Identifying Individuals at High Risk for HIV and Sexually Transmitted Infections With an Artificial Intelligence-Based Risk Assessment Tool.

Background: We have previously developed an artificial intelligence-based risk assessment tool to identify the individual risk of HIV and sexually transmitted infections (STIs) in a sexual health clinical setting. Based on this tool, this study aims to determine the optimal risk score thresholds to identify individuals at high risk for HIV/STIs. Methods: Using 2008-2022 data from 216 252 HIV, 227 995 syphilis, 262 599 gonorrhea, and 320 355 chlamydia consultations at a sexual health center, we applied MySTIRisk machine learning models to estimate infection risk scores. Optimal cutoffs for determining high-risk individuals were determined using Youden's index. Results: The HIV risk score cutoff for high risk was 0.56, with 86.0% sensitivity (95% CI, 82.9%-88.7%) and 65.6% specificity (95% CI, 65.4%-65.8%). Thirty-five percent of participants were classified as high risk, which accounted for 86% of HIV cases. The corresponding cutoffs were 0.49 for syphilis (sensitivity, 77.6%; 95% CI, 76.2%-78.9%; specificity, 78.1%; 95% CI, 77.9%-78.3%), 0.52 for gonorrhea (sensitivity, 78.3%; 95% CI, 77.6%-78.9%; specificity, 71.9%; 95% CI, 71.7%-72.0%), and 0.47 for chlamydia (sensitivity, 68.8%; 95% CI, 68.3%-69.4%; specificity, 63.7%; 95% CI, 63.5%-63.8%). High-risk groups identified using these thresholds accounted for 78% of syphilis, 78% of gonorrhea, and 69% of chlamydia cases. The odds of positivity were significantly higher in the high-risk group than otherwise across all infections: 11.4 (95% CI, 9.3-14.8) times for HIV, 12.3 (95% CI, 11.4-13.3) for syphilis, 9.2 (95% CI, 8.8-9.6) for gonorrhea, and 3.9 (95% CI, 3.8-4.0) for chlamydia. Conclusions: Risk scores generated by the AI-based risk assessment tool MySTIRisk, together with Youden's index, are effective in determining high-risk subgroups for HIV/STIs. The thresholds can aid targeted HIV/STI screening and prevention.

Assessing the effectiveness of HIV/STI risk communication displays among Melbourne Sexual Health Centre attendees: a cross-sectional, observational and vignette-based study.

INTRODUCTION: Increasing rates of sexually transmitted infections (STIs) over the past decade underscore the need for early testing and treatment. Communicating HIV/STI risk effectively can promote individuals' intention to test, which is critical for the prevention and control of HIV/STIs. We aimed to determine which visual displays of risk would be the most likely to increase testing or use of prevention strategies. METHODS: A vignette-based cross-sectional survey was conducted with 662 clients (a median age of 30 years (IQR: 25-36), 418 male, 203 female, 41 other genders) at a sexual health clinic in Melbourne, Australia, between February and June 2023. Participants viewed five distinct hypothetical formats, presented in a randomised order, designed to display the same level of high risk for HIV/STIs: icon array, colour-coded risk metre, colour-coded risk bar, detailed text report and guideline recommendation. They reported their perceived risk, concern and intent to test for each risk display. Associations between the format of the risk display and the intention to test for HIV/STI were analysed using logistic regression. RESULTS: About 378 (57%) of participants expressed that the risk metre was the easiest to understand. The risk metre (adjusted OR (AOR)=2.44, 95% CI=1.49 to 4.01) and risk bar (AOR=2.08, CI=1.33 to 3.27) showed the greatest likelihood of testing compared with the detailed text format. The icon array was less impactful (AOR=0.73, CI=0.57 to 0.94). The risk metre also elicited the most concern but was the most preferred and understood. High-risk perception and concern levels were strongly associated with their intention to have an HIV/STI test. CONCLUSIONS: Displaying risk differently affects an individual's perceived risk of an HIV/STI and influences their intention to test.

