BIOSORPTION OF CU(II) IONS FROM INDUSTRIAL EFFLUENTS BY RICE HUSK: EXPERIMENT, STATISTICAL, AND ANN MODELING

Heavy metal removal from wastewater is a significant research area and recommends sustainable development. The heavy metals cause harmful health effects, increase environmental toxicity. Adsorption is a very effective method for heavy metal removal. A fixed bed for Cu(II) removal using rice hush, an agricultural waste, is reported in this paper. The study was carried out to determine the breakthrough curves with varying operating variables like influent concentration (10–30 mg/L), flow rate (10–40 ml/min), and bed height (4–10 cm) at pH 6. The variation of the process variables like influent concentration, flow rate, and bed height were investigated. The experimental data shows that adsorption capacity increases with the rise of influent concentration. The maximum value of adsorption capacity is 10.93 mg/g at a flow rate of 10 ml/min, bed height 4 cm, and influent concentration 30 mg/L. The applicability of the MLR and ANN modeling has also been successfully carried out. ANN has better predictability than MLR. The findings revealed that rice husk could be used to treat copper-containing industrial effluents.

Effects of Influent Concentration and Flow Rate on the Sorption of Diesel Molecules on Kapok Fibers at Dynamic Conditions

Kapok fibers were used as a filtering medium in a column-type filtration set-up to separate diesel from water molecules in dynamic conditions. The amount of diesel flowing out the filtration system with respect to time was monitored. The times wherein the diesel first came out the filtering system (breakthrough time) were shorter at higher influent concentration and faster flow rate. Meanwhile, the total sorbed diesel molecules in the filtering system were increasing with the influent concentration while invariant with flow rate. The shorter breakthrough time was associated with the higher amount of diesel molecules that could be sorbed at a shorter time and the rate at which the overall processes of sorption-desorption-resorption proceeded. On the other hand, the sorption capacity of the system was viewed to be affected by the amount of moving diesel molecules that would interact with the kapok fibers and/or surface-sorbed diesel molecules but not by the contact time.

Combined anaerobic-aerobic and UV/H2O2 processes for the treatment of synthetic slaughterhouse wastewater

The biological treatment of a synthetic slaughterhouse wastewater (SSWW) was studied using an anaerobic baffled reactor (ABR) and an aerobic activated sludge (AS) at a laboratory scale, with total organic carbon (TOC) loading rates of 0.03–1.01 g/(L.day), total nitrogen (TN) loading rates of 0.01–0.19 g/(L.day), and a flow rate of 2.93 to 11.70 mL/min in continuous mode. Results revealed that combined anaerobic-aerobic processes had higher efficiency to treat SSWW than a single process. Up to 96.36% TOC, 80.53% TN, and 99.38% 5-day carbonaceous biochemical oxygen demand (CBOD5) removal from an influent concentration of 1,008.85 mgTOC/L, 419.77 mgTN/L, and 640 mgCBOD5/L at the hydraulic retention time (HRT) of 6.24 days and a flow rate of 3.75 mL/min was achieved. The UV/H2O2 process was studied to treat a secondary effluent of SSWW with TOC loadings of 64.88–349.84 mg/L. Up to 75.22% TOC and 84.38% CBOD5 removal were obtained for an influent concentration of 64.88 mgTOC/L at the HRT of 3 h with H2O2 concentration of 900 mg/L. An optimum molar ratio dosage of 13.87 mgH2O2/mgTOCin was also obtained. Combined anaerobic-aerobic and UV/H2O2 processes enhanced the biodegradability of the TOC, TN, and CBOD5 present in the SSWW. Up to 99.98% TOC, 82.84% TN, and 99.69% CBOD5 overall removals were obtained for an influent concentration of 1,004.88 mgTOC/L, 200.03 mgTN/L, and 640 mgCBOD5/L at the HRT of 4 days and a flow rate of 5.90 mL/min. A cost-effectiveness analysis (CEA) was performed for the optimum conditions for the SSWW treatment by optimizing total electricity cost and HRT, in which the combined anaerobic-aerobic and UV/H2O2 processes had an optimal TOC removal of 92.46% at an HRT of 41 h, a cost of $1.25/kg of TOC removed, and $11.60/m3 of treated SSWW. This process reaches a maximum TOC removal of 99% in 76.5 h with an estimated cost of $2.19/kg TOC removed and $21.65/m3 treated SSWW.

