In this paper, we describe a culture-based biochip for detecting microorganisms in environmental samples in an improved, timesaving, and cost-efficient manner. The biochips use the paraffinophilic nature of microorganisms to rapidly detect and differentiate them in sewage samples collected from wastewater treatment plants. A new method of depositing paraffin was developed in order to fabricate such biochips. The developed technique uses butanol solvent to keep paraffin liquid during deposition by spin-coating and thick photoresist for patterning. Using this approach, 18 mm glass biochips with paraffin layers of 5-70 µm have been successfully fabricated. These biochips were used to demonstrate rapid, 5-min detection of microorganisms responsible for reactor foaming in wastewater treatment.