SOUTH SIOUX CITY, Neb. (AP) — State regulators have revoked air and stormwater permits originally granted to a northeast Nebraska biogas plant that’s been plagued with problems and odor complaints.

An official who presided over the State Environment and Energy Department case said Big Ox Energy had continually failed to comply with state regulations.

“NDEE has provided Big Ox with many opportunities to come into compliance with its permits and regulations, but Big Ox has failed to do so,” hearing officer Melanie Whittamore- Mantzios wrote in her order.

The department cited Big Ox last April for failing to control emissions. The plant was taken out of operation that month for repairs and hasn’t cranked up since.

Tuesday’s ruling cited numerous environmental violation complaints and citations against Big Ox, which accepted organic waste from food and beverage manufacturers and converted it to methane for sale. Big Ox also received wastewater from other South Sioux City industries, pretreated it and discharged it to Sioux City, Iowa’s regional wastewater plant.

The Denmark, Wisconsin-based company has 30 days to appeal the ruling. A company spokesman didn’t immediately return an Associated Press message Thursday.

The plant has been under scrutiny since neighbors began complaining about odors after it opened in September 2016.

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