Combined anaerobic-aerobic and UV/H2O2 processes for the treatment of synthetic slaughterhouse wastewater

The biological treatment of a synthetic slaughterhouse wastewater (SSWW) was studied using an anaerobic baffled reactor (ABR) and an aerobic activated sludge (AS) at a laboratory scale, with total organic carbon (TOC) loading rates of 0.03–1.01 g/(L.day), total nitrogen (TN) loading rates of 0.01–0.19 g/(L.day), and a flow rate of 2.93 to 11.70 mL/min in continuous mode. Results revealed that combined anaerobic-aerobic processes had higher efficiency to treat SSWW than a single process. Up to 96.36% TOC, 80.53% TN, and 99.38% 5-day carbonaceous biochemical oxygen demand (CBOD5) removal from an influent concentration of 1,008.85 mgTOC/L, 419.77 mgTN/L, and 640 mgCBOD5/L at the hydraulic retention time (HRT) of 6.24 days and a flow rate of 3.75 mL/min was achieved. The UV/H2O2 process was studied to treat a secondary effluent of SSWW with TOC loadings of 64.88–349.84 mg/L. Up to 75.22% TOC and 84.38% CBOD5 removal were obtained for an influent concentration of 64.88 mgTOC/L at the HRT of 3 h with H2O2 concentration of 900 mg/L. An optimum molar ratio dosage of 13.87 mgH2O2/mgTOCin was also obtained. Combined anaerobic-aerobic and UV/H2O2 processes enhanced the biodegradability of the TOC, TN, and CBOD5 present in the SSWW. Up to 99.98% TOC, 82.84% TN, and 99.69% CBOD5 overall removals were obtained for an influent concentration of 1,004.88 mgTOC/L, 200.03 mgTN/L, and 640 mgCBOD5/L at the HRT of 4 days and a flow rate of 5.90 mL/min. A cost-effectiveness analysis (CEA) was performed for the optimum conditions for the SSWW treatment by optimizing total electricity cost and HRT, in which the combined anaerobic-aerobic and UV/H2O2 processes had an optimal TOC removal of 92.46% at an HRT of 41 h, a cost of $1.25/kg of TOC removed, and $11.60/m3 of treated SSWW. This process reaches a maximum TOC removal of 99% in 76.5 h with an estimated cost of $2.19/kg TOC removed and $21.65/m3 treated SSWW.

Combined anaerobic baffled reactor and UV/H2O2 process for the treatment of synthetic slaughterhouse wastewater

