Energy and material refineries of future: Wastewater treatment plants.

There have been many important milestones on humanity's long journey towards achieving environmental sanitation. In particular, the development of the activated sludge system can be claimed to be one of the most groundbreaking advances in the protection of both public health and the wider ecosystem. The first wastewater treatment plants (WWTPs) were developed over a century ago and were soon configured for use with activated sludge. However, despite their long history and service, conventional activated sludge (CAS) plants have become an unsustainable method of wastewater treatment. In addition, conventional WWTPs are intensive energy-consumers and at best allow only very limited material recovery. A paradigm shift to convert existing WWTPs into more sustainable facilities must therefore be considered necessary and to this end the wastewater biorefinery (WWBR) concept may be considered a solution that maximizes both energy and material recovery, in line with the circular economy approach.

Comparative evaluation of cost for preliminary and tertiary municipal wastewater treatment plants in Istanbul.

As the global economy continues to grow, the need for an economic evaluation of wastewater treatment plants (WWTPs) is increasing. Determination of cost functions (CFs) helps to assess the costs of WWTP and to be able to reach to the satisfactory financial levels of construction and operation practices in the early phases of a project. In this study, unit capital and operation and maintenance (O&M) costs were calculated by analyzing the real capital and operation and maintenance expenditures of 16 full-scale WWTPs in Istanbul. Besides, the impacts of treatment level and capacity on costs were investigated. The unit total capital cost was found as 0.013 ± 0.004 €/m3 and 0.054 ± 0.009 €/m3 for preliminary and tertiary treatment, respectively, whereas the unit total O&M cost were 0.011 ± 0.007 €/m3 and 0.077 ± 0.021 €/m3 for preliminary and tertiary treatment, respectively. Capital (investment) costs covered 58% of the total cost in preliminary WWTPs, whereas; O&M costs had the highest share (58%) in tertiary WWTPs. The results of this study confirmed that the level of treatment considerably affected the costs of WWTPs. Moreover, the CFs were separately derived for tertiary treatment including A2O with and without digester. The CFs obtained in this study are of utmost importance to be used in the economic evaluation of the planned WWTPs and in the management of existing ones.

Confectionery industry: a case study on treatability-based effluent characterization and treatment system performance.

Source-based wastewater characterization and stream segregation provide effective management of industrial wastewaters. The characterization of wastewater sources from a confectionery factory was presented and performance of the wastewater treatment plant was evaluated in this study. All of the wastewater sources in the factory, except the vacuum water line, can be characterized by high concentrations of soluble pollutants and low pH. High organic content of the wastewater generated from the confectionery industry promoted the application of anaerobic technology as a pre-treatment before the conventional aerobic treatment. The average chemical oxygen demand (COD) removal and biogas production for expanded granular sludge bed reactor were 88% and 1,730 Nm(3)/day, respectively. The effluent from the investigated facility can be used for irrigation provided that conductivity values are within acceptable limits.

The right method for midline laparotomy: what is the best choice for wound healing?

BACKGROUND: The techniques used for midline laparotomy affect healing in surgical wounds, but the relationship between cold scalpel and haemostatic methods (harmonic scalpel, diathermy) regarding wound healing remains unclear. There are also limited studies concerning the effects of harmonic scalpel on abdominal fascia. This study was aimed at comparing myofascial wound healing following laparotomy incision on fascia by cold scalpel (CS), harmonic scalpel (HS), and diathermy in terms of hydroxyproline content, inflammatory changes and tensile strength. MATERIALS AND METHODS: Twenty-seven male Wistar albino rats underwent midline laparotomy either with cold scalpel (CS), harmonic scalpel (HS) or diathermy. Fascia incisions were closed with continuous 4/0 polypropylene and skin incisions were closed with interrupted 4/0 polypropylene stitches. On the 7th postoperative day, the abdominal walls of the rats were tested for tensile strength. In addition, each abdominal fascia was evaluated for inflammation scores and hydroxyproline levels. RESULTS: HS caused less inflammation and necrosis in abdominal fascia compared to the diathermy group (p < 0.01 and p < 0.05, respectively), whereas the CS group showed no difference in inflammation scores, but had significantly lower necrosis scores than the HS and diathermy groups (p < 0.05 and p < 0.001, respectively). Hydroxyproline content of the fascia did not differ among groups, while the tensile strength of the wound was obviously higher in the CS group (p < 0.001). CONCLUSION: HS causes less inflammatory reaction and necrosis than diathermy, but more necrosis than CS. Fascia incisions with CS gains tensile strength faster than in other groups. HS appears to cause less tissue injury than diathermy and also has comparable results for wound healing. Further clinical studies on the impact of HS in fascia incisions are needed.

