Enhanced anaerobic biodegradability and inactivation of fecal coliforms and Salmonella spp. in wastewater sludge by using microwaves.

During continuous operation of three mesophilic-anaerobic digesters, the effect of microwave irradiation, as sludge thermal pretreatment (60 to 65 degrees C), was studied. The fecal coliforms log inactivation for microwaved/digested sludge was 4.2 +/- 0.4, whereas for conventionally heated/digested sludge and control were 2.9 +/- 0.5 and 1.5 +/- 0.5, respectively. In the case of Salmonella spp., no colonies were detected in 85% of the microwaved/digested samples. Considering the detection limit, the log inactivation of these samples was greater than 2.0 +/- 0.3. The conventionally heated/digested sludge and control showed log inactivations of 1.9 +/- 0.2 and 1.1 +/- 0.3, respectively. At the 95% confidence level, microwaved/digested sludge increased the biogas production by 16.4 +/- 5.6% and 6.3 +/- 2.4%, as compared to control and conventionally heated/digested sludge, respectively. When thermally treated sludge was analyzed for soluble chemical oxygen demand, microwaved waste-activated sludge showed considerable solubilization between 37 and 60 degrees C. Microwaved/digested sludge showed a reduction of capillary suction times by 11.1 +/- 5.9% and 10.7 +/- 5.6%, as compared to control and conventionally heated/digested sludge, respectively.     

Removal of arsenate and arsenite from aqueous solution by waste cast iron

The removal of As(III) and As(V) from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experiment: grind precipitate dust (GPD) and cast iron shot (CIS). The X-ray diffraction analysis indicated the presence of Fe0 on GPD and CIS. Batch experiments were performed under different concentrations of As(III) and As(V) and at various initial pH levels. Results showed that waste cast iron was effective in the removal of arsenic. The adsorption isotherm study indicated that the Langmuir isotherm was better than the Freundlich isotherm at describing the experimental result. In the adsorption of both As(III) and As(V), the adsorption capacity of GPD was greater than CIS, mainly due to the fact that GPD had higher surface area and weight percent of Fe than CIS. Results also indicated the removal of As(III) and As(V) by GPD and CIS was influenced by the initial solution pH, generally decreasing with increasing pH from 3.0 to 10.5. In addition, both GPD and CIS were more effective at the removal of As(III) than As(V) under given experimental conditions. This study demonstrates that waste cast iron has potential as a reactive material to treat wastewater and groundwater containing arsenic.     

Study on integrated management of PCB containing waste and PCB contaminated waste: proposal of new congeners for quantification

In the present study, new congeners were selected for the efficient management of PCB containing waste and PCB contaminated waste, and the applicability of these new indicators was confirmed. As a result, 8 indicator congeners and 4 index peaks which were named “Proposed new method 1” and “Proposed new method 2” were selected. For the assessment of a novel quantitative method, comparative tests using conventional methods were conducted, and the factors for total PCB were calculated for each method. Results from these tests showed that the average values for the factors of CEN/TC19/WG22, DIN 51527, and the test method by the disposal regulation for ocean dumping in Korea were 1.86, 3.47, and 2.52, respectively, while those for the proposed new method 1 and proposed new method 2 were 2.98 and 5.56, respectively. For PCB contaminated waste, the factor was found to be 1.99, 3.42, and 3.02 using the conventional methods, 2.67 using the proposed new method 1, and 5.57 using the proposed new method 2. It is expected that, in accordance with the results of the present study, the management of PCB waste can be integrated, regardless of the type of waste involved.     

Prenatal diagnosis of Pompe's disease (type ii glycogenosis) in chorionic villus biopsy using maltose as a substrate

Uncultured trophoblasts obtained from chorionic villus biopsy during the gestation period of 8–12 weeks were assayed for alpha-glucosidase activity using maltose as the substrate. Only one major form of maltase activity with a pH optimum at 4.0 was demonstrated. Using this method, we performed prenatal diagnosis on three pregnancies at risk for the infantile form of type II glycogen storage disease. Two affected fetuses and one unaffected fetus were predicted and the diagnosis was subsequently confirmed. The maltose assay offered a direct, simple, and sensitive method for prenatal diagnosis of Pompe's disease in the first trimester.     

Egg production by the subtropical copepod Undinula vulgaris

Egg production by Undinula vulgaris, collected off Kaneohe Bay, Hawaii, was measured under field and laboratory conditions on 16 occasions from June to December 1991. In situ rates ranged from 0 to 15.7 eggs female^-1 d^-1, with a mean of 6.4 eggs female^-1 d^-1, 2.1% female body carbon d^-1. Maximum in situ production was 53 eggs female^-1 d^-1, 17.2% C d^-1. Average egg production (Y, eggs female^-1 d^-1) was related to the concentration of particulate carbon (X, g C l^-1) by the Ivlev function, Y=13.9[1-e^{-0.0097 (x-10)}], with R ²=0.96. Individuals with the same feeding history produced more eggs at lower temperatures in the laboratory. Egg production was not significantly correlated with dry weight, and no noticeable temporal trend was found. Despite the elevated habitat temperatures (26 to 27°C) of this subtropical copepod, maximum fecundity of U. vulgaris was comparable to, but average rates were lower than, egg production rates of similarly-sized, temperate and borcal species of the genus Calanus. Our results caution against broad extrapolations of the temperature-growth relationship for temperate coastal copepods to species from poorly studied, oligotrophic regions of the oceans.Contribution No. 3257 from the School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA     