Effect of WeChat-based intervention on food safety knowledge, attitudes and practices among university students in Chongqing, China: a quasi-experimental study.

BACKGROUND: Food safety is of global importance and has been of concern in university settings in recent years. However, effective methods to conduct food safety education are limited. This study aims to evaluate the effects of an intervention on food safety knowledge, attitudes and practices (KAP) by social media, WeChat, among university students. METHODS: A quasi-experimental study was conducted in Chongqing, China. Two departments were recruited randomly from a normal university and a medical university. One department from each university was randomly selected as the intervention group and the other as the control group. All freshmen students in each selected department were chosen to participate in this study. One thousand and twenty-three students were included at baseline, and 444 students completed the study. This intervention was conducted through food safety-related popular science articles with an average of three articles per week released by WeChat official accounts called "Yingyangren" for two months to the intervention group. No intervention was conducted in the control group. An independent t-test was used to test statistical differences in the food safety KAP scores between the two groups. A paired t-test was used to test statistical differences in the food safety KAP scores between before and after the intervention. And quantile regression analysis was conducted to explore the difference between the two groups across the quantile levels of KAP change. RESULTS: After the intervention, compared with control group, participants in the intervention group did not score significant higher on knowledge (p = 0.98), attitude (p = 0.13), and practice (p = 0.21). And the scores of food safety knowledge and practices slightly improved after the intervention both in the intervention group (p = 0.01 and p = 0.01, respectively) and in the control group (p = 0.0003 and p = 0.0001, respectively). Additionally, the quantile regression analysis showed that the intervention had no effect on improving the food safety KAP scores. CONCLUSIONS: The intervention using the WeChat official account had limited effects on improving the food safety KAP among the university students. This study was an exploration of food safety intervention using the WeChat official account; valuable experience can be provided for social media intervention in future study. TRIAL REGISTRATION: ChiCTR-OCH-14004861.

Web-Based Risk Prediction Tool for an Individual's Risk of HIV and Sexually Transmitted Infections Using Machine Learning Algorithms: Development and External Validation Study.

BACKGROUND: HIV and sexually transmitted infections (STIs) are major global public health concerns. Over 1 million curable STIs occur every day among people aged 15 years to 49 years worldwide. Insufficient testing or screening substantially impedes the elimination of HIV and STI transmission. OBJECTIVE: The aim of our study was to develop an HIV and STI risk prediction tool using machine learning algorithms. METHODS: We used clinic consultations that tested for HIV and STIs at the Melbourne Sexual Health Centre between March 2, 2015, and December 31, 2018, as the development data set (training and testing data set). We also used 2 external validation data sets, including data from 2019 as external "validation data 1" and data from January 2020 and January 2021 as external "validation data 2." We developed 34 machine learning models to assess the risk of acquiring HIV, syphilis, gonorrhea, and chlamydia. We created an online tool to generate an individual's risk of HIV or an STI. RESULTS: The important predictors for HIV and STI risk were gender, age, men who reported having sex with men, number of casual sexual partners, and condom use. Our machine learning-based risk prediction tool, named MySTIRisk, performed at an acceptable or excellent level on testing data sets (area under the curve [AUC] for HIV=0.78; AUC for syphilis=0.84; AUC for gonorrhea=0.78; AUC for chlamydia=0.70) and had stable performance on both external validation data from 2019 (AUC for HIV=0.79; AUC for syphilis=0.85; AUC for gonorrhea=0.81; AUC for chlamydia=0.69) and data from 2020-2021 (AUC for HIV=0.71; AUC for syphilis=0.84; AUC for gonorrhea=0.79; AUC for chlamydia=0.69). CONCLUSIONS: Our web-based risk prediction tool could accurately predict the risk of HIV and STIs for clinic attendees using simple self-reported questions. MySTIRisk could serve as an HIV and STI screening tool on clinic websites or digital health platforms to encourage individuals at risk of HIV or an STI to be tested or start HIV pre-exposure prophylaxis. The public can use this tool to assess their risk and then decide if they would attend a clinic for testing. Clinicians or public health workers can use this tool to identify high-risk individuals for further interventions.

