-
1.
Pre-magnetized Fe0 as heterogeneous electro-Fenton catalyst for the degradation of p-nitrophenol at neutral pH.
Tian, Y, Zhou, M, Pan, Y, Cai, J, Ren, G
Chemosphere. 2020;:124962
Abstract
Pre-magnetized Fe0 (Pre-Fe0) was for the first time applied as heterogeneous catalyst to enhance the oxidation efficiency of electro-Fenton (EF) for the degradation of p-nitrophenol (PNP). The parameters including current, initial pH and pre-Fe0 dosage of Pre-Fe0/EF process were optimized and compared with other two processes (conventional Fe0/EF and electro-oxidation) to confirm its advantage. The rate constants of PNP removal were 1.40-3.82 folds of those by Fe0/EF process under various experimental conditions. The application of pre-Fe0 as catalyst could extend the working pH range from 3.0 to neutral conditions for PNP removal and reduce the Fe0 dosage from 2 to 0.5 mM corresponding to Fe0/EF, avoiding the second pollution of iron sludge. The superiority of Pre-Fe0/EF process was also verified to improve the degradation and mineralization of other phenols and antibiotics. Furthermore, a possible pathway of PNP degradation was revealed by the identification of intermediates and organic acids, and the possible mechanism of pre-Fe0 efficiently enhanced the EF efficiency was proposed. This work demonstrated that such a novel heterogeneous EF process using pre-Fe0 catalyst was clean and promising for the degradation of refractory organic pollutants.
-
2.
Unfolding microbial community intelligence in aerobic and anaerobic biodegradation processes using metagenomics.
Tikariha, H, Purohit, HJ
Archives of microbiology. 2020;(6):1269-1274
Abstract
Environmental factors and available nutrients influence microbial communities, and with that, there exists a dynamic shift in community structure and hierarchy in wastewater treatment systems. Of the various factors, the availability and gradient of oxygen selectively enrich a typical microbial community and also form the community stratification which could be established through metagenomics studies. In recent years, metagenomics with various sets of bioinformatics tools has assisted in exploration and better insight into the organization and relation of the taxonomical and functional composition and associate physiological intelligence of the microbial communities. The microbial communities, under defined conditions acquire a typical hierarchy with flexible but active network of the metabolic route, which ensures the survival needs of every member residing in that community and their abundance. This knowledge of community functional organization defines the rule in designing and improving biodegradation processes in case of both aerobic and anaerobic systems.
-
3.
Mechanistic insights into the enhanced removal of roxsarsone and its metabolites by a sludge-based, biochar supported zerovalent iron nanocomposite: Adsorption and redox transformation.
Li, B, Wei, D, Li, Z, Zhou, Y, Li, Y, Huang, C, Long, J, Huang, H, Tie, B, Lei, M
Journal of hazardous materials. 2020;:122091
Abstract
Roxarsone is a phenyl-substituted arsonic acid comprising both arsenate and benzene rings. Few adsorbents are designed for the effective capture of both the organic and inorganic moieties of ROX molecules. Herein, nano zerovalent iron (nZVI) particles were incorporated on the surface of sludge-based biochar (SBC) to fabricate a dual-affinity sorbent that attracts both the arsenate and benzene rings of ROX. The incorporation of nZVI particles significantly increased the binding affinity and sorption capacity for ROX molecules compared to pristine SBC and pure nZVI. The enhanced elimination of ROX molecules was ascribed to synergetic adsorption and degradation reactions, through π-π* electron donor/acceptor interactions, H-bonding, and As-O-Fe coordination. Among these, the predominate adsorption force was As-O-Fe coordination. During the sorption process, some ROX molecules were decomposed into inorganic arsenic and organic metabolites by the reactive oxygen species (ROS) generated during the early stages of the reaction. The degradation pathways of ROX were proposed according to the oxidation intermediates. This work provides a theoretical and experimental basis for the design of adsorbents according to the structure of the target pollutant.
-
4.
Effect of hydraulic retention time on micropollutant biodegradation in activated sludge system augmented with acclimatized sludge treating low-micropollutants wastewater.