Dynamics of microcystins-LR and -RR in the phytoplanktivorous silver carp in a sub-chronic toxicity experiment

A sub-chronic toxicity experiment was conducted to examine tissue distribution and depuration of two microcystins (microcystin-LR and microcystin -RR) in the phytoplanktivorous filter-feeding silver carp during a course of 80 days. Two large tanks (A, B) were used, and in Tank A, the fish were fed naturally with fresh Microcystis viridis cells (collected from a eutrophic pond) throughout the experiment, while in Tank B, the food of the fish were M. viridis cells for the first 40 days and then changed to artificial carp feed. High Performance Liquid Chromatography (HPLC) was used to measure MC-LR and MC-RR in the M. viridis cells, the seston, and the intestine, blood, liver and muscle tissue of silver carp at an interval of 20 days. MC-RR and MC-LR in the collected Microcystis cells varied between 268-580 and 110-292 microg g(-1) DW, respectively. In Tank A, MC-RR and MC-LR varied between 41.5-99.5 and 6.9-15.8 microg g(-1) DW in the seston, respectively. The maximum MC-RR in the blood, liver and muscle of the fish was 49.7, 17.8 and 1.77 microg g(-1) DW, respectively. No MC-LR was detectable in the muscle and blood samples of the silver carp in spite of the abundant presence of this toxin in the intestines (for the liver, there was only one case when a relatively minor quantity was detected). These findings contrast with previous experimental results on rainbow trout. Perhaps silver carp has a mechanism to degrade MC-LR actively and to inhibit MC-LR transportation across the intestines. The depuration of MC-RR concentrations occurred slowly than uptakes in blood, liver and muscle, and the depuration rate was in the order of blood>liver>muscle. The grazing ability of silver carp on toxic cyanobacteria suggests an applicability of using phytoplanktivorous fish to counteract cyanotoxin contamination in eutrophic waters.     

The effect of operational parameters on the photocatalytic degradation of pesticide

The photocatalytic degradation of Cartap Hydrochloride, a synthetic pesticide. has been investigated over coated TiO2 photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., Cartap Hydrochloride concentration, reaction time, light intensity and additive on the degradation rate of aqueous solution of Cartap Hydrochloride has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Cartap Hydrochloride solutions.     

Long-term effects of fertilization on the forms and availability of soil phosphorus in rice paddy

The changes in total P accumulation and P compounds with time in the plough layer in a paddy soil in southern Korea were investigated in relation to the continuous application of chemical fertilizers (NPK), straw based compost (Compost), combination these two (NPK+Compost) for 31 years. Continuous fertilization increased the total and inorganic P contents in plough layers. In NPK, inorganic P fraction did not change with time, but organic P content increased significantly. Long-term application of chemical fertilizer together with compost accelerated the decrease in the organic P fraction, presumably due to promoting microbial activity in the plow layer, and then increased significantly inorganic P fraction. Compost application decreased the residual P and Fe-P fractions and then increased inorganic P fraction, in spite of continuous compost application. Increase in total, inorganic and extractable P with time may be closely related to the increase in the availability of accumulated P for rice growth.     

Chemical composition and source apportionment of PM2.5 particles in the Sihwa area, Korea

To investigate the chemical characteristics of fine particles in the Sihwa area, Korea, atmospheric aerosol samples were collected using a dichotomous PM10 sampler and two URG PM2.5 cyclone samplers during five intensive sampling periods between February 1998 and February 1999. The Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES)/ICP-Mass Spectrometry (MS), ion chromatograph (IC), and thermal manganese dioxide oxidation (TMO) methods were used to analyze the trace elements, ionic species, and carbonaceous species, respectively. Backward trajectory analysis, factor analysis, and a chemical mass balance (CMB) model were used to estimate quantitatively source contributions to PM2.5 particles collected in the Sihwa area. The results of PM2.5 source apportionment using the CMB7 receptor model showed that (NH4)2SO4 was, on average, the major contributor to PM2.5 particles, followed by nontraffic organic carbon (OC) emission, NH4NO3, agricultural waste burning, motor vehicle emission, road dust, waste incineration, marine aerosol, and others. Here, the nontraffic OC sources include primary anthropogenic OC emitted from the industrial complex zone, secondary OC, and organic species from distant sources. The source impact of waste incineration emission became significant when the dominant wind directions were from southwest and west sectors during the sampling periods. It was found that PM2.5 particles in the Sihwa area were influenced mainly by both anthropogenic local sources and long-range transport and transformation of air pollutants.