Recovery of phosphorus, magnesium, and potassium from surplus activated sludge using existing sludge treatment facilities and thickened primary sludge.

The separation of P, K, and Mg from surplus activated sludge (SAS) was investigated using existing sludge treatment facilities and the thickened primary sludge (TPS). The addition of the TPS to the SAS storage tank accelerated the anaerobic release of the three elements from SAS with maximum efficiencies of about 60%. The efficiency of P release showed a significant correlation with the oxidation-reduction potential. Increasing the total solid concentration increased the release of elements. The released elements could be transferred to a separate liquid (SL) from a screw-press thickener, and maximum concentrations of P, K, and Mg were about 200, 60, and 35 mg/L, respectively. The addition of CaCl2 and NaOH solutions to SL precipitated P as hydroxyapatite. However, no precipitation of K and Mg occurred simultaneously with P, even when the pH of SL was increased to 9. These findings suggest that about 60% of P, K, and Mg can be separated from SAS into SL using existing sludge treatment facilities and TPS; however, a method other than precipitation would be needed to recover P and K from SL simultaneously.

Exploration of an efficient method for removing antibiotics from water and digested sewage sludge using Fe(VI): Kinetics and P phytoavailability and compostability in treated sludge.

Potassium ferrate (K2FeO4) containing hexavalent iron [Fe(VI)] is an environmentally friendly oxidant, which possesses strong oxidizing power to treat wastewater and sludge. Therefore, the present study investigated degradation of selected antibiotics, namely levofloxacin (LEV), ciprofloxacin (CIP), oxytetracycline (OTC), and azithromycin (AZI), in water and anaerobically digested sewage sludge samples using Fe(VI). The effects of different Fe(VI) concentrations and initial pH values on antibiotic removal efficiency were evaluated. Under the studied conditions, LEV and CIP were almost completely removed from water samples, following second-order kinetics. In addition, over 60% of the four selected antibiotics were removed from sludge samples using 1 g L-1 Fe(VI). Furthermore, P phytoavailability and compostability of Fe(VI)-treated sludge were evaluated using different extraction reagents and a small composting unit. The extraction efficiency of phytoavailable P using 2% citric acid and neutral ammonium citrate was approximately 40% and 70%, respectively. The mixture of Fe(VI)-treated sludge and rice husk was self-heated in a closed composting reactor through the biodegradation of organic matter derived from the treated sludge. Therefore, Fe(VI)-treated sludge may be used as an organic material containing phytoavailable P for compost.

Degradation of the endocrine-disrupting 4-nonylphenol by ferrate(VI): biodegradability and toxicity evaluation.

4-Nonylphenol (4-NP) is an endocrine-disrupting and persistent chemical and is partially degraded in conventional wastewater treatment processes. Ferrate(VI) can be used as an environment-friendly oxidizing agent to mediate 4-NP degradation. Thus, this paper evaluates the biodegradability of 4-NP and its degradation products after the addition of ferrate(VI). The biodegradability was examined using NP labeled with 14C as a tracer and activated sludge microorganisms as an inoculum. The addition of ferrate(VI) to the 4-NP solution spiked with the tracer resulted in no remarkable decrease in the concentration of 14C, indicating incomplete mineralization of 4-NP and formation of degradation products. The degradation products from 4-NP with Fe(VI) were estimated based on mass spectra, which detected a unique peak at m/z 223 at low intensity. Four hydrogen atoms might have been added to 4-NP by degradation with Fe(VI). In addition, the effect of ferrate(VI) concentration on the estrogenic activity of 4-NP in an aqueous solution was investigated using a yeast bioassay. The results show that estrogenic activity was significantly decreased at a mass ratio of Fe(VI) to 4-NP greater than or equal to 2.5.

Effect of dissolved soil organic matter on cesium adsorption by zeolite and illite.

In controlled landfill sites, soil layers are installed around radioactive waste to prevent the leaching of radioactive cesium (Cs). The Cs retention capacity of soil has been reported to be enhanced by mixing clay minerals. However, several studies have indicated that dissolved soil organic matter (DSOM) inhibits the Cs sorption by clay minerals. Therefore, this study assesses the effect of DSOM on the Cs sorption by zeolite and illite. Excitation emission matrix fluorescence spectroscopy was used for DSOM in the soil solution before and after contact with clay minerals. The results show that DSOM sorption onto clay minerals, particularly fulvic acid, inhibited Cs sorption. Batch sorption tests were conducted to obtain the sorption isotherms using two sample solutions, namely, soil and ionic solutions. Soil solution, which contained DSOM, was prepared by mixing soil and ultrapure water and filtration using a 0.3-µm glass fiver filter. Ionic solution was prepared by removing DSOM larger than 500 Da from the soil solution using dialysis. The amount of sorbed Cs in the soil solution was lower than that in the ionic solution. Comparing the Freundlich coefficients (KF) between the soil and ionic solutions, we found that the KF values of zeolite and illite for the ionic solution accounted for 6.4- and 4.4-fold higher than that for the soil solution, respectively.

