Reusability of iron sludge by solar photo-Fenton oxidation in treatment of Palm Oil Mill Secondary Effluent (POMSE) / Qistina Omar … [et al.]

Solar photo-Fenton oxidation process is one of the advanced oxidation processes that have been proposed as an alternative in wastewater treatment. This paper reports on the reusability of iron containing sludge generated from the solar photo-Fenton oxidation on Palm Oil Mill Secondary Effluent (POMSE) based on COD and colour removal since this ion (Fe2+) was used to react with H2O2 to generate more hydroxyl radicals. The experiment was conducted at pH3 using 1000 mL POMSE, 22.34g of Fe and 2.12 of COD/H2O2 ratio. The sample was characterized by using DR5000U spectrometer, DRB200 and DR2800. In this study, the capabilities to reuse the iron containing sludge was determined by recycling the sludge five times at three different contact times which were 15 min, 30 min and 60 min. The iron containing sludge from each cycle was used as a source of iron to react with added H2O2 in the treatment of POMSE. The result showed that the trend of COD removal decreased with increasing number of recycle. Highest COD removal was 82.14 % by using fresh iron and decreased to 74.98% at first recycle with 60 min contact time and the lowest was 32.70 % in fifth recycle with 15 min contact time. The colour removal using fresh iron for 60 min contact time gave slightly decreased value compared to 15 and 30 min contact times which were 96.52%, 97.74% and 97.72% respectively. The results showed a little fluctuation in readings for 60 min contact times compared to other two contact times but it not very significant. The fifth recycle of color removal for 60 min contact time gave high value, 74.77% of colour removal compared to 15 min (57.57%) and 30 min (63.18%) contact times. This can be conclude that the effective reusability of iron containing sludge for COD removal was until first recycle with 60 min contact time. Despite decreasing percentage of colour removal for each cycle, the value is still acceptable and can be categorized in high percent removal. In future, the iron containing sludge will be dried and baked at certain temperature to prevent any organic content that can discard the removal of COD before used in the treatment of POMSE.