Treatment and management of cleaning waste from monomer preparation for the production of 1.74 ultra high index lens

Date of Publication

2025

Document Type

Master's Thesis

Degree Name

Master of Engineering major in Chemical Engineering

Subject Categories

Engineering

College

Gokongwei College of Engineering

Department/Unit

Chemical Engineering

Thesis Advisor

Dr. Allan N. Soriano
Engr. Moises C. Florentino Jr.

Defense Panel Chair

Dr. Rhoda B. Leron

Defense Panel Member

Dr. Gian Paolo O. Bernardo
Dr. Arnel B. Beltran

Abstract (English)

The cleaning waste generated from reactor and filling hose line operations of 1.74 Ultra High Index raised serious concerns following the stoppage of hauling and treatment services by the third-party waste treater. This waste was found to be highly toxic, emitting hydrogen sulfide (H₂S) gas, and producing a strong malodor, which made handling and treatment extremely difficult. These challenges led to frequent breakdowns of the thermal oxidation unit and triggered complaints from nearby communities due to the foul odor. As a result, the waste began to accumulate and required special storage under negative temperature conditions to prevent adverse reactions. This situation posed a significant risk to the continuity of the 1.74 ultra-high index production line, which relies on consistent waste management.

To address the issue urgently and prevent production stoppage, the use of 20% (w/v) sodium hydroxide (NaOH) was explored, based on its established application in the oil and gas industry for scrubbing sulfur-containing compounds such as mercaptans. Laboratory trials were conducted to determine the optimal ratio between the cleaning waste and NaOH, using H₂S concentration as the effectiveness indicator. The reaction was monitored for temperature changes, which ranged from 25°C to a maximum of 45°C, and resulted in the formation of yellow to orange liquid and solid by-products. The process was then scaled up to a bench-scale setup using larger quantities of cleaning waste, which yielded consistent results. The optimal ratio was identified as 2.5:1 (NaOH 20% w/v : cleaning waste).

Subsequent physico-chemical analysis of the by-products revealed that the liquid waste was alkaline in nature, with a pH range of 12–14, and was classified as C399. The solid waste was found to be highly combustible and classified as F699. The process was reviewed, assessed, and validated by the safety team. Waste depletion activities were initiated, and in parallel, the team collaborated with the third-party waste treater to identify suitable treatment methodologies. The accepted treatment method for the liquid waste involved reusing it in the wet scrubbing unit of the thermal oxidizer, while the solid waste was subjected to direct combustion, with the resulting ash repurposed for composite hollow block production.

Abstract Format

html

Abstract (Filipino)

None

Abstract Format

html

Language

English

Format

Electronic

Keywords

Monomers

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Embargo Period

8-18-2025

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