Enhancement of denitrification by sulfur-based carrier in sequencing batch reactor (SBR) for advanced wastewater treatment.

This study was to enhance the nitrogen removal efficiency in the sequencing batch reactor (SBR) process by adding sulfur-based carriers. The nitrogen removal efficiency of the control group was compared with that of the experimental group through a two-series operation of SBR1 without carrier and SBR2 with the carrier under the condition of no external carbon source. A total nitrogen (T-N) removal efficiency of 6.6%, 72.6%, and 79.9% was observed in SBR1, SBR2 (5%), and (10%), respectively. The T-N removal efficiency was improved in the system with carriers, which showed an increase in the removal efficiency of approximately 91.7%. The results suggest that the inclusion of the carrier led to an elevation in the sulfur ratio, implying an augmented surface area for sulfur-based denitrifying microorganisms. Additionally, CaCO3 contributed essential alkalinity for sulfur denitrification, thereby preventing a decline in pH. Regardless of the carrier, the efficiency of organic matter removal surpassed 89%, indicating that the sulfur-based carrier did not adversely affect the biological reaction associated with organic matter. Therefore, autotrophic denitrification was successfully performed using a sulfur carrier in the SBR process without an external carbon source, improving the nitrogen removal efficiency.

Exposure dose and temperature of chlorine on deterioration of thin-film composite membranes for reverse osmosis and nanofiltration.

In this study, the effect of chlorine, which is used as a chemical cleaning agent or disinfection agent on membrane deterioration, was analyzed under various conditions during the membrane process. Reverse osmosis (RO: ESPA2-LD and RE4040-BE) and nanofiltration (NF: NE4040-70) membranes made of polyamide (PA) thin film composite (TFC) were used for evaluation. Chlorine exposure was performed at doses ranging from 1000 ppm h to 10,000 ppm h using 10 ppm and 100 ppm, and temperatures from 10 °C to 30 °C. Raw water containing NaCl, MgSO4, and dextrose was used to compare the filtration performance after exposure to each of the conditions studied. Reduction in removal performance and enhancement in permeability were observed as chlorine exposure increased. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscope (SEM) were employed to determine the surface characteristics of the decomposed membranes. ATR-FTIR was used to compare the intensity of the peaks related to the TFC membrane. Based on the analysis, the state of membrane degradation was elucidated. SEM was used to confirm visual degradation of the membrane surface. Permeability and correlation analyses were performed on CnT as an index for determining membrane lifetime in order to investigate the power coefficient. The relative influence of the exposure concentration and time on membrane degradation was explored by comparing the power efficiency according to the exposure dose and temperature.

Investigating the effects of physical properties of sulphur-based carriers on autotrophic denitrification.

In this study, four sulphur-based carriers (C1-C4) which have different mass ratio of sodium silicate to carrier from 30% to 50% (C1-C3) and the existence of water (C4) were prepared in order to evaluate the effect of the different physical properties on denitrification in sulphur-based autotrophic processes. While the apparent density and the compressive strength decreased as the proportion of sodium silicate increased and water was added in the carriers, the average pore size and the porosity increased from 0.43 to 3.13 µm and from 38% to 67%, respectively. The treatment system using the carrier C4 with the highest surface area was stabilized most rapidly and achieved the highest nitrogen removal efficiency of 85.6 ± 5.0% during a relatively short HRT of 3 h. The efficiency of nitrate removal was enhanced by 36.9% due to the increase of the ratio of sodium silicate in the carriers from C1 to C3, and more 4.8% point of removal rate increased in the carrier C4 by adding water to the carrier C3. The sum of Thiobacillus and Sulfurimonas was obtained up to 65.90% among the microbial community in the carrier C4 which has the highest distribution (38.35%) of pore size above 20 µm considered to be favourable for retaining autotrophic denitrifiers. From the above results, it is obvious that the physical properties of the sulphur-based carrier and its ability of denitrification can be influenced significantly by the composition of the carrier.

Removal of nitrogen from municipal wastewater by denitrification using a sulfur-based carrier: A pilot-scale study.

In the present study, to improve nitrate removal rate, a sulfur-based carrier was applied for autotrophic denitrification, and the removal rate was evaluated for advanced wastewater treatment without adding any external organic carbon source. Based on the results, an increased PAC concentration affected the removal efficiency of NO3--N, and the optimal concentration of PAC was at 15 wt%. During the 60 d operation of a pilot process with a capacity of 1 m3/d, the removal of T-N was 81.2% and 50.2% in reactors with and without sulfur-based carrier, respectively. The removal efficiency of NO3--N exhibited a similar trend to that of T-N. According to the results, the removal of T-N and NO3--N was noticeably enhanced to approximately 30% by adding a sulfur-based carrier to the A2O pilot system. In addition, microbial community in both reactors was dominated by Thiobacillus, which is an autotrophic microorganism, displaying a dominant denitrification status. The present study compared the relative efficiencies of nitrate removal in A2O pilot reactors with and without sulfur-based carriers for its successful application in real-scale autotrophic denitrification.

