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BackgroundHIV self-testing (HIVST), especially the secondary distribution of HIVST (SD-HIVST) initiated by sexual health influencers (SHIs), has been recognized as an effective strategy in promoting HIV testing, especially among men who have sex with men (MSM). This quasi-experimental study aimed to evaluate whether SHIs identified through the ensemble machine learning approach can distribute more HIVST than those who identified by the empiricalscale.MethodsWe will recruit eligible adults (≥18 years old) who were assigned male gender at birth, and willing to participate in potential SD-HIVST online. Participants will be assigned randomly to two groups (scale group or machine learning group), followed by a separate process of SHI identification based on the group assignment. After identification, all index participants (defined as identified SHIs who are verbally consented to participate in SD-HIVST or who directly order HIVST kits) will follow the same procedure for SD-HIVST acquisition and distribution. Index participants can order HIVST online and distribute them to members within their social networks (defined as alters) in-person or virtually through a personalized peer referral link. Once a unique alter uploads a photographed test result to the platform, both the alter and the corresponding index participant will receive a fixed incentive of 3 USD. The index MSM can order up to five HIVST in the first three months and ten HIVST in the following three months. Each index participant will need to complete a baseline survey at the first-time ordering and one to two follow-upbased on the times of ordering,, three months after ordering. This trial will be comparing 1) the mean number of alters motivated by each index participant in each group and 2) the mean number of newly-tested alters motivated by each index participant in each group.DiscussionIn promoting the efficacy of identifying SHIs for SD-HIVST, our study has the potential to enhance testing coverage, particularly among marginalized individuals and those who are reluctant to for HIV and other sexually transmitted infections.Trial registrationWe registered the study on the Chinese Clinical Trial Registry website on 4th November 2021, with registration numberChiCTR2000039632.

As a polycyclic aromatic hydrocarbon, environmental exposure to phenanthrene is widespread worldwide. The potential effects and mechanism of phenanthrene exposure on fasting plasma glucose (FPG) have not been well determined. In this study, we aim to explore the effects of phenanthrene exposure and AMER3 variants on fasting plasma glucose (FPG) through a longitudinal epidemiological study. Repeated measurements of five urinary hydroxyphenanthrene (OHPh) for 5739 participants with 7083 observations from the Wuhan-Zhuhai cohort were performed to analyze the relationships between total OHPh (ΣOHPh) and FPG using linear mixed models and restricted cubic spline functions. Then, we genotyped 2777 participants (4104 observations) using the Infinium OmniZhongHua-8 BeadChip and included all 14 single nucleotide polymorphisms (SNPs) within the AMER3 gene to analyze the interaction of the AMER3 on the relationship between ΣOHPh and FPG. We observed a U-shaped relationship between ΣOHPh and FPG, and the turning point of ΣOHPh was 2.512 μg/mmol Cr. When lower than the turning point, ΣOHPh was negatively associated with FPG, while higher than the turning point, ΣOHPh was positively associated with FPG. Furthermore, we observed interactions (P

Background The unclear mechanisms and severity of injuries in the injury pyramids for Chinese children and adolescents prevent the prioritization of interventions. This study aimed to describe the injury mechanisms and injury pyramids in this population to provide a priority for injury prevention strategies. Methods Death, hospitalization, and outpatient/emergency department visit data from patients aged 0 ~ 17 years with injuries were obtained from January 1, 2013, to December 31, 2017, in Zhuhai City, China. The injury mechanism ratios were calculated, and the injury pyramid ratios were drawn in proportion using injury mortality and the incidence of both injury hospitalizations and outpatient/emergency department injury visits. Results The top three mechanisms for injuries in children and adolescents treated in outpatient/emergency departments were falls (52.02%), animal bites (14.57%), and blunt injuries (10.60%). The top three mechanisms for injury hospitalizations were falls (37.33%), road traffic injuries (17.87%), and fire/burns (14.29%), while the top three mechanisms for injury deaths were drowning (32.91%), road traffic injuries (20.25%) and falls (13.92%). The incidence rate of outpatient/emergency department injury visits for children and adolescents was 11,210.87/100,000; the incidence rate of injury hospitalization was 627.09/100,000, and the injury death rate was 10.70/100,000. For each injury death, there were 59 injury hospitalizations and 1048 outpatient/emergency injury visits. Conclusions The injury mechanisms were different for injury-related outpatient/emergency department visits, hospitalizations, and deaths among children and adolescents. The injury mechanisms by sex at different stages of child development, and interventions should be formulated based on this finding. The ratios of the injury pyramids varied by age, sex, region, and injury mechanisms; minor nonfatal injuries were more common in children and adolescents. The differences in the severity and extent of the injuries suggested that injury interventions in children and adolescents still have a long way to go.

