Removal Efficiency Of CODCr Research Articles

Straw Biochar and Graphite Oxide Enhanced External Pressure Ultrafiltration for Leaded Wastewater Treatment.

In order to solve the problem of the low treatment efficiency of wastewater containing heavy metals in mining areas, straw biochar and graphene oxide enhanced external pressure ultrafiltration (SGU) was used to treat wastewater containing high concentrations of Pb2+. The operation parameters such as pH and temperature were optimized, and the removal efficiency of CODCr, NH3-N, turbidity and Pb2+ via SGU, straw biochar ultrafiltration (SU), ultrafiltration (UF), and conventional treatment (CT) were systematically investigated. The results showed that the pH and temperature of polluted water were 4.8-5.2 and 21-30 °C, respectively, the average removal rates of CODCr, NH3-N, turbidity and Pb2+ by SGU reached 91%, 97%, 98% and 95%, respectively, and the removal effect was better than that of other processes. In addition, under the backwash conditions of clean water, weak acid, and weak alkali, the membrane flux recovered 65%, 88%, and 89% of the new membrane, respectively. This study provides scientific and theoretical support for the advanced treatment of polluted water in mining areas.

Cu2(OH)3NO3/γ-Al2O3 catalyzes Fenton-like oxidation for the advanced treatment of effluent organic matter (EfOM) in fermentation pharmaceutical wastewater: The synergy of Cu2(OH)3NO3 and γ-Al2O3

The secondary effluent of fermentation pharmaceutical wastewater exhibits high chromaticity, elevated salinity, and abundant refractory effluent organic matter (EfOM), presenting significant treatment challenges and environmental threats. Herein, Cu2(OH)3NO3/γ-Al2O3 was fabricated through ultrasound-assisted impregnation and calcination to catalyze the Fenton-like oxidation for degrading organic pollutants in this secondary effluent. Under neutral conditions, with 400.00 mg/L H2O2, 8 g/L catalyst, and at 30 ℃, the EfOM and CODCr removal efficiencies can reach 96.90 % and 51.56 %, respectively. The Cu2(OH)3NO3/γ-Al2O3 catalyst possesses ideal reusability, maintaining CODCr, chromaticity, and EfOM removal efficiencies at 44.44 %-64.59 %, 85.45 %-93.45 %, and 61.00 %-95.00 % over 220 h in a continuous-flow catalytic oxidation system operated at room temperatures (15–25 ℃). Electron paramagnetic resonance results and density functional theory calculations indicate that •OOH may be the predominant reactive oxygen species, facilitated by the easier elongation of the OH bond in H2O2 compared to the OO bond. The adjusted electronic structure endows Cu2(OH)3NO3/γ-Al2O3 composite sites with superior catalytic selectivity for H2O2 activation compared to Cu2(OH)3NO3 single crystal sites, with γ-Al2O3 additionally facilitating H2O2 activation through electron donation. This research highlights the efficacy of Cu2(OH)3NO3/γ-Al2O3 in the advanced treatment of complex industrial wastewater, elucidating its catalytic mechanisms and potential applications.

Sustainable and effective catalytic particles for electrocatalytic combustion of refractory organic matter

The development of ultra-efficient, sustainable, and easily accessible catalytic particle (CP) is a useful strategy for hydroxyl radical generation in the three-dimensional electrolytic system (3D ECs). Herein, a crystalline fused CP composed of coal gangue, activated sludge, and iron sludge, were synthesized for refractory organic matter electrocatalytic combustion in a boron-doped diamond (BDD) 3D ECs. A rough and SnO2 semiconductor metal oxide pellet-anchored continuous interface was created through a one-pot calcination method. In determination of the CP agglomeration mechanism, XRD and XPS results displayed that discrete component of SiO2, Al2O3, and Na2O were transformed into a homogeneous quartz albite NaAlSi3O8 phase, and SnO2-Sb2O5 components formed and spread in the whole ball structure during high-temperature molding process. The newly designed CP exhibited incomparable phenol degradation capacity. The dichromate oxidizability (CODCr) removal efficiency of phenolic wastewater increased 14.3 % compared to the commercial active carbon packed system. The electrocatalytic oxidation capacity of CP was evaluated comprehensively under various working condition, e. g. different cathodes, present or absent of Cl- and persulfate agents, and with or without microbubble coupling. Our experimental results showed that considerable CODCr removal efficiency of 86.3 % was obtained with microbubble coupling oxidation using cell voltage 6.0 V and treating time 120 mins. Besides these, the designed CP presented outstanding stability, and CODCr removal efficiency slightly decreased 7.1 % after 10 cycle repetitions. The use of solid waste as the main material for CPs production not only realizes harmless treatment of solid wastes but also improve the 3D ECs significantly.

