Ali Yuzir

Characterization of aerobic granular sludge treating high strength agro-based wastewater at different volumetric loadings

Understanding the relationship between microbial community and mechanism of aerobic granulation could enable wider applications of granules for high-strength wastewater treatment. The majority of granulation studies principally determine the engineering aspects of granules formation with little emphasis on the microbial diversity. In this study, three identical reactors namely R1, R2 and R3 were operated using POME at volumetric loadings of 1.5, 2.5 and 3.5 kg COD m(-3) d(-1), respectively. Aeration was provided at a volumetric flow rate of 2.5 cms(-1). Aerobic granules were successfully developed in R2 and R3 while bioflocs dominated R1 until the end of experiments. Fractal dimension (D(f)) averaged at 1.90 suggesting good compactness of granules. The PCR-DGGE results indicated microbial evolutionary shift throughout granulation despite different operating OLRs based on decreased Raup and Crick similarity indices upon mature granule formation. The characteristics of aerobic granules treating high strength agro-based wastewater are determined at different volumetric loadings.

Influence of palm oil mill effluent as inoculum on anaerobic digestion of cattle manure for biogas production.

Anaerobic digestion for palm oil mill effluent (POME) is widely known for its potential in biogass production. In this study, the potential of using cattle manure for biogas production in complete mix anaerobic bioreactor was investigated using POME at unregulated pH and temperature. Two identical bioreactors were used in this study; namely R1 and R2 fed with cattle manure without and with POME as inoculum, respectively. Both bioreactors were allowed for five days to run in batch mode followed by semi continuous operations at HRT of 20 days. R2 produced 41% methane content compared to 18% produced in R1. A better COD percentage reduction of 45% was found in R2 which was operated with POME as inoculum compared to R1 with 35%. These results indicated that POME as inoculum has an influence on the start-up time and the rate of biogas produced.This findings will help in waste reduction.

Anaerobic Digestion of Paper Mill Wastewater

In general, paper mill wastewater contains complex organic substances which could not be treated completely using conventional treatment processes, e.g. aerobic processes. As a result, anaerobic technology is a promising alternative for paper mill wastewater treatment due to its ability to degrade hard organic compounds. In the present study, treatment of paper mill wastewater using a stage anaerobic reactor was investigated. The more specific objectives of this study were to confirm whether paper mill wastewater can be tolerated by methanogenic sludge and to assess the stability of reactor for measured parameters (e.g. COD removal, and methane composition). Results showed up to 98% COD removal efficiency in the anaerobic reactor when the reactor was operated at an OLR of 1.560 kg COD/m 3 .d. Anaerobic digestion can provide high treatment efficiency for recalcitrant substrates, which generates robust microorganism (acidogenesis and methanogenesis), for the degradation of recalcitrant compounds such as in the paper mill wastewater.

Impact of the herbicide (RS)-MCPP on an anaerobic membrane bioreactor performance under different COD/nitrate ratios

The degradation of (RS)-MCPP was investigated in an anaerobic membrane bioreactor (AnMBR) using nitrate as an available electron acceptor under different COD/NO(3)(-)-N ratios. Results showed high soluble COD removal efficiency (80-93%) when the reactor was operated at high COD/NO(3)(-)-N ratios. However, the COD removal started to decline (average 15%) at high nitrate concentrations coinciding with a drop in nitrate removal efficiency to 37%, suggesting that the denitrification activity dropped and affected the AnMBR performance when nitrate was the predominant electron acceptor. Additionally, the removal efficiency of (RS)-MCPP increased from 2% to 47% with reducing COD/NO(3)(-)-N ratios, whilst the (RS)-MCPP specific utilisation rate (SUR) was inversely proportional to the COD/NO(3)(-)-N ratio, suggesting that a lower COD/NO(3)(-)-N ratios had a positive influence on the (RS)-MCPP SUR. Although nitrate had a major impact on methane production rates, the methane composition was stable (approximately 80%) for COD/NO(3)(-)-N ratios of 23 or more.

