You can't. According to the query of official website of Zhejiang University, Zhejiang University Library can only return books offline, and it needs to return the lent books to the library itself. Zhejiang University, referred to as "Zhejiang University", is located in Hangzhou, Zhejiang Province. It is a comprehensive national key university directly under the Ministry of Education of People's Republic of China (PRC). It ranks among the national "double first-class", "2 1 1 project" and "985 project". It is the Nine Schools Alliance (C9), China University Presidents Association and Pacific Rim University Alliance.