Using machine learning approaches to predict timely clinic attendance and the uptake of HIV/STI testing post clinic reminder messages.

Timely and regular testing for HIV and sexually transmitted infections (STI) is important for controlling HIV and STI (HIV/STI) among men who have sex with men (MSM). We established multiple machine learning models (e.g., logistic regression, lasso regression, ridge regression, elastic net regression, support vector machine, k-nearest neighbour, naïve bayes, random forest, gradient boosting machine, XGBoost, and multi-layer perceptron) to predict timely (i.e., within 30 days) clinic attendance and HIV/STI testing uptake after receiving a reminder message via short message service (SMS) or email). Our study used 3044 clinic consultations among MSM within 12 months after receiving an email or SMS reminder at the Melbourne Sexual Health Centre between April 11, 2019, and April 30, 2020. About 29.5% [899/3044] were timely clinic attendance post reminder messages, and 84.6% [761/899] had HIV/STI testing. The XGBoost model performed best in predicting timely clinic attendance [mean [SD] AUC 62.8% (3.2%); F1 score 70.8% (1.2%)]. The elastic net regression model performed best in predicting HIV/STI testing within 30 days [AUC 82.7% (6.3%); F1 score 85.3% (1.8%)]. The machine learning approach is helpful in predicting timely clinic attendance and HIV/STI re-testing. Our predictive models could be incorporated into clinic websites to inform sexual health care or follow-up service.

A Machine-Learning-Based Risk-Prediction Tool for HIV and Sexually Transmitted Infections Acquisition over the Next 12 Months.

BACKGROUND: More than one million people acquire sexually transmitted infections (STIs) every day globally. It is possible that predicting an individual's future risk of HIV/STIs could contribute to behaviour change or improve testing. We developed a series of machine learning models and a subsequent risk-prediction tool for predicting the risk of HIV/STIs over the next 12 months. METHODS: Our data included individuals who were re-tested at the clinic for HIV (65,043 consultations), syphilis (56,889 consultations), gonorrhoea (60,598 consultations), and chlamydia (63,529 consultations) after initial consultations at the largest public sexual health centre in Melbourne from 2 March 2015 to 31 December 2019. We used the receiver operating characteristic (AUC) curve to evaluate the model's performance. The HIV/STI risk-prediction tool was delivered via a web application. RESULTS: Our risk-prediction tool had an acceptable performance on the testing datasets for predicting HIV (AUC = 0.72), syphilis (AUC = 0.75), gonorrhoea (AUC = 0.73), and chlamydia (AUC = 0.67) acquisition. CONCLUSIONS: Using machine learning techniques, our risk-prediction tool has acceptable reliability in predicting HIV/STI acquisition over the next 12 months. This tool may be used on clinic websites or digital health platforms to form part of an intervention tool to increase testing or reduce future HIV/STI risk.

Comparison of the patterns of chlamydia and gonorrhoea at the oropharynx, anorectum and urethra among men who have sex with men.

