Advanced treatment of gamma irradiation induced livestock manure using bioelectrochemical ion-exchange reactor.

Organic matter and nitrogen in livestock manure was pre-treated by gamma irradiation. The optimal dose ranged 30-50 kGy for solubilization of organic matter and nitrogen. Carbohydrates and proteins increased with the applied dose. Lipids did not show a regular increase pattern. A large amount of organic nitrogen in livestock manure was solubilized after gamma irradiation. The pre-treated livestock manure was treated using a bioelectrochemical ion-exchange reactor. High removal of organic matter and nitrogen was achieved with the applied dose of 50 kGy. The maximum 88.5% of chemical oxygen demand removal was obtained in the bioelectrochemical ion-exchange reactor due to readily biodegradable chemical oxygen demand fraction. Nitrogen removal was significantly affected by ammonia flux of ion-exchange membrane between anaerobic and aerobic chamber. With a high ammonia flux of 4.7513 mg/m2/sec, the maximum ammonia removal was 79.1%.

Characterization of modified PVDF membrane by gamma irradiation for non-potable water reuse.

Poly(vinylidene fluorine) (PVDF) membranes were grafted by gamma-ray irradiation and were sulfonated by sodium sulfite to modify the surface of the membranes. The characteristics of the modified PVDF membranes were evaluated by the data of Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscope (FE-SEM), the contact angle of the membrane surface and the water permeability. From the results of FT-IR, XPS and FE-SEM, it was shown that the modified membranes were successfully grafted by gamma-ray irradiation and were sulfonated. The content of oxygen and sulfur increased with the monomer concentration, while the content of fluorine sharply decreased. The pore size of the modified membranes decreased after gamma-ray irradiation. The contact angle and the water permeability showed that the hydrophilicity of the modified membranes played a role in determining the membrane performance. The feasibility study of the modified PVDF membranes for using non-potable water reuse were carried out using a laboratory-scale microfiltration system. Grey wastewater was used as the influent in the filtration unit, and permeate quality satisfied non-potable water reuse guidelines in the Republic of Korea.

Occurrence and ecological hazard assessment of selected veterinary medicines in livestock wastewater treatment plants.

The occurrence of some veterinary medicines in the livestock wastewater plants (WWTPs) was investigated. This investigation represented the occurrence of veterinary medicines to treat in the livestock WWTPs or be discharged into the water system in Korea since the sampling sites were widely distributed across the nation and samples were collected from the 11 livestock WWTPs. Nine antibiotics, two analgesics, and two disinfectants occurred in the livestock wastewater plants (WWTPs). From 11 livestock WWTP influents, chlortetracycline, oxytetracycline, acetylsalicylic acid, and disinfectants frequently occurred with the high concentrations. Meanwhile, sulfamethoxazole, erythromycin-H2O, and trimethoprim did not occur during sampling periods. The values for log Kow of each chemical showed a high correlation with the number of hydrogen bonding acceptors and were important parameters to estimate and understand the biodegradability and toxicity of a compound in the environment. The biodegradability of each compound was proportional to the hydrophilicity of each compound and the toxicity was proportional to the number of hydrogen bonding acceptors of each compound. The expected introductory concentration (EIC), predicted exposure concentration (PEC), and hazard quotient showed that the livestock WWTP effluents were hazardous to ecosystems.

Antibiotic resistance in bacteria isolated from freshwater aquacultures and prediction of the persistence and toxicity of antimicrobials in the aquatic environment.

The occurrence of antibiotic-resistant bacteria isolated from freshwater aquaculture effluents was investigated. The bacterial strains were collected from four different freshwater aquaculture effluents (catfish, trout, eel, and loach). Based on sequence of 16S rRNA, a total of 20 bacterial strains was isolated and one half of the isolated bacteria were Aeromonas sp. The antimicrobial sensitivity test was performed using the disc diffusion method. Individual antibiotic-resistant bacteria to antimicrobials were 41.7% and multiple antibiotic resistant bacteria were 58.3%. The disinfection of antibiotic-resistant bacteria by electron beam (E-beam) irradiation was carried out using an electron accelerator. Antibiotic-resistant bacteria were effectively disinfected by E-beam irradiation. The isolated bacteria were completely disinfected at a dose of less than 2 kGy. The persistence and toxicity of each antimicrobial in the aquatic environment was estimated due to the human health and ecosystems. In order to estimate the persistence and toxicity of antimicrobials in the aquatic environment, two quantitative structure activity relationship (QSAR) models were used. The persistence and toxicity of each antimicrobial were influenced on its hydrophobicity. In addition, QSAR models showed that isoelectric point and hydrogen bonding acceptor are key parameters to estimate the persistence and toxicity of antimicrobials in the aquatic environment.

