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The purpose of this work was to study the sulfur concentration on bioleaching of heavy metals from pig manure employing indigenous sulfur-oxidizing bacteria. Also, the variations in physicochemical properties of pig manure before and after bioleaching were investigated. The results showed that sulfur concentration significantly affected the rate of acidification, sulfate production and metal solubilization during pig manure bioleaching process. A Michaelis–Menten type equation was utilized to interpret the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. The rates of metal solubilization during pig manure bioleaching were well described by a first order kinetic equation related to time. After 12 days of bioleaching, 93%–97% of Zn, 96%–98% of Mn and 48%–94% of Cu were leached out from pig manure, respectively. The metals remaining in the pig manure residual were mainly existed in stable forms. In addition, elemental analysis showed that bioleaching process could significantly modify the dewaterbility and organic composition of pig manure. However, fertility analysis found that 9.0%–19.1% of nitrogen, 68.5%–71.0% of phosphorus, 76.5%–78.8% of potassium and 47.5%–49.4% of the total organic carbon (TOC) were lost from pig manure in the bioleaching process. Therefore, bioleaching process used in this study could be applied to remove heavy metals effectively from the pig manure, but more detailed studies need to be done to decrease the nutrients loss from pig manure.

A novel atmospheric pressure plasma microjet (APPμJ) array is proposed to realize maskless parallel micropatterned etching of materials. Due to applying microfabrication technology, the dimension and distance of multiple jets in an array can be adjusted at a micro/nanoscale. However, interactions among multiple jets often lead to inconsistency of microjets and nonuniformity of sample etching. In this study, a 1 × 2 APPμJ array with 90-μm nozzles and varying jetto-jet distance is developed. The effects of different operating factors on the consistency of the APPμJ array are investigated. The experiment results show that the consistency of the microjet array and uniformity of sample etching can be greatly improved by optimizing operating parameters, such as applied voltage, gas flow rate, and jet-to-jet distance.

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