Diversity and metabolic potentials of As(III)-oxidizing bacteria in activated sludge

2021 ◽  
Author(s):  
Rui Xu ◽  
Duanyi Huang ◽  
Xiaoxu Sun ◽  
Miaomiao Zhang ◽  
Dongbo Wang ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Carbon Fixation ◽  
Stable Isotope Probing ◽  
Synthetic Wastewater ◽  
Contaminated Water ◽  
Natural Environments ◽  
Genes Encoding ◽  
Treatment Facilities

Biological arsenite (As(III)) oxidation is an important process in the removal of toxic arsenic (As) from contaminated water. However, the diversity and metabolic potentials of As(III)-oxidizing bacteria (AOBs) responsible for As(III) oxidation in wastewater treatment facilities are not well documented. In this study, two groups of bioreactors inoculated with activated sludge were operated under anoxic or oxic conditions to treat As-containing synthetic wastewater. Batch tests of inoculated sludges from the bioreactors further indicated that microorganisms could use nitrate or oxygen as electron acceptors to stimulate biological As(III) oxidation, suggesting the potentials of this process in wastewater treatment facilities. In addition, DNA-based stable isotope probing (DNA-SIP) was performed to identify the putative AOBs in the activated sludge. Bacteria associated with Thiobacillus were identified as nitrate-dependent AOBs, while bacteria associated with Hydrogenophaga were identified as aerobic AOBs in activated sludge. Metagenomic binning reconstructed a number of high-quality metagenome-assembled genomes (MAGs) associated with the putative AOBs. Functional genes encoding for As resistance, As(III) oxidation, denitrification, and carbon fixation were identified in these MAGs, suggesting their potentials for chemoautotrophic As(III) oxidation. In addition, the presence of genes encoding secondary metabolite biosynthesis and extracellular polymeric substance metabolism in these MAGs may facilitate the proliferation of these AOBs in activated sludge and enhance their capacity for As(III) oxidation. Importance AOBs play an important role in the removal of toxic arsenic from wastewater. Most of the AOBs have been isolated from natural environments. However, knowledge regarding the structure and functional roles of As(III)-oxidizing communities in wastewater treatment facilities are not well documented. The combination of DNA-SIP and metagenomic binning provides an opportunity to elucidate the diversity of in situ AOBs community inhabited the activated sludges. In this study, the putative AOBs responsible for As(III) oxidation in wastewater treatment facilities were identified, and their metabolic potentials including As(III) oxidation, denitrification, carbon fixation, secondary metabolites biosynthesis, and extracellular polymeric substances metabolisms were investigated. This observation provides an understanding of anoxic and/or oxic AOBs during the A(III) oxidation process in wastewater treatment facilities, which may contribute to the removal of As from contaminated water.

Improving the hydrobiological analysis of activated sludge at the Minsk wastewater treatment facilities

2021 ◽  
pp. 26-36
Author(s):  
О.С. Дубовик ◽  
Р.М. Маркевич ◽  
Е.В. Гаврилович ◽  
И.А. Гребенчикова ◽  
В.В. Иванович
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Point System ◽  
Treatment Conditions ◽  
Filamentous Microorganisms ◽  
Different Seasons ◽  
Treatment Facilities ◽  
Favorable Conditions ◽  
Quantitative Account ◽  
Different Levels