Combination of ion exchange system and biological reactors for simultaneous removal of ammonia and organics.

A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH(4)(+) could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m(2) ∙ s of a maximum flux. On the other hand, the removal of NO(3)(-) was 3.5 times faster than NH(4)(+) and the maximum flux was calculated to be 3.4 mg N/m(2) ∙ s. The systems for NH(4)(+) and NO(3)(-) removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH(4)(+) was removed showing an average flux of 0.22 mg N/m(2) · s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH(4)(+) and organics.

Outcome after PSMA PET/CT based salvage radiotherapy in patients with biochemical recurrence after radical prostatectomy: a bi-institutional retrospective analysis.

Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) detects prostate cancer recurrence at low PSA levels. Radiotherapy with dose escalation to the former prostate bed has been associated with improved biochemical recurrence-free survival (BRFS). Thus, we hypothesized that PSMA PET/CT-guided salvage radiotherapy leads to improved BRFS. Methods: A total of 204 consecutive patients were referred for salvage radiotherapy following radical prostatectomy. PSMA PET/CT scans were performed and patients with PSA persistence (109 patients) or evidence of distant metastases (5 patients) were excluded from this analysis. Thus, the following analysis is based on a total of 90 patients who underwent PSMA PET/CT prior to radiotherapy due to biochemical recurrence and received salvage radiotherapy. In case of PET-positive findings, antiandrogen therapy was commenced before initiation of radiotherapy. BRFS (PSA ≤ 0.2 ng/ml) was defined as the study endpoint. Results: PET-positive lesions were detected in 42/90 (47%) patients: 24/42 (27%) fossa recurrence only, 12/42 (13%) pelvic lymph nodes only and 6/42 (7%) fossa and pelvic lymph node recurrence. Median PSA before radiotherapy was 0.44 (0.11 - 6.24). Cumulatively, a total dose of 70.0 Gy (67.2 - 72 Gy) was delivered to local macroscopic tumor, 66 Gy (59.4 - 70.2 Gy) to the prostatic fossa, 60.8 Gy (54 - 66 Gy) to PET-positive lymph nodes and 50.4 Gy (45 - 50.4 Gy) to the lymphatic pathways. After a median follow-up of 23 months, BRFS was 78%. Antiandrogen therapy was ongoing in 4 patients at last follow-up. No significant difference in BRFS between PET-positive (74%) vs. PET-negative patients (82%; p>0.05) was observed at last follow-up. Two patients had late genitourinary toxicity grade 3 and no patient had gastrointestinal toxicity ≥ 3 (NCI-CTCAE v4.03). Conclusion: PSMA PET/CT-guided salvage radiotherapy is an effective and safe local treatment option. No difference in BRFS between PET-positive and PET-negative patients was observed, indicating effective targeting of PET-positive lesions. PSMA PET/CT when readily available should be offered to patients with PSA recurrence for treatment individualization.

Removal of organic matter and nitrogen in swine wastewater using an integrated ion exchange and bioelectrochemical system.

Swine wastewater was treated using an integrated ion exchange and bioelectrochemical system. This system contains three chambers separated by a cation exchange membrane (CEM) and an anion exchange membrane (AEM). Each chamber acted as a bioanode chamber, an aerated biocathode chamber, and a denitrification chamber. To accelerate the ammonium transportation through CEM, a bioelectrochemical system was installed between bioanode and aerated biocathode. The current was provided by a programmable DC power supply. The average chemical oxygen demand (COD) removal efficiencies at applied voltages of 0, 1 and 3 V were 65.6%, 75.4% and 80.6%, respectively. Unlike the COD removal, the total nitrogen removal was proportional to the ammonium flux through the CEM. The average total nitrogen removal efficiencies at the applied voltages of 0, 1 and 3 V were 37.0%, 63.1% and 70.5%, respectively.

Pilot scale treatment of textile wastewater by combined process (fluidized biofilm process-chemical coagulation-electrochemical oxidation).