BACKGROUND HIV self-testing (HIVST) has been rapidly scaled up and additional strategies further expand testing uptake. Secondary distribution has people (indexes) apply for multiple kits and pass these kits to people (alters) in their social networks. However, identifying key influencers is difficult. OBJECTIVE This study aimed to develop an innovative ensemble machine learning approach to identify key influencers among Chinese men who have sex with men (MSM) for HIVST secondary distribution. METHODS We defined three types of key influencers: 1) key distributors who can distribute more kits; 2) key promoters who can contribute to finding first-time testing alters; 3) key detectors who can help to find positive alters. Four machine learning models (logistic regression, support vector machine, decision tree, random forest) were trained to identify key influencers. An ensemble learning algorithm was adopted to combine these four models. Simulation experiments were run to validate our approach. RESULTS 309 indexes distributed kits to 269 alters. Our approach outperformed human identification (self-reported scales cut-off), exceeding by an average accuracy of 11·0%, could distribute 18·2% (95%CI: 9·9%-26·5%) more kits, find 13·6% (95%CI: 1·9%-25·3%) more first-time testing alters and 12·0% (95%CI: -14·7%-38·7%) more positive-testing alters. Our approach could also increase simulated intervention efficiency by 17·7% (95%CI: -3·5%-38·8%) than human identification. CONCLUSIONS We built machine learning models to identify key influencers among Chinese MSM who were more likely to engage in HIVST secondary distribution. CLINICALTRIAL Our study was a secondary modeling analysis of an RCT, which was registered with the Chinese Clinical Trial Registry (ChiCTR) ChiCTR1900025433.

HIV self-testing (HIVST) is effective in improving the uptake of HIV testing among key populations. Complementary data on the economic evaluation of HIVST is critical for planning and scaling up HIVST. This study aimed to evaluate the cost of a community-based organisation (CBO)-led HIVST model implemented in China.An economic evaluation was conducted by comparing a CBO-led HIVST model with a CBO-led facility-based HIV rapid diagnostics testing (HIV-RDT) model. The full economic cost, including fixed and variable cost, from a health provider perspective using a micro costing approach was estimated. We determined the incremental cost-effectiveness ratios of these two HIV testing models over a 2-yeartime horizon (i.e. duration of the programs), and reported costs using US dollars (2021).From January 2017 to December 2018, a total of 4633 men were tested in the HIVST model, and 1780 men were tested in the HIV-RDT model. The total number of new diagnoses was 155 for HIVST and 126 for the HIV-RDT model; the HIV test positivity was 3.3% (95% confidence interval (CI): 2.8-3.9) for the HIVST model and 7.1% (95% CI: 5.9-8.4) for the HIV-RDT model. The mean cost per person tested was USD10.38 for HIVST and USD41.45 for HIV-RDT. The mean cost per diagnosed person was USD310.12 for HIVST compared with USD585.58 for HIV-RDT.Compared to facility-based HIV-RDT, a CBO-led HIVST program is cheaper and more effective among MSM living in China.