OBJECTIVE: Chlamydia and gonorrhoea are common sexually transmitted infections that infect the oropharynx, anorectum and urethra in men who have sex with men (MSM). This study aimed to examine the pattern of infection at more than one site (multisite) for chlamydia and gonorrhoea among MSM. METHODS: This was a retrospective study of MSM attending the Melbourne Sexual Health Centre for the first time between 2018 and 2019. We included MSM aged ≥16 years who had tested for Neisseria gonorrhoeae and Chlamydia trachomatis at all three sites (oropharynx, anorectum and urethra). We compared infections that occurred at a single site (termed single-site infection) and those that occurred at more than one site (termed multisite infections). RESULTS: Of the 3938 men who were tested for chlamydia and gonorrhoea, 498/3938 men (12.6%, 95% CI 11.5% to 13.6%) had chlamydia at any site, of whom 400/498 (80.3%, 95% CI 78.9% to 81.2%) had single-site chlamydia infection, and 98/498 (19.7%, 95% CI 16.2% to 23.1%) had multisite infections. A similar proportion of men had gonorrhoea at any site (447/3938, 11.4%, 95% CI 10.3% to 12.2%), but among these 447 men, single-site infection was less common (256/447, 57.3%, 95% CI 52.6% to 61.7%, p<0.001) and multisite infection (191/447, 42.7%, 95% CI 38.2% to 47.3%, p<0.001) was more common than chlamydia. There were also marked differences by anatomical site. Urethral infection commonly occurred as single sites (75/122, 61.5%, 95% CI 52.8% to 70.1%) for chlamydia but uncommonly occurred for gonorrhoea (12/100, 12.0%, 95% CI 5.6% to 18.3%, p<0.001). In contrast, anorectal infection uncommonly occurred as multisite infection for chlamydia (98/394, 24.9%, 95% CI 20.6% to 29.1%) but was common (184/309, 59.5%, 95% CI 54.0% to 64.9%, p<0.001) for gonorrhoea. CONCLUSIONS: The markedly different pattern of site-specific infection for chlamydia and gonorrhoea infections among the same MSM suggests significant differences in the transmissibility between anatomical sites and the duration of each infection at each site.

Critical timing and extent of public health interventions to control outbreaks dominated by SARS-CoV-2 variants in Australia: a mathematical modelling study.

OBJECTIVES: The exact characteristics of a coronavirus disease 2019 (COVID-19) outbreak that trigger public health interventions are poorly defined. The aim of this study was to assess the critical timing and extent of public health interventions to contain COVID-19 outbreaks in Australia. METHODS: A practical model was developed using existing epidemic data in Australia. The effective combinations of public health interventions and the critical number of daily cases for intervention commencement under various scenarios of changes in transmissibility of new variants and vaccination coverage were quantified. RESULTS: In the past COVID-19 outbreaks in four Australian states, the number of reported cases on the day that interventions commenced strongly predicted the size and duration of the outbreaks. In the early phase of an outbreak, containing a wildtype-dominant epidemic to a low level (≤10 cases/day) would require effective combinations of social distancing and face mask use interventions to be commenced before the number of daily reported cases reaches six. Containing an Alpha-dominant epidemic would require more stringent interventions that commence earlier. For the Delta variant, public health interventions alone would not contain the epidemic unless the vaccination coverage was ≥70%. CONCLUSIONS: This study highlights the importance of early and decisive action in the initial phase of an outbreak. Vaccination is essential for containing variants.

Modelling the potential role of saliva use during masturbation in the transmission of Neisseria gonorrhoeae at multiple anatomical sites.

Background Neisseria gonorrhoeae can be cultured from saliva in men with pharyngeal gonorrhoea and could theoretically be transmitted from the pharynx to the urethra when saliva is used as a lubricant for masturbation. In this work, we proposed that saliva use during masturbation may be a potential transmission route of gonorrhoea. Methods We analysed the transmission of Neisseria gonorrhoeae at the oropharynx, urethra and anorectum with mathematical models among men who have sex with men using data from six different studies. Model 1 included transmission routes (oral sex, anal sex, rimming, kissing, and three sequential sex practices). In Model 2, we added saliva use during solo masturbation and mutual masturbation to model 1. Results Model 2 could replicate single site infection at the oropharynx, urethra and anorectum and multi-site infection across six different datasets. However, the calibration of Model 2 was not significantly different from Model 1 across four datasets. Model 2 generated an incidence of gonorrhoea from masturbation of between 5.2% (95% CI: 3.2-10.1) to 10.6% (95% CI: 5.8-17.3) across six data sets. Model 2 also estimated that about one in four cases of urethral gonorrhoea might arise from solo masturbation and mutual masturbation. Conclusions Our models raise the possibility that saliva use during masturbation may play a role in transmitting gonorrhoea. This is an important area to explore because it contributes to the knowledge base about gonorrhoea transmission.

