There are 2 central waste water treatment plants in Samutprakarn province. One is situated at KM30 which consists of 85 tanneries in this surrounding area. The volumes of effluents discharge average daily 20,000 M3. All of the tanneries have to provide sedimentation pool for chrome waste in order to release chrome into minimized amount and discharge into the main sewage leading to the central treatment plant, or some tanneries use chrome recycle process before discharge into the main sewage to the treatment plant.