A laboratory scale for the combined processes of a biological anaerobic baffled reactor (ABR) and a UV/hydrogen peroxide (H2O2) was used to investigate the treatment of a synthetic slaughterhouse wastewater with various influent concentrations and various hydraulic retention times (HRT) at room temperature in this study. The results showed that the removal efficiencies of total organic carbon (TOC), chemical oxygen demand (COD), and 5-day carbonaceous biochemical oxygen demand (CBOD5) of the wastewater with an influent concentration of 973 mgTOC/L and a HRT of 3.8 days reached 89.9, 97.7, and 96.6%, respectively, in the ABR process, whilst the removal efficiency of TOC in the UV/H₂O₂ process reached 50.8% at a HRT of 3.6 h and H2O2 dosage of 1371 mgH2O2/L, leading to 95.0% of overall TOC removal of the combined processes. For comparison, the removal efficiencies of TOC, COD, and CBOD5 of the synthetic wastewater with an influent concentration of 158 mgTOC/L reached 64.9, 81.9, and 84.3% respectively, at an HRT of 2.5 h and a H2O2 dosage of 1371 mgH2O2/L in UV/H2O2 process alone. An optimum value of hydrogen peroxide was found to be 3.5 (mgH2O2/L)/(mgTOCin/L.h). After the ABR treatment, the ration of CBOD5/COD of the untreated wastewater changed from 0.4 to 0.6 and 0.5 to 0.2, and the ratio of COD/TOC of the wastewater decreased from 2.4 to 0.5 and 2.2 to 2.0, at the HRT of 3.8 and 0.9 days, respectively, indicating that the biodegradability of the wastewater was enhanced at a longer HRT in the ABR process. Afer the UV/H2O2 process treatment, the ratios of CBOC5/COD of the untreated and the ABR treated wastewater increased from 0.4 to 0.6 and 0.3 to 0.5, and the ratios of COD/TOC of the wastewaters decreased from 2.3 to 0.6 and 1.8 to 0.9, respectively, at the HRT of 2.5 h, indicating that the UV/H2O2 process had the ability to enhance the biodegradability of the wastewater. A kinetic model for the ABR process was obtained and used to evaluate the experimental findings. The parameters of the kinetic model for the ABR process were determined to be 3.1X10⁻2 for refractory coefficient, 0.4 for kinetic coefficient, 2.0 mg/L for half-saturation constant for hydrolyzed substrate, and 1.9 day⁻1 for the maximum specific growth rate of organism, respectively. The optimum HRT and the minimum total electricity cost were determined to be 78.9 h and $11.45 /kg of TOC removed for the ABR process, with 1000 mgTOC/L of the wastewater influent concentration, leading to 100.0 mgTOC/L of the effluent concentration which met the disposal level in Canada.

Combined anaerobic baffled reactor and UV/H2O2 process for the treatment of synthetic slaughterhouse wastewater

A laboratory scale for the combined processes of a biological anaerobic baffled reactor (ABR) and a UV/hydrogen peroxide (H2O2) was used to investigate the treatment of a synthetic slaughterhouse wastewater with various influent concentrations and various hydraulic retention times (HRT) at room temperature in this study. The results showed that the removal efficiencies of total organic carbon (TOC), chemical oxygen demand (COD), and 5-day carbonaceous biochemical oxygen demand (CBOD5) of the wastewater with an influent concentration of 973 mgTOC/L and a HRT of 3.8 days reached 89.9, 97.7, and 96.6%, respectively, in the ABR process, whilst the removal efficiency of TOC in the UV/H₂O₂ process reached 50.8% at a HRT of 3.6 h and H2O2 dosage of 1371 mgH2O2/L, leading to 95.0% of overall TOC removal of the combined processes. For comparison, the removal efficiencies of TOC, COD, and CBOD5 of the synthetic wastewater with an influent concentration of 158 mgTOC/L reached 64.9, 81.9, and 84.3% respectively, at an HRT of 2.5 h and a H2O2 dosage of 1371 mgH2O2/L in UV/H2O2 process alone. An optimum value of hydrogen peroxide was found to be 3.5 (mgH2O2/L)/(mgTOCin/L.h). After the ABR treatment, the ration of CBOD5/COD of the untreated wastewater changed from 0.4 to 0.6 and 0.5 to 0.2, and the ratio of COD/TOC of the wastewater decreased from 2.4 to 0.5 and 2.2 to 2.0, at the HRT of 3.8 and 0.9 days, respectively, indicating that the biodegradability of the wastewater was enhanced at a longer HRT in the ABR process. Afer the UV/H2O2 process treatment, the ratios of CBOC5/COD of the untreated and the ABR treated wastewater increased from 0.4 to 0.6 and 0.3 to 0.5, and the ratios of COD/TOC of the wastewaters decreased from 2.3 to 0.6 and 1.8 to 0.9, respectively, at the HRT of 2.5 h, indicating that the UV/H2O2 process had the ability to enhance the biodegradability of the wastewater. A kinetic model for the ABR process was obtained and used to evaluate the experimental findings. The parameters of the kinetic model for the ABR process were determined to be 3.1X10⁻2 for refractory coefficient, 0.4 for kinetic coefficient, 2.0 mg/L for half-saturation constant for hydrolyzed substrate, and 1.9 day⁻1 for the maximum specific growth rate of organism, respectively. The optimum HRT and the minimum total electricity cost were determined to be 78.9 h and $11.45 /kg of TOC removed for the ABR process, with 1000 mgTOC/L of the wastewater influent concentration, leading to 100.0 mgTOC/L of the effluent concentration which met the disposal level in Canada.

