scholarly journals Assessment of content and chemical forms of arsenic, copper, lead, and chromium in sewage sludge compost as affected by various bulking agents

2020 ◽  
Vol 43 (1) ◽  
pp. 56-66
Author(s):  
Mahboub Saffari ◽  
Vahid Reza Saffari ◽  
Hojatollah Khabazzadeh ◽  
Hormazd Naghavi

AbstractIn current study, the effect of various organic substances as bulking agents (BAs) including wheat straw, pistachio hull wastes, and tree leaves at different levels (10, 25, 45% v/v) were investigated on total concentration and chemical forms of Cu, Pb, Cr, and As in sewage sludge (SS) compost prepared by windrow method. According to the results, the composting process (with/without BAs), due to losses of SS mass and volume, increased the total concentration of heavy metals (HMs) compared to the un-composted SS sample (RSS). Evaluation of HMs chemical forms in prepared compost sample without BAs application (CSS) showed that the composting process reduced the mobility factor of As (from 28% to 20%), Pb (from 11.6% to 9.3%), and Cr (from 14.5% to 9.2%) compared to the RSS. Application of three BAs considerably decreased the mobility factor of As (17.5-18.8%), Pb (4.8-7.9%), and Cr (1.4-6.8%) compared to CSS and RSS. Changes of Cu mobility in prepared compost samples showed an unclear trend, however in some treatments, due to transferred organic fraction into exchangeable and carbonate fractions, increasing of this factor was obvious. Generally, the composting appeared to reduce As, Pb, and Cr availability by stabilizing the three metals and making them more stable and less mobile. In addition, the BAs application effect on HMs behavior of SS compost samples were so different and no specific kind of BAs can be recommended as a superior BAs in SS composting process.

2013 ◽  
Vol 15 (4) ◽  
pp. 513-521 ◽  

<p>The use of organic manures as amendments to improve soil organic matter level and long term soil fertility and productivity is gaining importance. The disposal of the great quantity of organic wastes produced by the municipal, agricultural and agroindustrial activities, is causing energetic, economic and environmental problems. Sludge composting and using them in agriculture should be a priority for their disposal. Sludge should be treated not as a waste but as a valuable non-farm sources of organic matter to soil. The composting process is a useful method of producing a stabilized material that can be used as a source of nutrients and soil conditioner in fields. The objective of this study was estimation of optimal dose of sewage sludge in composting mixture to obtain of mature and stable compost. The mixture was prepared from sewage sludge (10-40%), organic fraction of MSW(30%), grass (20-50%), sawdust as a bulking agents. Maximum temperature in the bioreactor reached 68.9&deg;C between 1st and 3rd day of composting, and the mean temperature during this period fluctuated from 36 to 46&deg;C. Later, the temperature gradually decreased and after 30 days of composting it approached ambient air temperature which means the end of process. There was significant impact of the high temperature on the rate of the process and of the extent of the hygienisation. The results show that all initial samples are infected with helminth eggs but there is a large variation in the degree of infection for the different sludge samples (102 to 256 eggs kg-1 d.m.). The inactivation of the helminth eggs in the compost can be accomplished, if the temperature inside of the reactor is sufficient as in the case M III and M IV. The final compost M III and M IV was well sanitized as a result of the high temperature achieved due to higher grass addition in those mixtures. Composts M I and M II can not be used in agriculture because of bad microbiological characteristic, however MII can be used for recultivation after hygienisation. The composted material assumed the appearance and structure similar to the so-called horticultural soil. As an exothermic process, composting caused very high loss of water in composted material. All the composts were granular, dark grey in color without foul odor and attained an ambient temperature after 30 days of composting, indicating the stable nature of composts. Additional researches are required in order to optimize the better organic and nitrogen compounds degradation during co-composting process.</p>


2001 ◽  
Vol 44 (10) ◽  
pp. 95-100 ◽  
Author(s):  
K.-Y. Chiang ◽  
S.-D. Yoi ◽  
H.N. Lin ◽  
K.-S. Wang

