Project description:In order to explore the influence of electrode spacing on the performance of the enhanced bioretention system, four bioretention cells with microbial fuel cell (BRC-MFC) systems with different electrode spacing were designed, and the effect of electrode spacing on system performance was revealed by analysing its water treatment capacity and electricity production efficiency. The results showed that BRC-MFC had good water treatment capacity and could produce electricity simultaneously. Compared with other BRC-MFC systems with spacing, the BRC3 system (with an electrode spacing of 30 cm) had significant water treatment capacity under different organic loads, especially under high organic load (C/N = 10) operation, COD removal rate was as high as 98.49%, NH4+-N removal rate was as high as 97%, and it had a higher output voltage of 170.46 ± 6.17 mV. It could be seen that proper electrode spacing can effectively improve the water treatment capacity of the BRC-MFC system. This study provided a feasible method for improving the performance of the BRC-MFC system, and revealed the relevant mechanism. A proper electrode spacing with sufficient carbon sources could effectively improve the water treatment capacity of the BRC-MFC system.
Project description:Bioretention, also known as rain garden, allows stormwater to soak into the ground through a soil-based medium, leading to removal of particulate and dissolved pollutants and reduced peak flows. Although soil organic matter (SOM) is efficient at sorbing many pollutants, amending the bioretention medium with highly effective adsorbents has been proposed to optimize pollutant removal and extend bioretention lifetime. The aim of this research was to investigate whether soil amended with activated carbon produced from sewage sludge increases the efficiency to remove hydrophobic organic compounds frequently detected in stormwater, compared to non-amended soil. Three lab-scale columns (520 cm3) were packed with soil (bulk density 1.22 g/cm3); activated carbon (0.5% w/w) was added to two of the columns. During 28 days, synthetic stormwater-ultrapure water spiked with seven hydrophobic organic pollutants and dissolved organic matter in the form of humic acids-was passed through the column beds using upward flow (45 mm/h). Pollutant concentrations in effluent water (collected every 12 h) and polluted soils, as well as desorbed amounts of pollutants from soils were determined using GC-MS. Compared to SOM, the activated carbon exhibited a significantly higher adsorption capacity for tested pollutants. The amended soil was most efficient for removing moderately hydrophobic compounds (log K ow 4.0-4.4): as little as 0.5% (w/w), carbon addition may extend bioretention medium lifetime by approximately 10-20 years before saturation of these pollutants occurs. The column tests also indicated that released SOM sorb onto activated carbon, which may lead to early saturation of sorption sites on the carbon surface. The desorption test revealed that the pollutants are generally strongly sorbed to the soil particles, indicating low bioavailability and limited biodegradation.
Project description:The dissolved metal adsorption and association was determined for ten different filter materials recommended and/or implemented in bioretention facilities. Batch adsorption and batch kinetic experiments were performed at lab-scale using both single and multi-metal solutions. Metal strengths and association were determined by sequential extraction analysis. All materials adsorbed metals and 90% of adsorption occurred within 1?h. However, as metal solutions became more complex, adsorption behavior changed. Generally, filter materials classified as sand with a naturally high pH, relatively low organic matter (OM) content and large specific surface area seem to be good choices for removing dissolved metals. Additionally, a chalk additive might improve metal adsorption whereas biochar did not significantly improve metal retention and may be an unwanted (due to degradation over time) extra source of OM. Regardless of filter material, metals primarily adsorbed to the exchangeable form which indicates that metal adsorption might not be permanent, but rather substantially reversible in some cases. More research is needed to assess whether dissolved metals adsorbed in filter materials of bioretention systems pose a delayed threat instead of an immediate threat. Finally, the authors strongly recommend filter materials intended for stormwater bioretention facilities to be tested prior to implementation.