Heterogeneous Fenton system driven by iron-loaded sludge biochar for sulfamethoxazole-containing wastewater treatment

In this study, the treatment performance of a heterogeneous Fenton system (Fe-BC + H2O2) driven by iron-loaded sludge biochar (Fe-BC) on wastewater containing sulfamethoxazole (SMX) was investigated using the CODcr removal efficiency (φ) as an indicator. The batch experimental results showed that the optimal operating conditions were as follow: initial pH 3, H2O2 concentration 20 mmol L−1, Fe-BC dose 1.2 g L−1, temperature 298 K. The corresponding φ was as high as 83.43%. The removal of CODcr was better described by BMG model and revised BMG (BMGL) model. According to the BMGL model, the φmax could be 98.37% (298 K). Moreover, the removal of CODcr was a diffusion-controlled process, while liquid film diffusion and intraparticle diffusion together determined its removal rate. The removal of CODcr should be a synergistic effect of adsorption and Fenton oxidation (real heterogeneous Fenton and homogeneous Fenton) and other pathways. Their contributions were 42.79%, 54.01% and 3.20%, respectively. For homogeneous Fenton, there seemed to be two simultaneous SMX degradation pathways: SMX→4-(pyrrolidine-11-sulfonyl)-aniline→N-(4-aminobenzenesulfonyl) acetamide/4-amino-N-ethyl benzene sulfonamides→4-amino-N-hydroxy benzene sulfonamides; SMX→N-ethyl-3-amino benzene sulfonamides→4-methanesulfonylaniline. In summary, Fe-BC had potential for practical application as a heterogeneous Fenton catalyst.

Advanced nitrogen removal performance and microbial community structure of a lab-scale denitrifying filter with in-situ formation of biogenic manganese oxides

Advanced nitrogen removal faces the challenges of high operational cost resulted from the additional carbon source and secondary pollution caused by inaccurate carbon source dosage in municipal wastewater. To address these problems, a novel carbon source was developed, which was the oxidation products of refractory organic matters in the secondary effluent of municipal wastewater treatment plant (MWWTP) by in-situ generated biogenic manganese oxides (BMOs) in the denitrifying filter. In the steady phase, the effluent chemical oxygen demand (CODcr), NO3−-N and total nitrogen (TN) in the denitrifying filter 2# with BMOs was 11.27, 9.03 and 10.36 mg/L, and the corresponding removal efficiency was 54.79%, 51.85% and 48.03%, respectively, which was significantly higher than those in the control denitrifying filter 1# that the removal efficiency of CODcr, NO3−-N and TN was only 32.30%, 28.58% and 29.36%, respectively. Kinds of denitrifying bacteria (Candidatus Competibacter, Defluviicoccus, Dechloromonas, Candidatus Competibacter, Dechloromonas, Pseudomonas, Thauera, Acinetobacter, Denitratisoma, Anaerolineae and Denitratisoma) and anammox bacteria (Pirellula, Gemmata, Anammoximicrobium and Brocadia) were identified in the denitrifying filters 1# and 2#, which explained why the actual CODcr consumption (1.55 and 1.44 mg) of reducing 1 mg NO3−-N was much lower than the theoretical CODcr consumption. While manganese oxidizing bacteria (MnOB, Bacillus, Crenothrix and Pedomicrobium) was only identified in the denitrifying filter 2#. This novel technology presented the advantages of no additional carbon source, low operational cost and no secondary pollution. Therefore, the novel technology has superlative application value and broad application prospect.

