Class A biosolids are solid by-product of wastewater treatment which meet Environmental Protection Agency requirements to be used as fertilizer in farms, vegetable gardens, and can be sold directly to consumers. In 2014, this study’s target nutrient recovery facility adopted thermal hydrolysis pretreatment and anaerobic digestion to upgrade biosolids quality from Class B (previously lime-stabilized) to Class A. In order to certify if this newly produced material met all regulatory requirements, we performed laboratory analysis to characterize fecal coliforms, volatile solids, and metals content. In addition, we showed a baseline for nutrient management of total nitrogen, phosphorus, and the change in levels of polybrominated diphenyl ethers (PBDEs). Samples were collected for over a year since the start of THP-AD operation. Results were compared with the Class B biosolids produced at the same facility. Based on EPA standards, Class A biosolids were produced with stable quality after March, 2015, 16 weeks after process initiation. This work suggests that THP-AD is effective in producing Class A biosolids. In general, PBDEs in biosolids decreased from 1790 ± 528 (Class B) to 720 ± 110 µg/kg d.w. Our results suggest that the total levels of PBDEs decrease, however, the impact of the THP-AD on specific congeners are complex.
|Commitee:||Andrade, Natasha Almeida, Kjellerup, Birthe Veno|
|School:||University of Maryland, College Park|
|School Location:||United States -- Maryland|
|Source:||MAI 57/01M(E), Masters Abstracts International|
|Keywords:||Anaerobic digestion, Biosolids, PBDEs, Thermal hydrolysis|
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