Environmental Technology

Han, Jichang; Thomsen, Laurenz; Pan, Kehou; Wang, Pu; Wawilow, Tatjana; Osundeko, Olumayowa; Wang, Song; Theilen, Ulf; Thomsen, Claudia

doi: 10.1080/09593330.2019.1604816pmid: 30961473

Various resources from a municipal wastewater treatment plant (MWTP) are available for microalgae cultivation plants, suggesting that a combination of these technologies can be used to produce microalgae biomass and remove contaminants at a low cost. In this study, the growth performance and nutrient removal efficiency of an indigenous Scenedesmus sp. in various wastewater media with different exchange patterns were investigated firstly, then transferred to a pilot-scale photobioreactor (located inside a MWTP) for bioremediation use. The temperature and pH of the platform were maintained at 15–30°C and 7.6, respectively. The , , and of the wastewater could be reduced to below 0.05, 0.40, and 0.175 mg L–1, respectively. Our results indicate that microalgae cultivation using the resources of a MWTP can achieve high algal biomass productivity and nutrient removal rate. Our study also suggests that efficient technology for controlling zooplankton needs to be developed.

Rathnayake, Buddhika; Heponiemi, Anne; Huovinen, Marjo; Ojala, Satu; Pirilä, Minna; Loikkanen, Jarkko; Azalim, Saïd; Saouabe, Mohammed; Brahmi, Rachid; Vähäkangas, Kirsi; Lassi, Ulla; Keiski, Riitta L.

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Su, Chengyuan; Deng, Qiujin; Lu, Yuxiang; Pan, Jiaqi; Chen, Wuyang; Chen, Shenglong; Deng, Xue; Lin, Xiangfeng; Huang, Zhi

doi: 10.1080/09593330.2019.1604818pmid: 30961470

The effects of circulation reflux and micro-aeration on the performance of a modified anaerobic baffled reactor (ABR) for treatment of traditional Chinese medicine (TCM) wastewater were evaluated. The characteristics of anaerobic sludge and microbial community structure in the modified ABR were also investigated. The results indicated that with conditions of reflux ratio of 1, reflux ratio of 2, reflux ratio of 2 with micro-aeration, and reflux ratio of 3, the modified ABR achieved an average COD removal efficiency of 90%, 87.7%, 87.8%, and 88.4%, respectively. In addition, the NH3-N average removal efficiency was 45.1%, 50%, 55.9%, and 55.4%, respectively. The analysis of excitation–emission matrix (EEM) fluorescence spectra of soluble microbial products (SMP) and extracellular polymeric substances (EPS) showed that there were tyrosine-like, aromatic protein-like, and coenzyme F420 substances in the sludge. The EPS were analysed by the Fourier transform infrared spectroscopy (FTIR), which showed that aromatic compounds were partially degraded, while the protein and polysaccharide compounds increased in each compartment of the modified ABR. Interestingly, the microbial community of anaerobic sludge analysis results showed that Chloroflexi was the dominant in the first, third and fourth compartments. Meanwhile, Levilinea and Methanothrix were the dominant species in the first and third compartments at the genus level.

Castrillón Cano, Laura; Londoño, Yudy Andrea; Pino, Nancy J.; Peñuela, Gustavo A.

doi: 10.1080/09593330.2019.1606287pmid: 30968737

Benzophenone-3 is an organic compound widely used as a UV filter, which has been reported as water pollutant and is connected with endocrine disruption in humans and animals. Expanded granular sludge beds (EGSB) are a form of an anaerobic digestion system, which has been successfully evaluated for wastewater treatment, and the removal of different compounds, however little is known about the effect of compounds as Benzophenone-3 in the performance of EGSB systems. In this study, we evaluate the effect of BP-3 on the performance, microbial structure and metabolism of EGSB reactors. For this purpose, biogas production, removal efficiencies of BP-3 and DQO were monitored. Changes in bacteria and archaea microbial structure were investigated using PCR-DGGE, and the effect on anaerobic metabolism was evaluated by measuring the expression of mcrA and ACAs genes through qRT-PCR. The systems remained stable and efficient throughout the operation stages, with CH4 percentages greater than 55% and COD and BP-3 removal percentages greater than 90%. The presence of different concentrations of Benzophenone-3 influenced the organization of microbial communities, especially archaea. However, this did not affect the stability and performance of the EGSB systems.

Zhu, Xiao-Ling; Bai, Yu-Hui; Wu, Jing; Xu, Lian-Zeng-Ji; Cheng, Ya-Fei; Fan, Nian-Si; Jin, Ren-Cun

doi: 10.1080/09593330.2019.1606856pmid: 30999824

While the application of mesophilic anammox process is currently the state of the art, the feasibility of a thermophilic anammox bioprocess is still unclear. In this study, we investigate whether glycine betaine (GB) addition can enhance the thermotolerance of mesophilic anammox biomass in the upflow anaerobic sludge blanket (UASB) reactors fed with synthetic wastewater at a nitrogen loading of approximately 4 kg N m–3 d−1. The results showed that during a long-term operation at 45°C with GB (0, 0.1, 1, 2 mM) addition, anammox performance became worse with the final effluent concentrations of NO2 –N of 145 ± 11.6 mg L−1 and nitrogen removal efficiency decreased from 92.3–6.9%. Specific anammox activity decreased from 392.1 ± 12.1–6.0 ± 0.8 mg N g−1 VSS d−1, which were not significantly higher than those in the control reactor. The content of heme c showed a stronger downward trend in T1 (with GB addition) than in the control reactor T0. The qPCR results showed that the relative abundance of Candidatus Kuenenia decreased in both the experimental (from 53.5–28.8%) and control reactors (from 54.1–35.1%). Overall, continuous addition of exogenous GB did not improve the thermotolerance of mesophilic anammox consortia at 45°C.

