scholarly journals Modified bentonite as a conditioning agent for stabilising heavy metals and retaining nutrients in sewage sludge for agricultural uses

2021 ◽  
Author(s):  
Yu Cheng ◽  
Kangmin Chon ◽  
Xianghao Ren ◽  
Meiling Li ◽  
Yingying Kou ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Analytic Hierarchy ◽  
Available Nitrogen ◽  
Available N ◽  
Modified Bentonite ◽  
Emerging Issues ◽  
Agricultural Use ◽  
Hierarchy Process ◽  
Optimal Mixing

Abstract The management and disposal of excess sludge are emerging issues owing to the high costs associated with treatment. In this study, the viability of a modified bentonite was investigated as a conditioning agent for the stabilisation of heavy metals (i.e., Cu, Zn, Cr, Pb, and Cd) and the retention of nutrient species (i.e., total nitrogen (TN), total phosphorous (TP), available nitrogen (available N), and Olsen-phosphorous (Olsen-P)) in sewage sludge for agricultural use. Five grams of modified bentonite resulted in the highest stabilisation rate of heavy metals and strongly contributed to the stabilisation of heavy metals. However, increased amounts of modified bentonite might increase the TN, available N, and TP losses in the conditioned sewage sludge. Through the analytic hierarchy process modelling, optimal concentrations of nutrient species and heavy metals remaining in the conditioned sewage sludge were achieved when the ratio of bentonite to sewage sludge was 1:12.5 (4 g bentonite : 50 g sludge). Moreover, the optimal mixing ratio of the conditioned sewage sludge to the soil (1:2) was suggested for agricultural use. Based on these observations, modified bentonite allowed the sewage sludge to be used as a fertiliser in agriculture by stabilising heavy metals and retaining nutrient species.

The Optimization of Thermal Pre-Treatment Time for Extracellular Polymeric Substances Extraction from Sewage Sludge

2015 ◽  
Vol 768 ◽  
pp. 496-505 ◽  
Author(s):  
Yu Yi Zheng ◽  
Hong Lin ◽  
Zhi Long Lin ◽  
Yi Fang Zeng ◽  
Yu Fang Yu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Sewage Sludge ◽  
Process Model ◽  
Extracellular Polymeric Substances ◽  
Treatment Time ◽  
Soluble Sugar ◽  
Analytic Hierarchy ◽  
Pre Treatment ◽  
Hierarchy Process ◽  
Optimum Extraction

This study aims to find out the optimum extraction time varied from 5 min to 60 min for extracellular polymeric substances (EPS) from sewage sludge pretreated at 80 °C. The change of the contents of EPS and its components under different time limit were recorded and compared. The results showed: the contents of soluble protein, TOC, soluble sugar and DNA was increased by 579.17 mg/l, 514.25 mg/l, 132.79 mg/l, and 34.69 mg/l, respectively, with the increase of thermal pre-treatment time during the process, and the DNA content increased the least, which indicating that the effect of thermal pre-treatment at 80 °C on cell lysis of sewage sludge was small. The EPS content, as a whole, was increased with the increase of thermal pre-treatment time. By analyzing the experimental data with the Analytic Hierarchy Process Model, which was used to identify the optimum thermal pre-treatment time of extracting EPS, the results showed that the effectiveness of EPS extraction from sludges was 30 min>60 min>50 min>20 min>40 min>10 min>5 min. Therefore, the 30 min was choosed as the optimum thermal pre-treatment time.

scholarly journals Effects of Medium-Term Amendment with Sewage Sludge on Soil Organic Fertility and on Heavy Metal Bioavailability

2017 ◽  
Author(s):  
Gabriella Rossi ◽  
Claudio Beni
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Physical And Mechanical Properties ◽  
Industrial Wastes ◽  
Organic Carbon Content ◽  
Medium Term ◽  
Italian Law ◽  
Agricultural Use ◽  
Properties Of Soil

The biomass fraction of processed municipal and industrial wastes added to soil can maintain, and in some case improve, the soil’s organic fertility. One of the main constraints in the agricultural use of the sewage sludge is its content of heavy metals. In the long term, soil administration of sewage sludge in agriculture could result in a risk of environmental impact. The aim of this research was to evaluate the effects of medium-term fertilization with sewage sludge diversely processed on the soil’s organic carbon content and humification – mineralization soil’s processes and on the physical and mechanical properties of soil. Furthermore, the heavy metals accumulation in soil, in their total and available form, has been investigated. After eight years of administration to soil, the use of sewage sludge as an agricultural soil amendment has contributed to maintaining the soil’s organic fertility. An increase in concentrations of total Ni and Zn was detected in soil. For bioavailable form (DTPA-extractable) this trend was evidenced for all heavy metals analysed. However, the concentrations of total and available heavy metals in the soil did not exceed the legal threshold established by Italian law for unpolluted soils.