Determinants and prediction of Chlamydia trachomatis re-testing and re-infection within 1 year among heterosexuals with chlamydia attending a sexual health clinic.

Background: Chlamydia trachomatis (chlamydia) is one of the most common sexually transmitted infections (STI) globally, and re-infections are common. Current Australian guidelines recommend re-testing for chlamydia 3 months after treatment to identify possible re-infection. Patient-delivered partner therapy (PDPT) has been proposed to control chlamydia re-infection among heterosexuals. We aimed to identify determinants and the prediction of chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia to identify potential PDPT candidates. Methods: Our baseline data included 5,806 heterosexuals with chlamydia aged ≥18 years and 2,070 re-tested for chlamydia within 1 year of their chlamydia diagnosis at the Melbourne Sexual Health Center from January 2, 2015, to May 15, 2020. We used routinely collected electronic health record (EHR) variables and machine-learning models to predict chlamydia re-testing and re-infection events. We also used logistic regression to investigate factors associated with chlamydia re-testing and re-infection. Results: About 2,070 (36%) of 5,806 heterosexuals with chlamydia were re-tested for chlamydia within 1 year. Among those retested, 307 (15%) were re-infected. Multivariable logistic regression analysis showed that older age (≥35 years old), female, living with HIV, being a current sex worker, patient-delivered partner therapy users, and higher numbers of sex partners were associated with an increased chlamydia re-testing within 1 year. Multivariable logistic regression analysis also showed that younger age (18-24 years), male gender, and living with HIV were associated with an increased chlamydia re-infection within 1 year. The XGBoost model was the best model for predicting chlamydia re-testing and re-infection within 1 year among heterosexuals with chlamydia; however, machine learning approaches and these self-reported answers from clients did not provide a good predictive value (AUC < 60.0%). Conclusion: The low rate of chlamydia re-testing and high rate of chlamydia re-infection among heterosexuals with chlamydia highlights the need for further interventions. Better targeting of individuals more likely to be re-infected is needed to optimize the provision of PDPT and encourage the test of re-infection at 3 months.

Diagnosis experiences from 50 hepatitis B patients in Chongqing, China: a qualitative study.

BACKGROUND: The aim of this study was to provide recommendations for reducing the impact of hepatitis B infection on patients with chronic hepatitis B by describing their experiences during the diagnosis process. METHODS: We conducted face-to-face interviews with 50 hepatitis B patients recruited by convenient sampling from an infectious diseases department of a teaching hospital in Chongqing, China from July to August 2019. Thematic analysis framework included interviewees' social demographic characteristics, diagnosis approach, signs and symptoms before diagnosis, feelings after diagnosis, and doctor's instructions. RESULTS: Most patients first detected hepatitis B through various types of physical examinations when the patients were asymptomatic or had only mild symptoms. Most patients were shocked, scared, or overwhelmed when they were diagnosed with hepatitis B. They were able to remember the doctor's instructions about maintaining a healthy lifestyle, but not impressed by the doctor's advice about regular follow-up liver function tests. The lack of regular follow-up has caused irreversible damage to some patients. CONCLUSIONS: Most patients are passively diagnosed with hepatitis B due to their lack of awareness on active hepatitis B prevention. Patients need professional mental health care to overcome the negative emotions that following the diagnosis. Physicians' instruction should emphasize the importance of regular follow-up liver function tests in addition to a healthy lifestyle.

