| Author | Nuchanart Leelakahakit |
| Call Number | AIT Thesis no.EV-09-16 |
| Subject(s) | Factory and trade waste--Purification
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | Rayon industry is a textile industry, uses large quantities of zinc in its manufacturing process. The industry produces huge quantities of highly polluted wastewater, especially a wastewater stream from the spinning process, which contains sulfate and zinc as major pollutants. Zn removal of wastewater discharged from the spinning process of rayon industry was studied by sequential precipitation of CaS0₄ and ZnS using lime and chemical sulfide. Optimum pH for CaS0₄ precipitation was ascertained by the jar test with synthetic wastewater. The study found that pH at 6 with contact time at 1.5 h was the optimum condition for CaS0₄ precipitation and the removal efficiency was more than 91.37%. The removal efficiency of zinc as ZnS was 1.06% lesser than the remaining dissolved zinc hydroxide more than 98.94 %. Based on the jar test result, calcium sulfate precipitation and zinc sulfide precipitation unit was carried out in the sequential precipitation process. The results from the precipitation unit showed that approximately 40-50 % of sulfate was removed as calcium sulfate precipitation. The sulfide removal efficiency as ZnS precipitation in all conditions was more than 90% removed. Additionally, sulfide concentration of more than 350 mg/L and sulfide loading rate of more than 210 mg/h removed zinc as ZnS precipitation with an efficiency of 97.26 %. The concentration of zinc in effluent was 2.6 mg/L. Moreover, the results from continuous precipitation process showed that more than 97 % of zinc was removed as ZnS precipitation. The concentration of zinc in effluent was in the range of 1.65 to 2.75 mg/L and it met the National Discharge Standard of 5 mg/l of zinc concentration. Cost benefit based analysis was on evaluation between conventional treatment and development technology. The analysis found out that O&M cost of developed technology was less than conventional treatment. |
| Year | 2009 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Annachhatre, Ajit P.; |
| Examination Committee(s) | Chongrak Polprasert;Preeda Pakpian; |
| Scholarship Donor(s) | National Science and Technology Development Agency (NSTDA), Thailand; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2009 |