Bomrungnok, Wichittra; Arai, Takamitsu; Yoshihashi, Tadashi; Sudesh, Kumar; Hatta, Tamao; Kosugi, Akihiko

doi: 10.1080/09593330.2019.1608314pmid: 30987543

Polyhydroxybutyrate (PHB) is a natural microbial polyester produced by a variety of bacteria and archaea from renewable resources. PHB resembles some petrochemical plastics but is completely biodegradable. It is desirable to identify suitable microbial strains and develop processes that can directly use starch from agricultural wastes without commercial amylase treatment. Here, PHB production using starch from agricultural waste was developed using a newly isolated strain, Bacillus aryabhattai T34-N4. This strain hydrolyzed cassava pulp and oil palm trunk starch and accumulated up to 17 wt% PHB of the cell dry weight. The α-amylase of this strain, AmyA, showed high activity in the presence of cassava pulp starch (69.72 U) and oil palm trunk starch (70.53 U). High expression of amyA was recorded in the presence of cassava pulp starch, whereas low expression was detected in the presence of glucose. These data suggest that starch saccharification by amyA allows strain T34-N4 to grow and directly produce PHB from waste starch materials such as cassava pulp and oil palm trunk starch, which may be used as low-cost substrates.

Xu, Weijie; Shafi, Mohammad; Penttinen, Petri; Hou, Shuzhen; Wang, Xin; Ma, Jiawei; Zhong, Bin; Guo, Jia; Xu, Meizhen; Ye, Zhengqian; Fu, Liqing; Huang, Qiying; Liu, Dan

doi: 10.1080/21622515.2019.1609096

Egbuikwem, Precious N.; Naz, Iffat; Saroj, Devendra P.

doi: 10.1080/09593330.2019.1609097pmid: 31038403

The unrestricted discharge of domestic and industrial wastewaters along with agricultural runoff water into the environment as mixed-wastewater pose serious threat to freshwater resources in many countries. Mixed-wastewater pollution is a common phenomenon in the developing countries as the technologies to treat the individual waste streams at source are lacking due to high operational and maintenance costs. Therefore, the need to explore the potential of the suspended growth process which is a well-established process technology for biological wastewater treatment is the focus of this paper. Different wastewater constituents: representing domestic, pharmaceutical, textile, petroleum, and agricultural runoff were synthesized as a representative of mixed-wastewater and treated in two semi-continuous bioreactors (R1 & R2) operated at constant operating conditions, namely MLSS (mg/L): 4640-R1, 4440-R2, SRT: 21-d, HRT: 48–72 h, and uncontrolled pH. The system attained stable condition in day 97, with average COD, BOD and TSS reduction as 84.5%, 86.2%, and 72.2% for R1; and 85.1%, 87.9%, and 75.1% for R2, respectively. Phosphate removal on average was by 74.3% in R1 and 76.6% in R2, while average nitrification achieved in systems 1 and 2 were 56.8% and 54.7%, respectively. The biological treatment system has shown potential for improving the quality of mixed-wastewater to the state where reuse may be considered and tertiary treatment can be employed to polish the effluent quality.

Elnakar, Haitham; Buchanan, Ian

doi: 10.1080/09593330.2019.1609589pmid: 31056013

In-plant wastewater treatment strategies to deal with bypass wastewater in excess of plant capacity are critical in securing sustainable wastewater management. To address this issue, potassium ferrate(VI), which is a dual disinfectant and coagulant, is assessed in this study as the sole chemical applied to enhance the primary treatment of bypass wastewater. The effect of rapid mixing speed is investigated for the first time along with potassium ferrate(VI) dosage by means of central composite design and response surface methodology. Escherichia coli (E. Coli), Faecal Coliform (FC), Total Suspended Solids (TSS), and Orthophosphates ( ) were considered as the process responses. All responses other than showed good agreement between the observed and modelled values. While there was no point of maximum or minimum response for both E. Coli and FC, whose removals were found to increase with the increase of both the mixing intensity and potassium ferrate(VI) dosages, TSS removal exhibited optimal responses. The effluent quality achieved by potassium ferrate(VI), as an independent treatment, can be sufficient for certain types of unrestricted and restricted irrigation reuse purposes suggested by World Health Organisation (WHO) reuse guidelines.

Praveena, Sarva Mangala; Rashid, Umer; Rashid, Suraya Abdul

doi: 10.1080/09593330.2019.1609590pmid: 31002023

There is limited information on the optimal processes to remove heavy metals in greywater. A Response Surface Methodology (RSM) via the Box–Behnken Design (BBD) approach was applied in this study to investigate and optimise the process variables of activation time (1.5–2.5 h), impregnation ratio (0.25–0.75) and zinc chloride (ZnCl2) percentage (20–60%) for the removal of heavy metal ions (Cd, Cu, Pb and Ni) associated with greywater treatment. The quadratic model was chosen to describe the effects of the process variables (activation time, impregnation ratio, ZnCl2 percentage) on predicting the responses (heavy metal ions removal) with low p-values (<.0001), high-adjusted R 2 and predicted R 2 values. Second order polynomial equations, ANOVA and three-dimensional surface plots were developed to evaluate the effects of each independent process variable and determine the optimal condition of each factor for heavy metal ions removal. The optimal activation time for the activated carbon variables was 1.8 h, with 56% ZnCl2 and 0.60 impregnation ratio. This showed that the observed values for removing the heavy metal ions (Cu, Cd, Pb and Ni) were close to the predicted values. A RSM-based field test via the BBD approach, involving different types of greywater samples (bathtubs, showers, hand basins and laundry machines) showed that the percentages of heavy metal ions removal fit the experimental results.