The performance of pilot scale combined process of fluidized biofilm process, chemical coagulation and electrochemical oxidation for textile wastewater treatment was studied. In order to enhance biological treatment efficiency, two species of microbes, which can degrade textile wastewater pollutants efficiently, were isolated and applied to the system with supporting media. FeCl3 x 6H2O, pH 6 and 3.25 x 10(-3) mol/l were determined as optimal chemical coagulation condition and 25 mM NaCl of electrolyte concentration, 2.1 mA/cm2 of current density and 0.71/min of flow rate were chosen for the most efficient electrochemical oxidation at pilot scale treatment. The fluidized biofilm process showed 68.8% of chemical oxygen demand (COD) and 54.5% of color removal efficiency, even though using relatively low MLSS concentration and short sludge retention time. COD and color removals of 95.4% and 98.5% were achieved by overall combined process. The contribution of fluidized biofilm process to the overall combined process was increased over 25.7% of COD reduction and 20.5% of color reduction by adopting support media in biological treatment. It can be thought that the fluidized biofilm process was effective, and pollutant loading on post-treatment was pretty much decreased by this system. This combined process was highly competitive in comparison to the other similar combined systems. It was concluded that this combined process was successfully employed and much effectively decreased pollutant loading on post-treatment for textile wastewater treatment at pilot scale.

COD reduction and decolorization of textile effluent using a combined process.

This study showed the effectiveness of biological pretreatment involving appropriate microorganisms and suitable support media in a combined process. The combined process consists of biological pretreatment, chemical coagulation and electrochemical oxidation. COD and color were reduced by 95.4% and 98.5% by the combined process, respectively.

Effects of various pretreatments for enhanced anaerobic digestion with waste activated sludge.

The purpose of this study was to enhance the efficiency of anaerobic digestion with waste activated sludge (WAS) by batch experiments. We studied the effects of various pretreatment methods (thermal, chemical, ultrasonic and thermochemical pretreatments) on the biogas production and pollutants reduction owing to solubilization enhancement, particle size reduction, increased soluble protein, and increased soluble COD. The thermochemical pretreatment gave the best results, i.e., the production of methane increased by more than 34.3% and soluble COD (SCOD) removal also increased by more than 67.8% over the control. In this case, the biogas production, methane production and the SCOD removal efficiency were about 5037 l biogas/m3 WAS, 3367 l methane/m3 WAS and 61.4%, respectively. Therefore, it is recognized that higher digestion efficiencies of the WAS were obtained through thermochemical pretreatment of the sludge.

Optimization for biodegradation of 2,4,6-trinitrotoluene (TNT) by Pseudomonas putida.

In this study, a strain of Pseudomonas putida KP-T202, isolated from the soil in a contaminated site, degraded 2,4,6-trinitrotoluene (TNT). In order to make this biodegradation process commercially feasible and reduce biodegradation time, optimal environmental factors are determined. At an initial concentration of 100 mg/l, TNT was totally degraded within 15 h under aerobic conditions. The optimal conditions for the biodegradation of TNT were found to be 30 degrees C, pH 7, 1% corn steep liquor (CSL), 0.025% NH,CI and 0.1% Tween 80; the reaction rate constant was 0.348 h(-1) These environmental conditions can be used to improve the efficiency of large-scale reactors for the treatment of TNT-contaminated wastewater and soil. In addition, the intermediates were identified as 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-dinitrotoluene and 2,6-dinitrotoluene.

Bioremediation of 2,4,6-trinitrotoluene contaminated soil in slurry and column reactors.

The bioremediation of 2,4,6-trinitrotoluene (TNT) contaminated soil was performed on a laboratory scale. To compare bioremediation methods, a soil slurry reactor and a soil column reactor were operated and the effects of supplemental sources were investigated. Optimal conditions for the two bioremediation systems for the removal of TNT were obtained. In the soil slurry reactor, about 60% of the 1000 mg/kg TNT contaminated soil was degraded after 10 d, nearly complete biodegradation (>99%) was achieved within 25 d, and the microorganisms grew and reached a maximum of 9.5 x 10(9) CFU/ml at 15 d. In the soil column reactor, about 50% of the 1000 mg/kg TNT contaminated soil was degraded after 25 d and nearly complete biodegradation (>99%) was achieved within 60 d. Microorganisms grew and reached a maximum of 9.8 x 10(10) CFU/g soil at 40 d. These results should help in determining the best bioremediation method and improving the design and operation of large scale clean up of contaminated sites by bioremediation systems.

Biokinetic parameter estimation for degradation of 2,4,6-trinitrotoluene (TNT) with Pseudomonas putida KP-T201.

