Different rapid startups for high-solid anaerobic digestion treating pig manure: Metagenomic insights into antibiotic resistance genes fate and microbial metabolic pathway.

High-solid anaerobic digestion (HSAD), as an emerging disposal technology for swine manure, was commonly hampered by the long lag phase and slow startup, resulting in poor performance. Rapid startups by different leachate reflux forms can solve the problem, but related study was scarcely reported. Therefore, metagenomic analysis was used to exploit the effects of different rapid startups on the biogas performance, antibiotic resistance genes (ARGs) removal and microbial metabolic pathway during HSAD. Compared anaerobic digestion with natural start (T1), three different rapid startups were set, including with autologous leachate reflux (T2), with water reflux (T3) and with exogenous leachate reflux (T4). The results showed that rapid startups (T2-T4) enhanced biogas yield and the cumulative methane yield was increased by 3.7-7.3 times compared with the control. Totally, 922 ARGs were found, most of which belonged to multidrug and MLS ARGs. About 56% of these ARGs could be reduced in T4, while just 32% of ARGs were reduced in T1. Antibiotic efflux pump is the main mechanism of microbial action, which could be decreased largely by these treatments. Moreover, all the rapid startups (T2-T4) made Methanosarcina content (9.59%-75.91%) higher than that in the natural startup of T1 (4.54%-40.27%). This is why these fast-startups helped methane production fast. Network analysis showed that microbial community and environmental factors (pH and VFAs) both contributed to the spread of ARGs. The reconstructed methane metabolic pathway by different identified genes showed that all methanogenesis pathways existed but acetate metabolic pathway was dominant. And the rapid startups made the abundance of acetate metabolic (M00357) higher than the natural startup.

Emerging Pollutants - Part II: Treatment.

Emerging pollutants (EPs) are a class of chemical pollutants that have potential or substantial threats to human health and ecological environment. EPs mainly include pharmaceuticals and personal care products, endocrine disrupting chemicals, antibiotics, persistent organic pollutants, disinfection by-products and other industrial chemicals, etc. In recent years, with the improvement of environmental analysis level, these substances have been detected frequently in urban sewage, surface water and drinking water all over the world. The continuous detection of EPs brings new challenges to water pollution control, and also makes EPs treatment an international research hotspot. This paper summarizes some research results on emerging pollutants treatment published in 2017.

Molecular biological methods in environmental engineering.

Environmental bioremediation technologies are undoubtedly more economical and environmental friendly, and present a good application prospect. Microorganisms can be used to monitor environmental changes for their quickly respond to environmental changes. Microbiological molecular biology methods have attracted more and more attention from human beings, and their applications in the environment is also expanding. Genomics, transcriptomics, proteomics, and metabolomics are four major molecular biology techniques. This review summarizes application of molecular biological methods in environmental engineering in 2017. The summary includes methods for DNA, RNA, and protein extraction, the application of four major technologies in the environmental field, and commonly used methods for in situ monitoring in the environment, including fluorescence in situ hybridization, real-time quantitative PCR, and amplicons sequencing technology.

Activated Sludge and other Aerobic Suspended Culture Processes.

In this paper, removal model of activated sludge, cultivation and application of granular sludge, the population dynamics, removal and influence of toxic pollutants, and design and control of the sewage treatment system are reviewed in 2017. Several studies suggest that the cultivation of granular sludge is mainly affected by aeration rate, hydraulic velocity and culture environment. Toxic pollutants can be partially degraded by microorganisms, which lead to the change of microbial community structure. The co-digestion of activated sludge and other solid wastes can produce biomass energy, which is a more promising and solid waste treatment method.

Anaerobic Process.

A review of the literatures published in 2017 on topics relating to anaerobic process issues in the improvement of biogas production and fermentation efficiency of various kinds of organic waste. New process methodology and technology of digestion is also presented. This review is divided into the following sections: pretreatment, organic waste and co-digestion, multiple-stage process, process methodology and technology.

Ranking media for multi-pollutant removal efficiency in bioretention.