The effects of nitric oxide supplementation and inhibition on bacterial translocation in bile duct ligated rats.

Obstructive jaundice promotes bacterial translocation from the gut, but the role of nitric oxide is controversial in this process. We studied the effects of nitric oxide synthase substrate, L-arginine, and nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, on bacterial translocation in bile duct ligated rats. The animals were randomized into five groups; control, sham, common bile duct ligation alone, nitric oxide inhibition, and nitric oxide supplementation. Obstructive jaundice was performed with common bile duct ligation. L-arginine or N(G)-nitro-L-arginine methyl ester was injected once daily for 14 days. Blood bilirubin level, liver histology, and bacterial translocation to the mesenteric lymph nodes as well as to the liver were assessed. The L-arginine supplemented group had the lowest bacterial translocation rate, but the most prominent hepatic fibrosis. Nitric oxide inhibition increased bacterial translocation to the mesenteric lymph nodes. Therefore, the administration of nitric oxide donor or inhibitor acts as a significant regulatory factor for bacterial translocation in obstructive jaundice.

Is synchronous bowel anastomosis safe?

In this study, we investigated the effects of synchronous anastomosis on intestinal healing in experimental colonic resection. Sprague-Dawley rats were randomized into 3 groups; control (group I), single anastomosis (group II) and synchronous (double) anastomosis (group III). Single and proximal anastomoses were located 3 cm distal to caecum, and distal anastomoses were done 3 cm distal to them. On the 7th postoperative day, bursting pressure, hydroxyproline level and histology of the anastomotic site were assessed. Bursting pressures and hydroxyproline levels indicated that impaired healing of proximal anastomoses in group III was evident. Proximal anastomoses in group III had the lowest hydroxyproline value and bursting pressure level. Significant fibrosis was observed in the histological examination of distal anastomoses in group III. Double colonic anastomoses is not as safe as single anastomoses and involves additional risk. The healing of proximal anastomosis is significantly altered after experimental synchronous resection.

Effect of granulocyte-macrophage colony stimulating factor on bacterial translocation after experimental obstructive jaundice.

OBJECTIVE: To investigate the effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on bacterial translocation promoted by obstructive jaundice. DESIGN: Controlled animal study. SETTING: University hospital, Turkey. ANIMALS: 30 male Wistar albino rats. INTERVENTIONS: The first group (n = 10) was the sham operation (control) group, and the second and the third (n = 10 each) had common bile duct (CBD) ligation and division under sterile conditions. The third group were also treated with GM-CSF 200 ng subcutaneously daily between the fifth and ninth postoperative days. All animals were killed on the tenth day, and evaluated biochemically and histopathologically. Mesenteric lymph nodes were cultured under aerobic conditions. MAIN OUTCOME MEASURES: Biochemical analysis, histopathological evaluation, and aerobic cultures. RESULTS: There was no bacterial translocation in either the control or GM-CSF groups, whereas Escherichia coli and Salmonella typhimurium were found in 4 and 2 animals, respectively in the ligation group. Although no aerobic bacteria was found in controls and the GM-CSF groups, bacterial translocation was 6/10 in the ligation alone group (p <0.01). CONCLUSION: Activation of inflammatory response with GM-CSF is highly effective in prevention of bacterial translocation in obstructive jaundice.