На основании накопленного опыта эксплуатации сооружений Минской очистной станции и обзора источников информации определена схема гидробиологического анализа активного ила, приведена форма регистрации результатов проведенного анализа. Для количественного учета нитчатых микроорганизмов разработана собственная пятибалльная система. Для нитчатых микроорганизмов, выявленных в активном иле, на основании анализа литературных данных определены условия, благоприятствующие их массовому развитию. В течение длительного периода времени, включающего разные сезоны года, проведена апробация усовершенствованной методики для мониторинга состояния иловой суспензии очистных сооружений двух площадок станции: классических четырехкоридорных аэротенков-вытеснителей первой площадки и биореакторов с каскадной денитрификацией второй площадки. Определены представители нитчатых микроорганизмов, постоянно обитающие в очистных сооружениях, выявлены доминирующие виды. Проведено сопоставление результатов анализа нитчатых форм и седиментационных характеристик активного ила. Сделаны заключения об особенностях биоценоза аэротенков первой площадки и биореакторов второй площадки, идентичности по видовому составу сообществ нитчатых бактерий, влиянии состава сточных вод и условий их очистки (нагрузка на ил, наличие зон с разным уровнем аэрации) на свойства иловой суспензии. Based on the accumulated experience in operating the Minsk Wastewater Treatment Facilities and a review of information sources, a scheme for the hydrobiological analysis of activated sludge was determined, and a form for recording the results of the analysis was provided. For the quantitative account of filamentous microorganisms, an original five-point system was developed. Based on the literature data analysis, favorable conditions for the mass growth of filamentous microorganisms found in activated sludge were determined. Over a long period of time, including different seasons of the year, the improved methodology was tested for monitoring the state of the sludge suspension at two sites of the treatment facilities: traditional four-line continuous-flow aeration tanks at the first site and bioreactors with cascade denitrification at the second site. The species of filamentous microorganisms, permanently living in wastewater treatment structures, have been identified, and the dominant species have been determined. The results of the analysis of filamentous forms and sedimentation characteristics of activated sludge are compared. Conclusions were made about the features of the biocenosis in the aeration tanks at the first site and in the bioreactors at the second site; about the identity of the species composition of the filamentous bacteria communities, the effect of the wastewater composition and treatment conditions (sludge load, occurrence of zones with different levels of aeration) on the properties of the sludge suspension.

scholarly journals PCR Detection of Genes Encoding Nitrite Reductase in Denitrifying Bacteria

1999 ◽  
Vol 65 (4) ◽  
pp. 1652-1657 ◽  
Author(s):  
Sara Hallin ◽  
Per-Eric Lindgren
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nitrite Reductase ◽  
Wastewater Treatment Plants ◽  
Paracoccus Denitrificans ◽  
Pcr Primers ◽  
Genes Encoding ◽  
Pcr Products ◽  
Key Enzyme ◽  
Sequence Relationships

ABSTRACT Using consensus regions in gene sequences encoding the two forms of nitrite reductase (Nir), a key enzyme in the denitrification pathway, we designed two sets of PCR primers to amplifycd 1- and Cu-nir. The primers were evaluated by screening defined denitrifying strains, denitrifying isolates from wastewater treatment plants, and extracts from activated sludge. Sequence relationships ofnir genes were also established. Thecd 1 primers were designed to amplify a 778 to 799-bp region of cd1-nir in the six published sequences. Likewise, the Cu primers amplified a 473-bp region in seven of the eight published Cu-nir sequences. Together, the two sets of PCR primers amplified nir genes in nine species within four genera, as well as in four of the seven sludge isolates. The primers did not amplify genes of nondenitrifying strains. The Cu primers amplified the expected fragment in all 13 sludge samples, but cd1-nir fragments were only obtained in five samples. PCR products of the expected sizes were verified as nir genes after hybridization to DNA probes, except in one case. The sequenced nir fragments were related to other nir sequences, demonstrating that the primers amplified the correct gene. The selected primer sites for Cu-nir were conserved, while broad-range primers targeting conserved regions of cd1-nir seem to be difficult to find. We also report on the existence of Cu-nir in Paracoccus denitrificans Pd1222.

Biological odour control by diffusion into activated sludge basins

2000 ◽  
Vol 41 (6) ◽  
pp. 127-132 ◽  
Author(s):  
R. P. Bowker
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
High Strength ◽  
Air Stream ◽  
Fine Bubble ◽  
Treatment Facilities ◽  
Odour Control ◽  
Odour Emissions ◽  
Air Streams

Diffusion of odourous air into activated sludge basins is an effective and economical approach for odour control at wastewater treatment plants. Over 30 facilities in North America practice this technique. Most of these applications are for dilute or moderate strength air streams with relatively low hydrogen sulfide (H2S) levels. Unfortunately, the lack of data documenting the effectiveness of the process and concerns for blower corrosion have limited its acceptance as a method for controlling odour emissions. This paper presents a compilation and review of wastewater treatment facilities that are currently using activated sludge diffusion. Performance data are tabulated, and information on operation and maintenance of the blower/diffuser systems are summarized. New data are presented that compare the effectiveness of coarse vs. fine bubble diffusers for treatment of a high strength, high-H2S air stream from sludge holding tanks at Concord, NH. Designand performance information is presented on a dedicated odour control system installed at Phoenixville, Pennsylvania in 1996 that collects high-H2S air streams from an influent chamber and primary clarifiers and diffuses it into a mechanically-aerated activated sludge basin. A cost-effectiveness analysis is presented for a blower/diffuser system installed exclusively for odour control. Methods used to overcome initial operational problems are discussed.