Polycyclic aromatic hydrocarbons (PAHs) have been reported to cause various health damages. However, some PAH derivatives are still used as agents, and some of them have hypoglycemic effects. Till now, few studies explored the relationship between urinary PAH metabolites and fasting plasma glucose (FPG). In this study, A total of 2682 non-smokers in the second follow-up of the Wuhan-Zhuhai cohort were included to explore the relationship between urinary PAH metabolites and FPG. FPG related epigenome-wide association study (EWAS) was conducted among 212 never smokers, and the mediation analysis was performed to find potential mediator cytosine-phosphoguanine (CpG) sites in the above relationship. The concentration of total urinary PAH metabolites was 3.60 (2.37, 5.85) μg/mmol Cr. The urinary PAH metabolites were negatively associated with FPG. Each 1-U increase in ln-transformed levels of 1-hydroxynaphthalene, 4-hydroxyphenanthrene, 9-hydroxyphenanthrene, or 2- hydroxyphenanthrene was associated with 0.008-, 0.007-, 0.010-, or 0.010- unit decreased in ln-transformed levels of FPG, respectively (all p 0.05). We found 28 new CpG sites related to FPG (FDR0.05) through EWAS. Mediation analysis found that cg11350141 on AMER3 mediated 41.91% of the negative association of total urinary PAH metabolites with FPG. These results provide a new clue for the development of hypoglycemic agents.

Background: Digital network-based methods may enhance peer distribution of HIV self-testing (HIVST) kits, but implementation research is needed to optimize this approach. We aimed to assess whether monetary incentives and peer referral could improve a secondary distribution program for HIVST among men who have sex with men (MSM) in China. Method: A three-arm randomized controlled trial was conducted in Guangdong Province, China. Individuals who were born biologically as males, aged 18 years or older, and ever had male-to-male sex were recruited as index participants via social media. Index participants were randomly assigned into one of the three arms: 1) standard secondary distribution (control) group, 2) secondary distribution with monetary incentives (SD-M) group, and 3) secondary distribution with monetary incentives plus peer referral (SD-M-PR) group. Index participants were encouraged to distribute HIVST kits to members within their social networks (defined as alters). Index participants in the SD-M group received a fixed $3 USD incentive for each verified test by an alter. Index participants in the SD-M-PR group could send personalized peer referral links for kit applications to alters in addition to receiving $3 per verified test by an alter. The primary outcomes were mean number of alters tested and newly tested alters motivated by each index in each group, compared using bootstrapping methods and statistical tests. We also conducted an economic evaluation alongside the trial, using microcosting from a health provider perspective with a 3-month time horizon. Economic costs are presented as USD (2020). This trial was registered with Chinese Clinical Trial Registry, ChiCTR1900025433. Analysis was performed on an intention to treat basis, and missing data were handled using complete data analysis. The study design and results are reported according to CONSORT 2010 guidelines. Findings: Between October 21, 2019, and September 1, 2020, we enrolled 309 eligible index participants (control: 102; SD-M: 103; SD-M-PR: 104). The mean number of unique tested alters motivated by each index was 0·57±0·96 in the control group, compared with 0·98±1·38 in the SD-M group (mean difference [MD] 0·41, 95% CI: 0·08-0·74), and 1·78±2·05 in the SD-M-PR group (MD=1·21, 95% CI: 0·77-1·65). The mean number of newly tested alters motivated by each index was 0·16±0·39 in the control group, compared with 0·41±0·73 in the SD-M group (MD=0·25, 95% CI: 0·09-0·41), and 0·57±0·91 in the SD-M-PR group (MD=0·41, 95% CI: 0·22-0·60), respectively. The average cost per alter tested was $96·18 in the control group, $61·58 (36% reduction) in the SD-M group, and $41·56 (57% reduction) in the SD-M-PR group. Interpretation: Monetary incentives alone and the combined intervention of monetary incentives and peer referral can promote secondary distribution of HIVST among MSM. Monetary incentives can also expand HIV testing by encouraging first-time testing through secondary distribution by MSM. Trial Registration: This trial was registered with Chinese Clinical Trial Registry, ChiCTR1900025433. Funding Statement: National Natural Science Foundation of China. Declaration of Interests: We declare no conflicts of interest. Additional notes: Abbott sponsored the annual conference of UNC project-China in Guangzhou, December 2020. The study was conducted and completed before the conference and Abbott did not participate in any study procedures. Ethics Approval Statement: All participants gave digital written informed consent by providing electronic signatures before the online survey. Ethics approval was obtained through the Zhuhai CDC, and the study protocol of the trial is published.