Boonnorat, J, Kanyatrakul, A, Prakhongsak, A, Honda, R, Panichnumsin, P, Boonapatcharoen, N
Chemosphere. 2019;:606-615
Abstract
This research investigates the effect of hydraulic retention time (HRT) on micropollutant biodegradation of two-stage activated sludge (AS) system augmented with acclimatized sludge treating low-micropollutants wastewater. The experimental wastewater was a mixture of landfill leachate and agriculture wastewater, and HRT was varied between 24, 18, and 12 h. The results showed that, under 24 h HRT, the micropollutant biodegradation efficiencies were 87-93% for bisphenol A (BPA), 2,6-di-tert-butyl-phenol (2,6-DTBP), di-butyl-phthalate (DBP), di-(ethylhexyl)-phthalate (DEHP); 75-81% for carbamazepine (CBZ), diclofenac (DCF); and 88% for N,N-diethylmeta-toluamide (DEET). The degradation efficiencies were similar under 18 h HRT: 87-93% for BPA, 2,6-DTBP, DBP, DEHP; 75-80% for CBZ, DCF; and 80% for DEET. However, the efficiencies substantially declined under 12 h HRT: 71-93%, 55-60%, and 50%, respectively. Importantly, the findings revealed that HRT plays a crucial part in micropollutant biodegradation of bioaugmented AS system. More specifically, too short an HRT (12 h) results in low micropollutant removal efficiency, and too long an HRT (24 h) contributes to low daily throughput and high treatment operation cost. As a result, moderate HRT (18 h) is operationally and economically optimal for bioaugmented AS system treating low-micropollutants wastewater.
-
5.
Pseudogemmobacter bohemicus gen. nov., sp. nov., a novel taxon from the Rhodobacteraceae family isolated from heavy-metal-contaminated sludge.
Suman, J, Zubrova, A, Rojikova, K, Pechar, R, Svec, P, Cajthaml, T, Ulbrich, P, Ridl, J, Strnad, H, Uhlik, O
International journal of systematic and evolutionary microbiology. 2019;(8):2401-2407
Abstract
The creamy white to beige, aerobic, non-motile, ovoid to rod-shaped, Gram-stain-negative strain, Cd-10T, was isolated from heavy-metal-contaminated sludge from a decantation basin of a heavy metal processing factory based on its ability to tolerate CdCl2 in the cultivation medium. In the reconstruction of its phylogeny based on 16S rRNA gene sequences, strain Cd-10T clustered with species of the genera Gemmobacter, Xinfangfangia, Tabrizicola and Rhodobacter within the family Rhodobacteraceae. Its 16S rRNA gene sequence exhibited 96.32 % pairwise similarity to the type strain of Xinfangfangia soli, 95.3 % to that of Gemmobacter intermedius, followed by Tabrizicola fusiformis (95.10 %), Rhodobacter sediminis (94.88 %), Gemmobacter nectariphilus and Rhodobacter capsulatus (both 94.81 %). The major respiratory quinone was Q-10 accompanied by Q-9, the fatty acid profile consisted predominantly of C18 : 1ω7c, C18 : 0, C16 : 0 and C16 : 1ω7c, the major polar lipids were phosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylcholine and diphosphatidylglycerol. An analysis of the percentage of conserved proteins deduced from draft or complete genomic sequences of strain Cd-10T and representatives of its closest relatives suggested that strain Cd-10T is a member of a novel genus within the Rhodobacteraceae family for which we propose the name Pseudogemmobacter. Strain Cd-10T (=DSM 103618T=NCCB 100645T) is the type strain of Pseudogemmobacter bohemicus gen. nov., sp. nov., the type species of the genus Pseudogemmobacter gen. nov.
-
6.
Competitive dynamics of anaerobes during long-term biological sulfate reduction process in a UASB reactor.
Chen, H, Wu, J, Liu, B, Li, YY, Yasui, H
Bioresource technology. 2019;:173-182
Abstract
To reveal the long-term competitive dynamics of anaerobes in anaerobic bioreactors with sulfate reduction, a comprehensive structured mathematical model was designed for an extension of the Anaerobic Digestion Model No. 1 (ADM1). Sulfate reduction bacteria (SRB) were categorized into acetogenic-likewise SRB (ASRB) and methanogenic-likewise SRB (MSRB). Experimental data from 329 days of continuous operation of a laboratory-scale upflow anaerobic sludge bed (UASB) reactor was used for model calibration and validation. Results show that the model has a good agreement with experimental data and that three stages including the MPA dominant, stalemate and SRB dominant stages were clearly appeared throughout the whole competition period. The model was capable of predicting the long-term dynamic competition of sulfidogens and methanogens for electrons. This could explain a long-term of over 200 days needed for the SRB out-competing the MPA, and support speculation that the SRB could finally out-compete both the AcB and the MPA.
-
7.
Current status and future prospects of sewer biofilms: Their structure, influencing factors, and substance transformations.
