The application of lead dioxide-coated titanium anode in the electroflotation of palm oil mill effluent

The electroflotation of palm oil mill effluent (POME) using lead dioxide-coated titanium anode on a laboratory scale was described. The anode was found to be corrosion-resistant under the conditions of the experiment. The feasibility of the process was determined by monitoring the effluent quality as a function of electrolysis time. Simultaneous flotation of suspended particles and anodic destruction of soluble substances in POME were observed. About 40% of the COD of the dissolved substances of POME could be anodically destroyed together with 86% of suspended particles, made up of mainly plant cell debris, floated off. It is envisaged the electroflotation process could form the first stage of a treatment system with aerobic or physicochemical process as secondary treatment step.     

Baseline study of methane emission from anaerobic ponds of palm oil mill effluent treatment

The world currently obtains its energy from the fossil fuels such as oil, natural gas and coal. However, the international crisis in the Middle East, rapid depletion of fossil fuel reserves as well as climate change have driven the world towards renewable energy sources which are abundant, untapped and environmentally friendly. Malaysia has abundant biomass resources generated from the agricultural industry particularly the large commodity, palm oil. This paper will focus on palm oil mill effluent (POME) as the source of renewable energy from the generation of methane and establish the current methane emission from the anaerobic treatment facility. The emission was measured from two anaerobic ponds in Felda Serting Palm Oil Mill for 52 weeks. The results showed that the methane content was between 35.0% and 70.0% and biogas flow rate ranged between 0.5 and 2.4 L/min/m(2). Total methane emission per anaerobic pond was 1043.1 kg/day. The total methane emission calculated from the two equations derived from relationships between methane emission and total carbon removal and POME discharged were comparable with field measurement. This study also revealed that anaerobic pond system is more efficient than open digesting tank system for POME treatment. Two main factors affecting the methane emission were mill activities and oil palm seasonal cropping.     

Optimization of hydroxyl radical production using electro‐Fenton method for chemical oxygen demand reduction in diluted palm oil mill effluent

Palm oil mill effluent (POME) is a well‐known highly polluting wastewater due to its extremely high contents of organic matter, suspended solids and nutrients. In this study, we used electro‐Fenton method to treat POME by optimizing OH? generation from hydrogen peroxide (H₂O₂) under low voltage input (1.5–6.0 V). A set of electro‐Fenton system was set up using stainless steel as the anode and graphite as the cathode. Four parameters namely retention times, concentrations of H₂O₂ as well as FeSO₄ catalyst and applied voltages were studied. The results were reflected in the form of removal efficiency of chemical oxygen demand (COD). The optimum conditions to degrade organic matter in POME were found to be in 4 h retention time with the respective H₂O₂ and FeSO₄ catalyst concentrations of 0.05 and 0.10 M, and the power input of 1.5 V. Under such conditions, the maximum COD removal efficiency achieved 94%. The electro‐Fenton treatment was found to have higher efficiency than the conventional Fenton treatment. Without the electrolysis, the COD removal efficiency of the conventional Fenton treatment was only 48%.     

厌氧生物处理抑制动力学及其应用

通过对厌氧生物处理动力学模型、厌氧生物处理抑制动力学模型的发展及现状的介绍，综述了盐度、中间产物及重金属对厌氧生物处理的抑制动力学的研究成果。     

Methane production from industrial wastes by two-phase anaerobic digestion

Although much attention has been paid to energy recovery from municipal sewage, industrial liquid waste is a larger potential source of renewable energy. In certain industrial sectors it is possible, in theory to displace almost all of the purchased fuels by recovering the energy content of the waste in suitable forms and utilizing them within the plant. Anaerobic digestion is probably the only available process that can achieve the dual goal of energy recovery from aqueous wastes and stabilization of the pollution load. This paper presents data illustrating the limitations and vulnerability of the conventional digestion process to this end, and discusses the application and advantages of an innovative and advanced fermentation system, two-phase digestion. Results of operation of bench-, pilot- and full-scale two-phase digestion plants with several types of industrial liquid wastes are presented. Industrial sectors that could benefit from commercial-scale application of this new process are indicated.     