Potential effect of antiseptic mouthwash on the incidence of Neisseria gonorrhoeae among men who have sex with men: a mathematical modelling study.

OBJECTIVES: The incidence of Neisseria gonorrhoeae and its antimicrobial resistance is increasing in many countries. Antibacterial mouthwash may reduce gonorrhoea transmission without using antibiotics. We modelled the effect that antiseptic mouthwash may have on the incidence of gonorrhoea. DESIGN: We developed a mathematical model of the transmission of gonorrhoea between each anatomical site (oropharynx, urethra and anorectum) in men who have sex with men (MSM). We constructed four scenarios: (1) mouthwash had no effect; (2) mouthwash increased the susceptibility of the oropharynx; (3) mouthwash reduced the transmissibility from the oropharynx; (4) the combined effect of mouthwash from scenarios 2 and 3. SETTING: We used data at three anatomical sites from 4873 MSM attending Melbourne Sexual Health Centre in 2018 and 2019 to calibrate our models and data from the USA, Netherlands and Thailand for sensitivity analyses. PARTICIPANTS: Published available data on MSM with multisite infections of gonorrhoea. PRIMARY AND SECONDARY OUTCOME MEASURES: Incidence of gonorrhoea. RESULTS: The overall incidence of gonorrhoea was 44 (95% CI 37 to 50)/100 person-years (PY) in scenario 1. Under scenario 2 (20%-80% mouthwash coverage), the total incidence increased (47-60/100 PY) and at all three anatomical sites by between 7.4% (5.9%-60.8%) and 136.6% (108.1%-177.5%). Under scenario 3, with the same coverage, the total incidence decreased (20-39/100 PY) and at all anatomical sites by between 11.6% (10.2%-13.5%) and 99.8% (99.2%-100%). Under scenario 4, changes in the incidence depended on the efficacy of mouthwash on the susceptibility or transmissibility. The effect on the total incidence varied (22-55/100 PY), and at all anatomical sites, there were increases of nearly 130% and large declines of almost 100%. CONCLUSIONS: The effect of mouthwash on gonorrhoea incidence is largely predictable depending on whether it increases susceptibility to or reduces the transmissibility of gonorrhoea.

Optimization nutrient removal at different volume ratio of anoxic-to-aerobic zone in integrated fixed-film activated sludge (IFAS) system.

This study evaluated the influence of different volume ratios of the anoxic-to-aerobic zone (Vano/Vaer) on the enhancement of nitrogen and phosphorus removal in an integrated fixed-film activated sludge (IFAS) system. As the Vano/Vaer increased from 1:2 to 2:1, the removal of organic carbon, nitrogen and phosphorus nutrients of the IFAS system was improved. At Vano/Vaer = 1:1, the removal effect of nitrogen and phosphorus nutrients was optimal, and the average removal rates of COD, NH4+-N, TN, and TP of the system reached 90 ± 3.2%, 98.2 ± 1.4%, 88.9 ± 2.2%, and 89.1 ± 2.7%, respectively. As the volume of the anoxic zone continued to increase, the denitrifying phosphate-accumulating capacity of the system was enhanced, and the highest ratio of specific anoxic and aerobic phosphorus uptake rate could reach 65.3%. Analysis of the molecular evaluation showed that, the proportion of nitrifying bacteria in the biofilm gradually increased as Vano increased. Moreover, denitrifying phosphate-accumulating organisms (DNPAOs), ammonia-oxidizing archaea (AOA), and anaerobic ammonium oxidizing (Anammox) bacteria were all enriched all showed enrichment in the biofilm of fiber carriers, which further strengthened the system's synergistic removal of nitrogen and phosphorus.

Current status, existent problems, and coping strategy of urban drainage pipeline network in China.