Introduction: HIV self-testing (HIVST) is effective in improving the uptake of HIV testing among key populations. Complementary data on the cost-effectiveness of HIVST is critical for planning and scaling up HIVST. This study aimed to evaluate the cost-effectiveness of a community-based organization (CBO)-led HIVST model implemented in China. Method: A cost-effectiveness analysis (CEA) was conducted by comparing a CBO-led HIVST model with a CBO-led facility-based HIV rapid diagnostics testing (HIV-RDT) model. The full economic cost, including fixed and variable cost, from a health provider perspective using a micro costing approach was estimated. We determined the cost-effectiveness of these two HIV testing models over a two year time horizon (i.e. duration of the programs), and reported costs using US dollars (2020). Results: From January 2017 to December 2018, a total of 4,633 men tested in the HIVST model, and 1,780 men tested in the HIV-RDT model. The total number of new diagnosis was 155 for HIVST and 126 for the HIV-RDT model; the HIV test positivity was 3.3% (95% confidence interval (CI): 2.8-3.9) for the HIVST model and 7.1% (95% CI: 5.9-8.4) for the HIV-RDT model. The mean cost per person tested was $14.57 for HIVST and $24.74 for HIV-RDT. However, the mean cost per diagnosed was higher for HIVST ($435.52) compared with $349.44 for HIV-RDT.Conclusion: Our study confirms that compared to facility-based HIV-RDT, a community-based organization led HIVST program could have a cheaper mean cost per MSM tested for HIV in China. Better targeting of high-risk individuals would further improve the cost-effectiveness of HIVST.

Shigella sp. is a highly infectious intestinal pathogen worthy of serious attention that is widely present in aquaculture water and some other polluted water types and might inhibit embryonic development as a biological pollutant. In this study, acute toxicity tests in which Xenopus tropical embryos were exposed to Shigella flexneri at subpathogenic concentrations (10

BACKGROUND Social network–based strategies can expand HIV/syphilis self-tests among men who have sex with men (MSM). Sexual health influencers are individuals who are particularly capable of spreading information about HIV and other sexually transmitted infections (STIs) within their social networks. However, it remains unknown whether a sexual health influencer can encourage their peers to self-test for HIV/syphilis. OBJECTIVE The aims of this study were to examine the impact of MSM sexual health influencers on improving HIV/syphilis self-test uptake within their social networks compared to that of nonsexual health influencers. METHODS In Zhuhai, China, men 16 years or older, born biologically male, who reported ever having had sex with a man, and applying for HIV/syphilis self-tests were enrolled online as indexes and encouraged to distribute self-tests to individuals (alters) in their social network. Indexes scoring >3 on a sexual health influencer scale were considered to be sexual health influencers (Cronbach α=.87). The primary outcome was the mean number of alters encouraged to test per index for sexual health influencers compared with the number encouraged by noninfluencers. RESULTS Participants included 371 indexes and 278 alters. Among indexes, 77 (20.8%) were sexual health influencers and 294 (79.2%) were noninfluencers. On average, each sexual health influencer successfully encouraged 1.66 alters to self-test compared to 0.51 alters encouraged by each noninfluencer (adjusted rate ratio 2.07, 95% CI 1.59-2.69). More sexual health influencers disclosed their sexual orientation (80.5% vs 67.3%, P=.02) and were community-based organization volunteers (18.2% vs 2.7%, PPPP CONCLUSIONS Being a sexual health influencer was associated with encouraging more alters with less testing access to self-test for HIV/syphilis. Sexual health influencers can be engaged as seeds to expand HIV/syphilis testing coverage.