Three-Dimensional Biofilm Electrode Reactors with Polyurethane Sponge Carrier for Highly Efficient Treatment of Pharmaceuticals Wastewater Containing Tetrahydrofuran

Three-dimensional biofilm electrode reactors (3D-BERs) exhibit efficacy in the removal of refractory wastewater of pharmaceuticals due to the resistance of pharmaceutical wastewater to biodegradation. In this paper, a new 3D-BER with a polyurethane sponge carrier was applied to the treatment of pharmaceutical wastewater containing tetrahydrofuran (THF) with an objective of exploring the removal efficiency, degradation pathway and main functions of microorganisms of 3D-BERs for wastewater containing THF. The results indicate that when the voltage is 10 V, the highest CODCr removal efficiency is (95.9 ± 1.6)%. Compared to the control group, the removal rate was increased by 21.97 ± 4.69%. The main intermediates of THF, γ-butyrolactone and 4-hydroxybutyric acid, were detected, respectively, by Gas Chromatography–Mass Spectrometry (GC–MS), indicating that 3D-BERs contribute to the degradation of THF with electro-oxidation as well as microbial synergism. Microorganisms, such as Proteobacteria with extracellular electron transfer capacity, Bacteroidetes capable of degrading complex carbon sources and parthenogenic anaerobic bacteria Firmicutes, were found to be enriched by high-throughput sequencing analysis in 3D-BERs, which were conducive to the degradation of refractory pollutants. At the genus level, Chryseobacterium, Brevundimonas, Erysipelothrix, and Desulfovibrio were the main functional genera, whose degradation of THF intermediates was found by functional prediction, mainly through chemoheterotrophy, aerobic chemoheterotrophy, etc. It is to be hoped that this study will provide a solution to the practical treatment of pharmaceutical wastewater containing THF via this new 3D-BER system with a polyurethane sponge carrier.

Fate of organic fractions of greywater in combined process of vacuum-ultraviolet (VUV/UV)/ozone pre-oxidation with enhanced coagulation

Pre-ozonation is often used as an effective method to assist coagulation in removing organic contaminants. In this study, a new process that combining ozone (O3) with vacuum ultraviolet (VUV/UV) process (VUV/UV/O3) is investigated to enhance the removal of organic matters in greywater from public buildings or household. The influence of organic characteristics (molecular weight distribution, hydrophobicity, and fluorescence) in greywater on VUV/UV/O3 enhanced coagulation has not been fully studied. Herein, organic matters of greywater were separated and classified, and fates of organic fractions by VUV/UV/O3 enhanced coagulation were clarified. Greywater contains tryptophan-like and tyrosine-like proteins, and terrestrially derived humic-like substances. The highest UV254, LAS, DOC and CODCr removal efficiency from greywater could reach up to 47.54%, 58.92%, 17.96% and 15.76% in VUV/UV/O3 enhanced coagulation, respectively. The removal efficiency of tryptophan-like and tyrosine-like in filtrates of varied molecular weight ranges by VUV/UV/O3 enhanced coagulation was 93.59%–98.13% and 89.86%–95.53%, respectively. VUV/UV/O3 enhanced coagulation was effective for the removal of bio-polymers, humic substances and low molecular weight acid ≤ 30 kDa, while it was insignificant for that of 0.22 µm - 100 kDa. Particle size of flocs increased significantly in filtrates obtained from increasing membrane pore size, indicating that macromolecular organic matter was more likely to form flocs. Finally, the VUV/UV/O3 could improve coagulation on the removal of varied organic pollutants and improve sedimentation by changing the flaky flocs to dense ones. Therefore, the results demonstrate VUV/UV/O3 is an effective pre-oxidation method to enhance the effect of coagulation on greywater treatment.

Study on feasibility and mechanism of the subcritical oxidation of waste drilling mud