Bioretention is an effective best management practice for urban stormwater. This study aims to provide guidance for selecting the best bioretention medium in terms of pollutant removal capacity. Fuzzy set theory was applied with the improved analytic hierarchy process (IAHP) for weight determination, thus forming the fuzzy synthetic evaluation model, to assess the comprehensive efficiencies of certain sand media. This work is the first to use this method to study bioretention. Results demonstrated that the fuzzy synthetic evaluation model was a rational choice for the selection of bioretention media. The studied media were ranked by pollutant removal capacity as follows: Media III > Media V > Media I > Media VI > Media II > Media VII > Media IV. Media I had the best comprehensive removal efficiency and infiltration rate in bioretention. Moreover, the removal rates for Cd2+, Zn2+ and Pb2+ were excellent (>80%), those for Cu2+ and NH+4-N fluctuated from 58.1% to 92.7% and 64.7% to 95.9%, respectively, and those for NO-3-N and TP of the seven media did not show distinct differences.

Sustainability.

Selected 2016 publications on the focus of Sustainability are reviewed and discussed here. The followings are the topics presented: • Sustainable water and wastewater utilities •Sustainable water resources management • Stormwater and green infrastructure • Sustainability in water and wastewater treatment •Life cycle assessment (LCA) applications • Sustainability for water and energy, • Sustainability and asset management.

Stream, Lake, and Reservoir Management.

This review on stream, lake, and reservoir management covers selected 2016 publications on the focus of the following sections: Stream, lake, and reservoir management • Water quality of stream, lake, and reservoir • Reservoir operations • Models of stream, lake, and reservoir • Remediation and restoration of stream, lake, and reservoir • Biota of stream, lake, and reservoir • Climate effect of stream, lake, and reservoir.

Emerging Pollutants - Part II: Treatment.

Emerging contaminants are considered as some substances of actual or potential threat to human health or environment, which include pharmaceutical, personal care products, endocrine disruptors, nanoparticles, antibiotic resistance genes and chemicals used in packaging products, etc. How to treat these emerging pollutants in water bodies with green, high efficiency and low-cost has become the focus of attention. The purpose of this review is to summarize published researches on emerging pollutants treatment in 2017.

Activated Sludge and other Aerobic Suspended Culture Processes.

This is a literature review for the year 2016 regarding to activated sludge in upflow anaerobic sludge blanket, sequencing batch reactor and membrane bioreactor. This article reviews process modeling and kinetic, population dynamic, pollution control, and system design and operation. Compared to past reviews, several topics show increasing concerns in 2016, like anammox process. It refers to the adsorption and biodegradation of nutrition by granular sludge, also including the emerging micropollutant like pharmaceuticals. Activated sludge codigestion with microalgal, municipal solid waste, food waste and agricultural waste to produce biomass energy was also mentioned.

Anaerobic Process.

This is a review of the literatures published in 2016 on the focus of Anaerobic Process. It is divided into the following sections. Pretreatment Organic waste Multiple-stage co-digestion Process Methodology and Technology.

Mixing and Transport.

This section covers research published during the calendar year 2016 on mixing and transport processes. The review covers mixing and transport of anaerobic digesters.

Molecular Biological Methods in Environmental Engineering.

Microorganisms can respond fast to the environmental changes, and well suited for environmental assessment. DNA and RNA are generally extracted by extraction kits. After extraction, molecular biological methods including genomics, transcriptomics, proteomics and metabolomics are applied to characterize the genetic and functional diversity of microorganisms. Quantitative PCR, FISH and mass sequence of amplicons are also described. This review provides environmental engineers and microbiologists an overview of important advancements in molecular techniques and highlights the application of these methods in diverse environments.

Simultaneous Bioreduction of Multiple Oxidized Contaminants Using a Membrane Biofilm Reactor.