Background: The unclear mechanisms and severity of injuries in the injury pyramids for Chinese children and adolescents prevent the prioritization of interventions. This study aimed to describe the injury mechanisms and injury pyramids in this population to provide a priority for injury prevention strategies. Methods: Death, hospitalization, and outpatient/emergency department visit data from patients aged 0~17 years with injuries were obtained from January 1, 2013, to December 31, 2017, in Zhuhai City, China. The injury mechanism ratios were calculated, and the injury pyramid ratios were drawn in proportion using injury mortality and the incidence of both injury hospitalizations and outpatient/emergency department injury visits. Results: The top three mechanisms for injuries in children and adolescents treated in outpatient/emergency departments were falls (52.02%), animal bites (14.57%), and blunt injuries (10.60%). The top three mechanisms for injury hospitalizations were falls (37.33%), road traffic injuries (17.87%), and fire/burns (14.29%), while the top three mechanisms for injury deaths were drowning (32.91%), road traffic injuries (20.25%) and falls (13.92%). The incidence rate of outpatient/emergency department injury visits for children and adolescents was 11,210.87/100,000; the incidence rate of injury hospitalization was 627.09/100,000, and the injury death rate was 10.70/100,000. For each injury death, there were 59 injury hospitalizations and 1,047 outpatient/emergency injury visits. Conclusions: The injury mechanisms were different for injury-related outpatient/emergency department visits, hospitalizations, and deaths among children and adolescents. The injury mechanisms by sex at different stages of child development, and interventions should be formulated based on this finding. The ratios of the injury pyramids varied by age, sex, region, and injury mechanisms; minor nonfatal injuries were more common in children and adolescents. The differences in the severity and extent of the injuries suggested that injury interventions in children and adolescents still have a long way to go.

Background Social media and secondary distribution (distributing self-testing kits by indexes through their networks) both show strong promise to improve human immunodeficiency virus (HIV) self-testing uptake. We assessed an implementation program in Zhuhai, China, which focused on the secondary distribution of HIV/syphilis self-test kits among men who have sex with men (MSM) via social media. Methods Men aged ≥16 years, born biologically male, and ever had sex with another man were recruited as indexes. Banner ads on a social media platform invited the participants to apply for up to 5 self-test kits every 3 months. Index men paid a deposit of US$15/kit refundable upon submitting a photograph of a completed test result via an online submission system. They were informed that they could distribute the kits to others (referred to as “alters”). Results A total of 371 unique index men applied for 1150 kits (mean age, 28.7 [standard deviation, 6.9] years), of which 1141 test results were returned (99%). Among them, 1099 were valid test results; 810 (74%) were from 331 unique index men, and 289 tests (26%) were from 281 unique alters. Compared to index men, a higher proportion of alters were naive HIV testers (40% vs 21%; P < .001). The total HIV self-test reactivity rate was 3%, with alters having a significantly higher rate than indexes (5% vs 2%; P = .008). A total of 21 people (3%) had a reactive syphilis test result. Conclusions Integrating social media with the secondary distribution of self-test kits may hold promise to increase HIV/syphilis testing coverage and case identification among MSM.

Background Human immunodeficiency virus (HIV) testing is a crucial strategy for HIV prevention. HIV testing rates remain low among men who have sex with men (MSM) in China. Digital network-based secondary distribution is considered as an effective model to enhance HIV self-testing (HIVST) among key populations. Digital platforms provide opportunities for testers to apply for HIVST kits by themselves, and secondary distribution allows them to apply for multiple kits to deliver to their sexual partners or members within their social network. We describe a three-arm randomized controlled trial to examine the effect of monetary incentives and peer referral in promoting digital network-based secondary distribution of HIVST among MSM in China. Methods Three hundred MSM in China will be enrolled through a digital platform for data collection. The eligibility criteria include being biological male, 18 years of age or over, ever having had sex with another man, being able to apply for kits via the online platform, and being willing to provide personal telephone number for follow-up. Eligible participants will be randomly allocated into one of the three arms: standard secondary distribution arm, secondary distribution with monetary incentives arm, and secondary distribution with monetary incentives plus peer referral arm. Participants (defined as “index”) will distribute actual HIV self-test kits to members within their social network (defined as “alter”) or share referral links to encourage alters to apply HIV self-test kits by themselves. All index participants will be requested to complete a baseline survey and a 3-month follow-up survey. Both indexes and alters will complete a survey upon returning the results by taking a photo of the used kits with the unique identification number. Discussion HIV testing rates remain suboptimal among MSM in China. Innovative interventions are needed to further expand the uptake of HIV testing among key populations. The findings of the trial can provide scientific evidence and experience on promoting secondary distribution of HIVST to reach key populations who have not yet been covered by existing testing services. Trial registration The study was registered in the Chinese Clinical Trial Registry (ChiCTR1900025433) on 26, August 2019, http://www.chictr.org.cn/showproj.aspx?proj=42001. Prospectively registered.