Waste drilling mud (WDM) is a hazardous and refractory waste generated during the exploration of oil and gas fields. WDM has high chemical oxygen demand (COD) and high salinity, making it difficult to handle WDM. In this study, WDM was treated under subcritical conditions without and with hydrogen peroxide (H2O2) or potassium persulfate (K2S2O8). The removal efficiency of CODCr (COD was measured by potassium dichromate method) reached 98.20% ~.99.6%. The contents of twelve heavy metals in liquid products were lower than the emission limit except for arsenic. But arsenic concentration decreased by 65.25%. Those detected heavy metals were almost completely removed into solid products. In addition, after introducing K2S2O8 as an oxidant, the removal efficiency of total organic carbon (TOC) in the liquid increased by 58.34% and 13.43% compared with additive-free and H2O2, respectively. The removal efficiency of total nitrogen (TN) was the same as above, also increased by 70% and 59.26%, respectively. The results showed that the introduction of K2S2O8 was more effective in treating WDM under subcritical conditions. Moreover, the introduction of K2S2O8 can generate sulfate ions. Sulfate ions can form stable metal salts with lead and barium, which was conducive to the immobilization of heavy metals. This study provides a new way for the harmless treatment of WDM, and also further expands the application scope of subcritical oxidation.

Study on the application and optimization of domestic sewage treatment demonstration based on a novel biofilter-constructed wetland coupling system

A novel biofilter-constructed wetland coupling system has been applied more than 160 domestic sewage treatment projects in different cities of Zhejiang province, China. The performance of a randomly selected project (flux rate was 27.0 m3/d) based on the coupling system was evaluated in long-term, and the effluent monitoring by big data analysis showed a relatively stable and good water quality. The effluent concentrations of CODCr, NH4+-N and TP were 37.57 ± 11.17 mg/L, 5.64 ± 1.69 mg/L and 0.82 ± 0.16 mg/L, respectively, which met the first-class of "Standards for Discharge of Water Pollutants from Rural Domestic Sewage Treatment Facilities" (DB33/973–2015). The concentrations of effluent TP showed a strong polynomial curve fitting with effluent NH4+-N concentrations (R2 = 0.9329) according to the big data analysis. Besides, the concentrations of effluent CODCr had a strong positive linear correlation with the concentrations of effluent NH4+-N (R2 = 0.9297), which increased with the increase of effluent TP concentrations (R2 = 0.6957). Results also showed pH ranged from 6.46 to 6.57, and C/N (CODCr/NH4+-N) had stronger correlation with pH (R2 = 0.6441), while the concentration of effluent NH4+-N and effluent TP had weak correlation with pH (R2 = 0.3348 and R2 = 0.4834, respectively). The findings might have very important guiding significance for the future monitoring methods of water effluent quality of treatment facility and the cost reduction of monitoring management. Moreover, a demonstration and experiments were carried out for a contrast study of the enhanced system (b) and original system (a). The removal efficiency of CODCr, NH4+-N and TP of the enhanced system (b) was 81.33, 90.22 and 75.44%, respectively, which increased by 4.33, 9.11 and 13.77%, respectively, compared to the original system (a).

하수처리수의 3차처리를 위한 고도산화법(AOP)의 적용성에 관한 연구

Ozone has been applied in combination with various processes for the tertiary treatment of municipal wastewater. However, in Korea, the ozone process is mainly employed for the reuse of tertiary treated wastewater, and an enhanced advanced oxidation process (AOP) is needed to realize the large-scale reuse of treated wastewater. In this study, various AOPs employing ozone (only ozone process, O₃+H₂O₂, O₃+UV, O₃+GAC) were used to analyze the TOC, CODcr, and color treatment efficiencies of municipal wastewater and evaluate its applicability of wastewater reuse. The O₃+H₂O₂ process showed the highest TOC removal efficiency of 62.0%, while the O₃+GAC and only ozone processes exhibited the TOC removal efficiencies of 58.9% and 59.3%, respectively. The TOC removal pattern of the O₃+UV process was similar to that of the O₃+H₂O₂ process. The TOC removal efficiency of the O₃+UV process, 61.0%, was slightly lower than that of the O₃+H₂O₂ process. The CODcr removal efficiencies of the O₃+UV and O₃+H₂O₂ processes were 75.8% and 77.0%, respectively. However, the TOC and CODcr removal efficiencies were different within the error range, so there was no significant difference in the processing efficiencies of the methods investigated. The color removal efficiencies of the O₃+UV (57.8%) and O₃+H₂O₂ (57.4%) processes were 57.8%, 57.4%. respectively and it showed similar pattern.