Analysis of pre-heated crude palm oil,palm oil methyl ester and its blends as fuel in a diesel engine

Diesel engines are widely used in the surface transport system. They are the main source of economic growth of a nation. Nowadays, awareness of the environment compels people to adopt stringent emission norms. The rapid depletion of fossil fuels and the increase in the emission levels have caused concerns globally. An eco-friendly alternate is required to fulfil the growing demand. This paper focuses on alternate fuels and the importance of choosing palm oil. The energy density and higher cetane number are its major advantages. Also it reduces environmental pollution drastically. The viscosity of palm oil is a problem like other vegetable oils, which affects the fuel spray pattern. It reduces the efficiency of the combustion to a large extent. To overcome the problem, the pre-heating technique and transesterification process are adopted in this work. Performance tests were conducted on a single cylinder, four-stroke, direct injection diesel engine coupled with eddy current dynamometer, and emission was monitored using an AVL exhaust gas analyser. The results indicated that vegetable oil fuels have lower brake thermal efficiency compared to that of diesel. Pre-heated oil and methyl ester showed an appreciable reduction in hydrocarbon (HC) and carbon monoxide (CO) emissions and higher exhaust temperature and nitric oxide (NO_x) emission.     

Anaerobic treatment kinetics of palm oil sludge

Treatment of palm oil sludge using the completely-mixed, suspended growth, continuous anaerobic fermentation system was studied in a laboratory scale. Biokinetic coefficients for system with and without solids recycle were evaluated. The treatment systems were effective in the removal of BOD, COD, and volatile suspended solids. The gas production rate averaged around 0.91 g⁻¹ BOD utilized with an energy yield of 20,000 J g⁻¹ BOD utilized for units with _c greater than 25 days. The _c^m, minimum solids retention time, was calculated to be more than 10 days. Measured _c^m was, however, lower than 7 days.     

超声与碱预处理剩余污泥中温两相厌氧消化

以北方某污水处理厂(A/O工艺)剩余活性污泥为研究对象,考察了超声波与生石灰联合预处理对后续剩余污泥两相中温厌氧消化的影响,结果表明:两相反应器内污泥絮体被充分破坏,厌氧消化过程中在产酸相和产甲烷相内,NH3-N浓度均有提高,但是没有出现磷的显著释放。     

Strategies for lipids and phenolics degradation in the anaerobic treatment of olive mill wastewater

Strategies are proposed for the anaerobic treatment of lipid and phenolic-rich effluents, specifically the raw olive mill wastewater (OMW). Two reactors were operated under OMW influent concentrations from 5 to 48 g COD L⁻¹ and Hydraulic Retention Time between 10 and 5 days. An intermittent feeding was applied whenever the reactors showed a severe decay in the methane yield. This strategy improved the mineralization of oleate and palmitate, which were the main accumulated Long-Chain Fatty Acids (LCFA), and also promoted the removal of resilient phenolic compounds, reaching remarkable removal efficiencies of 60% and 81% for two parallel reactors at the end of a feed-less period. A maximum biogas production of 1.4 m³ m⁻³ d⁻¹ at an Organic Loading Rate of 4.8 kg COD m⁻³ d⁻¹ was obtained. Patterns of individual LCFA oxidation during the OMW anaerobic digestion are presented and discussed for the first time. The supplementation of a nitrogen source boosted immediately the methane yield from 21 and 18 to 76 and 93% in both reactors. The typical problems of sludge flotation and washout during the anaerobic treatment of this oily wastewater were overcome by biomass retention, according to the Inverted Anaerobic Sludge Blanket (IASB) reactor concepts. This work demonstrates that it is possible to avoid a previous detoxification step by implementing adequate operational strategies to the anaerobic treatment of OMW.     

污泥两相厌氧消化反应器生物相研究

采用中温两相厌氧消化处理污泥,通过对颗粒污泥形成过程中的污泥含水率、VS/TS、产气率、所产气体的甲烷含量及污泥元素等分析和对颗粒污泥中优势产甲烷菌的扫描（SEM）电镜观察,阐明了颗粒污泥的形成过程及特性。     

Recent developments in the application of oil palm fibers in cement composites

Fibers obtained from different parts of the oil palm tree (Elaeis guineensis) have been under investigation for possible use in construction. Studies have been carried out investigating the engineering properties and possible applications of these fibers. However, the experimental methods employed and the values of mechanical and physical properties recorded by various authors are inconsistent. It has therefore become necessary to organize information which would be useful in the design of oil palm fiber cement composites and help researchers and engineers make informed decisions in further research and application. This review provides information about fibers from different parts of the oil palm, their properties, enhancement techniques, current and potential application in cement composites.     

