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In this study, three start-up techniques of modified anaerobic inclining-baffled reactor (MAI-BR) were performance to understand the effect of inoculum source and effluent recycle on the treatment of recycled paper mill effluent (RPME). Flocculant anaerobic sludge from a palm oil mill pond and digested anaerobic sludge from a sewage treatment plant were inoculated in the first and second start-up/phase1, respectively. Results show that high chemical oxygen demand (COD) removals of 93 and 88% were achieved in the first and second start-up/phase1, respectively. The amount of methane produced in the second start-up/phase1 within 15 d was doubled as compared to the amount produced in the first start-up, with a higher methane content of 79% (as compared to 62% in the first start-up). This result indicated that the inoculum source has a significant effect on the reactor performance. The results in the second start-up/phase2 also showed that COD removal and methane production increased up to 94% and 0.52 L CH4/d, respectively. This finding can conclude that the use of effluent recycle has a favorable effect on the performance of MAI-BR. During the first start-up, second start-up/phase1, and second start-up/phase2, the volatile fatty acid/alkalinity compartmental ratios were varied at 0.01–0.06, 0.03–0.43, and 0.02–0.14, respectively, and the overall effluent pH levels were higher than 6.5. The findings indicate the stability of the MAI-BR system in treating RPME. [ABSTRACT FROM PUBLISHER]

As textile wastewater is a major source of surface water pollutants when not sufficiently treated prior to discharge, strict disposal regulations were set and monitored by environmental authorities. As such, continuous research is necessary in textile wastewater remediation. In this study, real textile wastewater samples were directly collected from the wastewater discharge point of a manufacturer in Prai, Malaysia. Various particle sizes of clinoptilolite were applied to treat the wastewater in a series of batch experiments at a predetermined dosage, pH, and contact time. Removal of three main parameters [i.e. color, suspended solids (SS), and chemical oxygen demand (COD)] was monitored. The removal rates of color, SS, and COD were 47.9, 48, and 37.4%, respectively, at particle sizes larger than 2 mm and then increased to 91, 96, and 62%, respectively, at particle sizes of 75–250 μm. The highest COD removal of 70% was also achieved at particle sizes smaller than 75 μm. These findings indicate that 75–250 μm is the optimal size range of clinoptilolite for simultaneous removal of the three parameters under the same experimental conditions. After wastewater treatment, the residual concentration of SS was 10 mg/L, which is within the standard limit of 50 mg/L effluent discharge. [ABSTRACT FROM PUBLISHER]

Three start-up techniques were investigated to evaluate the suitability of the bench-scale modified anaerobic inclining-baffled reactor (MAI-BR) for the treatment of recycled paper mill effluent (RPME) and to achieve an improved understanding of the inoculum to substrate ratio (ISR). The ISR ratios used were 3.53, 1.17, and 10.63 g volatile suspended solids (VSS)/g chemical oxygen demand (COD) for the first, second, and third start-ups, respectively. On a 30-d duration, the first start-up succeeded in removing 72% of the COD with an effluent pH of 6.2 and a methane production of 0.076 L/d. The second start-up was considered unfavorable after 16 d because of low methane production and effluent pH level. The third start-up with a 21-d duration was the best because of its 87% COD removal, 6.82 effluent pH, and 0.164 L/d methane production. The effluent volatile fatty acid (VFA)/alkalinity ratios were concurrently varied as 0.56, 0.45, and 0.034 for the first, second, and third start-ups, respectively. Subsequently, the VSS/TSS ratio of 0.78–0.86 formed in the reactor was sufficient to control biomass washout. The third start-up demonstrated that an ISR of more than 10 g VSS/g COD is an important factor that leads to a successful and efficient start-up operation. The batch feeding rate must be as low as 0.1 g COD/L d. Furthermore, the VFA/alkalinity ratio of the third start-up was excellent. The bench-scale unique design of the MAI-BR showed good performance in the RPME treatment within a period of less than one month. [ABSTRACT FROM AUTHOR]

