Omer Hulusi Dede

Comparison of the Composting Performance of Four Different Sewage Sludge Amendments

ABSTRACT. High moisture content of sewage sludge is a major constraint in composting, and therefore sewage sludge needs to be mixed with bulking agents that have a high water absorption ratio and better structural stability. In this study, dewatered sludge has been mixed with four different bulking agents in terms of physicochemical properties, with a 1:1 (v/v) proportion of sawdust (SW), hazelnut husk (HH), corn straw (CS), or pine litter (PL), and the composting performances of bulking agents were investigated by considering temperature rise, CO2, H2S evolution, organic matter (OM) removal, C/N ratio, and dissolved organic carbon (DOC) removal. Three of the mixtures, namely, HH, PL, and SW, provided better initial composting conditions, ensuring an appropriate water–air balance within the compost matrix. CS was not able to supply sufficient porosity due to the smaller water absorption ratio and higher degradation rate, which induced anaerobic conditions. Among the mixtures, a higher and faster temperature rise (max 56.5°C) and CO2 release was provided by HH, while OM removal (53%) and DOC degradation were higher with the CS mixture, despite the low temperature rise and low peak value of CO2 release. Relatively low degradable carbonaceous contents of SW delayed all the composting indicators measured in the study. HH significantly enhanced bioreactions and accelerated the stability of sludge compost by providing both structural stability and a readily available carbon source, significantly shortening the composting time.

Comparison of composted biosolid substrate for containerized turfgrass production

Composts produced from composting municipal sewage sludge with bulking agent, namely hazelnut husk (HH), pine litter (PL), corn straw (CS) and sawdust (SW), were seeded with turfgrass mix and cultivated in a container to compare the suitability of composted substrates to produce turfgrass in greenhouse conditions. The performance of substrate was determined by both substrate properties compared to standard peat and by measuring plant growth parameters on each substrate during turfgrass sod establishment. In general, the physico-chemical properties of all substrates were satisfactory for container substrates, but HH and PL substrates performed better in plant growth parameters than in SW and CS composts. The comprehensive growth index values obtained for plants growing in peat, HH and PL were 0.94, 0.87 and 0.84, respectively, which were higher than those in the CS and SW. Plant growth showed linear above-ground dry matter accumulation in all substrates, but was slower in SW and CS. HH and PL substrates appeared to be suitable for containerized sod production for natural soil and peat substitution. Biosolid proved to be an efficient component as a nutrient source ingredient of composted substrates for turfgrass.

Effect of solarization on the removal of indicator microorganisms from municipal sewage sludge

The effect of solarization on bacterial inactivation in sewage sludge was studied using thermotolerant coliforms, enterococci and Escherichia coli (E. coli) as the indicator organisms. Solarization significantly increased the sludge temperature. The maximum temperatures were achieved at the beginning of the second week, reaching 65, 58, 55 and 50°C at depths of 0–10, 10–20, 20–30 and 30–40 cm, respectively. E. coli was found to be the most sensitive microorganism and was reduced to undetectable levels after 9 d at all monitored sludge depths. Thermotolerant coliforms were rapidly inactivated but were not reduced to below the detection limit. The inactivation curves of enterococci showed both shoulders and tailing, indicating a larger heat resistant fraction than with E. coli and the thermotolerant coliforms. Overall, the results suggest that the temperature regime produced by solarization was sufficient to reduce bacterial indicators to an acceptable level, meeting the pathogen regulation limit, in two weeks.

PHYSICOCHEMICAL CHARACTERIZATION OF HAZELNUT HUSK RESIDUES WITH DIFFERENT DECOMPOSITION DEGREES FOR SOILLESS GROWING MEDIA PREPARATION

In this study, the main physical, physiochemical, and chemical properties of hazelnut husk have been determined for the suitability as a container growing medium. Four substrates were prepared based upon decomposition degree: raw (H1), medium decomposed (H2, H3), and strongly decomposed hazelnut husk samples (H4), to determine the optimum growing medium parameters. Particle size was the key parameter to determine the physical properties, which was decreased with the increasing decomposition degrees. The main physical parameters were in the ranges for the ideal growing medium characteristics for H4. Except for raw material (H1), chemical characteristics such as pH, electrical conductivity (EC), carbon (C)/nitrogen (N), and nutrients were within acceptable ranges. The results indicated that hazelnut husk could be an alternative growing media component for containerized crops, if optimum particle size within the range of 0-2mm is obtained, for both aeration and water holding requirements.

