Recently, bathes have been suspected to an important source of indoor exposure to volatile organic compounds(VOCs). Two experiments were conducted to evaluate chloroform exposure and corresponding body burden by exposure routes while bathing. Another experiment was conducted to examine the chloroform dose during dermal exposure and the chloroform decay in breath after dermal exposure. The chloroform dose was determined based on exhaled breath analysis. The exhaled breath concentration measured after normal baths (2.8 ㎍/㎥) was approximately 13 times higher that measured prior to normal bathes (0.2 ㎍/㎥). Based on the means of the normalized post exposure chloroform breath concentration, the dermal exposure was estimated to contribute to 74% of total chloroform body burden while bathing. The internal dose from bathing (inhalation plus dermal) was comparable to the dose estimated from daily water ingestion. The risk associated with a weekly, 30-min bath was estimated to be 1 x 10^-5, while the risk from daily ingestion of tap water was to be 0.5 × 10^-5 for 0.15 1 and 6.5 × 10^-5 for 2.0 1. Chloroform breath concentration increased gradually during the 60 minute dermal exposure. The breath decay after the dermal exposure showed two-phase mechanism, with early rapid decay and the second slow decay. The mathematical model was developed to describe the relationship between water and air chloroform concentrations, with R^2 = 0.4 and p<0.02.

Batch experiments were performed to evaluate the effect of sludge acclimation and contact load on the behavior of phosphorus and organic substrates under anaerobic conditions. Four different sludges were acclimated in the sequencing batch reactors operated by intermittent aeration. All the experiments performed in a bench scale have shown the following results: 1. The unreleaseable phosphorus contents for four different sludges are the range of 16 ㎎ P/g SS to 24 ㎎ P/g SS, depending on the sludge acclimation conditions. 2. All the specific substrate uptake rates(SSUR) are expressed in the first order equation for releaseable phosphorus contents. The reaction rate coefficient, k, has the values of 4.0, 8.9, and 13.8 mg COD/㎎ P/hr, depending on the contact load and sludge species. 3. As reaction proceeds, the ratios of ΔP to - ΔCOD at high contact load are almost constant. in the range of 0.10 to 0.14, but at low contact load, they increase from 0.08 to 0.27.