Forward osmosis with direct contact membrane distillation using tetrabutylphosphonium p-toluenesulfonate as an effective and safe thermo-recyclable osmotic agent for seawater desalination.

A phosphonium-based ionic liquid (IL) with lower critical solution temperature (LCST) property was assessed as a reusable draw solution (DS) for forward osmosis (FO). Tetrabutylphosphonium p-toluenesulfonate ([P4444]TsO) was successfully synthesized by neutralization reaction. Characterization results reveal its ability to generate sufficient osmotic pressure (14-68 bars for 0.5-2 M DS) to create a gradient across the FO membrane. Its thermal, physico-chemical and other colligative properties are favorable for its application as an osmotic agent. The LCST behavior of [P4444]TsO was found reversible and its phase separation from water can be done above its cloud point temperature Tc ∼57 °C. In vitro cytotoxicity tests from LDH and MTT assay reveal that it can be safely used as DS at an effective concentration EC30 ∼57 mg L-1 as its non-toxic level. Results from FO operations demonstrate that 2 M [P4444]TsO DS can effectively treat saline feed like seawater (0.6 M NaCl) with reasonable Jv = 1.35 ± 0.15 L m-2h-1, low Js = 0.0038 ± 0.00049 mol m-2h-1, and considerably low specific solute flux (Js/Jv âˆ¼ 0.0028 mol L-1). After FO, ∼98% of [P4444]TsO was precipitated by heating the DS at 60 °C and conveniently reused with consistent FO performance. Direct contact membrane distillation (DCMD) was found effective in removing the residual 2% [P4444]TsO in the DS supernatant to finally produce high-quality effluent with concentrations way below the EC30 limit. Cost estimates for the entire process reveal the potential of FO combined with thermo-cyclic [P4444]TsO regeneration with DCMD for desalination application.

Application of Physical and Chemical Enhanced Backwashing to Reduce Membrane Fouling in the Water Treatment Process Using Ceramic Membranes.

This study investigated the improvement of operating efficiency through physical cleaning and chemical enhanced backwashing (CEB) using ceramic membranes with high permeability and chemical safety compared to organic membranes. The turbidity and DOC (Dissolved Organic Carbon) concentrations were selected to ensure that the degree of contamination was always constant. The operating pressures were fixed at 100, 200, and 300 kPa, and the filtration was terminated when the effluent flow rate decreased to 30% or less from the initial value. After filtration, backwashing was performed at a pressure of 500 kPa using 500 mL backwash water. The membrane was cleaned by dipping in NaOCl, and a new washing technique was proposed for steam washing. In this study, we investigated the recovery rate of membranes by selectively performing physical cleaning and CEB by changing the influent water quality and operating pressure conditions.

Nitrogen Removal by Sulfur-Based Carriers in a Membrane Bioreactor (MBR).

Sulfur-based carriers were examined to enhance the nitrogen removal efficiency in a mixed anoxic⁻anaerobic-membrane bioreactor system, in which sulfur from the carrier acts as an electron donor for the conversion of nitrate to nitrogen gas through the autotrophic denitrification process. A total nitrogen removal efficiency of 63% was observed in the system with carriers, which showed an increase in the removal efficiency of around 20%, compared to the system without carriers. The results also indicated that the carriers had no adverse effect on biological treatment for the organic matter and total phosphorus. The removal efficiencies for chemical oxygen demand (COD) and total phosphorus (TP) were 98% and 37% in both systems, respectively. The generation of sulfate ions was a major disadvantage of using sulfur-based carriers, and resulted in pH drop. The ratio of sulfate in the effluent to nitrate removed in the system ranged from 0.86 to 1.97 mgSO42-/mgNO3--N, which was lower than the theoretical value and could be regarded as due to the occurrence of simultaneous heterotrophic and autotrophic denitrification.

Effect of powdered activated carbon on integrated submerged membrane bioreactor-nanofiltration process for wastewater reclamation.

