Shifts of live bacterial community in secondary effluent by chlorine disinfection revealed by Miseq high-throughput sequencing combined with propidium monoazide treatment.

Chlorine disinfection is a commonly used disinfection process in wastewater treatment, but its effects on the indigenous bacterial community in treated wastewater have not been fully elucidated. In this study, secondary effluent samples collected in four wastewater treatment plants (WWTPs) were selected for chlorine disinfection. Shifts in the bacterial community compositions in secondary effluent samples upon chlorine disinfection, both immediately and after 24 h of storage, were investigated using Illumina MiSeq sequencing combined with propidium monoazide (PMA) treatment.

Prevalence of antibiotic-resistant bacteria in a lake for the storage of reclaimed water before and after usage as cooling water.

Wastewater reclamation and reuse is a promising way to relieve water scarcity by substituting for natural water consumption by industrial cooling. However, health concerns regarding cooling water originating from reclaimed water are increasing because an abundance of antibiotic-resistant bacteria (ARB) has been detected in reclaimed water. To assess the potential increase of ARB risks in reclaimed water after reuse for industrial cooling, the prevalence of six types of ARB was investigated in water and sediment samples from Lake Gaobeidian, which serves as an artificial circular storage reservoir for reclaimed water for cooling reuse.

[Inactivation and reactivation of antibiotic-resistant bacteria during and after UV disinfection in reclaimed water].

Prevalence of antibiotic-resistant bacteria in wastewater effluents is concerned as an emerging contaminant. To estimate inactivation and reactivation potentials of antibiotic-resistant bacteria by UV disinfection, inactivation and reactivation of penicillin-, ampicillin-, cephalexin-, chloramphenicol-and rifampicin-resistant bacteria in the secondary effluent were studied under different UV doses. The results showed that the inactivation ratios of penicillin-, ampicillin-, cephalexin-and chloramphenicol-resistant bacteria were higher than 4-log, which was closed to that of total heterotrophic bacteria; however, the inactivation ratio of rifampicin-resistant bacteria was lower (3.

Simulation of Biomass Accumulation Pattern in Vapor-Phase Biofilters.

Existence of inert biomass and its impact on biomass accumulation patterns and biofilter performance were investigated. Four biofilters were set up in parallel to treat gaseous toluene. Each biofilter operated under different inlet toluene loadings for 100 days.

[Mechanisms of UV photodegradation on performance of a subsequent biofilter treating gaseous chlorobenzene].

To provide insight into effects of UV pretreatment on a subsequent biofilters, the mechanisms of UV pretreatment on biofilter performance were further studied. Results showed that gaseous chlorobenzene UV photodegradation products resulted in a pH decrease from 6-8 to 4-7 in filter bed. Ozone produced by UV photodegradation changed the physical properties of biofilm by reducing biofilm thickness and oxidizing surface part of the extra-cellular polymer substance, which promoted the oxygen, nutrient and pollutant transfer to biofilm.

Modeling of a combined ultraviolet-biofilter system to treat gaseous chlorobenzene I: model development and parametric sensitivity.

A new type of a combined ultraviolet (UV)-biofilter system for air pollution control is developed. In this paper, two conceptual mathematical submodels of the UV reactor and standalone biofilter are developed. All model parameters have been determined by independent experiments or have been taken from literature.

Stimulative effects of ozone on a biofilter treating gaseous chlorobenzene.

Recalcitrant volatile organic compounds with low biodegradabilities pose challenges for biofiltration technologies. In this study, the effects and mechanism of adding ozone on the performance of a biofilter were investigated. A biofilter treating chlorobenzene was set up and operated continuously for 265 days under different inlet ozone concentrations.

Advantages of combined UV photodegradation and biofiltration processes to treat gaseous chlorobenzene.

A combined ultraviolet photodegradation and biofiltration (UV-BF) process was developed to treat gaseous chlorobenzene. The performance of this process was evaluated under various operating conditions, including different inlet concentrations, residence times, and transient loadings, and compared with a control biofiltration (BF) process. Furthermore, the acute biotoxicities of the photodegradation products, the bioaerosol emissions from biofilters, the biomass accumulation and pressure drop in biofilters were investigated.

Effects of UV pretreatment on microbial community structure and metabolic characteristics in a subsequent biofilter treating gaseous chlorobenzene.

