Management Of Collection Of The Wastewater In Environmental Analysis Laboratory And Study On Their Treatment

Chemical analysis laboratory wastewater of environmental subject is complexed and more dangerous that is more difficultly to be treated than municipal sewage. During teaching and research, laboratories will produce a lot of wastewater needed to be under strict management. Otherwise, it will do harm to the natural environment. As people continue to be aware of environmental protection, as well as increasingly stringent discharge standards, laboratory wastewater treatment is essential. However, there is no clear laboratory wastewater treatment scheme.Based on the laboratory wastewater from School of Environment and Municipal Engineering of Xi’an University of Architecture and Technology, this dissertation composed. Through analysis and experimental study, it proposed the labortory wastewater collection management methods and the main treating operation parameters of organic wastewater and heavy metal wastewater. This provides solutions of colletion and sorting process for all these kinds of laboratory wastewater. The main research conclusions are as follows:(1) According to relevant water environment protection laws and regulations in our country and in accordance with the characteristics of the waste liquid of environment disciplinary analysis laboratory in universities, an analysis of the need for waste liquid collection was given. In view of the collection of waste liquid problems existed in the environment disciplinary analysis laboratory in universities currently, the principle of waste liquid category was proposed. Based on the waste classification of school in some countries and regions, some recommendations were given in the environmental analysis laboratories. It classifies into halogen-containing organic wastewater, halogen-free organic wastewater, wastewater containing heavy metals, cyanide wastewater, mercury containing wastewater, fluoride wastewater, waste acid, waste alkali and other wastewater needed not treatment, etc., and collects separately by this management method. How to treat these types of wastewater, such as halogen-free organic waste(referred the organic waste) and waste containing heavy metals(referred the heavy wastewater) respectively in economical and efficient way needs to study.(2) Pre-treatment of organic wastewater from an academic research laboratory using iron-carbon micro-electrolysis of lab-scale was investigated in this study. Orthogonal experimental design was adopted to optimize operating condition using chemical oxygen demand(COD) removal as the target parameter, hydraulic retention time(HRT), pH and aeration rate as the control factors. By the orthogonal experiment, the best conditions are pH=5, HRT=6h and aeration rate =12L/h, respectively. Maxima of 85% of COD can be removed under the optimum operating condition, refractory organic compounds in the wastewater were degraded efficiently, and BOD5/COD of the wastewater was increased from 0.1 to above 0.4 so that the biodegradability of experimental wastewater was improved significantly. Conclusions can be made that iron-carbon micro-electrolysis method is suitable for treating laboratory wastewater. It is estimated that the processing cost is about 9.84 Yuan RMB/m3 wastewater.(3)After using NaHSO3 to reduce Cr6+ to Cr3+, chemical precipitation process was adopted to treat heavy metal wastewater and the optimum reaction conditions were discussed. The results showed that, the efficiency of Cr6+ being reduced to Cr3+ is the most highest, closed to 100%, when the pH was lower than 3 and the dosage of NaHSO3 was 8g/L. When the dosage of Ca(OH)2 was adjusted to pH within 7 to 8, water quality can meet the requirements that effluent total chromium <1.5mg / L, Ag + <0.5mg / L, Fe3 + <5-10 mg / L, pH within 6.5 to 9.5 range and all of the metal ion precipitation could be the best.