Simultaneous removal of carbon and nitrogen from organic-rich wastewater with Anammox / 生物工程学报

In order to simultaneously remove carbon and nitrogen from organic-rich wastewater, we used an up-flow anaerobic sludge bed/blanket (UASB) reactor that was started up with anammox with high concentration of carbon and nitrogen by gradually raising the organic loading of influent. We optimized the removal of nitrogen and carbon when the chemical oxygen demand (COD) concentration varied from 172 to 620 mg/L. During the entire experiment, the ammonium and total nitrogen removal efficiency was higher than 85%, while the average COD removal efficiency was 56.6%. The high concentration of organic matter did not restrain the activity of anammox bacteria. Based on polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and tapping sequencing analyses, the Planctomycete, Proteobacteria, Chloroflexi, Chlorobi bacteria are detected in the UASB reactor, which indicated complex removal pathway of carbon and nitrogen coexisted in the reactor. However, a part of Planctomycete which referred to anammox bacteria could tolerate a high content of organic carbon, and it provided help for high performance of nitrogen removal in UASB reactor.

Enrichment regulation of anammox bacteria in the anammox start-up process / 生物工程学报

To study the enrichment regulation of anammox bacteria during the whole start-up process of anammox reaction, two reactors with addition of carries of Spherical Plastic (SP) and Bamboo Charcoal (BC) and one without carrier (CK) were used to start anammox reaction. Then FISH and q-PCR analyses for the growth of all anammox bacteria were conducted during the operational process. The results indicate that the number of anammox bacteria in all reactors increased with time during the whole start-up process, which was consistent with the removal rate of ammonium and nitrite. On day 123 of stable phase, the percent of anammox cells in the sludge of CK, SP and BC accounted for 23.3%, 32.6% and 43.7%, respectively. The number of anammox bacteria 16S rRNA gene copies was (25.64 +/- 2.76) x 10(7), (47.12 +/- 2.76) x 10(7) and (577.99 +/- 27.25) x 10(7) copies g(-1) VSS in the sludge of CK, SP and BC, respectively. Carrier addition could dramatically increase enrichment of anammox bacteria. BC addition significantly increased the anammox bacteria number in the UASB reactor which resulted in the acceleration of the anammox start-up process. In addition, the max specific growth rate and the minimum doubling time were 0.064 d(-1) and 10.8 d in BC reactor. The max specific growth rate of anammox bacteria in BC reactor was 1.78 times and 1.88 times greater than that in CK and SP reactor, respectively. Therefore, the FISH and q-PCR analyses were suitable for determining the enrichment regulation of anammox bacteria during the start-up time, while a bit of differences in results existed between the two analytical methods due to the difference in analysis targets.

A comparative study of PTT and CT tests for coagulation evaluation of cardiovascular system external communicating devices / 生物医学工程学杂志

Based on GB/T16886.4-2003 Standard, the coagulation effects of 5 cardiovascular system external communicating devices made consist of metal and polymer were assessed using the partial thromboplastin time (PTT) and Lee-White coagulation time (CT) tests. The results indicate that PTT test is a stable and valuble method for evaluating the coagulating pathway disturbance of the devices. In line with GB/T 16886.4-2003 Standard, PTT test is a recommendable method for evaluating the external communicating devices Based on GB/T14233.2-2005 Standard, CT test is a method more liable to variation, compared with PTT test. This is due to the complex relativity in the test itself, due to all the factors of coagulating cascade, and due to the individual difference of animal. The question of how to select proper negative control for coagulation evaluation of the Cardiovascular System External Communicating Devices in clinical setting for CT test should be addressed and studied.

Comparison between hemolysis percentage measurement and hemiglobincyanide measurement for standardizing the evaluation of hemolytic properties of biomaterials / 生物医学工程学杂志

In this study, two methods--the supernatant hemoglobin spectrophotometry, i.e. hemolysis percentage measurement(according to ISO/TR 7405) and the hemiglobincyanide measurement(according to ISO 10993-4)--were used to assay the hemolytic properties of hydroxyapatite(bioceramics) and collagen (polymer). The results showed that the conclusions drawn from using the two methods were basically consistent, and the latter was more sensitive, stable and comparable. However, some of the procedures in the hemiglobincyanide method were not defined in details. So based on our experiments we have offered some suggestions and improvements, which do not deviate from ISO and ASTM standards, for hiher practicability of usig it in standardizing the evaluation of the hemolytic properties of biomaterials. Hemiglobincyanide measurement is worthy of wider application.