## 2 Wastewater Treatment by Microalgae
### Industrial Wastewater
#### 2.3.3 Microalgae Treatment of Industrial Wastewater
\begin{table}
\begin{tabular}{c c c c} \hline
**Wastewater** & **Pretreatment Method** & **Microalgae** & **References** \\ \hline Anaerobic digested starch & Allowed to settle for several hours and filtered & _Chlorella pyrenoidosa_ (FACHB-9) & [105] \\ Anaerobic digested starch & Allowed to settle for 5–7 h in a settling tank & _Chlorella pyrenoidosa_ (FACHB-9) & [127] \\ processing & and filtered with 270 mesh (53 lm) polyester & _Chlorella pyrenoidosa_ (FACHB-9) & [127] \\  & filter bags & _Chlorella_ sp. & [73] \\ Raw dairy & Settled by gravity overnight and filtered & _Chlorella_ sp. & [73] \\  & through guze & _Chlorella_ sp. & [128] \\  & Centrifuged at 8000 rpm for 10 min and & _Chlorella_ sp. & [129] \\  & sterilized at 121 \({}^{\circ}\)C for 30 min & _Chlorella_ sp. & [128] \\  & Addition of 1 mL of SuperFloc C-581 flocculant & & \\  & per 50 mL of effluent. Settled for 20 min then & _Chlorella_ sp. & [130] \\ Pulp and paper industry & filtered through a mesh filter with pore size of & _Nannochloropsis aculata_ & [131] \\  & 5 μm and sterilized with a 500 mL bottle top & _Chlorella_ sp. & [132] \\  & polystyrene filter with pore size of 0.22 μm. & _Chlorella_ sp. & [133] \\ Raw dairy & Centrifuged (5000 rpm, 10 min) & _Chlorella zofingiensis_ & [134] \\  & then autoclaved & & \\ \hline \end{tabular}
\end{table} 
Table 10: _Cont._
Figure 6: Nutrients and COD removals from industrial wastewater by microalgae species [17,85,91,94,96,98,99,100,103,105,107,109,110,113,115,117,118,120,123,124,126,127,1307]. In another study, _Chloerella_ sp. L166 was co-cultured with soybean effluent (COD: 5320 mg L\({}^{-1}\), TN: 106.99 mg L\({}^{-1}\), TP: 23.28 mg L\({}^{-1}\)) and CO\({}_{2}\) from flue gas [96]. The concentration of chlorophyll a was 48.08 mg L\({}^{-1}\), when the N/P ratio was 5:1 in the 20% soybean effluent and 5% CO\({}_{2}\) (0.1 vvm) [96]. Furthermore, _Chloerella_ sp. L166 obtained the maximum removal efficiencies of TN of 96.07, TP of 95.55%, COD of 78.20% and a CO\({}_{2}\) fixation of 28.60% [96]. Therefore, it was discovered that _Chloerella_ sp. L166 had the capacity to remove CO\({}_{2}\) in flue gas while also treating a soybean processing effluent [96]. In a recent piece of work, [PERSON] et al. [120] employed a soy sauce processing effluent (NH\({}_{4}\)-N: 168.44 mg L\({}^{-1}\),TN: 173.53 mg L\({}^{-1}\), COD: 3263.33 mg L\({}^{-1}\)) as a culture medium to feed _Spirulina_ and remove pollutants. The findings showed that _Spirulina_ NCU-Sm grew well in raw soy sauce wastewater and produced a maximum biomass of 1.984 g L\({}^{-1}\) with a removal efficiency 93.86% for NH\({}_{4}\)-N, 81.76% for TN and 84.08% for COD [120]. Researchers have also evaluated the wastewater from oil-producing industries such as olive oil and palm oil to determine the potential of microalgae to treat this type of wastewater and produce a microalgal biomass as well as compounds with high added values such as lipids and carbohydrates [92,121,130]. During the 14 days of culture, [PERSON] et al. employed different ratios of palm oil effluent diluted with marine water (0, 20, 40, 60 and 80% dilutions) to cultivate _Nannochloropsis_ sp. compared to palm oil effluent diluted with Walne's medium [121]. They discovered that _Nannochloropsis_ sp. thrived well in 60% palm oil mill effluent diluted with marine water, had the best specific growth rate of 0.39/d, the maximum cell density of 7.93 107 cell/mL, 61.60% lipids, and could remove 11.31 mg/mg/d of the  
Figure 7: Wastewater pollutants mechanisms of bioremediation by microalgae.