The purpose of this study is to determine the biodegradation kinetics of 2,4,6-trinitrotoluene (TNT) by a newly isolated microorganism. Hundreds of microorganisms were isolated from explosives-contaminated soil in Korea. Examination of culture tests revealed that a few species of microorganisms have good ability to degrade TNT. The most efficient one was selected and identified as Pseudomonas putida KP-T201. Biodegradation of TNT was tested in a batch reactor using a pure culture of P. putida KP-T201. The effect of different concentrations of TNT on the rate of bacterial biodegradation was investigated. The Haldane equation seems to be an adequate expression for the cell growth data, and the kinetic constants obtained were mu(m)=0.65 h(-1), K(S)=0.62 mgl(-1), and K(i)=115 mgl(-1). The dependence of the bacterial specific growth rate on the concentration of TNT could be explained as a conventional model of substrate inhibition.

Comparison of disperse and reactive dye removals by chemical coagulation and Fenton oxidation.

The composition of wastewater from the dyeing and textile processes is highly variable depending on the dyestuff type and typically has high COD and color. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by combination of chemical coagulation and Fenton oxidation. In addition, performances between Fe3+ coagulation and Fenton oxidation of dye solutions were compared by measuring COD and dye removals, distributions of zeta potential, concentration of suspended solid were investigated. Fenton oxidation in combination with Fe3+ coagulation has shown to effectively remove COD and dye. About 90% of COD and 99% of dye removals were obtained at the optimum conditions. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. The COD and dye removed per unit Fe3+ coagulant added for disperse dye solutions were higher than those for reactive dye solutions. Therefore, the disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions. Conversely, reactive dye solutions have higher applicability of Fenton oxidation than disperse dye solutions due to their higher solubility, lower suspended solids concentrations and higher SCOD/TCOD ratios. The COD and dye removed per Fe2+ Fenton reagent added for reactive dye solutions are respectively higher than those for disperse dye solutions.

Effects of electron beam irradiation and temperature on the treatment of swine wastewater using an ion exchange biological reactor.

Swine wastewater was treated using an ion exchange biological reactor (IEBR). Organic matter and nutrient in swine wastewater were pre-treated by electron beam irradiation. The optimal dose for solubilization of organic matter in swine wastewater ranged from 20 kGy to 75 kGy. The carbohydrates, proteins, and lipids were investigated as proteins and lipids mainly contained the solubilized organic matter. The solubilization of organic matter in swine wastewater was affected by the combination effects of temperature and dose. The maximum chemical oxygen demand (COD) and ammonia removal efficiencies were 74.4% and 76.7% at a dose of 0 kGy under room temperatures (23.0°C). The removal of ammonia was significantly affected by low temperature (15.3°C). On the other hand, the removal of phosphorus was not a function of electron beam irradiation or temperature because struvite is one of the main removal mechanisms under anoxic conditions.

Enhancement of struvite purity by re-dissolution of calcium ions in synthetic wastewaters.

Although it is widely known that the presence of Ca ions inhibits the nucleation and growth of struvite, which consists of NH4(+), PO4(3-), and Mg(2+), there is a lack of knowledge on actual Ca contents in struvite co-precipitates at various N and P concentrations and the corresponding effects on the sizes of the precipitates. Therefore, to address this challenge, this study designed synthetic wastewaters including the variety of N and P concentrations, and conducted batch experimental reactions with each wastewater to investigate Ca precipitation and size distributions of the precipitates. The molar ratio of Mg:P:N was confined to 1:1:7, while the initial Ca(2+) concentrations were chosen to be 30-60 mg/L, which are typical Ca concentrations in real wastewaters. The result of the batch experiments confirmed that the presence of Ca caused smaller solids than struvite as indicated in previous studies, and there was competition between Ca-phosphate and Mg-N- PO4 (struvite) reactions, as expected. At the beginning of the experiment (∼1 min), fast Ca-phosphate precipitation was dominant because free Ca and P ions were quickly removed while Mg and N concentrations gradually reduced. However, as the nucleation and crystal growth processes elapsed, dissolved Mg and N concentrations continuously decreased, but dissolved Ca concentrations could rise again at high N and P concentration conditions. The interesting phenomenon is that such increases of Ca concentrations probably results from the thermodynamic energy differences between struvite and Ca-phosphate formations. A high thermodynamic driving force of struvite precipitation could drive the re-dissolution of Ca-ions from the Ca-phosphate compounds with low saturation states. This result is expected to be applied for increasing the struvite purity by the Ca re-dissolution through the thermodynamic spontaneity without additional energy input.