Project description:Excessive phosphorus (P) contributes to eutrophication by degrading water quality and limiting human use of water resources. Identifying economic and convenient methods to control soluble reactive phosphorus (SRP) pollution in urban runoff is the key point of rainwater management strategies. Through three series of different tests involving influencing factors, continuous operation and intermittent operation, this study explored the purification effects of bioretention tanks under different experimental conditions, it included nine intermittent tests, single field continuous test with three groups of different fillers (Fly ash mixed with sand, Blast furnace slag, and Soil), and eight intermittent tests with single filler (Blast furnace slag mixed with sand). Among the three filler combinations studied, the filler with fly ash mixed with sand achieved the best pollution reduction efficiency. The setting of the submerged zone exerted minimal influence on the P removal of the three filler combinations. An extension of the dry period slightly promoted the P purification effect. The combination of fly ash mixed with sand demonstrated a positive purification effect on SRP during short- or long-term simulated rainfall duration. Blast furnace slag also presented a positive purification effect in the short term, although its continuous purification effect on SRP was poor in the long term. The purification abilities of soil in the short and long terms were weak. Under intermittent operations across different seasons, SRP removal was unstable, and effluent concentration processes were different. The purification effect of the bioretention system on SRP was predicted through partial least squares regression (PLS) modeling analysis. The event mean concentration removal of SRP was positively related to the adsorption capacity of filler and rainfall interval time and negatively related to submerged zones, influent concentration and volume.
Project description:Drinking water treatment residuals (DWTRs) are a promising media amendment for enhancing phosphorus (P) removal in bioretention systems, but substantial removal of dissolved P by DWTRs has not been demonstrated in field bioretention experiments. We investigated the capacity of a non-amended control media (Control) and a DWTR-amended treatment media (DWTR) to remove soluble reactive P (SRP), dissolved organic P (DOP), particulate P (PP), and total P (TP) from stormwater in a two-year roadside bioretention experiment. Significant reductions m SRP, PP and TP concentrations and loads were observed in both the Control and DWTR media. However, the P removal efficiency of the DWTR cells were greater than those of the Control cells for all P species, particularly during the second monitoring season as P sorption complexes likely began to saturate in the Control cells. The difference in P removal efficiency between the Control and DWTR cells was greatest during large storm events, which transported the majority of dissolved P loads in this study. We also investigated the potential for DWTRs to restrict water flow through bioretention media or leach heavy metals. The DWTRs used in this study did not affect the hydraulic performance of the bioretention cells and no significant evidence of heavy metal leaching was observed during the study period. Contrasting these results with past studies highlights the importance of media design in bioretention system performance and suggests that DWTRs can effectively capture and retain P without affecting system hydraulics if properly incorporated into bioretention media.
Project description:ChIP-Seq for H3K27 trimethylation was performed for two HPV-positive and two HPV-negative squamous cell carcinoma cell lines. The data served two purposes. First, the data were used as an example implementation of our novel ChIP-Seq Peak Prioritization pipeline, PePr. We have developed the PePr pipeline, a ChIP-Seq Peak Prioritization pipeline that accounts for the variation among replicates and peak location relative to a gene. We show, using a transcription factor dataset (which exhibited small variation among samples), that PePr performs favorably compared to commonly used peak callers and that it achieves balanced sensitivity and specificity. We also show, using histone modification data (which exhibited larger variation among samples), that PePr can improve the detection of differential H3K27me3 regions compared with a common current approach. Using data from ChIP-Seq and gene expression experiments performed in parallel on the same samples, we show that the incorporation of functional annotations can improve the prioritization of functional sites. Secondly, the data were used to assess real differences in the genome-wide H3K27me3 profiles between HPV-positive and HPV-negative carcinoma cell lines. Careful analysis and integration of the data with DNA methylation and gene expression data performed on the same cell lines demonstrated striking differences exist. ChIP-Seq for H3K27 trimethylation was performed for two HPV-positive and two HPV-negative squamous cell carcinoma (SCC) cell lines. Input DNA was also sequenced for each sample to serve as a control. The goal was to determine overall differences in H3K27me3 patterns observed between the HPV-positive and HPV-negative SCC cell lines.