scholarly journals Evaluating the impacts of triclosan on wastewater treatment performance during startup and acclimation

2017 ◽  
Vol 77 (2) ◽  
pp. 493-503 ◽  
Author(s):  
R. M. Holzem ◽  
C. M. Gardner ◽  
C. K. Gunsch
Keyword(s):  
Wastewater Treatment ◽  
Community Diversity ◽  
Synthetic Wastewater ◽  
Batch Reactors ◽  
Ammonia Oxidizing Bacteria ◽  
Sequencing Batch Reactors ◽  
Anaerobic Digesters ◽  
Treatment Performance ◽  
Treatment Facilities ◽  
The Impact

Abstract Triclosan (TCS) is a broad range antimicrobial agent used in many personal care products, which is commonly discharged to wastewater treatment facilities (WWTFs). This study examined the impact of TCS on wastewater treatment performance using laboratory bench-scale sequencing batch reactors (SBRs) coupled with anaerobic digesters. The SBRs were continuously fed synthetic wastewater amended with or without 0.68 μM TCS, with the aim of determining the effect of chronic TCS exposure as opposed to a pulse TCS addition as previously studied. Overall, the present study suggests inhibition of nitrogen removal during reactor startup. However, NH4+ removal fully rebounded after 63 days, suggesting acclimation of the associated microbial communities to TCS. An initial decrease in microbial community diversity was observed in the SBRs fed TCS as compared to the control SBRs, followed by an increase in community diversity, which coincided with the increase in NH4+ removal. Elevated levels of NO3− and NO2− were found in the reactor effluent after day 58, however, suggesting ammonia oxidizing bacteria rebounding more rapidly than nitrogen oxidizing bacteria. Similar effects on treatment efficiencies at actual WWTFs have not been widely observed, suggesting that continuous addition of TCS in their influent may have selected for TCS-resistant nitrogen oxidizing bacteria.

scholarly journals Removal of organics and metal ion nanoparticles from synthetic wastewater by activated sludge process (ASP)

2014 ◽  
Author(s):  
Tarunveer Singh ◽  
Shubhanshu Jain
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Metal Ions ◽  
Organic Contaminants ◽  
Metal Ion ◽  
Treatment Plant ◽  
Poor Quality ◽  
Treated Wastewater ◽  
Synthetic Wastewater ◽  
Batch Reactors

Adsorption technique is widely used for removal of toxic organic contaminants from aqueous streams. Owing to the hazardous or otherwise undesirable characteristics of phenolic compounds in particular, their presence in wastewater from municipal and industrial discharge is one of the most important environmental issue. The discharge of poor quality effluents by the chemical-based laboratories and refineries in India is posing a serious threat to water sources and wastewater treatment installations alike. Our study was set up in the Indo - French Unit for Water & Wastewater Technologies (IFUWWT), IIT Delhi. The main objective of this study was to assess the efficiency of a laboratory-scale activated sludge treatment process in producing a final effluent conforming to regulatory standards of Central Pollution Control Board, India (CPCB norms) with regards to COD and metal ion loads. The study was conducted in three principal stages: characterization of wastewater containing nanoparticles; treatability studies of laboratory generated discards and investigations of heavy metal ions before and after treatment. The various raw effluent parameters analyzed were COD, BOD, F/M ratio, Sludge Value Index, Total Solids and concentrations of Cu, Ag and Zn. Studies were conducted using two aerobic sequencing batch reactors (SBR). MLSS of the aeration basin was calculated to be 7180±261.3 mg/L while the F/M ratio was kept down to 0.1560±.0149; besides, an SVI of 107.24 mL/g complied with the state of bioreactor’s sludge. These set of values suggested to set an extended aeration processes for the reactors. Accordingly, the detention time in aeration basin was 24 hours. The results showed over 98% influent COD reduction and nearly 100% removal of metal ions. The sample used was operated on sludge collected from Vasant Kunj Wastewater Treatment plant. Based on the results from waste characterization and treatability studies, it was decided that the mixed liquor discharged in the activation tank should have glucose solution and laboratory discarded sample in 1:1 ratio. The reactor was operated on a glucose fed batch basis for 30 days. For the sake of metal analysis, the digested water samples were analyzed for the presence of copper, silver and zinc using the ElementAS AAS4141 Atomic Absorption Spectrophotometer (by Electronics Corporation of India Ltd). The biosorption capacities were found to be over 95% in all the cases with the minimum correlation coefficient for calibration curve being 0.9811. Such a high sludge yield is suggestive of the fact that heavy metals are in very low concentrations in the considered carboy sample. Because of these insignificant values, the amount of metal ions introduced to the system gets adsorbed almost completely, hence leaving behind no metal ion within the supernatant. Well-treated wastewater has enormous potential as a source of water for crops, households and industry.