Different physical, chemical, and biological treatment methods are used to eliminate heavy metals and pollutants from wastewater and landfill leachate. Sequencing batch reactor (SBR) is a type of biological treatment. This study was conducted to study heavy metals elimination from urban wastewater and landfill leachate using an adsorbent, namely powdered ZELIAC (PZ) that improved SBR. PZ consists of portland cement, limestone, rice husk ash, activated carbon, and zeolite. Response surface methodology and central composite design were used to elucidate the nature of the response surface in the experimental plan and determine the optimum settings of the independent variables [aeration rate (L/min), contact time (h), and leachate to wastewater ratio (%; v/v)] and their reactions. To study the aerobic process, four dependent factors (Fe, Mn, Ni, and Cd) were evaluated as reactions. The results indicated that compared with SBR, PZ-SBR removed heavy metals more efficiently. At the optimum contact time (11.70 h), aeration rate (2.87 L/min), and leachate to wastewater ratio (20.13%) in PZ-SBR, removal efficiencies for Fe, Mn, Ni, and Cd were 79.57, 73.38, 79.29, and 76.96%, respectively. [ABSTRACT FROM PUBLISHER]

Leachate is a liquid produced from the biodegradation of solid waste in landfill and is normally referred as highly polluted wastewater. Various treatment methods are available and it is highly depended on the characteristics of the leachate. One of the common and simplest methods is using coagulation process. The application of pre-hydrolyzed coagulants in coagulation process is well known for water and wastewater treatment. However, information on the application of pre-hydrolyzed coagulants, especially pre-hydrolyzed iron (PHI), in partially stabilized leachate treatments is not well documented. This study examined the application of PHI on the partially stabilized leachate by determining the optimum basicity ratio, pH, and dose through the removals percentage of suspended solid (SS), color, and chemical oxygen demand (COD). Laboratory jar tests revealed that the optimum PHI basicity ratio, pH, and dosage were 0.1, 5, and 0.2 g/L Fe, respectively. The optimum removals of SS, color, and COD were 99, 95, and 58% respectively. The results indicated that PHI could be potentially useful coagulant for removing SS, color, and COD from partially stabilized landfill leachate. [ABSTRACT FROM PUBLISHER]

Leachate is a major pollution source associated with municipal solid waste landfill. This study was carried out to evaluate the effectiveness of various techniques in treating mature landfill leachate generated from landfill in Malaysia, a tropical country. Treatment processes such as biological, ion exchange, coagulation–flocculation, adsorption, advanced oxidation processes (AOPs), and flotation were analyzed. The efficiency of each process was analyzed based on chemical oxygen demand (COD), color, and NH3-N percentage removals. Ion exchange treatment via cationic/anionic sequence achieved the best removal of color (96.8%), COD (87.9%), and NH3-N (93.8%) from leachate as compared with other treatment methods. Coagulation–flocculation and AOPs were successful for COD and color removals from leachate. However, both could not treat NH3-N effectively. Biological treatment could remove NH3-N (71%) effectively, but it was poor in terms of COD (29%) and color (22%) removals. Adsorption via a new carbon–mineral composite exhibited better removal of both COD (68.4%) and NH3-N (92.6%) from stabilized leachate. [ABSTRACT FROM AUTHOR]

Hibiscus rosa-sinensis is a biodegradable material that has not yet been tested for its flocculating properties. The objective of this study was to examine the efficiency of coagulation--flocculation processes for the removal of suspended solids (SS) from landfill leachate using aluminium sulphate (alum) and Hibiscus rosa-sinensis leaves extract at different pH and dosages. The experiments confirmed the positive coagulation properties of the investigated natural coagulant. The extracts from Hibiscus rosa-sinensis leaves had an isoelectric point at pH 4 and acted as a bridging mechanism in removing 74% of SS (8,000 mg/L dosage at pH 6) which was comparable with 78% SS removal using 7,000mg/L alum (at pH 6). [ABSTRACT FROM AUTHOR]

Among numerous techniques, electro-oxidation occupies a noticeable place in landfill leachate treatment. In recent years, electro-oxidation processes have been shown to be effective alternative for the removal of refractory organic compounds from stabilized landfill leachate. This paper aims to provide an overview about the effectiveness and mechanism of electro-oxidation processes employed for stabilized landfill leachate treatment. A review of the recent literature published on the electro-oxidation processes (i.e. electrochemical, electro- Fenton, photoelectro-Fenton, photoelectrochemical, and electrochemical peroxidation) performance and efficiency in stabilized leachate treatment are summarized and presented in this study. This study concluded that, although the high treatment cost caused by the energy consumption may limit electro-oxidation techniques, electro-oxidation processes are still a promising and effectual technology for the reduction of pollutants in stabilized landfill leachate. [ABSTRACT FROM AUTHOR]