Tylosin degradation during manure composting and the effect of the degradation byproducts on the growth of green algae.

In this study, we investigate the tylosin degradation in sheep feces during composting. The sheep feces containing tylosin were composted using the laboratory-scale composting units. Tylosin was degraded during composting, and the half-life of tylosin degradation decreased with increasing temperature from 40 °C to 65 °C. The tylosin degradation in sheep feces can be attributed to the microorganisms in the feces and not to heating because tylosin did not degrade over a period of 48 h at temperatures of 0 °C-65 °C in sterilized water. The artificial rainwater solution extracted from the composted sample did not inhibit the growth of Raphidocelis subcapitata, a type of green alga. Our results indicate that composting the feces containing tylosin is effective in degrading tylosin, which may result in the preservation of agricultural fields as well as nearby aquatic environments.

Removal of nonylphenol and nonylphenol monoethoxylate from water and anaerobically digested sewage sludge by Ferrate(VI).

Nonylphenol (NP) and nonylphenol monoethoxylate (NP1EO) have toxic and persistent characteristics, and are incompletely degraded in conventional wastewater treatment processes. These compounds are present in sewage sludge that can be reused as fertilizers or soil conditioners. Accordingly, NP and NP1EO should be properly removed before being discharged in the environment. In this study, potassium ferrate (K2FeO4) containing hexavalent iron (Fe(VI)) was used as an environment-friendly oxidizing agent to mediate NP and NP1EO degradation. The aim of this study was to investigate the effects of pH and Fe(VI) dosage on the degradation of NP and NP1EO in water and anaerobically digested sewage sludge samples. In water samples, under conditions examined in this study, maximum removal efficiencies for NP and NP1EO were 98% and 92%, respectively. For digested sewage sludge samples, the maximum removal efficiencies of NP and NP1EO were 58% and 96%, respectively. The results demonstrated that Fe(VI) can potentially degrade NP and NP1EO in water and digested sewage sludge samples. However, organic matter as a matrix in the sludge sample would inhibit the degradation of NP and NP1EO by Fe(VI). The pH values before and after adding K2FeO4 to the samples had an obvious influence on the removal of NP and NP1EO.

Determination of tylosin excretion from sheep to assess tylosin spread to agricultural fields by manure application.

Antibiotics administered to livestock are partly excreted with urine and feces. As livestock excrement is used as manure on agricultural fields, soil may be contaminated by excreted antibiotics, potentially resulting in the development of antibiotic-resistant bacteria. Therefore, it is necessary to determine the amount of antibiotic administered to livestock that could spread to agricultural fields through manure application. This study reveals the excretion ratio of tylosin from sheep. After developing an analysis procedure for tylosin in urine and feces from sheep, a tylosin excretion study was performed with two sheep. Tylosin was excreted in urine and feces for four days, after which its concentrations dropped below the limits of quantification (urine: 0.5µg/kg, feces: 2.4µg/kg). The total excretion ratio was 11% on average. The results of our study can provide useful knowledge for treating excrement in order to prevent the spread of antibiotics to agricultural fields through manure application.

[A case of hepatic metastasis from colon cancer successfully treated with 5-FU, levofolinate (l-LV) and low-dose CPT-11].

The patient was a 67-year-old man in whom hepatic metastasis from transverse colon cancer was detected 15 months after transverse colectomy (D2). We treated the patient by systemically administering 2 courses of 5-FU 750 mg/day with l-LV 350 mg/day (once weekly for 6 weeks per course). Assessment of therapeutic effects by CT showed PD in the patient. As a second-line therapy, we treated the patient by systemically administering 3 courses of 5-FU 750 mg/day, l-LV 350 mg/day and CPT-11 40 mg/day x 3 days (once a week for 4 weeks per course). After 3 courses of this chemotherapy, CT examination revealed a reduction in the tumor size of the liver, and CEA levels decreased at the end of this chemotherapy. This chemotherapy also showed no high-grade toxicities. l-LV/5-FU/low-dose CPT-11 seems to be effective for metastatic colon cancer, and safe from the toxicity standpoint.