Abstract
This study was designed to characterize sludge of three different ages (36 months old, 3 months old and fresh sludge referred to as Type 1, Type 2 and Type 3 sludge respectively) in an endeavor to appreciate their suitability for use as manure for arable agriculture. Sludge properties including volatile solid and nutrient contents, concentrations of the heavy metals As, Cd, Cr, Co, Cu, Mn, Pb, Ni and Zn as well as coliform population were determined. The concentrations of plant nutrients in the sludge followed the order Type 3 sludge > Type 2 > Type 1 sludge with nutrient content scores of 1.4, 2.1 and 2.6 respectively. Scores for potential leachability of heavy metals from the three sludge were 2.1, 1.9 and 2.3 for Type 1, 2 and 3 sludge respectively, indicating that Type 2 sludge would release a higher concentration of heavy metals to the environment than the other two sludge types. The faecal coliform population in Type 3 sludge was higher than in Types 2 and 3 sludge with values of 5.6log 10 MPN/10g dry solid, 4.6log 10 MPN/10g dry solid and 2.7log 10 MPN/10g dry solid respectively. These results revealed that the nutrient contents and heavy metal concentrations in the three sludge types may not hinder their application to soil for arable purposes but steps to allow for further pathogen reduction need to be taken to reduce health risks. Journal of Applied Sciences and Environmental Management Vol. 10(3) 2006: 109-115
Highlights
This study was designed to characterize sludge of three different ages (36 months old, 3 months old and fresh sludge referred to as Type 1, Type 2 and Type 3 sludge respectively) in an endeavor to appreciate their suitability for use as manure for arable agriculture
This study was designed to evaluate the quality of the sludge produced at this plant in terms of its heavy metals concentrations, pathogen load, nutrient contents and other physico-chemical and biochemical properties that may affect its fertilizer value
Volatile solid content in sludge correlates directly with the amount of OM contained in the sludge (US EPA, 1984)
Summary
Sludge Sampling: Three types of sludge differentiated by their ages (36 months old, 3 months, fresh sludge from the drying beds referred to as Type 1, Type 2 and Type 3 sludge respectively) were used in this study. Type 3 sludge samples were collected from sludge drying beds which were about to be emptied onto the sludge piles. Considering the fact that a high concentration of metals and coliforms in the sludge would degrade its fertilizer value, the sludge type with the highest concentration of each heavy metal as well as faecal coliform was scored 1 and that with the lowest concentration scored 3. These scores were averaged and used to compare the fertilizer value of the three sludge types
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