Influence of step increases in hydraulic retention time on (RS)-MCPP degradation using an anaerobic membrane bioreactor.

The effects of different hydraulic retention time (HRT) on (RS)-MCPP utilisation was investigated by decreasing the feed flow rate in an anaerobic membrane bioreactor (AnMBR). Results showed an average COD removal efficiency of 91.4%, 96.9% and 94.4% when the reactor was operated at HRT 3, 7 and 17 d, respectively. However, when the HRT was reduced to 1d, the COD removal efficiency declined to just only 60%, confirming the AnMBR is stable to a large transient hydraulic shock loads. The (RS)-MCPP removal efficiency fluctuated from 6% to 39% at HRT 3 d, however when it was increased to 7 and 17 d, the removal efficiency increased to an average of 60% and 74.5%. In addition, (RS)-MCPP specific utilisation rates (SUR) were dependent on the HRT and gradually improved from 18 to 43 μg mg VSS(-1) d(-1) as flow rate increased.

Performance of an innovative multi-stage anaerobic reactor during start-up period

Start-up of an anaerobic reactor is a relatively delicate process and depends on various factors such as wastewater composition, available inoculum, operating conditions and reactor configuration. Accordingly, systematized operational procedures are important, mainly during the start-up of an anaerobic reactor. In this paper, the start-up performance of an innovative multi-stage anaerobic reactor using synthetic wastewater at various organic loading rates (OLRs) was investigated. In Phase 1 of the experimental study, the reactor was operated at hydraulic retention time (HRT) of 1 day with corresponding OLR of 1.07 kg COD.m -3 .d -1 . Thereafter, the reactor was operated at intermittent feeding (Phase 2), with HRT of 1.4 day and OLR of 0.82 to 2.45 kg COD.m -3 .d -1 . Results showed up to 71% COD reduction in the Phase 1 of the experimental study. However, in Phase 2, when the reactor was operated at intermittent feeding, the COD removal efficiency increased from 75 to 92%. It can be concluded that the multi-stage anaerobic reactor system performed better at intermittent feeding, indicating that the reactor required low loading rate and sufficient HRT for gradual acclimatization for reactor start-up. The reduction of the period necessary for the start-up and improved operational control are important factors to increase the efficiency the reactor system. Key words: Anaerobic reactor start-up, biomass, glucose wastewater, intermittent feeding, multi-stage anaerobic reactor.

Anaerobic Pre-treatment of Pharmaceutical Wastewater using Packed Bed Reactor

Effluents from manufacturing operations in the pharmaceutical industry, such as antibiotic formulation, usually contain recalcitrant compounds. An approach towards appropriate technology for the treatment of pharmaceutical wastewaters has become imperative due to strict water quality legislation for environmental protection. Typically, pharmaceutical wastewater is characterized by high chemical oxygen demand (COD) concentration, and some pharmaceutical wastewaters can have COD as high as 80,000 mg.L-1. Due to high organic content, anaerobic technology is a promising alternative for pharmaceutical wastewater treatment. Consequently, in the present study, an anaerobic packed bed reactor was employed to treat highly polluted pharmaceutical wastewater. The effect of organic loading rate (OLR) was assessed by adjusting feed substrate concentration and hydraulic retention time (HRT). The reactor performance was characterized in terms of chemical oxygen demand (COD) removal, volatile fatty acid (VFA), gas production, methane yield and pH. At an average reactor OLR of 1.58 kg COD.m-3.d-1 (HRT 5.6 d), the average soluble COD reduction was 73%. However, when the OLR was increased to 2.21 and 4.66 kg COD.m-3.d-1 the COD removal efficiency decreased gradually until 60 - 70% soluble COD removal was observed. Further increase of the OLR resulted in only around 53% soluble COD removal (average) was observed at an OLR of 5.71 kg COD.m-3.d-1, signifying as OLR was increased; the increasing load of complex pharmaceutical wastewater may have affected the methanogens.

