, biological and chemical processes take place. We argue that prior to implementing SM, the dynamics of the sewer system should be investigated in order to identify optimum ways of deploying SM without endangering the reliability of the system. Specifically, both wastewater extraction and sludge return could result in altering the biochemical process of the network, thus unintentionally leading to degradation of the sewer infrastructure. We propose a novel Monte-Carlo based method that takes into account both spatial properties and water demand characteristics of a given area of SM deployment while simultaneously accounting for the variability of sewer network dynamics in order to identify potential locations for SM implementation. The outcomes of this study suggest that the method can provide rational results and useful guidelines for upscale SM technologies at a city level.

Is preservation of the adrenal vein mandatory in laparoscopic adrenal-sparing surgery?

BACKGROUND AND OBJECTIVE: Adrenal tissue-sparing or partial adrenalectomy evolved initially for patients with bilateral synchronous adrenal surgical pathology to preserve vital adrenal volume. In the laparoscopic era, the exact criteria for performing such procedures laparoscopically have yet to be defined. Controversy exists regarding the importance of preserving the adrenal vein, main or accessory. The aim of this retrospective study was to present our short series of laparoscopic tissue-sparing adrenalectomies with vein preservation. Our main goal is not to support partial adrenalectomy as an alternative to total (this is already advocated by many surgeons) but to emphasize the vein-preserving technique. METHODS: Seven patients with peripherally located either aldosterone-producing adenomas (4 cases) or myelolipomas (4 cases) underwent laparoscopic lateral partial adrenalectomy. One patient harbored an aldosterone-producing adenoma and a myelolipoma as well. The main adrenal vein was identified and preserved in 6 patients and the accessory vein in one. RESULTS: No conversion to open adrenalectomy was necessary, and no perioperative morbidity or mortality occurred. Three adenoma patients are normotensive 44, 23, and 20 months postoperatively, while the fourth one's pressure is refractory. CONCLUSIONS: Surprisingly, total adrenalectomies preceded the partial ones, which is controversial compared with other procedures. Laparoscopic lateral partial adrenalectomy is a technically challenging tissue-sparing operation. Meticulous dissection allows preservation of the middle artery and main or accessory vein resulting in a functioning adrenal stump.

Feasibility of laparoscopic adrenalectomy for large pheochromocytomas.

BACKGROUND AND OBJECTIVES: The majority of surgeons consider large and potentially malignant pheochromocytomas an absolute contraindication for laparoscopic adrenalectomy (LA). The aim of this study was to evaluate the risks and outcomes of LA in patients with this anomaly. METHODS: Five patients (2 males, 3 females) with large (>6 cm) pheochromocytomas were selected. Preoperative investigation demonstrated no evidence of invasive carcinoma. All patients received alpha-blocker preparation for at least 20 days. Laparoscopic adrenalectomy via a lateral transperitoneal approach was performed in all cases. RESULTS: Patient's median age was 48 years, and the median tumor size was 10.8 cm. No capsular disruption and no hypertensive crises occurred during the operation. The median operating time was 148 minutes and blood loss was <150 mL. Conversion to open adrenalectomy occurred in 2 patients owing to intraoperative evidence of carcinoma. No postoperative morbidity or mortality occurred. All patients are disease free after a median follow-up of 13 months. CONCLUSIONS: In experienced hands, LA can be proposed for large and potentially malignant pheochromocytomas. Conversion to open adrenalectomy is mandatory if local invasion, capsular disruption, or technical difficulties are observed during the operation.