ASTM D932-85 (R2002) pdf free.Standard Test Method for lron Bacteria in Water and Water-Formed Deposits.
1.1 Regardless of the method used to concentrate the solids in the water, keep them moist until examined.
1.2 Mud samples should be collected from the mud-water interface for maximum bacterial populations.
1.3 Transfer the deposit or mud samples to wide-mouth bottles and add clean, chlorine-free water to cover the deposits and maintain moisture until examined. Protect the samples from sunlight and hold at 4°C during transportation and storage.
1.4 As soon as possible after collection of the solids, microscopically examine them for the presence of iron bacteria.
2.1 Place a portion of the sample on the slide and apply a cover glass. A spatula or wide-mouth pipet can be used to transfer the sample to the slide. Use a pipet when flocs of material are encountered, as the flocs settle to the tip when the pipet is held in a vertical position, and concentrate in the first drop. In the case of very dilute solids or a water sample,concentrate the organisms by centrifuging, pour off the supernatant liquid, and repeat if necessary.
2.2 An alternative procedure is to filter a suitable volume of the dilute solids or the entire water sample through a 0.45-um membrane filter in an appropriate membrane filtration assembly (holder, tubing, trap, flasks and vacuum pump). For this test it is not necessary to sterilize the filter assembly for each sample, but the assembly should be thoroughly cleaned between tests.
2.3 Examine the slide under the microscope to determine if encrusted or colorless sheaths are present. Note the presence of the twisted stalks of Gallionella at this point, since treatment with acid in accordance with 9.4 will dissolve the delicate stalks.
3.1 The report shall state“Present” or” Not found, probably absent.” Make a statement as to the relative abundance of the organisms present. Make a negative report only after examination of several slides.
4.1 Since this standard is a qualitative type test, precision and bias statements cannot be provided.ASTM D932 free download.