Composting sewage sludge amended with different sawdust proportions and textures and organic waste of food industry – assessment of quality

Abstract

The quality of compost made from dewatered sewage sludge, sawdust (SD) and organic wastes of a potato-processing industry (OW), in terms of chemical and biological properties, was assessed. Mixtures of the sludge, SD and OW were composted for 57 days in insulated containers at two C:N ratios (approximately 30 : 1 and approximately 20 : 1) and SD textures (coarse- and fine-textured SD). The parameters monitored over this period were pH, electrical conductivity (EC), C:N ratio, CO2 evolution and two spectrophotometric ratios (Q2/6 and Q2/4). All the studied parameters were in general similarly influenced by initial C:N ratio and texture of SD except for EC, Q2/6 and Q2/4. At high C:N ratio of both textures, the EC of the final products increased but were less than those of low C:N ratio of both textures. Thus, final product can be used alone as growth medium without the need for grinding or blending with other materials. The spectrophotometric ratios (Q2/6 and Q2/4) dramatically decreased two weeks after composting and then slightly increased at the end of composting process. However, coarse-textured SD at the low C:N ratio and fine-textured SD at both C:N ratios resulted in lower Q2/6 and Q2/4 ratios, reflecting a better degree of aromatic condensation and organic matter humification. Considering these parameters, co-composting sludge with fine-textured SD and OW at high initial C:N ratio would represent the best compromise.

Management of sewage sludge by composting using fermented water hyacinth

“…These are cellulosic materials, which provide more structure and volume while reducing moisture and improving aeration. Although these additives theoretically improve the mixtures through a high C/N ratio (41-635), their degradation is limited due to their high lignin content (Ammari et al 2012). Other types of amendments have been used as inorganic conditioners of the SS composting, such as pumice (Wang et al 2011), tezontle (volcanic rock) (Ramírez-Coutiño et al 2013), zeolites (Villaseñor et al 2011), or recyclable plastic (Zhou et al 2014).…”

“…However, SS is characterized by a high moisture content (80-88.5 %) and a C/N ratio of 4.9-11, far lower than optimal values (Chen and Xin-Wu 2010; Kulikowska and Klimiuk 2011). To improve the initial conditions for the composting of SS, amendments such as sawdust (Ammari et al 2012), straw (Muñoz et al 2013), or tree bark (Doublet et al 2010) have been utilized. These are cellulosic materials, which provide more structure and volume while reducing moisture and improving aeration.…”

A bioeconomic Approach for the Production of Biofertilizers and their influence on Faba Bean (Vicia faba L) Productivity

“…Sewage sludge can hardly be composted alone, because of its compacted structure, high water content, and low C/N ratio, then sewage sludge needs to be mixed with dry and carbon-rich materials like food industry waste, sawdust, vegetal remains, straw and wood chips, which act as bulking agents, absorbing the moisture and providing the composting mass with an appropriate degree of sponginess and aeration; the end product enables adding a significant amount of carbon without adding large amounts of phosphorus and nitrogen (Ammari et al, 2012;Zhao et al, 2015;Banegas et al, 2007;Yousefiet al, 2013). Compost with a C/N ratio between 9/1 and 10/1 is considered as mature, also is recommended a C/N ratio below 16/1, to avoid nitrogen blockade due to competition between microorganisms and plants (Ammari et al, 2012).…”

“…Compost with a C/N ratio between 9/1 and 10/1 is considered as mature, also is recommended a C/N ratio below 16/1, to avoid nitrogen blockade due to competition between microorganisms and plants (Ammari et al, 2012).…”

Assessment of co-composting of sludge and woodchips in the perspective of environmental impacts (EASETECH)

“…Co-composting of municipal sludge and other materials, including municipal solid waste (Lu et al, 2009), saw dust (Yousefi et al, 2013), and food industry waste (Ammari et al, 2012), is therefore promising given their complementary characteristics. Garden waste, which normally has loose structure, low water content, and high C/N ratio, is widely applied in co-composting with sludge (Albrecht et al, 2010;El Fels et al, 2014).…”