This study tests a hydrogen-based membrane biofilm reactor (MBfR) to investigate simultaneous bioreduction of selected oxidized contaminants, including nitrate (-N), sulfate (), bromate (), chromate (Cr(VI)) and para-chloronitrobenzene (p-CNB). The experiments demonstrate that MBfR can achieve high performance for contaminants bioreduction to harmless or immobile forms in 240 days, with a maximum reduction fluxes of 0.901 g -N/m2·d, 1.573 g /m2·d, 0.009 g /m2·d, 0.022 g Cr(VI)/m2·d, and 0.043 g p-CNB/m2·d. Increasing H2 pressure and decreasing influent surface loading enhanced removal efficiency of the reactor. Flux analysis indicates that nitrate and sulfate reductions competed more strongly than , Cr(VI) and p-CNB reduction. The average H2 utilization rate, H2 flux, and H2 utilization efficiency of the reactor were 0.026 to 0.052 mg H2/cm3·d, 0.024 to 0.046 mg H2/cm2·d, and 97.5% to 99.3% (nearly 100%). Results show the hydrogen-based MBfR may be suitable for removing multiple oxidized contaminants in drinking water or groundwater.

Sustainability.

This review on Sustainability covers selected 2015 publications on the focus of Sustainability. It is divided into the following sections : • Sustainable water and wastewater utilities • Sustainable water resources management • Stormwater and green infrastructure • Sustainability in wastewater treatment • Life cycle assessment (LCA) applications • Sustainability and energy in wastewater industry, • Sustainability and asset management.

Stream, Lake, and Reservoir Management.

This review on stream, lake, and reservoir management covers selected 2015 publications on the focus of the following sections: • Biota • Climate effect • Models • Remediation and restoration • Reservoir operations • Stream, Lake, and Reservoir Management • Water quality.

Emerging Pollutants - Part II: Treatment.

Emerging contaminants are considered as some substances of actual or potential threat to human health or environment, which include endocrine disruptors, pharmaceutical, personal care products, nanoparticles, antibiotic resistance genes and chemicals used in packaging products, etc. The disposal and treatment of emerging contaminants has become a key problem in the field of water pollution control. The purpose of this review is to summarize published researches on emerging pollutants treatment in 2015.

Molecular Biological Methods in Environmental Engineering.

Bacteria, acting as catalysts, perform the function of degrading pollutants. Molecular biological techniques play an important role in research on the community analysis, the composition and the functions of complex microbial communities. The development of secondary high-throughput pyrosequencing techiniques enhances the understanding of the composition of the microbial community. The literatures of 2015 indicated that 16S rDNA gene as genetic tag is still the important method for bacteria identification and classification. 454 high throughput sequencing and Illumina MiSeq sequencing have been the primary and widely recognized methods to analyze the microbial. This review will provide environmental engineers and microbiologists an overview of important advancements in molecular techniques and highlight the application of these methods in diverse environments.

Activated Sludge and other Aerobic Suspended Culture Processes.

This is a literature review for the year 2015 and contains information specifically associated with suspended growth processes including activated sludge, upflow anaerobic sludge blanket, and sequencing batch reactors. The review encompasses modeling and kinetics, nutrient removal, system design and operation. Compared to past reviews, many topics show increase in activity in 2015. These include, fate and effect of xenobiotics, industrial wastes treatment with sludge, and pretreatment for the activated sludge. These topics are referred to the degradation of constituents in activated sludge. Other sections include population dynamics, process microbiology give an insight into the activated sludge. The subsection in industrial wastes: converting sewage sludge into biogases was also mentioned.

Agricultural Waste.

In recent years, the quantity of agricultural waste has been rising rapidly all over the world. As a result, the environmental problems and negative impacts of agricultural waste are drawn more and more attention. Therefore, there is a need to adopt proper approaches to reduce and reuse agricultural waste. This review presented about 200 literatures published in 2015 relating to the topic of agricultural waste. The review examined research on agricultural waste in 2015 from the following four aspects: the characterization, reuse, treatment, and management. Researchers highlighted the importance to reuse agricultural waste and investigated the potential to utilize it as biofertilizers, cultivation material, soil amendments, adsorbent, material, energy recycling, enzyme and catalyst etc. The treatment of agricultural waste included carbonization, biodegradation, composting hydrolysis and pyrolysis. Moreover, this review analyzed the differences of the research progress in 2015 from 2014. It may help to reveal the new findings and new trends in this field in 2015 comparing to 2014.