Rare earth real wastewater treatment by pilot scale using new concept continuous treatment process

Rare earth (RE) containing radioactive species and a variety of toxic pollutants The treatment of real wastewater is very important for environmental protection. In this study, a new concept of continuous process consisting of precipitation, adsorption, and oxidation was developed without the use of chemicals. In the sedimentation step, waste oyster shell(WOS) and a PE tube diffuser(PE250) containing Na2S (PECa/S), PECa/S were prepared, which were used to precipitate heavy metals with a removal efficiency of 97% or more. In the adsorption step, fluorine (F), arsenic (As), and thorium (Th) were precipitated and removed when heavy metals were removed using coal mine drainage sludge (CMDS) and an adsorbent (PUCMDS) made of polyurethane (PU). Running a semi and pilot scale continuous process using PECa/S, PUCMDS and O3/HC systems resulted in a semi and pilot scale operating period of 120 and 62 days, and 60.26, 797.84, 46.94, 78.62 g, and 7.120 kg and 266.35, 42556.8, 191.95, 3108.43 g and 629.84 kg for As, F, Th, Pb and CODcr has been removed respectively. In addition, the removal efficiencies of As, F, Th, Pb and CODcr were 99.75, 99.98, 93.60, 99.99, and 88.82%, respectively, when treating real RE wastewater using the pilot scale system. Without the use of agitated reactors and regulators, the new concept of continuous process can effectively treat RE real wastewater, and the quality of the process outlet has met the pollutant limits recommended by EPA and China for irrigation.

Bacterial community composition of internal circulation reactor at different heights for large-scale brewery wastewater treatment

This study analyzed bacterial community structure for large-scale brewery wastewater treatment at different heights in internal circulation (IC) reactor. Proteobacteria, Bacteroidetes and Chloroflexi were dominant bacteria, which accounted for 64.17%, 64.04%, 59.87% and 55.79% in phylum level, respectively. The unidentified bacteria were accounted for a large proportion in genus level, available data showed that Longilinea, Desulfomicrobium, Caldithrix, Geobacter and Syntrophorhabdus were relatively abundant. Organic fermentation, hydrolysis, and acidification were mainly completed at the bottom, and production of hydrogen and methane were completed in the upper and middle part of reactor. Alpha diversity and cluster distance analysis showed the bacterial community could be divided into bottom, middle and upper part of IC reactor. The IC reactor possessed the CODCr removal efficiency of 80% − 84.09%, and BOD5 of 77.50% − 86% for brewery wastewater. This study would provide bacterial analysis references of IC reactor for industrial wastewater treatment in future.

Flocculation behaviors of a novel papermaking sludge-based flocculant in practical printing and dyeing wastewater treatment

In our previous studies, several papermaking sludge-based flocculants (PSBFs) were synthesized from wood pulp papermaking sludge. The structure-activity relationships of the PSBFs have been investigated in simulated dye wastewater treatment, but their efficiencies in practical printing and dyeing wastewater (PPDW) treatment are unknown. Herein, an PSBF was prepared, and its performance is discussed in comparison to polyaluminium chloride (PAC) and polyacrylamide (PAM) in PPDW treatment. The PSBF was used in three ways: as an independent flocculant, as a PAC aid, or used to treat the effluent of the PAC system. The results indicated that adding PSBF alone produced similar color and chemical oxygen demand (CODCr) removals as the PAC system alone, but PSBF performed better than PAC when the pH of PPDW was higher than 7.0. Adding PSBF as a PAC aid improved the color, CODCr and turbidity removals, but the elimination efficiencies were slightly lower than those of the PAC + PAM system. However, when PSBF was used as a flocculant to treat the effluent of the PAC system (PAC → PSBF), the effluent qualities were enhanced. Compared with the PAC system, the color and CODCr removals of PAC → PSBF system increased by 16.21% and 13.26%, respectively. The excitation and emission matrix fluorescence results indicated that PSBF removed tryptophan-like pollutants more efficiently than PAC. Considering the pH requirements of the subsequent bioreactor treatment in practice, the PAC → PSBF system were also investigated at the PPDW pH level of 7.0. Its maximum removal efficiencies of color, CODCr and turbidity were 90.17%, 32.60% and 82.50%, respectively.

