M. Hakimi Ibrahim

Land Application of Sewage Sludge: Physicochemical and Microbial Response

In the present review, we address the effects of sewage sludge amendment on soil physicochemical properties and on soil microbial biomass. Sewage sludge is a by-product of sewage treatment processes and is increasingly applied to agricultural lands as a source of fertilizer, and as an alternative to conventional means of disposal. The particular characteristics of sewage sludge depend upon the quality of sewage from which it is made, and the type of treatment processes through which it passes. Sewage sludge may substitute for inorganic fertilizers because it is rich in organic and inorganic plant nutrients. However, the presence of potentially toxic metals and pathogens in sewage sludge often restricts its uses. Ground water and food chain contamination resulting from sewage sludge amendment is one major concern worldwide. The health of soils is represented by a composite of their physical, chemical and biological properties. Amending soil with sewage sludge modifies the physicochemical and biological properties of soils. Perhaps the central constituent of soil that is important in the context of sewage sludge amendment is microbial biomass. Soil microbial biomass, the key living part of the soil, is very closely associated with the content of organic matter that exists in arable agricultural soils. When sewage sludge is land-applied, soil enzyme activities may be directly or indirectly affected by the presence of heavy metals. In several studies, results have shown that sewage sludge amendment increased soil microbial and soil enzyme activities; however, reduction in soil enzyme activity has also been reported. When incubation periods of sewage sludge were longer, heavy metal bioavailability increased. Soil pathogenic activity has also been reported to increase as a result of land application of sewage sludges. The level of pathogens in treated sewage sludge (biosolids) depends on the processes used to treat wastewater and sewage sludge. Agricultural application of sewage sludge may result in the transport of pathogens through aerosols downwind of sludge storage or dispersal sites, may contaminate ground water, stock ponds, or may produce food chain contamination from eating food grown in sludge-treated land.

Properties enhancement of resin impregnated agro waste: oil palm trunk lumber:

In this study, the kiln-dried oil palm trunk (OPT) was impregnated with phenol formaldehyde (PF) and urea formaldehyde (UF) resin as a matrix using high-pressure vaccum impregnation chamber. Different percentages of resin were loaded in oil palm trunk lumber (OPTL) and compared with kiln-dried OPT and rubberwood (RW). The physical, mechanical, and environmental properties were studied according to BS and ASTM standards. The morphology of resin-loaded OPTL was analyzed by scanning electron microscopy (SEM), while thermal characterization was carried out by thermogravimetric analysis. In general, the OPTL exhibited better values of physical and mechanical properties than dried OPT and OPTL (50% resin loading), which were slightly lower than RW; however, OPTL exhibited good thermal stability compared with dried OPT and RW. Furthermore, the OPTL exhibited a high resistance against termites. The observation of SEM micrograph showed that OPTL with PF resin loading exhibited better morphology than OPTL with UF resin loading, and full penetration of resin into OPT structures was observed.

Fly Ash for Agriculture: Implications for Soil Properties, Nutrients, Heavy Metals, Plant Growth and Pest Control

Annual fly ash production ranges from 2 MT in the Netherlands to 112 MT in India, whereas fly ash utilisation ranges from 100% in the Netherlands to 38% in India. Over the past few decades there has been interest in developing strategies to use fly ash in agriculture. It is indeed economical to use fly ash as a soil amendment. Reviews on fly ash in agriculture are scarce. The potential of fly ash as a resource material is due to its specific physical properties such as texture, water holding capacity, bulk density, and pH. Moreover fly ash contains almost all essential plant nutrients. Fly ash can be used as an amendment in soil. Fly ash can improve soils physical and chemical properties, reduce pest dammade on crops and increase crop yields. The amount and method of fly ash application to soil depend on the type of soil, the crop grown and fly ash characteristics. Besides positive effects fly ash may contain also toxic metals and radionuclides. Therefore use of fly ash should be done with care, notably by taking into account the uptake of metals by plants. This chapter describes the properties of fly ash, and the effect of fly ash on soil properties, nutrients, heavy metals uptake by plants, yields and pest control.

Energy recovery potential and environmental impact of gasification for municipal solid waste

ABSTRACT Currently the world is facing numerous environmental problems associated with waste management, climate change and global warming. Therefore, research and development has shifted towards utilising solid waste as an alternative to diminishing fossil fuels. The availability of large amounts of waste and its potential to supply a substantial amount of energy have been widely recognised by the scientific community. Municipal solid waste can be transformed into usable forms of energy through either biological or thermochemical processes (viz. combustion, pyrolysis and gasification). Gasification is considered one of the most efficient routes to convert waste into energy, and is a widely accepted technology that harnesses energy stored in waste. Moreover, for any process to be feasible overall its environmental performance has to be taken into consideration. Recent reports have supported the fact that the gasification process can be carried out with no threat to the environment or human health. The coming decades will reveal the environmental performance of various commercial waste gasifiers currently in operation as strong competitors of other thermochemical conversion processes. Therefore, this review aims to understand the process of gasification, energy recovery potential, environmental impact and technical challenges to tackle the problem of climate change and ultimately reach the goal of sustainability.

The Growth and Reproduction of Eisenia fetida and Eudrilus eugeniae in Mixtures of Empty Fruit Bunch and Palm Oil Mill Effluent

ABSTRACT A laboratory experiment was carried out to determine the potential of vermicomposting technology for vermiculture of the earthworms (Eisenia fetida and Eudrilus eugeniae) in the management of empty fruit bunch (EFB) with palm oil mill effluent (POME sludge). A total of six vermicomposters filled with different fractions of EFB and POME sludge were used for this study. This process was carried out with EFB that was pre-composted using microbes. Biomass gain and cocoon production of E. fetida and E. eugeniae were recorded weekly for 12 weeks. Maximum worm biomass was recorded for E. fetida in 70% EFB + 30% POME (4.90 ± 0.12 g earthworm−1) feed mixture. Maximum cocoons were also recorded for E. fetida in 70% EFB + 30% POME (44 ± 1.3 cocoons). Finally, the results indicated that the addition of 30, 40, and 50% of POME sludge to the EFB is adequate during the vermicomposting, suggesting that E. fetida may be a better choice than E. eugeniae for the rapid propagation of earthworms in oil palm wastes.