Urban drainage pipeline systems collect and transport domestic sewage, industrial wastewater, and rainwater. They are important components of urban infrastructure. The quality of drainage facilities directly determines the level of urban development and affects the urban landscape and sanitary environment. In recent years, however, the phenomenon of "attaching importance to construction, despising management and maintenance" has prevailed in China's urban drainage pipeline network. The problems such as structural damage, corrosion, and blockage of the sewage pipelines are becoming increasingly prominent in China, causing a lot of operational challenges such as direct discharge of sewage, backward irrigation of river and lake water, infiltration of external water, and overflow pollution. To comprehensively acquire these information about China's urban drainage pipeline network, this paper reviews current status of construction, operation, management and maintenance, existent problems, and coping strategy of the sewage pipelines. Finally, future directions are also discussed in detail for rational construction and maintenance of sewage pipelines.

Modelling the multiple anatomical site transmission of Mycoplasma genitalium among men who have sex with men in Australia.

Mycoplasma genitalium (M. genitalium) is a recently recognised and important sexually transmitted infection among men who have sex with men (MSM). The role of oral sex, rimming, and kissing on M. genitalium transmission in MSM is unclear. We created four deterministic susceptible-infectious-susceptible epidemic models to examine the role that different sexual behaviours play in transmitting M. genitalium at the oropharynx, urethra anorectum among men who have sex with men in Australia. Our results suggest that oral and anal sex without other sexual practices (model 1) replicate well single site infection at the oropharynx, urethra and anorectum and also multi-site infection. If kissing or rimming are added to model 1 (i.e., model 2-4) no substantial improvements in the calibration of the models occur. Model 1 estimates that 3.4% of infections occur at the oropharynx, 34.8% at the urethra and 61.8% at the anorectum. Model 1 also estimates that the proportion of incident M. genitalium transmitted by anal sex was 82.4%, and by oral sex was about 17.6%. Our findings could provide an enhanced understanding of M. genitalium transmission in MSM, thus providing insights into what sexual practices contribute most to transmission.

Modeling sulfide production in full flow concrete sewers based on the HRT variation of sewerage.

The corrosion and odor in concrete sewers are mainly related to the sulfide production, which is, under certain circumstances, directly proportional to the hydraulic retention time (HRT) of the sewer. To reduce the corrosion and control the odor in concrete sewers, it is necessary to model the production of sulfide in the concrete sewers with different HRTs. However, previous researches were mostly carried out in simulated Perspex-made sewers, and the obtained theoretical formulas based on the Monod equation were impractical because of the complexity. An actual concrete pipe with domestic sewage was employed in this study to obtain a simple but practical model, which can be applied to quantitively describe the sulfide production according to the HRT of the sewer and the chemical oxygen demand (COD) of the sewage. The empirical equation obtained was rs = (0.045 × lnHRT + 0.071) × ([COD] - b)0.6, the coefficient is a logarithmic function of the HRT, and the sulfide production rate and COD have a power relationship. Based on the data of COD and HRT obtained in the realistic sewer, the production of sulfide in the sewer can be predicted for better maintaining sewers through sulfide control.

The second pregnancy has no effect in the incidence of macrosomia: a cross-sectional survey in two western Chinese regions.

BACKGROUND: After the implementation of the universal two-child policy in China, the increase in parity has led to an increase in adverse pregnancy outcomes. The impact of one and two fetuses on the incidence of fetal macrosomia has not been fully confirmed in China. This study aimed to explore the differences in the incidence of fetal macrosomia in first and second pregnancies in Western China after the implementation of the universal two-child policy. METHODS: A total of 1598 pregnant women from three hospitals were investigated by means of a cross-sectional study from August 2017 to January 2018. Participants were recruited by convenience and divided into first and second pregnancy groups. These groups included 1094 primiparas and 504 women giving birth to their second child. Univariate and multivariate logistic regression analyses were performed to discuss the differences in the incidence of fetal macrosomia in first and second pregnancies. RESULTS: No significant difference was found in the incidence of macrosomia in the first pregnancy group (7.2%) and the second pregnancy group (7.1%). In the second-time pregnant mothers, no significant association was found between the macrosomia of the second child (5.5%) and that of the first child (4.7%). The multivariate logistic regression model showed that mothers older than 30 years are not likely to give birth to children with macrosomia (odds ratio (OR) 0.6, 95% confidence interval (CI) 0.4,0.9). CONCLUSIONS: The incidence of macrosomia in Western China is might not be affected by the birth of the second child and is not increased by low parity.

