In this study, decolourization and COD removal of Reactive Red 120, Remazol Brilliant Blue, Reactive Green 19 and Reactive Black 5 by ozonation and biological treatment were evaluated to apply for wastewater treatment containing azo dye. The performance of COD and colour removal in the single-stage ozonation-biological treatment was also compared with the multi-stage ozonation-biological treatment processes. Ozonation transforms the functional groups in azo dye to produce more biodegradable by products, which is easily removed by biological treatment. Ozonation is efficient for decolourization of Reactive Red 120, Remazol Brilliant Blue, Reactive Green 19 and Reactive Black 5 even with lower ozone dose (0.3 mg O 3 . mg dye -1 ). Contrarily, significant decreased in COD concentration was only observed within higher range of ozone doses (1.2 mg O 3 . mg dye -1 ). Higher COD removal at high ozone dose was due to complete oxidation of azo dye. The result indicated that biodegradable fraction of COD could be further oxidized and completely removed by ozonation. COD removal for Reactive Red 120 in the single stage ozonation-biological treatment and ozonation-biological treatment that repeated for 4 times were 58 % and 75 % respectively. The improvement of COD removal in the multi-stage ozonation-biological treatment was attributed to the production of biodegradable fraction of COD.

No abstract

In the recent decades, Malaysia has been known as the one of the palm oil producers and exporters. The increasing of the production and demand of palm oil tends to increase the Palm Oil Mill Effluent (POME). Undeniably, the conventional biological treatment has been implemented to reduce the organic matters but insufficient to satisfy the discharge standard by the local authority. Consequently, the biological treated POME has to be treated further to meet the stringent discharge standard. Hence, an advanced oxidation processes (AOPs), electro-oxidation process (EOP) has been applied to treat further the biologically treated POME. There are two stages in this study, EOP carried on with catalyst and electrode (Al and Fe). Therefore, the performance of EOP is evaluated by investigating the removal efficiency on the organic parameters like COD, colour, suspended solid and NH3-N. The operational parameters are the pH adjustment (pH 3, 5, 7 and 9), contact time ranging from 0 to 60 min and the dosage of catalyst (H2O2 and TiO2). The highest degradation of the parameters was obtained under the most acidic solution pH 3, with addition of TiO2 by using Al electrode. The percentages of removal are 96.58 % of colour, 98.74 % of SS and 84.85 % of COD.

The ability of biosorbents, which are a combination of orange peels and tea waste to treat copper (II) using the biosorption method was examined. The experiment was performed under batch biosorption studies with various operating parameters. The pH, biosorbent dosage, contact time, and initial copper (II) concentration were optimized from pH 3 - 8, 0.25 - 1.0 g, 2 - 20 minutes and 10 - 100 mg/L, respectively. The findings found that a pH of 5.5, a biosorbent dosage of 0.75 g, a contact period of 5 minutes, and an initial copper (II) concentration of 10 mg/L were shown to be the best operating parameters for copper (II) biosorption. For isotherm models, the experimental data for copper (II) biosorption was fitted to the Langmuir isotherm with R2 value of 0.7775 compared to the Freundlich isotherm model with R2 value of 0.1073. The value for RL was 0.4, indicating that copper (II) biosorption using the combination of orange peels and tea waste is favourable. For kinetic models, the experimental data for copper (II) biosorption was well fitted to the pseudo-second-order kinetic model with R2 value of 0.9865 compared to the pseudo-first-order kinetic model with R2 value of 0.1006. In conclusion, the combination of orange peels and tea waste functions very well for biosorption of copper (II).

The world has been using fossil fuels to generate energy for centuries and has had adverse effects on the environment; hence renewable energy needs to be discovered and developed. Biohydrogen production is renewable energy since it emits no greenhouse gases and may provide clean energy. Therefore, this study aimed to investigate the optimum headspace ratio and biohydrogen production for suspended and immobilized cells using Palm Oil Mill Effluent (POME) as the fermentation substrate, while its anaerobic sludge acted as the inoculum. Five different ratios were investigated, which are 0.2, 0.3, 0.4, 0.5, and 0.6. These are equivalent to working volume (WV) of 80 mL, 70 mL, 60 mL, 50 mL, and 40 mL, respectively. The solution contained 10 % of inoculum and 90 % (v/v) of the feedstock. For immobilized cells, additional of glass beads as carrier material was added into the solution, using the ratio of 1:1 for anaerobic sludge (mL) to support carrier (g). The kinetic study was investigated using a modified Gompertz equation whereby for suspended cells, the best ratio was 0.3, with the highest biohydrogen concentration of 357.6 ppm. Meanwhile, the optimum ratio for the immobilized cell was 0.2, with the highest biohydrogen concentration of 479.3 ppm. Based on the kinetic studies, the kinetic parameters for suspended cells were: Hm = 89.8 mL, Rm = 6.8 mL/h, and λ = 0.1 hr. Meanwhile for immobilized cell, the kinetic parameters were: Hm = 73.6 mL, Rm = 6.9 mL/h and X λ 0 hr. In conclusion, selecting the suitable headspace ratio could affect the biohydrogen quality and improve the effectiveness of the production rate.

The production of palm oil, though, results in the generation of huge quantities of polluted wastewater normally referred as palm oil mill effluent (POME). It gives adverse impacts to the environment, particularly if it is not properly treated. POME are known to have various types of liquids, residual oil and suspended solid as it has very high strength waste in its untreated form. Although conventional biological processes are normally efficient for the degradation of pollutants occurring in wastewater, most of these compounds are not effectively removed. As a result, further treatment is needed to meet more stringent discharge standards of Department of Environment (DOE), Malaysia. This research focused on treatment of POME by using electro-oxidation process (EO). It was done to identify the performance of EO process for colour, chemical oxygen demand (COD), suspended solids (SS), and Ammoniacal-nitrogen NH3-N) removal as well as the relative effects of different operational parameters such as pH, type of electrodes and contact time. The pH was varied between 3 and 11, using Ferum (Fe) and Aluminium (Al) electrode, and contact time from 0 to 120 min. The most suitable pH, contact time and type of electrode were pH 3, 120 min and Aluminium electrode, respectively. Therefore, EO process at specified level can be used as an efficient and effective post-treatment technology to meet the standard regulatory requirements.

Wastewater includes the Palm Oil Mill Effluent (POME) that gives adverse impacts to the environment especially for water pollution when it is not treated properly. POME are known to have various types of liquids, residual oil and suspended solid as it has very high strength waste in its untreated form. Although conventional biological processes are normally efficient for the degradation of pollutants occurring in wastewater, most of these compounds are not effectively removed. As a result, further treatment is needed to meet more stringent discharge standards of Department of Environment (DOE). This research focused on treatment of POME by using electro-oxidation process (EO). It was done to identify the performance of EO process for colour, chemical oxygen demand (COD), suspended solids (SS), ammoniacal-nitrogen (NH3-N), and turbidity removal as well as the relative effects of different operational parameters such as pH, type of electrodes and contact time. The pH was varied from 3 to 11, the electrodes were aluminium and iron and the contact time was from 0 to 120 min. The most suitable pH, contact time and type of electrode were pH 3, 120 min and Al electrode.