Effects of influent concentration and different valence cations on solute preferential transport in inter-tidal zone of Yellow River Estuary

The migration of land-based pollutants in tidal flat sediments has an important impact on the marine ecological environment. The effects of three influent concentrations and two cation valence states on the preferential transport of NO3-N in the sediments of the Yellow River Estuary were studied by soil column experiments. Results showed that the preferential flow and solute transport were more obvious with the increase of influent concentration; The solute potential was increased in the process of solute transport, which led to the rapid flow, shortened the total time, and facilitated the solute transport speed in the soil; The cation in the sediment of the Yellow River Estuary has little effect on the transport of nitrate nitrogen, and the initial penetration time of the penetration curve using Ca (NO3)2 as tracer was a little later than that using KNO3 as tracer, but it is not obvious.

IDENTIFICATION OF NITROUS OXIDE GENERATION IN SUBSURFACE WASTEWATER INFILTRATION SYSTEM FILLED WITH MIXED MATRIX

Subsurface wastewater infiltration systems (SWIS) are one of the important sources of nitrous oxide (N2O) production; understanding the biological processes and contributions of N2O will help control the amount of N2O produced. To quantitatively reveal the contribution of nitrification and denitrifiaction processes, 8 g potassium nitrate with 99.99 atom % 15N (i.e. 15N accounts for 99.99% of the total N) was dissolved in the influent (concentration: 3.3 g/L). Results showed that nitrification released more N2O within 0–12 h, accounting for 79.6 ± 2.4%. The denitrification process accounted for 88.5 ± 1.3% for N2O generation after the 12th hour. Thus, in order to effectively control the release of N2O, the denitrification process should be given more attention. The maximum release rate of N2O was 8.45 ± 0.8 mg/m2·h, which occurred near the end of the first wetting-drying cycle. Since then, peaks appeared periodically, mostly in the “rest” periods.

THE PRE-EVALUATION OF CROSSLINKED ANION EXCHANGE (CAX) RESIN ON NITRATES REMOVAL

This study is present the result of synthesizing crosslinked anion exchange (CAX) resin bearing quaternary ammonium functionalities. Crosslinked anion exchange of poly(HEMA-co-EGDMA-co-VBC) were synthesized via the modified suspension polymerization technique, then treated in hyper-crosslinking reaction to increase specific surface area (SSA) of CAX beads resin from ~5 to 124 m2/g and followed by amination treatment with N,N-dimethylbutylaminee (DMBA) to obtain CAX resin. After functionalized process, the amount of nitrogen content increased and intensity at 1265 cm-1 that assigned for chloromethyl group has decreased, showing that DMBA successfully being attached to the backbone. CAX resin was fully characterized by using Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FT-IR) respectively. A pre-evaluation study was carried to investigate the performance of CAX beads resin to remove nitrate by using ion exchange method. Three parameters were used to study the sorption process; contact time, influent concentration and amount of resin used. For overall sorption, the sorption managed to obtain 88 % nitrate removal by using 0.5 g of CAX resin at 50 ppm influent concentration within 1-hour contact time and the highest adsorption of CAX achieved was 93 % removal of nitrate ions within 4-hours contact time.