To provide insight into effects of UV pretreatment on microorganisms in subsequent biofilters, the changes of microbial community structure and metabolic characteristics of biofilters with (UV-BF) and without (BF) UV pretreatment were studied. The respiratory quinone and BIOLOG methods were used to analyze microbial community structure and metabolic characteristics, respectively. The results indicated the quinone profiles, the species of dominant quinone and its molar fraction of the biofilm in both biofilters showed different behaviors.

Reduction of toxic products and bioaerosol emission of a combined ultraviolet-biofilter process for chlorobenzene treatment.

A combined process involving ultraviolet (UV) photodegradation and biofiltration was developed to treat gaseous chlorobenzene. The toxicity of the photodegradation products and the bioaerosol emissions from the biofilter were investigated. The experimental results showed that a standalone UV photodegradation of chlorobenzene can result in products having significant acute toxicity and genotoxicity, whereas a biofiltration process can produce a high concentration of bioaerosols, which are a potential health risk.

Effects of operation conditions on removal rate constant and quantum yield of gaseous chlorobenzene degradation in a photochemical reactor.

A photochemical reactor with a low-pressure mercury ultraviolet (UV) lamp was established to treat waste gas containing chlorobenzene. Operation conditions such as light intensity, gas humidity, and inlet chlorobenzene concentration were varied. Two significant parameters, the removal rate constant and the quantum yield (relating to removal kinetic and light energy utilization), were investigated under each set of conditions.

[Establishment and application of gaseous chlorobenzene UV-photodegradation model].

This work was attempted to provide a model to describe the performance of an UV photochemical reactor to remove gaseous chlorobenzene. Based on photochemical process and linear source sphere emission (LSSE) irradiation energy distribution, the model established in this study indicated that the performance of the reactor was dependent on the local volumetric rate of energy absorption (LVREA) inside reactor, the empty bed residence time and the inlet concentration. Moreover, the model was used to predict the outlet concentrations under the operating conditions of various inlet chlorobenzene concentrations and empty bed residence time.

Biodegradation of gaseous chlorobenzene by white-rot fungus Phanerochaete chrysosporium.

Objective: To evaluate the effect of white rot fungus Phanerochaete chrysosporium on removal of gaseous chlorobenzene.

Methods: Fungal mycelium mixed with a liquid medium was placed into airtight bottles. A certain amount of chlorobenzene was injected into the headspace of the bottles under different conditions.

Chemical identification and acute biotoxicity assessment of gaseous chlorobenzene photodegradation products.

In order to evaluate the ecological safety and feasibility of UV photodegradation processes for the treatment of halogenated aromatic hydrocarbons, the chemical composition and acute biotoxicity of gaseous chlorobenzene photodegradation products were investigated. Results showed that the main products of chlorobenzene photodegradation included hydrochloric acid, acetic acid, formic acid, phenol and chlorophenol. Roughly 64% of the removed chlorobenzene was converted into phenol, making it the most significant product formed.

[White rot fungi biofilter treating waste gas containing chlorobenzene].

A novel gas-solid phase bioreactor, using bamboo as support material, inoculated with white rot fungi Phanerochaete chrysosporium was established to treat waste gas containing chlorobenzene. The performance of P. chrysosporium bioreactor was examined under different conditions.

[Characterization of thermophilic strain SY-14 with capability to lyse bacterial cells].

One spore-forming thermophilic bacterial strain SY-14, isolated from sewage sludge compost, showed significant capability to lyse bacterial cells. The strain was identified as Geobacillus sp. based on morphological characteristics and homology identification of 16S rDNA sequence.

[Chemical removal of excess biomass from biofilters].

Biomass control techniques are very important for biofilters treating volatile organic compounds (VOCs) to enhance their long-term operation performance. In this study, four paralleled biofilters were set up treating toluene gas. The chemical removal of excess biomass and its impact on biofilter operation were investigated.

[Metabolic properties of the microbial community in the biofilters using biolog microplates].

It is very important to know the structure and metabolic function of the microbial community in a bioreactor in order to improve its performance. In this study, two biofilters, packed with wood chips and granular activated carbons respectively, were operated for 160 days to treat toluene gas. The metabolic profiles of the microbial communities in the biofilters were monitored using Biolog microplates periodically during the experiments.