Improvement of the Wettability Properties of Compost Using Seaweed

ABSTRACT. Composting substrate components from a wide variety of organic materials are becoming more prevalent in ornamental growing medium mixes. Hazelnut husk (HH) and seaweed (HHSW) composts were investigated for their different hydro-physical roles in substrate dynamics. The water repellent material HH was composted either solely or mixed with seaweed (1:1 by volume) and the hydro-physical properties related to the water retention and wettability of the two composts were evaluated using the water drop penetration (WDPT) and molarity of ethanol droplet (MED) tests and contact angle (θ) determination. The addition of seaweed to the HH compost mixture had positive effects on the water holding capacity, water conductivity, air porosity, and wettability characteristics compared to pure HH compost. Although both composts exhibited signs of hydrophobicity under dry conditions, the repellency rate was more severe in the pure HH compost. The wettability tests results indicate that seaweed improved the hydrophobicity of HH compost by at least two ranking classes, from severe hydrophobicity to moderate hydrophobicity. Also, the contact angle reduced from 107° to 103° by composting seaweed. Seaweed was found to have an influence on the hydrological properties when incorporated as a compost component with the HH substrate.

Development of nutrient-rich growing media with hazelnut husk and municipal sewage sludge

ABSTRACT The aim of the present study was to develop structurally stable, nutrient-rich and environmentally safe growing media by combining waste material: crop residue hazelnut husk (HH) and municipal sewage sludge. In order to achieve this goal, lignocellulosic HH residue was mixed with nutrient-rich sewage sludge (S) in various proportions: HH 100%; HH + S1 87.5% : 12.5%; HH + S2 75% : 2 5%; HH + S3 50% : 5 0%. Following composting, the key physical, chemical and microbiological properties of the growing media were characterized for long-term ornamental nursery crops. The addition of S to the mixture had both significant detrimental and remedial effects on physical properties such as reduced total porosity and water-holding capacity, whilst improved the air capacity, wettability and shrinkage. S content of growing media significantly enriched the plant nutrients, especially the most desired soluble and organic nitrogen fractions and micro nutrients. Germination tests and microbiological analysis confirmed the products as environmentally safe ornamental growing media. We conclude that composting of HH with S is a viable alternative for the development of nutrient-rich growing media and recycling of such waste in the ornamental industry could be a beneficial method in order to sustain waste management and crop production.

Mitigation of soil loss from turfgrass cultivation by utilizing poultry abattoir sludge compost and biochar on low-organic matter soil

ABSTRACT Commercial turfgrass cultivation is one of the main ornamental industries world-wide; however, successive turfgrass sod cutting from the same site removes surface soil, leading to a decline in soil organic matter, impairment of soil fertility and degradation of environment. The present study was aimed to investigate the applicability of poultry abattoir sludge compost (PASC) and biochar (BC) on the establishment of turfgrass by evaluating plant growth performance and mitigation of soil loss by organic waste amendments. The experimental study was designed on the soil which had originally low-organic matter content and previously used as a turfgrass sod harvested site in a sandy loam soil. Incorporation of PASC to soil improved the physicochemical properties in terms of bulk density (BD), water holding capacity (WHC), cation exchange capacity (CEC), pH, total nitrogen, total organic carbon (TOC), and organic matter (OM) by 37 (±2)%, 45 (±3)%, 55 (±3)%, 21 (±2)%, 48 (±2)%, 90 (±10)%, and 96 (±4)%, respectively. PASC-amended treatments enhanced the turfgrass growth rate more than the BC due to its increased nutrient availability. Incorporation of 100 Mg ha–1 (mega gram per hectare) PASC in surface soil with or without BC decreased the mineral soil removal rate by half of the respective soil (control) treatments. The results of the present study confirmed the utilization of PASC and BC as promising agro-industrial-based fertilizers in turfgrass sod production for sustainable soil and nutrient management. GRAPHICAL ABSTRACT