The anaerobic digestion process produces methane while stabilizing sludge. As of 2020, 62 anaerobic digesters in public wastewater treatment plants are operational in Korea. Many researchers have studied to improve digester performance. Thermal hydrolysis technology is one of the pre-treatment methods for treating sludge. Reduced retention time and enhanced biogas production are the main advantages of sludge disintegration at relatively high temperatures and pressures. But nutrients like nitrogen and phosphorus are released from the pre-treated sludge. Phosphorus is a non-renewable resource that is essential to food production. Wastewater receives 20% of the total phosphate discharge, while 90% of the influent phosphorus load is in sludge. For efficient phosphorus recovery, it is essential to comprehend the phosphorus release characteristics during wastewater treatment, including anaerobic digestion. Biological or chemical processes can achieve phosphorus removal to comply with the effluent discharge limits regulations. The three primary sources of phosphorus in sludge are aluminum-bound phosphorus (Al-P), polyphosphate in phosphorus-accumulating organisms (PAOs), and iron-bound phosphorus (Fe-P). Anaerobic digestion is the typical method for recovering carbon and phosphorus. However, previous research has demonstrated that most phosphorus in anaerobic digestion occurs as a solid phase coupled with heavy metals. Therefore, the poor mass transfer rate results in a slow phosphorus release. Due to the recent growth in interest and significance of phosphorus recovery, many researchers have studied to improve the quantity of phosphorus released into the liquid phase through chelation addition, process operation optimization, and disintegration using sludge pre-treatment. The study aims to investigate characteristics of the phosphorus release associated with the thermal hydrolysis breakdown of sludge and propose a method for recovering phosphorus in a wastewater treatment plant. When solubilizing sludge using thermal hydrolysis pre-treatment, organic phosphates, inorganic phosphates, and polyphosphates are converted into ortho-phosphate. Therefore, applying thermal hydrolysis, anaerobic digestion, and phosphorus recovery processes (struvite formation or microbial electrolysis cells) can recover carbon and phosphorus.

Oral toxicity of double-stranded RNA (dsRNA) specific to integrin β1 subunit (SeINT) was known in a polyphagous insect pest, Spodoptera exigua. For an application of the dsRNA to control the insect pest, this study prepared a recombinant Escherichia coli expressing dsRNA specific to SeINT. The dsRNA expression was driven by T7 RNA polymerase overexpressed by an inducer in the transformed E. coli. The produced dsRNA amount was proportional to the number of the cultured bacteria. The bacteria gave a significant oral feeding mortality to S. exigua larvae with a significant reduction of the SeINT expression. The resulting insect mortality increased with the fed number of the bacteria. Pretreatment with a sonication to disrupt bacteria cell wall membrane significantly increased the insecticidal activity of the transformed bacteria. Compared to the control bacteria transformed by non-recombinant vector, the larvae fed the bacteria expressing dsRNA specific to SeINT suffered tissue damage in the midgut epithelium, which was characterized by a loose cell-cell contact and a significant cell death. The dsRNA-treated larvae were significantly more susceptible to a Cry toxin derived from Bacillus thuringinesis (Bt) than the larvae treated only with Cry toxin. This study demonstrates that a transformed bacterium expressing dsRNA specific to SeINT has a significant insecticidal activity by oral application against S. exigua and makes the target insects to be highly susceptible to Bt toxin.

이 글의 목적은 박경리 『토지』에 나타난 유교 담론을 연구하는 것이다. 작품에 나타난 유학자들의 담론 양상은 크게 세 가지로 분류할 수 있다. 첫 번째 유학 담론은 외세의 부당한 개입에 맞서 물리적 대결을 해야 한다는 주장이다. 작품에 나타난 가장 대표적 인물은 김 훈장이다. 『토지』는 김 훈장을 통해 일제에 대해 물리적 대결을 하려는 당대 유학자들의 진정성을 인정하면서도, 그 한계를 비판하고 있다. 두 번째 유학 담론은 현실의 부정성을 비판하면서 맞서 싸우지 않고 도피해야 한다는 주장이다. 유학의 도(道)를 미래에까지 계승하기 위해서는 의미없는 죽음보다는 비겁하지만 목숨을 부지하는 것이 더 중요하다고 생각했기 때문이다. 세 번째 유학 담론은 시류에 편승해야 한다는 주장이다. 그들은 자신들의 기득권을 바탕으로 시류에 편승하여 엘리트로서의 역사적 과제를 무시하고 사적 이익을 취하였다. 조준구로 대표되는 이 유형의 인물들은 『토지』에서 가장 크게 비판을 받는다.