[Relation between oxygen uptake rate and biosorption of activated sludge against chemical substance].

In this study, the elucidation of the toxicity mechanism was undertaken regarding the IC(50) of the oxygen uptake rate (OUR) with relevance to the biosorption as a toxicity evaluation of chemical substances for activated sludge (AS). At the IC(50) of<100 mg/l, malachite green (MG) and crystal violet (CV) were confirmed in the group showing relatively strong OUR inhibition. These dyes were markedly biosorbed by AS in a short time. The biosorption for AS showed a weak tendency in linear alkyl benzene sulfonate (LAS), alkyl ethoxy sulfonate (AES), alpha-olefine sulfonate (AOS), sodium dodecyl sulfate (SDS), formaldehyde (FA), benzalkonium chloride (BZaC), benzethonium chloride (BZeC), rhodamine 6G (R-6G) and fuchsine (Fuc) in which the IC(50) belonged to the 100-1000 mg/l group, when it was compared with CV and MG. In ethanol (EtOH), isopropanol (PrOH), nile blue (NB), evans blue (EB), methylene blue (MB), methyl orange (MO), paraquat (PQ), chlorophyllin (Chl) and auramine (Aur), the IC(50) was large, and the biosorption of AS was weak at 0-15%. The biosorption of MG for AS followed the adsorption isotherm equation Y=0.002X(0.511) of Freundrich. The correlation coefficient was gamma=0.998 (n=8), and a very high correlation was obtained. In the qualitative OUR curve by AS pretreated with MG or CV which belonged to the IC(50) small group, the inhibition of remarkable OUR was observed. Therefore, the findings of the present investigation suggest that the inhibition of the OUR for AS by the tested chemical substances was markedly affected by the biosorption.

[Development of the new desiccator system for measuring the removal effect of the formaldehyde as an indoor air pollutant by the adsorbent].

The new desiccator system with measures for the prevention of dew drops and the processing of the formaldehyde (FA) gas discharged from the final desiccator was produced, and the FA removal rate for various adsorbents was examined. For the prevention of dew drops in the desiccator, a hygroscopic bottle containing silica gel was used next to the FA gas generator, and humidity was adjusted by adjusting the interval between the FA gas outlet (a) and the desiccant (b). The removal of the harmful FA gas discharged from the final desiccator (n=5) is an important in the environmental preservation. To solve this problem, the FA gas was passed through an oxidation bottle containing KMnO(4)-H(2)SO(4) solution, and it was possible to confirm the complete decomposition of the FA by increase of the CO(2) and elimination of the FA. For the determination of the FA concentration in the desiccator, 100 ml air was beforehand collected using a gas collector into a 100 ml vial bottle containing 2 ml distilled water, and 50 ml of air from each desiccator was injected using a glass syringe. This was left under a slightly reduced pressure for 20 min, and the FA concentration was determined by the AHMT method. The FA removal rate after 1 h for each adsorbent (0.5 g) was 50% or more for chitin, KIMCO and silica gel. The removal efficacy for activated carbon was higher for fine particles than for coarse particles, and a dose-response relationship was established.

Influences of drugs on the oxygen uptake rate and biosorption of activated sludge.

To prevent pollution of the water environment by drugs, we evaluated factors affecting the elimination of drugs by inducing reactions between the pharmaceutical chemicals originating from the drugs and activated sludge (AS) in test tubes. Of 30 pharmaceutical chemicals examined, ibuprofen (IBP) as an anti-inflammatory drug most markedly inhibited the oxygen uptake rate (OUR) of AS, and its IC50 was 172 mg/l. The IBP elimination from the wastewater was due to the significant biosorption by AS and was based on the time-response and dose-response relationships. In the pharmaceutical chemical group (1) (diclofenac Na, ketoprofen, indomethacin, salicylic acid, mefenamic acid, phenylbutazone, chlorpromazine.HCl, furosemide, tolbutamide and warfarin K) showing a relatively significant OUR inhibition (IC50, 200-500 mg/l), protein binding (75-99.7%), and the biosorption by AS also tended to be significant. In group (2) (acetaminophen, kanamycin.H2SO4, antipyrine, ethenzamide, gentamicin.H2SO4, cyclophosphamide.HCl, aminophylline, procainamide.HCl and cimetidine) showing a negligible OUR inhibition (IC50 > or =2000 mg/l), the protein binding was slight (0-74%), and biosorption by AS was also negligible. For the IBP and group (1), AS was pretreated with a certain excessive amount of each pharmaceutical chemical, and the qualitative OUR curves of the AS-synthetic sewage-II after washing showed a significant OUR inhibition immediately after the start of the reaction. Group (2), as well as the control group showed no OUR inhibition. These results suggest that the degree of OUR inhibition of AS by pharmaceutical chemicals is affected by the protein binding and the degree of biosorption. This suggests that pharmaceutical chemicals with a significant protein binding possibility can be eliminated from the wastewater by binding to AS.