The aim of this study was to determine the effect of powdered activated carbon (PAC) on the overall performance of a submerged membrane bioreactor (SMBR) system integrated with nanofiltration (NF) for wastewater reclamation. It was found that the trans-membrane pressure of SMBR increased continuously while that of the SMBR with PAC was more stable, mainly because water could still pass through the PACs and membrane even though foulants adhered on the PAC surface. The presence of PAC was able to mitigate fouling in SMBR as well as in NF. SMBR-NF with PAC obtained a higher flux of 8.1 LMH compared to that without PAC (6.6 LMH). In addition, better permeate quality was obtained with SMBR-NF integrated process added with PAC. The present results suggest that the addition of PAC in integrated SMBR-NF process could possibly lead to satisfying water quality and can be operated for a long-term duration.

Nitrification denitrification enhanced biological phosphorous removal (NDEBPR) occurs in a lab-scale alternating hypoxic/oxic membrane bioreactor.

Strict anaerobic or anoxic maintenance of the system and process susceptibility to low organic loading are major concerns in nitrification denitrification enhanced biological phosphorous removal (NDEBPR). The study has initiated NDEBPR in a lab-scale alternating hypoxic/oxic membrane bioreactor by developing an enhanced mixed microbial culture capable of removing 97±2% COD, 99±0.84% NH(3)-N, 90±3% TN, and 96±1% TP-PO(4)(3-) with 20-day SRT. The viable cells ranging from 1.6×10(8) to 2.0×10(8)cells/ml estimated from the total bacterial genomic DNA (6.43-7.83 µg DNA/ml) represented only 5% of the MLVSS indicating low microbial biomass concentration. Reducing the organic load from 1250 to 750 mg COD/ml as glucose did not deteriorate the effluent quality (3.77±1.0 mg N-TN/l; 0.08±0.24 mg NH(3)-N/l; and 0.32±0.10 mg PO(4)(3-)-P/l). These observations are characteristics of activated sludge that harbors denitrifying polyphosphate accumulating organisms (DPAOs). The results showed that NDEBPR can be achieved under alternating hypoxic/oxic conditions.

Relapsed spontaneous spinal epidural hematoma associated with aspirin and clopidogrel.

An acute spontaneous spinal epidural hematoma (SSEH) is a rare spinal pathology. A 57-year-old man who had hypertension and had been on dual antiplatelet therapy with aspirin and clopidogrel for primary prevention presented with the sudden onset of mid back pain and monoplegia of the left lower extremity. Magnetic resonance imaging revealed an epidural hematoma, and the patient underwent emergency hemilaminectomy for evacuation. However, the symptoms worsened, and complete paraplegia developed. A second procedure to remove the recurrent hematoma was performed. No vascular malformation or other possible cause for SSEH was found other than the aspirin and clopidogrel medication. This case report describes relapsed SSEH caused by the combination of aspirin and clopidogrel medication and urges caution in prescribing dual antiplatelet agents.

The functional effect of epigallocatechin gallate on ischemic stroke in rats.

We evaluated the efficacy of epigallocatechin gallate (EGCG) for improving function in rats with transient middle cerebral artery occlusion (MCAO). Three procedures underwent for each groups; MCAO and EGCG treatment, MCAO without treatment (MCAO control), and sham operation. Function was evaluated on days 1, 5, 10, and 14 after ischemia, using a modified sticky-tape test and the percentage weight borne on the paretic leg. Infarct volume did not differ between the EGCG-treated and MCAO control groups. Compared with the MCAO control group, the EGCG-treated group showed improved forelimb function and had normal function by day 10 (P<0.05). The improvements persisted until day 14 postischemia. In contrast, hind limb function did not differ between the EGCG-treated and MCAO control groups. Thus, EGCG improved certain aspects of function of forelimb until day 14 after MCAO in rats.

New method to perform medial plantar proper digital nerve conduction studies.

OBJECTIVE: We describe a technique that records the sensory nerve action potential (SNAP) of the medial plantar proper digital nerve (MPPDN), which is the final sensory branch of the medial plantar nerve. METHODS: We obtained antidromic MPPDN responses from 118 healthy volunteers, with surface recording electrodes placed on the medial side of the first metatarsal head of the great toe, with electrical stimulation applied at the 40% distance of the heel to great toe reference line. Antidromic SNAP parameters were recorded and normative reference values were obtained. RESULTS: The stimulation site that corresponded to 40% of the reference line was located at a mean distance of 8.7+/-1.2 cm from the recording electrodes. MPPDN responses were easily obtained in all but 9 limbs. The mean SNAP amplitudes obtained by our technique were 16.1+/-6.7 microV, and the lower and upper range values were 6.4 microV and 34.4 microV, respectively. CONCLUSION: Antidromic stimulation of the MPPDN at a distance of 8-10 cm from the medial side of the first metatarsal head of the great toe yields in reliable SNAP responses. SIGNIFICANCE: This technique should be useful in the evaluation of the MPPDN involvement in Joplin's neuroma.