Objective To carry out the risk assessment on health effects of viruses in reused wastewater in city.Methods During May-November in2002,the concentration of total coliform and fecal coliform in water sample s collected from waste water after secondary treatment of wastewater treatment plant and reused waste water treated by conventional wastewater-reuse technical process in Xian Baishiqiao Wastewater Treatmen t Center were determined,and the hypothesis testing on the normal distribution of monitoring data was carried out.Meanwhile the removal efficacy of coliform in wastewater with chlorine disinfection was ob-served.The beta-Possion model,the model for evaluating the infection probability of pathogenic microorganism in drinking water,and Monte Carlo simulated method were used for the risk assessment on health effects of viruses in reused wastewater in city.Re sults The monitoring data on concentrations of fecal coliform in water samples collected from secondarily treated wastewater and reused wastewater showed log-normal distribution.The removal efficacies of coliform from wastewater were4log at condi-tions of7mg /L chlorine and20-minute contact time,and5log at conditions of15mg /L chlorine and20-minutes-contact time.The means of annual risk value of health effects of viruses in reused wastewater were1.21?10 -6 for the reuse of wastewater in greening and4.31?10 -8 for the reuse in irrigation of farmland respectively,the highest risk values for these two reuse methods were all below10 -4 ,the acceptable annual risk value for drinking water ruled by Surface Water Treatment Rules published by USEPA.The probability of annual risk value

Objective:To compare the efficacy of oblique lumbar interbody fusion (OLIF) and minimally invasive interbody fusion (MI-TLIF) for degenerative lumbar spondylolisthesis.Methods:Data of 40 patients with I-II degree single level degenerative lumbar spondylolisthesis from January 2018 to December 2018 were retrospectively analyzed. According to the operation procedure, they were divided into two groups: OLIF group and MI-TLIF group, and each group had 20 patients. There were 15 males and 5 females in the OLIF group, aged 50.3±8.8 years; and there were 13 males and 7 females in the MI-TLIF group, aged 51.7±8.7 years. According to the Meyerding's grade system, there were 16 patients of type I in the OLIF group and 15 cases in the MI-TLIF group; and there were 4 patients of type II in the OLIF group and 5 cases in the MI-TLIF group. The operation time, intra-operative hemorrhage, postoperative drainage, recessive blood loss and albumin loss were recorded. The CRP and ESR on the third day after operation, the VAS score and ODI score before and after operation were recorded. The lumbar lordosis (LL), fused segmental lordosis (FSL) and disc height (DH) before and after operation were recorded. The time of getting out of bed and walking and the hospital stay were recorded. Paired t-test was used to analyze the data.Results:Forty patients successfully underwent the operation. The operation time of OLIF group was 96±20 min, with intraoperative blood loss of 61±32 ml and postoperative drainage volume of 18±8 ml. The operation time of MI-TLIF group was 132±26 min, with intraoperative blood loss of 262±102 ml and postoperative drainage volume of 95±42 ml; and there was statistical difference between the two groups ( t=4.901, 8.404, 8.064; P< 0.001). On the third day after operation, the occult blood loss was 139±47 ml in the OLIF group and 486±192 ml in the MI-TLIF group; the albumin loss was 4.2±1.9 g/L in the OLIF group and 10.2±3.9 g/L in the MI-TLIF group; CRP was 34±11 mg/L in the OLIF group and 106±39 mg/L in the MI-TLIF group; ESR was 41±15 mm/1 h in the OLIF group and 71±24 mm/1 h in the MI-TLIF group, and there all were statistical differences between the two groups ( t=7.838, 6.184, 7.983, 4.675; P< 0.001). The VAS scores were 2.2±1.5, 1.8±1.3 and ODI scores were 14%±11%, 59%±17%, respectively. There was no significant difference between the two groups. The LL were 33.41°±9.25°, 32.07°±9.54°, FSL were 11.59°±5.09°, 10.61°±4.56° and DH were 10.35±2.30 mm, 10.85±1.85 mm, respectively. There was no significant difference between the two groups. The follow-up time was 13.5±2.3 months in the OLIF group and 14.1±2.8 months in the MI-TLIF group. Three patients in the MI-TLIF group had radiation pain in the lower extremity on the third day after operation, which relieved after NSAID drugs and mannitol treatment. In the group of OLIF, the skin temperature of the left lower extremity increased in 1 case on the first day after operation, in which sympathetic chain injury was considered, and the patient recovered after 2.5 months; in the group of OLIF, the numbness in the front of the left thigh and the weakness of flexion of the hip was found in 3 cases, in which the edema or injury of the psoas major muscle was considered. Conclusion:Compared with MI-TLIF in the treatment of I, II degree single segment degenerative lumbar spondylolisthesis, OLIF has the advantages of shorter operation time, less intraoperative and postoperative blood loss, lower inflammation index, earlier time to get out of bed and shorter hospital stay. However, the outcomes of the two surgeries were similar.