Reducing the environmental footprint of wastewater screenings through anaerobic digestion with resource recovery

Screenings produced as the first stage of wastewater treatment and currently disposed of to landfill, are rich in volatile organic solids, nitrogen and phosphorus which could be recovered through anaerobic digestion. Biochemical methane potential (BMP) tests on screenings demonstrated a methane yield of 0.33 m³ methane/kg volatile solids (VS) and a VS destruction of 50%. Consequently, the effect of a range of hydraulic retention time (HRT) and organic loading rates (OLRs) was evaluated in lab‐scale continuously fed mesophilic digesters. The highest methane yield of 0.416 Nm³ methane/kg VS added was observed with an HRT of 15 days and an OLR of 2.5 kg VS/m³/day, when up to 65% of the VS were destroyed. If treated by anaerobic digestion, every dry tonne of screenings digested would divert 466 kg from landfill, save 4.6 tonne equivalent carbon dioxide (CO_{2 eq}) and deliver 3.4 MWh of renewable energy.     

超高温两相厌氧反应器处理黄浆废水

采用超高温(70℃)两相厌氧反应器处理玉米加工过程中产生的黄浆废水,考察了进水COD浓度和负荷、C/N值等对系统除污效能的影响。结果表明:工艺运行稳定,在低C/N值和低负荷条件下,产酸反应器对COD的去除率为 47. 5%,酸化率(VFA/COD)为 52. 7%,蛋白质水解率为 95%,产甲烷反应器对COD的去除率为 91. 8%,两相总去除率为 97. 0%;在中高进水COD浓度和低C/N值条件下,产酸反应器对COD的去除率为 57. 6%,产甲烷反应器的为 88. 1%,两相总去除率为 93. 8%。当C/N值大幅度增加时产酸反应器对COD的去除率明显降低,而产甲烷反应器则有所增加,使总去除率仍可达 90%以上。     

有机负荷冲击下两相厌氧工艺的稳定性研究

抗有机负荷冲击能力强是两相厌氧工艺的一个重要特点,而流量和水质的突变是引起冲击负荷的主要原因.通过153 d的生产性试验研究,探讨了进水COD浓度和水量对两相厌氧系统稳定运行的影响,分析了有机负荷对系统处理效果的影响.指出不同的有机负荷变化幅度,对两相厌氧系统的稳定性和处理效果的影响程度有所不同,尤其是有机负荷在3 d内由15.69 kg-COD/(m3·d)突然升至40.87 kgCOD/(m3·d),系统对COD的去除率降至50%,系统的处理性能和稳定运行至少需要20 d才得以恢复.     

中温两相厌氧消化工艺处理混合污泥的效能

采用中温(35℃)两相厌氧消化工艺处理初沉污泥与剩余污泥的混合样(1∶1),以实现污泥的稳定化。结果表明,在水力停留时间约为10 d、有机负荷为2.75 kgVS/(m3.d)时,对TCOD的去除率可达46%,对VS的去除率为41%;产甲烷相反应器的最大比产甲烷活性为0.19LCH4/(gVS.d),并保持相对稳定;两相反应器内污泥的比脱氢酶活性都出现了增长,并维持在25~32μgINTF/(mgVS.h)之间;经消化后污泥的沉降性和脱水性变差。     

Sorption kinetics of heavy oil into porous carbons

Sorption kinetics of heavy oil into porous carbons was evaluated by a concept of liquid sorption coefficient obtained from the weight increase of heavy oil with sorption time, which was measured by a wicking test. Exfoliated graphite, carbonized fir fibers and carbon fiber felts were used as porous materials. It was found that the liquid sorption coefficient of fibrous carbons was twice larger than that of exfoliated graphite. Such a difference in the liquid sorption coefficient between the exfoliated graphite and two fibrous carbons was caused by a difference in effective sorption porosity and tortuosity between them. For the exfoliated graphite and carbonized fir fibers, the liquid sorption coefficient and the effective sorption porosity were strongly dependent on their density. The maximum values of both liquid sorption coefficient and effective sorption porosity of the exfoliated graphite were shown at the bulk density around 16 kg/m³. The liquid sorption coefficient of the carbonized fir fibers increased with increasing the density in the range from 6 to 30 kg/m³. When the carbonized fir fibers were densified above 30 kg/m³, the sorption rate was saturated. On the other hand, the sorption kinetics into the carbon fiber felt was almost independent of the bulk density, because the density of the carbon fiber felt is not effective for the pore structure. The effect of bulk density on the sorption kinetics could be supported from an analysis of pore structure of the porous carbons with different densities, which was measured by mercury porosimeter.     

