## 2 Wastewater Treatment by Microalgae
### Industrial Wastewater
#### 2.3.2 Pretreatment  
The industrial wastewater must be pretreated after characterization and before treatment with microalgae. Similarly to domestic and agricultural wastewaters, the procedures employed in the literature include sedimentation, filtration, acidification and centrifugation for the removal of suspended materials, as well as an autoclave or UV radiation sterilization for the removal of bacteria and other microorganisms found in industrial wastewater (Table 10). Filtration has also been used to remove germs depending on the pore size of the filter employed, for example, [PERSON] et al. utilized the membrane filtration with a pore size of 0.22 um to filter and sterilize industrial wastewater [8]. They reported that soy sauce wastewater composition had changed after sterilization by an autoclave at 121 \({}^{\circ}\)C for 30 min, with a change in the chemical oxygen demand from 3263.33 to 3463.33 mg L\({}^{-1}\), total organic carbon from 992.00 to 1042.80 mg L\({}^{-1}\), total nitrogen from 173.53 to 176.49 mg L\({}^{-1}\), ammonium nitrogen from 168.44 to 158.85 mg L\({}^{-1}\) and the total phosphorus from 10.21 to 5.57 mg L\({}^{-1}\), and there was no change in the soy sauce wastewater color [120].  
\begin{table}
\begin{tabular}{c c c c} \hline
**Wastewater** & **Pretreatment Method** & **Microalgae** & **References** \\ \hline Tobacco & Filter-sterilized by a 0.22 μm membrane filter & _Chorella pyrenoidosa_ & [8] \\  & (Millipore, USA) & (No.FACHB-863) & [8] \\ Palm oil mill (POME) & Filtered through a microfiber mesh and & _Chorella zofingiensis_ & [98] \\ Cassava processing & Autoclaved at 121 \({}^{\circ}\)C for 15 min, then filtered & _Arthospira platensis_ & [101] \\  & Filtered with filter cloth and re-filtered through & & \\ Palm oil mill (POME) & glass microfibers filter ([PERSON], Grade GF/C & \\  & 1.2 mm) and autoclaved at 121 \({}^{\circ}\)C and at a & _Nannochloropsis_ sp. & [121] \\  & pressure of 15 psi for 20-30 min & _Spirulina_ NCU-Sm & [120] \\ Soy sauce & Centrifuged (1644\(\times\) g 5 min), then autoclaved & _Sci_enedesmus_ sp. HXY5 & [126] \\ Potato & Acidified with sulfuric acid to pH 5, then & _Sci_enedesmus_ sp. HXY5 & [126] \\  & autoclaved at 121 \({}^{\circ}\)C for 30 min & _Chorella pyrenoidosa_ & [17] \\ Olive oil washing & glass wool pre-filter and cellulose nitrate & _Chorella_ sp. L166 & [96] \\  & Centrifuged (5000 rpm), and filtered by a & _Chorella_ sp. L166 & [96] \\ Soybean processing & microporous filter membrane (0.45 μm), then & _Chorella_ sp. L166 & [96] \\  & sterilized by high-pressure steam at & 121 \({}^{\circ}\)C & _Chorella_ sp. L166 & [96] \\ Vinegar production & Centrifuged for 10 min at 5000 rpm, and & _Chorella_ sp. L166 & [112] \\ Soybean processing & sterilized at 121 \({}^{\circ}\)C and 120 kPa for 20 min & _Chorella_ sp. L166 & [112] \\ Anaerobic palm oil mill & Centrifuged at 8000 rpm for 10 min & _Sci_enedesmus_ sp. and _Chorella_ sp. L166 & [94] \\ Starch processing plant & Filtered through 0.45 mm polyester filters and & _Chorella_ sp. L166 & [122] \\ Cassava & sterilized through UV-B radiation (UV doses & 810 mJ cm\({}^{-2}\) at a distance of 10 cm) & _Chorella_ sp. L166 & [102] \\ Anaerobically digested starch & Allowed to settle for 5-7 h in several tanks and filtered using polyester filters (1 μm) & _Chorella_ sp. L166 & [103] \\ Raw dairy & Filtered through a non-woven geotextile & _Chorella_ sp. L166 & [104] \\  & membrane (100 GSM grade) & _Sci_enedesmus_ sp. and _Chorella_ sp. L166 & [113] \\ Seafood processing & Filtered through 0.45 μm pore size GF/C glass & _Chorella_ sp. L166 & [108] \\ pesticides industry, & & _Sci_ened