UV-TiO_2 photocatalytic disinfection and photoreactivation of pathogenic bacterium in municipal wastewater

The disinfected bacteria will be a photoreactivation under the irradiation of the sunlight,and the light intensity plays an important role in the bacteria resurrection.The effect of light intensity on photoreactivation of Escherichia coli(E.coli) and Enterococcus faecalis(E.faecalis) in secondary effluents which were disinfected respectively by pure UV and UV-TiO_2 was investigated.The results show that the disinfection efficiency of UV-TiO_2 is much higher than that of the pure UV disinfection.The photoreactivation rate of E.coli is much higher in pure UV disinfection than in UV-TiO_2 photocatalytic disinfection.Under high light intensity in UV-TiO_2 disinfection,high resurrection rate can be induced.However,a higher resurrection rate can be introduced even under low light intensity in pure UV disinfection alone.Meanwhile,UV-TiO_2 disinfection has a strong inhibition effect on E.faecalis photoreactivation.When the light intensity is lower than 21 μW/cm^2,nearly no resurrection of E.faecalis occurs after 72 h resurrection irradiation,and a little resurrection rate is observed only under a strong photoreactivating light intensity.

Performance of alkaline pretreatment on pathogens inactivation and sludge solubilization

Inactivation of pathogen indicators(i.e.,faecal coliforms,Salmonella spp.,faecal streptococcus,and helminth eggs)were investigated during alkaline pretreatment(pH=10 and 12)in this study.The performance of alkaline pretreatment on the inactivation pathogens,kinetic of pathogens inactivation and sludge solubilization was evaluated.Results of alkaline pretreatment showed that the complete inactivation periods of pathogens time were 1.5 d,1.5 d,2 d,2.5 d,3 d,3 d and 3 d for faecal sludge total solids(TS)of 1%,2%,4%,6%,8%,10%and 12%,respectively.The kinetics of pathogen inactivation can be predicted better by Weibull than the first-order model.Meanwhile,the relationship between alkaline pretreatment time and the TS content of the sludge agrees with the exponential equation(y=1.3543e10.002x,1%≤x≤8%)and logarithmic equation(y=3,8%≤x≤12%).Furthermore,alkaline pretreatment can improve sludge solubilization and has a more significant effect on protein solubilization than on soluble chemical oxygen demand(SCOD).

Aggregation-induced emission biomaterials for anti-pathogen medical applications:detecting,imaging and killing

Microbial pathogens,including bacteria,fungi and viruses,greatly threaten the global public health.For pathogen infections,early diagnosis and precise treatment are essential to cut the mortality rate.The emergence of aggregation‐induced emission(AIE)biomaterials provides an effective and promising tool for the theranostics of pathogen infections.In this review,the recent advances about AIE biomaterials for anti-pathogen theranostics are summarized.With the excellent sensitivity and photostability,AIE biomaterials have been widely applied for precise diagnosis of pathogens.Besides,different types of anti-pathogen methods based on AIE biomaterials will be presented in detail,including chemotherapy and phototherapy.Finally,the existing deficiencies and future development of AIE biomaterials for anti-pathogen applications will be discussed.

Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival

Tomato plant waste（TPW） was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS（total solid） concentrations of 2%, 4% and 6% respectively, at mesophilic（37 ± 1°C） and room（20–25°C） temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416 L/kg VS（volatile solids）. The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR（polymerase chain reaction） were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA（volatile fatty acid） concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.

Locally enhanced electric field treatment (LEEFT) for water disinfection

Water disinfection is a critical step in water and wastewater treatment.The most widely used chlorination suffers from the formation of carcinogenic disinfection by-products(DBPs)while alternative methods(e.g.,UV,O3,and membrane filtration)are limited by microbial regrowth,no residual disinfectant,and high operation cost.Here,a nanowire-enabled disinfection method,locally enhanced electric field treatment(LEEFT),is introduced with advantages of no chemical addition,no DBP formation,low energy consumption,and efficient microbial inactivation.Attributed to the lightning rod effect,the electric field near the tip area of the nanowires on the electrode is significantly enhanced to inactivate microbes,even though a small external voltage(usually<5 V)is applied.In this review,after emphasizing the significance of water disinfection,the theory of the LEEFT is explained.Subsequently,the recent development of the LEEFT technology on electrode materials and device configurations are summarized.The disinfection performance is analyzed,with respect to the operating parameters,universality against different microorganisms,electrode durability,and energy consumption.The studies on the inactivation mechanisms during the LEEFT are also reviewed.Lastly,the challenges and future research of LEEFT disinfection are discussed.