Effect of Mecoprop (RS)-MCPP on the biological treatment of synthetic wastewater in an anaerobic membrane bioreactor

The effects of Mecoprop (RS)-MCPP were investigated in an anaerobic membrane bioreactor (AnMBr) fed with synthetic wastewater containing stepwise increases in Mecoprop concentration, 5-200 mg L(-1) over 240 days. Effects were observed in terms of soluble chemical oxygen demand (COD) removal efficiency, volatile fatty acid (VFA) production, and methane yield. Soluble COD removal efficiency was stable at Mecoprop concentrations below 200 (±3) mg L(-1), with an average of 98 (±0.7)% removal. However, at 200 (±3) mg L(-1) Mecoprop, the COD removal efficiency decreased gradually to 94 (±1.5)%. At 5 mg L(-1) Mecoprop, acetic and propionic acid concentrations increased by 60% and 160%, respectively. In contrast, when Mecoprop was increased to 200 (±3) mg L(-1), the formation and degradation of acetate was unaffected by the higher Mecoprop concentration, acetate remaining below 35 mg L(-1). Increases in the Mecoprop specific utilization rate were observed as Mecoprop was increased stepwise between 5 and 200 mg L(-1).

Removal of Acid Blue25 from aqueous solutions using Bengal gram fruit shell (BGFS) biomass

ABSTRACT The feasibility for the removal of Acid Blue25 (AB25) by Bengal gram fruit shell (BGFS), an agricultural by-product, has been investigated as an alternative for high-cost adsorbents. The impact of various experimental parameters such as dose, different dye concentration, solution pH, and temperature on the removal of Acid Blue25 (AB25) has been studied under the batch mode of operation. pH is a significant impact on the sorption of AB25 onto BGFS. The maximum removal of AB25 was achieved at a pH of 2 (83.84%). The optimum dose of biosorbent was selected as 200 mg for the removal of AB25 onto BGFS. Kinetic studies reveal that equilibrium reached within 180 minutes. Biosorption kinetics has been described by Lagergren equation and biosorption isotherms by classical Langmuir and Freundlich models. Equilibrium data were found to fit well with the Langmuir and Freundlich models, and the maximum monolayer biosorption capacity was 29.41 mg g−1 of AB25 onto BGFS. The kinetic studies indicated that the pseudo-second-order (PSO) model fitted the experimental data well. In addition, thermodynamic parameters have been calculated. The biosorption process was spontaneous and exothermic in nature with negative values of ΔG° (−1.6031 to −0.1089 kJ mol−1) and ΔH° (−16.7920 kJ mol−1). The negative ΔG° indicates the feasibility of physical biosorption process. The results indicate that BGFS could be used as an eco-friendly and cost-effective biosorbent for the removal of AB25 from aqueous solution.

Full Factorial Experimental Design for Carbamazepine Removal Using Electrochemical Process: a Case Study of Scheming the Pathway Degradation

Carbamazepine is an antiepileptic drug which is considered one of the persistent compounds detected in Malaysian aquatic environment. In this present study, a full factorial experimental design was applied for the analysis of effect NaCl amount, initial concentration of carbamazepine, applied voltage and treatment time on the electrochemical removal percentage of carbamazepine. However, applied voltage was found as the most significant factor with p = 0.00 lower than 95% confidence level. The investigation of effect NaCl and Na2SO4 on the pathway degradation for carbamazepine was provided using liquid chromatography-time of flight/mass spectrometry (LC-TOF/MS). The results showed that new by-products were identified such chloro-epoxy carbamazepine, and other by-products, were detected in the presence of NaCl and Na2SO4 electrolytes. High inhibition percentage of Escherichia coli (E. coli) bacteria was observed at 24.0 h incubation time for both NaCl and Na2SO4 electrolytes after 80 and 20 min of treatment, respectively.