Environmental consequences of the use of sewage sludge compost and limestone outcrop residue for soil restoration: salinity and trace elements pollution

Panettieri

et al. 2021

Waste Biomass Valor

Purpose Seaweed blooms are an irregular but frequent phenomenon in many coastal areas and during the touristic season, can cause limitations for recreational use of beaches. Here, we propose composting of seaweed removed from the shoreline as alternative to current management practices (e.g. disposal in landfills or incineration). Methods A co-composting strategy with garden prune waste was chosen for the treatment of seaweed blooms removed from the beaches. Composting was performed in windrows of 10 m long, 1.5 m wide and 1 m high using different ratios of algae and garden prune residues (1:2; 1:1 and 2:1) at a composting facility in Rota (Cádiz, Spain). Results Characteristic temperature profiles consisting of a very brief mesophilic phase, a 15–20-day thermophilic phase (maximum of 50–70 °C) and a second mesophilic phase (40–35ºC) after 30–50 days were observed. After curing for more than 160 days, a stabilized non-phytotoxic composted material (50–70 g kg−1 C; 2–3 g kg−1 N; C/N ratio of 21–27 and electrical conductivity between 1.8–2.4 mS cm−1) was obtained. Composting worked best using a 2:1 ratio (prune waste:algae). The composted organic material showed larger presence of stabilized lignin-derived compounds as assessed via nuclear magnetic resonance. No odors were detected during the composting process suggesting that open-air treatment is feasible. Conclusion The co-composting strategy provides a safe, local and sustainable approach to deal with seaweed blooms during peaks of recreational use and in situations where algae have to be removed. Graphic Abstract

Section: Chemical Characterization Of the Final Productsmentioning

confidence: 79%

Composting as Sustainable Managing Option for Seaweed Blooms on Recreational Beaches

Panettieri

et al. 2021

Waste Biomass Valor

“…The application of biosolids increased the soil salinity (Table 1 and Figure 4). Other authors have highlighted the risk of increasing soil salinity with high doses of sewage sludge (Reddy and Crohn, 2012; Pérez-Gimeno et al, 2016), which can cause a depletion in plant survival (Fuentes et al, 2010). L. scoparium has been previously considered salt tolerant (Cassaniti et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Response of a Pioneering Species (Leptospermum scoparium J.R.Forst. & G.Forst.) to Heterogeneity in a Low-Fertility Soil

et al. 2019

Root foraging may increase plant nutrient acquisition at the cost of reducing the total volume of soil explored, thereby reducing the chance of the roots encountering additional patches. Patches in soil seldom contain just one nutrient: the patch may also have distinct textural, hydrological, and toxicological characteristics. We sought to determine the characteristics of root foraging by a pioneering species, Leptospermum scoparium, using pot trials and rhizobox experiments with patches of biosolids. The growth of L. scoparium was increased by <50 t/ha equiv. of biosolids but higher doses were inhibitory. Roots foraged patches of biosolids in a low-fertility soil. There was no evidence of chemotaxis, rather, the roots proliferated toward the patch of biosolids, following chemical gradients of nitrate. While the biosolids also contained high concentrations of other nutrients (P, K, and S), only significant chemical gradients of nitrate were found. Once the roots encountered a patch of biosolids, the growth of the plant increased to a level similar to plants growing in soil homogeneously mixed with biosolids or surface-applied biosolids. Our results indicate that roots forage nitrate, which is mobile in soil, and that gradients of nitrate may lead to patches containing other less mobile nutrients, such as phosphate or potassium.

“…High salinity may also lead to the salinization of groundwater and soil. Pérez-Gimeno et al [44] evaluated the water salinity and trace elements pollution from sewage sludge compost. The use of CSS was considered as a potential source of salts in soil rehabilitation.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Heavy Metals in Sewage Sludge during Land Application Process in China: A Review

2017

Abstract:The safe disposal of sewage sludge during the process of municipal wastewater treatment has become one of the major concerns of increased production. Land application was thought of as a more economical method for sewage sludge disposal than landfill and incineration. However, the presence of heavy metals in sewage sludge restricted the use of land application. The environmental risk of heavy metals was dependent on their contents, chemical speciations, and soil characteristics. Composting and chemical immobilization were the commonly used methods to immobilize the heavy metals in sewage sludge. The immobilization mechanism and speciation transformation of heavy metals during the composting process were presented. Aluminosilicate, phosphorus-bearing materials, basic compounds, and sulfides were reviewed as the commonly used chemical immobilizing agents. The problems that occur during the immobilization process were also discussed. The combination of different methods and the modification of chemical immobilizing agents both improved the fixation effect on heavy metals.