THE PROBLEM OF DISPOSAL AND DESTRUCTION OF SEWAGE SLUDGE AND ITS SOLUTIONS (REVIEW)

2017 ◽  
pp. 35-48
Author(s):  
I.M. Karp ◽  
K.Ye. Pyanykh ◽  
Ye.Ye. Nikitin
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Industrial Wastewater ◽  
Industrial Process ◽  
High Hardness ◽  
Thermal Methods ◽  
Sludge Disposal ◽  
Oxidative Pyrolysis ◽  
Agricultural Use ◽  
Harmful Substances

Sewage sludge of cities usually are formed of municipal and industrial wastewater. They contain many harmful substances such as heavy metals, mineral substances, harmful substances of organic origin wastes (solid domestic wastes, feces, etc.), bacterial pollutants. The problem of utilizing and secure disposal of precipitation of urban wastewater (WWS) is a global. It is not solved fully by this time. European trends of sewage sludge disposal are the reduction or total ban on their agricultural use and disinfecting organic pollutants by thermal methods. Acquires distribution WWS combustion in a fluidized bed. Low-temperature technology of sewage sludge disposal in which the heavy metals remain in the solid residue of the process are interesting. This are pyrolysis, oxidative pyrolysis and gasification. The Gas Institute of NAS of Ukraine conducted preliminary tests of utilizing of dry granular WWS in the reversed process of gasification. Producer gas and pellets with high hardness were obtained; pellets can be used as fillers in construction. Technological scheme of the industrial process is proposed. Bibl. 24, Fig. 7, Tab. 1.

scholarly journals Selection of Feasible Leaching Method for Recovery of Heavy Metals from E-waste using Analytic Hierarchy Approach

2021 ◽  
Author(s):  
Garima Minocha ◽  
vinita khandegar ◽  
Sanigdha Acharya
Keyword(s):  
Heavy Metals ◽  
Technology Development ◽  
Precious Metals ◽  
Economic Feasibility ◽  
Analytic Hierarchy ◽  
Aqua Regia ◽  
Major Threat ◽  
Leaching Methods ◽  
Hierarchy Process ◽  
Selection Of

Abstract Amount of e-waste is increasing tremendously over the years, from almost getting doubled each year. 40 % e-waste consists of many metals and precious metals. The rapid growth in technology development is alarming, as a result more and more e-waste is generating. This leads to myriad problems for handling or management of e-waste. Traditional methods of disposal of e-waste such as landfilling, composting and incineration is major threat to the environment and life. In this study recovery of metals through hydro-metallurgical process such as thiosulfate (M1), iodide (M2) aqua-regia (M3) and thiourea (M4) leaching methods were compared in terms of economic feasibility, environmental impact and reagent reuse in order to find out a feasible leaching method using Analytic Hierarchy Process (AHP). The selection of feasible leaching method has been performed by applying the Saaty, ranking. From the final ranking are, thiosulfate (M1) scored = 0.09, iodide (M2) = 0.16, aqua-regia (M3) = 0.39 and thiourea (M4) = 0.39. From the result M3 and M4 are the feasible method for recovery of heavy metals from E-waste.

scholarly journals Comparison of the Potential Ecological and Human Health Risks of Heavy Metals from Sewage Sludge and Livestock Manure for Agricultural Use

Toxics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 145
Author(s):  
Baoling Duan ◽  
Qiang Feng
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Sewage Sludge ◽  
Health Risks ◽  
Swine Manure ◽  
Carcinogenic Risk ◽  
Human Health Risks ◽  
Adults And Children ◽  
Agricultural Use ◽  
The Mean

Sewage sludge and livestock (chicken, swine and cattle) manure samples were collected from the Yanmenguan Cattle Herbivorous Livestock Area to compare the potential ecological and human health risks caused by heavy metals contained in them. In this study, the Class II level of Quality Control of Imported Organic Fertilizers is selected as the limit standard value of heavy metals. Based on the mean content values, no heavy metal in cattle manure was higher than the limit standard value; the content of Cu in swine manure was higher than the limit of Cu; the content of Zn in sewage sludge, chicken manure and swine manure were all higher than the limit of Zn; and the content of Cr in sewage sludge and chicken manure were all higher than the limit of Cr. Results indicated that sewage sludge and livestock manure all had high contents of Zn, Cu and Cr. The mean pollution index (PI) suggested that Cu, Zn, As and Cr in sewage sludge and livestock manures all induced potential ecological risks. According to the mean Nemerow’s synthetic pollution index (PN) values, swine manure had the highest potential ecological risk for agricultural use. Daily exposure to Cu, Zn and Cr was higher than other heavy metals from sewage sludge and livestock manures, and heavy metal exposure was always higher for children than adults, with ingestion as the main pathway. Non-carcinogenic risk was caused mainly by Cu and Cr, based on the higher hazard quotient (HQ) values for adults and children. There was no non-carcinogenic risk for all people, except exposure of Cu from swine manure for children, which was 1.76 times higher than the threshold value of 1. According to the mean hazard index (HI) values, only swine manure had a non-carcinogenic risk for children. As the carcinogenic risk index (Risk) values were continuously greater for As than Cd, As had a higher carcinogenic risk than Cd. There was no carcinogenic risk for any single heavy metal, although As exposure from sewage sludge was found to have an inapparent carcinogenic risk for both adults and children. Regarding the RISK value, sewage sludge had an unacceptable carcinogenic risk for adults and children, and swine manure had an unacceptable risk for children only. In general, for both non-carcinogenic and carcinogenic risks, ingestion was the main pathway, and children were more sensitive than adults. Comparing the four kinds of organic waste, cattle manure was the safest for agricultural use in terms of ecological and human health risks. In multiple comparisons, swine manure was significantly different regarding potential ecological risk and non-carcinogenic risk, and sewage sludge was significantly different regarding carcinogenic risk.

Sign in / Sign up

Export Citation Format

Share Document