Effect of operating temperature on the efficiency of ultra-short-sludge retention time activated sludge systems.

There are abundant recyclable carbon, nitrogen, and phosphorus resources in wastewater and their efficient recovery is a heavily studied topic at present. As an effective means of carbon and phosphorus recovery, the ultra-short-sludge retention time (SRT) activated sludge (USSAS) system has increasingly attracted the attention of researchers. In this study, the capture efficiency and mechanism of carbon/phosphorus, and the microbial characteristics of the USSAS system, were studied at different temperatures (12, 18, 24, and 30 °C) and a 3-day SRT. The results showed that temperature had little effect on the carbon capture efficiency but had a considerable impact on the carbon capture mode. Increasing temperature decreased the EPS content and increased the biological metabolic activity, then decreasing adsorption but increasing the biotransformation effect. There was a negative correlation between temperature and phosphorus capture efficiency. As the temperature increased, the biological phosphorus removal effect decreased, but the adsorptive phosphorus removal effect gradually increased. With decreasing temperatures, the mixed liquid volatile suspended solid (MLVSS)/mixed liquid suspended solid (MLSS) value increased, but there was a risk of sludge bulking. Kinetic parameters confirmed microbial energy storage under lower temperature conditions and high biological activity under higher temperature conditions.

Current operation state of wastewater treatment plants in urban China.

Wastewater treatment plants (WWTPs) in urban China generally face operational difficulties. To comprehensively analyze the current operation status and determine the factors that caused difficulties in urban domestic WWTPs, we conducted a questionnaire survey, and 18 operating conditions of scale-level WWTPs in seven regions in China were investigated. The research results showed that, of the 467-urban domestic WWTPs surveyed in China, approximately 63.17% of the WWTPs' hydraulic loading rates (HLRs) are greater than 80%, 67.02% of the WWTPs have mixed liquor suspended solids (MLSS) concentrations greater than 4000 mg/L, and 95.93% of the WWTPs' mixed liquor volatile suspended solids to mixed liquor suspended solids (MLVSS/MLSS) ratios are lower than 0.7. The WWTP energy consumption accounts for approximately 1% of the national electricity consumption, and approximately 100,000 tons of various chemicals are consumed every year. A high HLR, a high activated sludge concentration and low sludge activity, design value mismatches with actual values, high energy and material consumption, etc. have become the main operational difficulties of urban domestic WWTPs. In this study, the main barriers that hinder improving the operating efficiency of WWTPs were investigated, the causes of operational dilemmas were analyzed, and pathways were jointly explored to solve them. This study may provide valuable implications for industry practitioners with a comprehensive grasp of the industry's current status and related policy formulation.

Effects of biotin on promoting anammox bacterial activity.

Anaerobic ammonium oxidation (anammox) bacteria significantly improve the efficiency and reduce cost of nitrogen removal in wastewater treatment plants. However, their slow growth and vulnerable activity limit the application of anammox technology. In this paper, the enhancement of biotin on the nitrogen removal activity of anammox bacteria in short-term batch experiments was studied. We found that biotin played a significant role in promoting anammox activity within a biotin concentration range of 0.1-1.5 mg/L. At a biotin concentration of 1.0 mg/L, the total nitrogen removal rate (NRR) increased by 112%, extracellular polymeric substance (EPS) secretion and heme production significantly improved, and anammox bacterial biomass increased to maximum levels. Moreover, the predominant genus of anammox bacteria was Candidatus Brocadia.