A novel denitrifying phosphorus removal and partial nitrification, anammox (DPR-PNA) process for advanced nutrients removal from high-strength wastewater

This study developed a novel DPR-PNA (denitrifying phosphorus removal, partial nitrification and anammox) process for sustaining high-strength wastewater treatment in a modified continuous flow reactor without external carbon source. After 259-days operation, a synchronous highly-efficient total inorganic nitrogen, PO43--P and CODcr removal efficiencies of 88.5%, 89.5% and 90.1% were obtained, respectively even influent nitrogen loading rate up to 3.2 kg m−3 d−1. Batch tests revealed that denitrifying phosphorus accumulating organisms (DPAOs) using NO3−-N as electron acceptors significantly enriched (74% in total PAOs), which emerged remarkable positive impacts on deep-level nutrient removal as the key limiting factor. Furthermore, the NO2−-N inhibitory threshold value (∼20.0 mg L−1) for DPAOs was identified, which demonstrated as an inhibitory component in excessive recycling NOx−-N. From the molecular biology perspective, Dechloromonas-DPAOs group (18.59%) dominated the excellent dephosphatation performance, while Nitrosomonas-AOB (ammonia oxidizing bacteria) group (16.26%) and Candidatus_Brocadia-AnAOB (anammox bacteria) group (15.12%) were responsible for the desirable nitrogen loss process. Overall, the present work highlighted the novel DPR-PNA process for nutrients removal is a promising alternation for wastewater of high nitrogen but low carbon.

Optimization of Bench-scale Shipboard STP Operating Conditions for Artificial Wastewater Treatment

This study intended to optimize the favorable operating conditions for Bench-scale shipboard STP by using artificial wastewater. For this purpose, the previously developed advanced sequence batch reactor and membrane bioreactor (MBR) combined system by our group was adopted at Bench-scale to study the applicability of this system for wastewater treatment and for the removal of nutrient and organic matter. The COD:T-N:T-P ratios of the influent were adjusted at 10:3:1 and the aeration during MBR process was provided at 7 min aeration and 3 min stop. The operating conditions were optimized by measuring the removal efficiencies of CODcr, T-P, and T-N at different time intervals of mixing and aeration. The operating conditions included mixing and aeration for 90:30, 80:40, 70:50, and 60:60 min, respectively. The optimal removal efficiencies were achieved under mixing and aeration for 70 min and 50 min, respectively, using Bench-scale shipboard STP. The results of the present study were in accordance with the MEPC.227(64) regulations for the removal of CODcr, phosphorus, and nitrogen for advanced shipboard wastewater treatment. A further study is required to evaluate a detailed mechanism of shipboard STP to justify the MEPC.227(64) regulations.

Hydroponic Chlorophytum comosum cultivating in distinct nutrient concentration, combined with biofilm treating eutrophic water bodies

AbstractPhytoremediation technology using aquatic plants combined with microorganisms in constructed ecological floating bed (EFB) is increasingly applied to remediate eutrophic water. Utilizing the hydroponic Chlorophytum comosum, in combination with biofilm developed in polymeric fibrous carriers from sequencing batch reactor (SBR), to fabricate EFB, was implemented to reduce pollution and improve water quality for eutrophic water. The results indicated that the hydroponic C. comosum with long root and leaf, rich Chlorophyll, low cell membrane permeability and strong antioxidant activity enzymes was obtained through different nutrient concentration test. The combination of the hydroponic C. comosum and the biofilm developed in polymeric fibrous carriers could remove 75% chemical oxygen demand (CODCr), 61% permanganate index (PI), 50% total nitrogen (TN) and 57% total phosphorus (TP). Specially, the combination group exhibited higher removal efficiency of CODCr, PI and TN, compared with the sole biofilm group or the sole hydroponic C. comosum group. The result demonstrated that the combination of hydroponic C. comosum and the biofilm to construct the EFB was capacity to repair the eutrophic Huajin River.

Microporous intermittent aeration vertical flow constructed wetlands for eutrophic water improvement.

