## 4 Advanced Bioreactors for Hydrocarbon-Containing Wastewater Treatment
### Anaerobic and Hybrid (An anaerobic-Aerobic) Bioreactors
& \multirow{3}{*}{COD, NH3-N and phosphorus removal of 83, 100} & \multirow{3}{*}{[65]} \\  & & & & 89\% \\ \hline \multirow{3}{*}{Petrochemical wastewater} & \multirow{3}{*}{Pipen photodetectors} & Filamentous microalgae _Tribonema_ & \multirow{3}{*}{COD, NH3-N and phosphorus removal of 83, 100} & \multirow{3}{*}{[66]} \\  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \hline \multirow{3}{*}{Petroleum refinery wastewater} & \multirow{3}{*}{Pilot HyVAB} & Filamentous microalgae _Tribonema_ & \multirow{3}{*}{COD and 91\% of the soluble COD removal} & \multirow{3}{*}{[15]} \\  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & & 89\% \\ \hline \multirow{3}{*}{Metformin-containing wastewater} & \multirow{3}{*}{Pilot HyVAB} & Granular sludge from paper and pulp wastewater treatment facility. Continuously operating at varying organic loading rates for 92 days. & \multirow{3}{*}{COD and 91\% of the soluble COD removal} & \multirow{3}{*}{[67]} \\  & & & & 89\% \\ \cline{1-1} \cline{4-4}  & & & 89\% \\ \cl  
system consisted of UASB and aerobic packed-bed biofilm (PBB) reactors was applied to remove PAHs from refinery wastewater (COD of 435 mg/L; TPH of 1520 mg/L; PAH of 10.33 mg/L), resulting in the total COD removal efficiency of 81.07% and the complete removal of three PAHs (naphthalene, phenanthrene and pyrene) after 118 days [68]. In other study, a combination of UASB and BAF reactors was used by [PERSON] et al. [45] in a field pilot study of the treatment of heavy oil wastewater with high organic loads (COD of 129.8-1238 mg/L; oil of 24.5-315.5 mg/L) and low N and P contents. By operating the system for 252 days (including the start-up of 128 days), the COD, ammonia nitrogen (NH3-N) and SS were removed by 74%, 94% and 98%, respectively. The authors suggested that most of the alkanes were degraded by the UASB process, while the BAF played important roles both in degrading organic compounds and removing NH3-N and SS. [PERSON] et al. [46] used two MBBRs filled with suspended ceramicsite for the sequential anaerobic-aerobic treatment ofinery wastewater (COD of 675-742 mg/L; O&G of 42-48 mg/L) at the continuous flow mode for 124 days. The results showed that COD and NH3-N removal efficiencies were higher than 85% at the HRT values of 72 and 36 h. Additionally, the removal of 16 PAHs detected in the influent was 39.4 and 74.6% for anaerobic and aerobic MBBRs, respectively. More complex hybrid system integrating a hydrolysis acidification (HA) reactor, a MBBR and an ozonation-biologically activated carbon (O\({}_{3}\)-BAC) unit was used to treat heavy oil wastewater (COD of 1020-1250 mg/L; oil of 108-127 mg/L), resulting in 95.8 98.9 and 94.4% removals of COD, oil and ammonia, respectively [47]. The HA process improved the biodegradability of complex organics, while the MBBR process played an important role in the oxidative removal of hydrocarbons. The ozonation process further enhanced the biodegradability of the MBBR effluent and, finally, deep treatment was completed in the BAC reactor. Another novel two-stage system coupling a stirred-tank HA reactor with a series of algal photobioreactors was investigated for the treatment of acrylonitrile butadiene styrene resin-manufacturing wastewater (COD of 856 \(\pm\) 11 mg/L) [65]. The coupling system achieved deep cleaning of the benzene-containing wastewater (COD, NH\({}_{3}\)-N and phosphorus removal rates were 83, 100 and 89%, respectively) while producing a considerable _Chlorella_ sp. biomass at low cost. A filamentous microalgae _Tribonema_ sp. was used by the same research group in open photobioreactors integrated with the traditional anaerobic/oxic process to treat low-concentration petrochemical wastewater (COD of 312.8 \(\pm\) 15.6 mg/L) [66].