###### Abstract
Additionally, as a zerovalent iron solution added into sulfide can generate sulfides and iron oxides, many scholars have added zerovalent iron to biosludge from husbandry wastewater containing high concentrations of sulfides, and found that the generation of hydrogen sulfide was significantly controlled [21; 22]. This indicates that the addition of zerovalent iron could resolve the odorous water problem caused by hydrogen sulfide. Furthermore, a study by [PERSON] et al. showed the benefits of zerovalent iron on bioremediation of PCE [23]. The study conducted remediation tests in four groups: (a) natural attenuation, (b) addition of lactic acid, (c) addition of zerovalent iron, and (d) addition of lactic acid integrated with zerovalent iron. The results revealed that, in the group with lactic acid added, when the microbes degraded PCE to _cis_-1,2-dichloroethene (DCE), the concentration of _cis_-1,2-DCE could not be reduced effectively and the generation of VC was not observed. In the zerovalent iron group, decreases in PCE and TCE concentrations were observed; however, the _cis_-1,2-DCE concentration continued to increase and could not be effectively reduced. In the group with lactic acid integrated with zerovalent iron, PCE was gradually degraded into VC and the concentration of VC gradually decreased. Therefore, the addition of zerovalent iron also helps overcome the bottleneck of in situ bioremediation in degrading compounds into VC through reductive dechlorination. Although the addition of zerovalent iron can promote the degradation of VC derivatives and solve many in situ bioremediation-derived problems, such as acidification and odors, zerovalent iron is a solid that may, after injection, be synthesized with environmental substances and precipitate, thereby limiting the distance of transmission. [PERSON] et al. used pneumatic injection and direct injection methods and observed the distance of transmission of emulsified zerovalent iron after injection [24]. The results revealed that the transmission distance through pneumatic injection was approximately 2.1 m and the maximal transmission distance through direct injection was 0.89 m. The majority of the nano-iron contained in the chemical was converted into magnetite after 2.5 years and the particle size varied from 35-140 nm to 0.1-1 \(\upmu\)m. The results suggested that zerovalent iron reacts in underground environments over time and forms coordination complexes, which have enlarged particle sizes and might affect the distance of transmission. Ferrous lactate (FL) can be dissolved in water to form aqueous solutions for injection, which is convenient for in situ operation and may have a longer distance of transmission than solid zerovalent iron. This study evaluated the feasibility of using two types of self-made emulsions combined with FL in the bioremediation of TCE-contaminated sites. First, a microcosm test was conducted to evaluate the differences between the two types of self-made emulsions and commercial emulsion and to evaluate if remediation effectiveness increased after the addition of FL. Then, in situ biological field tests were conducted to understand the steps required to implement bioremediation with self-made emulsion combined with FL. The results can serve as a reference for in situ remediation.