Optimization of Ozonation Process for the Reduction of Excess Sludge Production from Activated Sludge Process of Sago Industry Wastewater Using Central Composite Design

Abstract

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R 2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

Holistic sludge management through ozonation: A critical review

“…However, a contact time of 20 min was adequate to achieve maximum COD solubilisation when ozone dosage was 0.37 g O 3 /g SS. Similarly, Subha and Muthukumar (2012) observed that increasing contact time from 1 to 12 minutes maximized VSS reduction to 81%, but beyond this period the VSS reduction decreased to 32% due to the activity of radical scavengers.…”

“…Manterola et al, (2008) did not observe any significant change in the soluble COD of sludge after ozonation at different HRTs (10-57 min), which meant that a short HRT (e.g., 10 min) was sufficient to reach maximum sludge solubilisation. Other studies caution that increasing contact time may in fact reduces sludge reduction due to the formation of radical scavengers (Naso et al, 2008;Subha & Muthukumar, 2012). Naso et al, (2008) varied the ozone contact time (0-30 min) at different ozone dosages, and found that 30 min resulted in the maximum COD solubilisation at the ozone range of 0.05-0.07 g O 3 /g SS.…”

Optimization of biostimulant for bioremediation of contaminated coastal sediment by response surface methodology (RSM) and evaluation of microbial diversity by pyrosequencing

“…RSM is an experiential, modeling and analysis engineering technique used to evaluate the relationship between a set of controllable experimental factors and observed results (Subha and Muthukumar, 2012). Experiments aimed to study the effect of BSB size, BSB distance, and time on COD and VS reduction were chosen.…”

Ozonation improves physical attributes in domestic sewage effluent

“…Once dissolved in water, the ozone reacts with a large number of organic compounds in two different possible ways: direct oxidation, such as molecular ozone, or indirect reaction through the formation of secondary oxidants, such as free radicals, particularly the hydroxyl radical (Subha and Muthukumar, 2012;Wajahat et al, 2019).…”