This paper presents a total phosphorus online real-time monitoring system integrated with on-chip digestion based on the merits of optofluidic technology. The integrated optofluidic device contains a hollow optical fiber employed for pretreatment and digestion of phosphorus solution samples, a polydimethylsiloxane (PDMS)-based micromixer with convergent&ndash, divergent walls designed to enable sufficient mixing and chromogenic reaction, and a couple of optical fiber collimators attached with a Z-shaped flow cell for optical detection. Details of system design and fabrication are introduced in this paper. In the experiment, on-chip digestion of four typical phosphates in aqueous solution including organophosphorus and inorganic phosphorus is investigated under different reaction conditions, such as digestion temperature, concentration of oxidant and pH value, and the optimal reaction parameters are explored under different conditions. Meanwhile, we demonstrate the online real-time monitoring function of the optofluidic device, and the digestion mechanisms of four different phosphates are analyzed and discussed. Compared with the national standard method, we find that the measurement accuracy and sensitivity are acceptable when the concentration of total phosphorus is between 0.005&ndash, 0.9 mg/L (by weight of P) in aqueous solution, which covers the range defined in the national standard. The traditional digestion time of several hours is greatly reduced to less than 10 s, and the content of total phosphorus can be obtained in a few minutes. The integrated optofluidic device can significantly shorten the test time and reduce the sample amount, and also provides a versatile platform for the real-time detection and analysis of many biochemical samples.

Background Social network–based strategies can expand HIV/syphilis self-tests among men who have sex with men (MSM). Sexual health influencers are individuals who are particularly capable of spreading information about HIV and other sexually transmitted infections (STIs) within their social networks. However, it remains unknown whether a sexual health influencer can encourage their peers to self-test for HIV/syphilis. Objective The aims of this study were to examine the impact of MSM sexual health influencers on improving HIV/syphilis self-test uptake within their social networks compared to that of nonsexual health influencers. Methods In Zhuhai, China, men 16 years or older, born biologically male, who reported ever having had sex with a man, and applying for HIV/syphilis self-tests were enrolled online as indexes and encouraged to distribute self-tests to individuals (alters) in their social network. Indexes scoring >3 on a sexual health influencer scale were considered to be sexual health influencers (Cronbach α=.87). The primary outcome was the mean number of alters encouraged to test per index for sexual health influencers compared with the number encouraged by noninfluencers. Results Participants included 371 indexes and 278 alters. Among indexes, 77 (20.8%) were sexual health influencers and 294 (79.2%) were noninfluencers. On average, each sexual health influencer successfully encouraged 1.66 alters to self-test compared to 0.51 alters encouraged by each noninfluencer (adjusted rate ratio 2.07, 95% CI 1.59-2.69). More sexual health influencers disclosed their sexual orientation (80.5% vs 67.3%, P=.02) and were community-based organization volunteers (18.2% vs 2.7%, P Conclusions Being a sexual health influencer was associated with encouraging more alters with less testing access to self-test for HIV/syphilis. Sexual health influencers can be engaged as seeds to expand HIV/syphilis testing coverage.