两相厌氧产氢产甲烷工艺的最新研究进展

利用两相厌氧产氢、产甲烷方法处理各种有机废物和有机废水,可实现有机废物的无害化、减量化、稳定化及资源化,是目前该领域的研究热点。介绍了国内外有关两相厌氧产氢、产甲烷处理有机废水和固体废弃物的最新研究进展,包括两相厌氧处理的有机质及反应器类型、产酸段的动力学模型及产氢相和产甲烷相的优势菌群等。已有结果表明,采用两相厌氧产氢、产甲烷反应器处理有机废水及有机固体废弃物,可实现产氢和产甲烷最大化,具有良好的应用前景。     

Effects of ferric hydroxide on the anaerobic biodegradation kinetics and toxicity of vegetable oil in freshwater sediments

Biodegradation of vegetable oil in freshwater sediments exhibits self-inhibitory characteristics when it occurs under methanogenic conditions but not under iron-reducing conditions. The basis of the protective effect of iron was investigated by comparing its effects on oil biodegradation rate and the toxicity of oil-amended sediments to those of clay and calcium, which reduce the toxicity of oil-derived long-chain fatty acids by adsorption and precipitation, respectively. Kinetic parameters for an integrated mixed-second-order model were estimated by nonlinear regression using cumulative methane production as the response variable and used to compare the effects of the three treatment factors on the rate of oil biodegradation. Ferric hydroxide was the only factor that significantly (P<0.05) increased the rate of methane production from canola oil, whereas calcium significantly reduced the oil biodegradation rate. Measurement of sediment toxicity using the Microtox Solid-Phase Test showed that inhibitory products formed within 5 days of oil addition, but the sediment toxicity decreased over time as the extent of oil mineralization increased. None of the other amendments significantly reduced the toxicity of oil-containing sediments. Since ferric hydroxide stimulated the rate of oil biodegradation without affecting the toxicity of oiled sediments, it must operate through a mechanism that is different from those previously described for clay and calcium.     

Kinetics of alachlor transformation and identification of metabolites under anaerobic conditions

Alachlor is one of the two most commonly used herbicides in the United States. In the environment, little mineralization of this compound has been found to occur, and metabolites of alachlor may be formed and could accumulate. The objectives of this study were to determine the rate of alachlor biotransformation and to identify the transformation intermediates formed under aqueous denitrifying, methanogenic, and sulfate-reducing conditions. Second-order biotrasnformation coefficients for alachlor were determined to be 7.6 × 10⁻⁵ (±4.0 × 10⁻⁵), 2.9 × 10⁻³ (±1.6 × 10⁻³), and 1.5 × 10⁻² (±1.4 × 10⁻²) 1 mg VSS⁻¹ day⁻¹ under denitrifying, methanogenic, and sulfate-reducing conditions, respectively. Acetyl alachlor and diethyl aniline were positively identified as transformation products of alachlor under all conditions. In denitrifying reactors aniline was identified as a product of alachlor. When acetyl alachlor was fed as the parent compound, aniline was also identified as a transformation product under methanogenic conditions. This research showed that although alachlor is degraded under denitrifying, methanogenic, and sulfate-reducing conditions, significant concentrations of several metabolites are formed and are only slowly degraded.     

Performance characteristics of the anaerobic baffled reactor

An anaerobic sludge blanket process, termed the anaerobic baffled reactor (ABR), has been developed and shows promise for industrial wastewater treatment. It combines the advantages of high stability and reliability with a high void volume. The risk of clogging and sludge bed expansion with resulting high microbial losses is reduced and there is no need for special gas collection or biological solids separation systems. Organic loadings as high as 36 g COD l^?1day^?1 have been achieved with COD removal rates of more than 24 g COD l^?1 day^?1 and methane production rates exceeding 6 volumes per day per unit volume of reactor. The hypothesis, that the ABR may be adequately modeled as a fixed-film reactor, has been supported. Therefore, a unified approach, based on fundamentals of bacterial kinetics and mass transport, appears useful for modeling this and similar systems. Pilot plant studies are necessary to determine the scaling factors of the system as well as the overall efficiency and costs.