Impact of Sewage Sludge Leaching on Soil Constituents and Quality

Abstract

Activated sludge treatment plants generate large quantities of sludge each year, thereby posing a serious environmental problem. This study aims to experimentally assess the effect of rainwater on the leaching of sludge components. In this context, a percolation test was set up, and composed of PVC cylinders into which the solid substrate was introduced. Five modalities of the solid substrate were used: a sludge modality, a soil modality and three modalities with increasing percentage of sludge (1%, 5% and 25%) in the soil. The percolation water is collected during the rainy months in bottles placed below each column. Solid substrate samples were taken before the test and after one year. The physicochemical analysis of the percolation water showed an increase in the electrical conductivity, BOD5, COD, nitrogen compounds and phosphate compounds which were proportional to the percentage of sludge. The pH of the sewage sludge leachates varies from 7.61 to 7.98. Zinc and copper were the most mobilized metals. A year following the installation of the percolation test, electrical conductivity, total phosphorus (TP) and orthophosphate (PO4) contents decreased for the solid substrates using the five modalities. Furthermore, ammonium (NH4) and nitrates (NO3) levels decreased in soil mixed with 1 to 25% of sludge due to their leaching by rainwater. Collectively, these data show that the leachates through the soil mixed with sludge are stable and loaded with NO3, a plant nutrient that can contaminate the groundwater as well as the surface waters inducing their eutrophication. Furthermore, addition of sludge to the soil improves the levels of carbon, total nitrogen, TP and PO4 in the soil and thereby soil fertility. The addition of sludge, however, is not without soil contamination with heavy metals. Such soil contamination would cause pollution of surface and ground water. Reaching certain severity, it should call for the adoption of prompt measures for the protection of environment and human health.

Future of the Waste Management in Distilleries for home Fruit Growers – Case from Slovakia

“…The direct use of bio-waste may have a negative effect on the arable soil as well as on the water quality. (Zerrouqi et al, 2020) The implementation will require a coordinated action made at the national level that will lead to a harmonized approach in this field. The higher cost for distilleries may be compensated by funding from national, EU and other international funds dedicated to the green energy and circular economy.…”

Modern approaches to treatment and recovery of secondary sludge of domestic sewage

“…Результати натурних досліджень експериментальних асфальтобетонних покриттів, модифікованих техногенними відходами (осадом стічних вод), свідчать про високу їх якість, вони не поступаються за своїми показниками покриттю з традиційного асфальтобетону [42] Багато дослідників повідомляли про позитивний досвід використання мулу стічних вод для відновлення деградованого природного та антропогенного ґрунту [47], контролю ерозії, стабілізації схилів [48], виробництва харчової добавки до раціону тварин [49], у сільському господарстві [50,51] для виробництва гумусових грунтів [25] та добрив. Однак, використання осадів стічних вод в якості добрив може призводити до великих ризиків для здоров'я людей та забруднення навколишнього середовища [52].…”