Swine wastewater treatment using a unique sequence of ion exchange membranes and bioelectrochemical system.

An ion exchange biological reactor (IEBR) treated organic matter and nitrogen in swine wastewater at 23 °C. The enhanced IEBR enhanced the ammonium flux by electrochemical attraction. The abiotic ammonium fluxes at the applied voltage of 0, 1, and 3 V were 1.33, 1.79, and 2.73 mg/m(2)/s, respectively. In the meantime, the ammonium fluxes caused by biological nitrification at the applied voltage of 0, 1, and 3 V were 1.54, 2.07, and 3.59 mg/m(2)/s, respectively. Removal of organic matter and nitrogen in swine wastewater was proportional to the applied voltage. The average SCOD removal efficiencies at the applied voltage of 0, 1, and 2V were 59.7%, 60.2%, and 67.0%, respectively. The average total nitrogen removal efficiencies at the applied voltage of 0, 1, and 2V were 39.8%, 49.5%, and 58.7%, respectively.

Simultaneous nitrification and denitrification in a CEM (cation exchange membrane)-bounded two chamber system.

A novel process was developed to induce a simultaneous oxidation of ammonia and denitrification in a single system consisting of two chambers separated by a cation exchange membrane. One was an anoxic chamber and the other was an aerobic chamber. The maximum mass flux via the membrane was calculated as 0.83mg NH(4)(+)-N/m(2)s in a batch test when the initial concentration of NH(4)(+) was 700 mg N/L. And it was observed that NO(3)(-) and NO(2)(-) moved via the membrane in a reverse direction when NH(4)(+) was transported. When the system was operated in a continuous mode by feeding a wastewater containing glucose and NH(4)(+), it was observed that soluble chemical oxygen demand and NH(4)(+) were simultaneously removed showing 99% and 71 approximately 86% of efficiency, respectively. Denitrification occurred in the anoxic chamber and nitrification was carried out in the aerobic chamber.

Carbon source recovery from waste activated sludge by alkaline hydrolysis and gamma-ray irradiation for biological denitrification.

The recovery of an organic carbon source from a waste activated sludge by using alkaline hydrolysis and radiation treatment was studied, and the feasibility of the solubilized sludge carbon source for a biological denitrification was also investigated. The effects of an alkaline treatment and gamma-ray irradiation on a biodegradability enhancement of the sludge were also studied. A modified continuous bioreactor for a denitrification (MLE reactor) was operated by using a synthetic wastewater for 47 days. Alkaline treatment of pH 10 and gamma-ray irradiation of 20 kGy were found to be the optimum carbon source recovery conditions. COD removal of 84% and T-N removal of 51% could be obtained by using the solubilized sludge carbon source through the MLE denitrification process. It can be concluded that the carbon source recovered from the waste activated sludge was successfully employed as an alternative carbon source for a biological denitrification.

Removal of arsenite and arsenate using hydrous ferric oxide incorporated into naturally occurring porous diatomite.

In this study, a simplified and effective method was tried to immobilize iron oxide onto a naturally occurring porous diatomite. Experimental resultsfor several physicochemical properties and arsenic edges revealed that iron oxide incorporated into diatomite was amorphous hydrous ferric oxide (HFO). Sorption trends of Fe (25%)-diatomite for both arsenite and arsenate were similar to those of HFO, reported by Dixit and Hering (Environ. Sci. Technol. 2003, 37, 4182-4189). The pH at which arsenite and arsenate are equally sorbed was 7.5, which corresponds to the value reported for HFO. Judging from the number of moles of iron incorporated into diatomite, the arsenic sorption capacities of Fe (25%)-diatomite were comparable to or higher than those of the reference HFO. Furthermore, the surface complexation modeling showed that the constants of [triple bond]SHAsO4- or [triple bond]SAsO4(2-) species for Fe (25%)-diatomite were larger than those reference values for HFO or goethite. Larger differences in constants of arsenate surface species might be attributed to aluminum hydroxyl ([triple bond]Al-OH) groups that can work better for arsenate removal. The pH-controlled differential column batch reactor (DCBR) and small-scale column tests demonstrated that Fe (25%)-diatomite had high sorption speeds and high sorption capacities compared to those of a conventional sorbent (AAFS-50) that is known to be the first preference for arsenic removal performance in Bangladesh. These results could be explained by the fact that Fe (25%)-diatomite contained well-dispersed HFO having a great affinity for arsenic species and well-developed macropores as shown by scanning electron microscopy (SEM) and pore size distribution (PSD) analyses.