To enhance eutrophic water improvement effect, three parallel lab-scale oxidation pond-vertical subsurface flow constructed wetland-stable pond combined systems with different microporous intermittent aeration positions were constructed. The purification effect of each system was determined, and the contribution rate of each part of the system was also calculated. The characters of bacterial community under different aeration positions were also analyzed. Microporous intermittent aeration rate of 5mg/L was chosen as the aeration rate for follow-up experiment. The result showed that the best CODCr, total nitrogen, and total phosphorus removal efficiencies were achieved by the combined system with bottom microporous intermittent aeration, and the efficiencies were 71.04%, 79.52%, and 95.10%, respectively. The best ammonium nitrogen removal efficiency was 92.62% and was achieved by the combined system with surface microporous intermittent aeration. After analyses, 14 strains of bacteria associated with the removal of N elements were found and 8 strains of bacteria associated with P element cycle were found.

Study on the flocculation condition of Poly-Silicate-Aluminum-Ferric (PSiAF) coagulant prepared with coal gangue as raw material

Si, Al, Fe were leached from coal gangue to prepare Poly-silicate-aluminum-ferric (PSiAF) coagulant. The optimal dosage and the most adaptive pH value was explored when PSAF was used to treat simulated wastewater, simulated dyeing wastewater and domestic sewage respectively. The flocculation conditions of PSiAF were investigated with the removal efficiency of turbidity, CODCr or chrominance as the inspecting parameters. The experiment results show that, when PSiAF was usede to treat the three kinds of water sample, the optimal dosage is 1.2ml/L, and the most adaptive pH is 8 for simulation wastewater, under this condition, the turbidity removal ratio was 76.04%, the CODCr removal ratio was 58.33%. There is no decolorization effect for simulation dyeing wastewater, and PSiAF is not suitable for simulation dyeing wastewater. the optimal dosage is 8.0ml/L, and the most adaptive pH is 6 for domestic sewage, under this condition, the turbidity removal ratio was 67.25.04%, the CODCr removal ratio was 46.15%.

Electricity generation from sweet potato-shochu waste using microbial fuel cells

Electricity generation and treatment of sweet potato-shochu waste, acidic and organic-rich slurry, was examined using cassette-electrode microbial fuel cells (CE-MFCs). Among CE-MFCs with raw (73g-chemical oxygen demand chromium CODCr/L) and different concentration of diluted sweet potato-shochu waste (0.5, 1, 5, 10, and 20g-CODCr/L) without pH control, the maximum power density (1.2W/m3) and CODCr removal efficiency (67.4±1.8%) were observed in the CE-MFCs with 10g-CODCr/L shochu waste. The concentration of organic acid was decreased to below the quantification limits during the 9-day operation in the CE-MFC with 10g-CODCr/L shochu waste. During the same period, the electrolyte pH was increased from 4.2 to 6.6. Microbial community analysis revealed that the genus Clostridium (75.4%) was predominant in the CE-MFCs with raw shochu waste, whereas Bacteroides (65.3%) and Clostridium (12.1%) were predominant in the CE-MFCs with 10 g-CODCr/L shochu waste.

Effect of Aeration Modes and COD/N Ratios on Organic Matter and Nitrogen Removal in Horizontal Subsurface Flow Constructed Wetland Mesocosms

A series of mesocosm-scale horizontal subsurface flow constructed wetlands (HSSF-CWs) were established. In Experiment 1, four artificial aeration (AA) modes, including pre-aeration at 24 h before the input of influent water (PA), aeration at 6 h (6AA) and 12 h (12AA) after the input of influent water and non-aeration (NA), were tested to obtain an optimal aeration mode for chemical oxygen demand (CODCr) and nitrogen removal. The results showed that aeration after the input of influent water could improve the removal efficiencies of CODCr and ammonia-nitrogen (NH4⁺-N), but lead to an accumulation of nitrate-nitrogen (NO3−-N). The above observation demonstrated that a single aeration cannot create an ideal alternation of aerobic and anaerobic conditions for simultaneous nitrification and denitrification. Therefore, HSSF-CWs with intermittent aeration (IA), after the input of influent water and NA were established to evaluate the combined effects of IA and influent COD/N ratios on pollutant removal in Experiment 2. The HSSF-CW with IA exhibited a better performance in CODCr and nitrogen removal compared to HSSF-CW with NA. The highest removal percentages of CODCr (90.1%), NH4+-N (99.8%) and total nitrogen (TN, 99.5%) were achieved at a COD/N ratio of 9.3 in HSSF-CW with IA.