Development of a zero liquid discharge approach for cooling tower blowdown in petrochemical industry | |
| Author | Mov Chimeng |
| Call Number | AIT Thesis no.EV-14-08 |
| Subject(s) | Petrochemicals industry Cooling towers |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-14-08 |
| Abstract | Cooling system is considered as an important unit operation in any Petrochemical industries where large portion of water is used to cool down heat from polymerization and monomerization processes. Meanwhile, to keep consistent performance, some portion of cooling tower blowdown (CTBD), full of TDS, silica and hardness, is periodically withdrawn. However, this water is recovered for reuse in cooling tower by CTBD treatment plan using UF and RO, but huge amount of concentrate of UF and RO system are still finally discharged. Therefore, in first phase of this study, water auditing was conducted to understand the performance of CTBD treatment plant in Petrochemical Industry. The audit results indicated that there was no significant operation problem in the plant since difference of input and output was less than 30%. Around 180 m³ /day of UF and RO concentrate were discharged without any further recovery process. Pilot scale of Zero Liquid Discharge (ZLD) system was used in this study to recover discharge. ZLD system was designed with two stage of RO system which equipped with different type of pretreatment system, Ceramic MF for first stage RO, Chemical precipitation (hardness and silica) with Duraflow MF for second stage RO. Referring to experimental result, up to 85% of water could be recovered back to cooling tower, while only less than 4% was rejected from second stage RO which consisted high strength of TDS, hardness and silica. In addition, concentrate of ceramic MF and Duraflow MF, full of suspended solids, was less than 9% combined together. Proposed ZLD system was designed with 360 m³ /day of designed flow and 80% water recovery. From this proposed system, investment cost and O&M cost of system were estimated where ceramic MF dominated 50% of total cost and Chemical precipitation with Duraflow MF occupied more than 55% of O&M cost as well. Moreover, treatment cost was calculated around 40 baht/m³ which was 10 baht/m³ more expensive than current water price in TPAC (30 baht/m³ ). Hence, proposed ZLD system might be not very attractive from industry’s point of view. Nevertheless, the future discharge regulations and policies, water shortage condition, and corporate social responsibility issues could be the main driving force for industry to accept ZLD system. Moreover, further study on pretreatment system like ceramic membrane and chemical precipitation must bring down substantial amount of investment and O&M cost as well. At the end of the day, ZLD system will gradually be attracted by industrial sector for water reuse and recovery. |
| Year | 2014 |
| 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 and Management (EV) |
| Chairperson(s) | Visvanathan, C.; |
| Examination Committee(s) | Annachhatre, Ajit P.;Thammarat Koottatep; |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2014 |