scholarly journals Coke oven wastewater treatment by two activated sludge systems

2013 ◽  
Vol 8 (1) ◽  
pp. 16-22
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nutrient Removal ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Coke Oven ◽  
Synthetic Wastewater ◽  
Removal Efficiencies ◽  
Activated Sludge Systems

In this study two bench scale activated sludge systems were used, a CSTR and an SBR for the treatment of coke – oven wastewater. Both reactors were inoculated with activated sludge from a municipal wastewater treatment plant. At the first stages of operation, reactors were feed by a mixture of municipal wastewater and synthetic wastewater. Full acclimatization of the microorganisms to synthetic wastewater was achieved in 60 days. The operation of the reactors was divided into three distinct periods. The first period was characterized by the treatment of high organic but non-toxic synthetic wastewater. During this period COD and BOD5 removal efficiencies reached 95 and 98% respectively, in both reactors. Nutrient removal was better in the SBR reactor rather than in the CSTR. In the second period phenol was added in concentrations up to 300 mg l-1. Degradation of phenol started about the 20th day after its introduction to the reactors. In this period no effects of phenol to nutrient removal were observed, whereas the removal efficiency of organic matter in both reactors was slightly decreased. During the third period phenol concentrations of the influent were gradually increased to 1000 mg l-1, while cyanide and thiocyanite were added to the influent composition to concentrations reaching concentrations of 20 and 250 mg l-1 respectively. The composition of the influent of this period was a full assimilation of coke oven wastewater. Introduction of increased phenol concentrations along with cyanide compounds initiated irreversible effects on the activated sludge microfauna of the CSTR causing inherent problems to the treatment process, while SBR showed greater capacity to withstand and degrade toxic compounds. The beginning of this period was characterized by decreased settleability of the suspended solids as well as decrease of organic matter and nutrient removal efficiencies. Monitoring of the effluent characteristics during this period reported over 90% for organic load, 85% of nutrient removal and over 90% of phenol and cyanide removal in SBR, while the removal efficiencies for the CSTR were 75, 65 and 80% respectively.

scholarly journals The present situation and trends of wastewater treatment in small settlements and rural areas of Lithuania

2019 ◽  
pp. 243-250
Author(s):  
Regimantas Dauknys
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Surface Waters ◽  
Rural Areas ◽  
Biological Treatment ◽  
Wastewater Treatment Plants ◽  
Present Situation ◽  
Treatment Facilities ◽  
Biological Filters ◽  
Activated Sludge Systems

This article presents the wastewater treatment in small settlements and rural areas ofLithuania, including descriptions of capacity and loading of wastewater treatment plants(WWTPs), types of treatment facilities, and development trends of biological treatmentfacilities. In 2000 Lithuania had 597 WWTPs with capacity up to 1000 m3/d, 95% of them arethe biological treatment plants. Today the most of these WWTPs are unloaded due to thetendency to centralise wastewater treatment in rural areas of Lithuania that were in the eightand ninth decades.In small settlements and rural areas of Lithuania the aeration facilities are predominant. In theeight and ninth decades practically only the activated sludge systems were built. The situationbegan to change in the last decade of the last century: the biological filters and soil filtrationfacilities with discharge into surface waters were applied more frequently, so the building ofaeration facilities started to decrease.

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