Li, W, Zheng, T, Ma, Y, Liu, J
The Science of the total environment. 2019;:133815
Abstract
With rapid urbanization, sewer systems are extensively being constructed for the collection and transportation of sewage to minimize the severe environmental and health issues, especially relating to the spread diseases. The existence of abundant biofilms on the inner walls of sewers could lead to potential risks such as sewer explosions, poisonous gas leaks, and pipe corrosions with the transformations of various kinds of pollutants. Therefore, it is urgent to clarify their inner mechanisms to safely govern sewer systems. In this study, the characteristics of sewer biofilms including their structure, influencing factors, and substance transformations were analyzed in-depth. The results reveal that sewer biofilms (1.0 mm depth approximately) consist of large quantities of inorganic and some organic substances, while the abundant functional genus of the bacteria and archaea are summarized. Sewer biofilms influencing factors were determined to be sewer operation mode, sewage characteristics, and shear stress. Further, the transformation of organics, sulfur, and nitrogen as well as emerging micropollutants (such as, biomarkers, antibiotic resistance genes, and engineered nanoparticles) was investigated to guarantee sewer security and public health. Therefore, the current review could be considered as guidance for researchers and decision-makers.
-
8.
Deep dewatering process of sludge by chemical conditioning and its potential influence on wastewater treatment plants.
Wang, S, Ma, C, Zhu, Y, Yang, Y, Du, G, Li, J
Environmental science and pollution research international. 2019;(33):33838-33846
Abstract
FeCl3, quick lime, and cationic polyacrylamide (CPAM) were used for excess sludge conditioning from wastewater treatment plant (WWTP) and the dewatering performance by different chemical conditioners was investigated. Experimental results showed that FeCl3 could make small and concentrated sludge particles. Furthermore, new mineral phase structures for building a dewatering framework were obtained by the addition of quick lime, and the coagulation capacity was enhanced by the formation of colloid hydroxyl polymer, which was induced due to the alkaline environment. In addition, the floc particle size significantly increased after the CPAM dosage. The bound water could be released with the stripping of tightly bound extracellular polymeric substance (EPS). Therefore, the dewatering performance and efficiencies were improved and subsequently the hypothetical sludge deep dewatering process was depicted in accordance with the variation of EPS. However, high-strength refractory organics in sludge filtrates caused by quick lime pyrolysis could lead to the unstable operation of the WWTP, because the relatively high concentrations of organic compounds with benzene were dominant in sludge dewatering filtrates.
-
9.
Research progress and application prospect of anaerobic biological phosphorus removal.
Yang, F, Zhang, C, Rong, H, Cao, Y
Applied microbiology and biotechnology. 2019;(5):2133-2139
Abstract
Anaerobic biological phosphorus removal has proposed a new direction for the removal of phosphorus from wastewater, and the discovery of phosphate reduction makes people have a more comprehensive understanding of microbial phosphorus cycling. Here, from the perspective of thermodynamics, the bioreduction reaction of phosphate was analyzed and its mechanism was discussed. The research progress of phosphate reduction and the application prospects of anaerobic biological phosphorus removal from wastewater were introduced, pointing out the situation and guiding the further research in this field.
-
10.
Growth performance, metal accumulation and biochemical responses of Palak (Beta vulgaris L. var. Allgreen H-1) grown on soil amended with sewage sludge-fly ash mixtures.
Sharma, B, Kothari, R, Singh, RP
Environmental science and pollution research international. 2018;(13):12619-12640
Abstract
Agricultural utilization of sewage sludge (SS) and fly ash (FA) has become both, a common practice and an alternative disposal method for these wastes all around the world. The present study was conducted to assess the effect and viability of co-application of SS and FA (SLASH) in four mixing ratios denoted as A [4 (SS): 1(FA)], B [4 (SS): 2 (FA)], C [4 (SS): 3 (FA)] and D [4 (SS): 4(FA)] at three application rates viz. 20, 40 and 60% (w/w) with agricultural soil on biochemical, physiological and growth response of Palak (Beta vulgaris L. var. Allgreen H-1), a commonly used green leafy vegetable. SLASH amendment modified the physico-chemical properties of soil and increased the concentration of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn) in soil and plant parts however, within the Indian permissible limit except for Cr, Cd and Zn in shoot. Experimental results revealed decrease in morphological and growth parameters such as root and shoot length, leaf area, root, shoot biomass etc. Lipid peroxidation, ascorbic acid, proline and protein content increased however, total chlorophyll and carotenoid content decreased indicating towards heavy metal stress induced biochemical and physiological response in Palak plants. Significant increase in yield was seen in some of the treatments viz. three mixing ratios B, C and D, with maximum increment shown by mixture D at 20 and 40% amendment rate. The results of this study suggest that though SLASH amendment for growing Palak improved the physico-chemical properties of soil amended and also the yield of the plants in some treatments, it may not be a good option due to risk of contamination of heavy metals such as Cr, Cd and Zn showing higher accumulation.