Background: Social media and secondary distribution (distributing self-testing kits by indexes through their networks) both show strong promise to improve HIV self-testing uptake. We assessed an implementation program in Zhuhai, China, which focused on the secomdary distribution of HIV/syphilis self-test kits via social media. Methods: Men of age 16 or above, born biologically male, and ever had sex with another man were recruited as indexes. Banner ads on a social media platform invited the participants to apply for up to five self-test kits every three-months. Index men paid a deposit of 15 USD/kit (refundable) upon submitting a photograph of a completed test result via an online submission system. They were informed that they could distribute the kits to others (referred to as “alters”). Findings: A total of 649 men applied for 1150 kits (mean age=28•7±6.9), of which 1141 test results were returned (99%). Among them, 1099 were valid test results, 810 (74%) were from 331 unique index men, and 289 tests (26%) were from 281 unique alters. Compared to index men, a higher proportion of alters were HIV new testers (40% VS. 21%. The total HIV self-test reactivity rate was 3% (20/612), with alters having a significantly higher rate than indexes (5% VS 2%). A total of 21 people (3%) had a reactive syphilis test result. Interpretation: Integrating social media with the secondary distribution of self-test kits may hold promise to increase HIV/syphilis testing coverage and case identification among men who have sex with men. Funding: Zhuhai CDC and NIH. Declaration of Interest: None declared. Ethical Approval: The study protocol was approved by the Zhuhai Municipal Center for Diseases Control and Prevention. Inform consent was collected from each index participants. This study was reported by following the STROBE Statement.

Wastewater containing EDTA-Ni (ethylenediaminetetraacetic acid nickel salt) must be treated due to its high toxicity, accumulation of nickel and non-degradability. In the present study, effect of carbon chain length of dithiocarbamate on the removal efficiency of Ni 2+ from an EDTA-Ni solution has been analyzed. Sodium dimethyl dithiocarbamate, sodium diethyl dithiocarbamate and sodium dibutyl dithiocarbamate were used to study their Ni 2+ removal performances from various types of EDTA-Ni solutions. Mechanisms of reactions between different dithiocarbamates and Ni 2+ were also studied. The results indicate that the rate of Ni 2+ increased with an increase in the carbon chain length of dithiocarbamate. Infrared spectral analysis inferred that the three dithiocarbamates had similar removal mechanisms despite having different carbon chain lengths: all showing Ni 2+ chelation. The thiol of dithiocarbamate captures Ni 2+ and tends to produce an insoluble chelate. The results from scanning electron microscope show that for longer carbon chain, the chelate product is more closely packed. Therefore, removed efficiency by sodium dibutyl dithiocarbamate was higher. Meanwhile coexistence of Cr 6+ , Cu 2+ and Fe 3+ inhibited the removal of Ni 2+ , but Zn 2+ promoted it. Metal ion impact became clearer as carbon chain length increased. The chelation capability of the three dithiocarbamates with metal ions was: Cr 6+ 3+ 2+ 2+ and Cu 2+ > Zn 2+ . Finally, these dithiocarbamates were tested in actual electroplating wastewater to validate our conclusions. After sodium dibutyl dithiocarbamate treatment, all residual metals' concentrations met the new tougher requirements announced by the Department of Environmental Protection of Guangdong province in Document No.25.

The study aimed to develop a rapid and practical Fenton treatment technique for sludge dewatering. The results indicated that the Fenton reaction time could be shortened to 5 min under suitable conditions. In addition, an orthogonal experimental design method was used to optimize the rapid Fenton treatment process. The optimal conditions were as followings, pH 3, Fe 2+ of 50 mg/g DS (dry solids), H 2 O 2 of 30 mg/g DS and lime of 50 mg/g DS, at which the specific resistance to filtration (SRF) reduction efficiency of 96% was achieved. The dosage of Fe 2+ was demonstrated to be the most significant factor affecting sludge dewaterability. Furthermore, the lowest extracellular polymeric substances (EPS) concentration in the sludge supernatant was measured under the optimal conditions, suggesting that Fenton’s reagent acted both as an oxidant and as an effective coagulant for the sludge fragments. The morphology of the sludge cake exhibited a relatively regular and spongy block-like structure, which could maintain high permeability during high-pressure filtration. With the novel filter press achieved the squeezing pressure up to 40 MPa, the water content of sludge cake could be reduced to 55.1 ± 0.6%. Additionally, the economic assessment shows that the rapid Fenton treatment combined with high-pressure filtration can be a suitable technique for sewage sludge dewatering.