Search

This research evaluated cow dung compost (CDC), goose dung compost (GDC), and duck dung compost (DDC) as peat addition in growing media used for the production of pumpkin seedlings. Commercial substrate (peat: vermiculite: perlite=3:1:1, v/v) was used as the control (CK). The partial addition in peat of each waste compost in the mixtures were 10%, 20%, and 30% (v/v). The results showed that all compost in mixtures increased bulk density, total porosity, electrical conductivity, and mineral content, but negatively affected the pH and organic matter of the growing media compared to CK. CDC in mixture increased ventilation porosity and gaswater ratio and decreased water-holding porosity compared to CK, which was the opposite of the effect of GDC and DDC. The mixtures elaborated with GDC showed better growth, biomass, gas exchange parameters, and physiological indicators of seedling plants than other treatments in varying degrees, which depended on the additional amount of GDC. DDC inhibited plant growth and gas exchange parameters, especially in high addition rate; however, it had a slight promotion effect on chlorophyll content and quality because DDC was rich in minerals. GDC was better than CDC and DDC as a partial addition for peat in the cultivation of pumpkin seedlings. [ABSTRACT FROM AUTHOR]

Old landfill leachate is normally rich in colloidal particles, has low organic compound, poor biodegradability and hard to be biologically treated. The suspended particles are generally dispersed, negatively charged and do not settle by gravity due to their instability and repulsion. This paper aimed to evaluate the effectiveness of SnCl4 as a positively charged coagulant in treating concentrated colour and suspended solids (SS) from an old leachate sampled at one of the local landfills in Malaysia (Alor Pongsu Landfill Site, Keria Perak), which may also represent other landfills with similar property. The mechanism and the effect of pH, zeta potential (ZP) and particle size of colloids on the reduction of the pollutants were evaluated through standard coagulation and flocculation experiment with ZP measurement. The standard jar test was examined at a pre-determined SnCl4 dosage and varied from pH 3 to pH 12. The raw leachate was found negatively charged throughout pH 3 to pH 12. Adding a positively charged SnCl4 increased the leachate surface charge to close to the point of zero charges (IEP) at pH 8 with −0.4 mV. Generally, as the pH value increase from acidic to basic condition, the raw leachate becomes more negatively charged as at higher pH values It was also found that the pH of the solution correlated with the size of the particles, where 221.3 d.nm was recorded from pH 4 to pH 11 and improved to the largest size 660 d.nm at pH 3. The highest colour and SS performance were observed at optimum pH 8 with reductions of 98.9% and 100%, respectively The reduction of repulsive forces at this pH promoted the collision of particles and thus made the aggregation possible. ZP measurement in is important as it provides an early estimation of the effective pH for the optimum coagulation and flocculation process of landfill leachate contributed by the colloidal particles. [ABSTRACT FROM AUTHOR]

Landfills are the third largest source of the greenhouse gas methane, contributing to 25% of global warming. Therefore, the characterization of national municipal solid waste (MSW) and estimation of methane generation rate are very important for the solid waste management (SWM) toward sustainable development goal no. 13, climate action. This study presents (a) an assessment of daily MSW generation, (b) the characterization of MSW, and (c) an evaluation of the methane generation rate constant (k value) in Mogadishu, Somalia. The MSW samples were collected from three (3) sampling zones (Zones 1, 2, and 3; 204 households) and weighted (kg). Next, the waste generation per person per day was estimated. The MSW characterization includes sorting (based on plastic/polythene, food wastes, wood, metals, yard waste, paper/cardboard, textile, glass/ceramic and miscellaneous components, %), the determination of bulk density (kg/L), and measuring moisture content (%). The k values were evaluated from the percentages of different components in MSW based on first-order decay models. Mogadishu city generated 1671.03 kg MSW per week (maximum on Friday: 348.72 kg, and minimum on Monday: 152.04 kg). The total mean MSW generation rate observed in this study was 0.2 kg/person/day. The solid waste generation found was in the decreasing order of food waste > plastic/polythene > yard waste > miscellaneous > papers/carboard > wood > glass/ceramic > textiles > metals by weight. The average bulk density was found to be 0.269 kg/L. The average moisture content was ranged from 61.6 to 73%. The total k values were categorized as fast (Zone 1: 0.216053 yr−1, Zone 2: 0.228739 yr−1, and Zone 3: 0.244595 yr−1) and moderate (Zone 3: 0.244595 yr−1) degradation. This research serves as Somalian MSW baseline data and projected the methane generation rate from the MSW production in the country. The MSW sorting may reduce the impact of global warming and is highly recommended for better SWM in the future. [ABSTRACT FROM AUTHOR]