This study investigated the stabilization of heavy metals in a sewage sludge composting process using kaoline addition. The results indicate that the temperature increased rapidly to the thermophilic phase (&gt;55°C) at day 1. The additives enhanced the rate of biodegradation and microbial activity during the co-composting process. The changes in pH (ranging from 8 to 8.5) and electrical conductivity (EC) (≤3 mS/cm) were in compliance with the best conditions during the co-composting process. The C/N ratio was determined in each co-compost sample as an indicator of the co-compost maturity. From the end product of the co-compost experiment, changes in the ratios indicate that the additives promote the co-compost maturation rate. Based on the physicochemical characteristics of the co-compost, the potential use for sewage sludge resource recovery as manure is suggested. The total concentrations of Pb, Cd, Cr, Cu, and Zn in the co-compost product were far below the limit values for agricultural use. The leachability of Pb, Cu, and Cr decreased with increasing co-composting time. That is, the kaoline additive has an inhibitory capacity for leaching heavy metals. The Cd concentrations in the sludge compost were below the detection limits. Because the total concentration of Zn was high in the sludge compost and most soluble Zn was leachable, the leachability of Zn ranged from 25% to 29%. As a result of the physicochemical characteristics and heavy metal stabilization, the selected additive was shown to improve the sewage sludge compost quality and provide information for agricultural applications.


1991 ◽  
Vol 23 (10-12) ◽  
pp. 1979-1989 ◽  
Author(s):  
H. Ishii ◽  
K. Tanaka ◽  
M. Aoki ◽  
T. Murakami ◽  
M. Yamada

This paper reports the results of experiments on the static pile composting process undertaken in different conditions. The experiments have revealed the following:–In order to compost dewatered sludge with polymer without any bulking agents, we used recycled compost to adjust the moisture content of dewatered sludge.When the moisture content of feed mixture, which was dewatered sludges and recycled composts, was lowered to approximately 50%, the raw sludge could be composted by either natural ventilation or intermittent aeration.–When the BOD of feed mixture was lower than 50 g/kg-DS, the fermentation temperature did not reach 60°C and the moisture content of the mixture was not lowered during composting period.–The required composting time was approximately 50 days for natural ventilation (at an average temperature of 10°C or 24°C) and approximately 35 days for intermittent aeration (at an average temperature of 10°C to 24°C), when the moisture content and the BOD of finished compost was 40% or less and 30 g/kg-DS or less, respectively.–There was a highly positive correlation between the amount of water evaporated and the amount of BOD removed. This result suggested that the amount of water evaporation could be deduced from the amount of BOD removed.


2018 ◽  
Vol 250 ◽  
pp. 853-859 ◽  
Author(s):  
Difang Zhang ◽  
Wenhai Luo ◽  
Yun Li ◽  
Guoying Wang ◽  
Guoxue Li

Energies ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 1582 ◽  
Author(s):  
Heiner Brookman ◽  
Fabian Gievers ◽  
Volker Zelinski ◽  
Jan Ohlert ◽  
Achim Loewen

In many areas of application, the influence of hydrothermal carbonization (HTC) on the composition of organic pollutants is still unexplored. In this study, sewage sludge (SS) was carbonized and the input as well as the hydrochar were examined for the organic pollutants: polychlorinated biphenyls (PCB), polychlorinated dibenzo-dioxins (PCDDs), and polychlorinated dibenzo-furans (PCDFs). The process temperatures of carbonization were 200 °C, 220 °C, and 240 °C and the holding time was 5 h for all tests. The total concentration of PCBs was relatively stable for all temperatures, whereas the toxicity equivalent (WHO-TEQ) at 200 °C and 220 °C increases compared to the input material. The strongest impact on toxicity was observed for PCDDs where concentrations were reduced for higher temperatures, whereas the toxicity increases by more than 16 times for temperatures of 240 °C. The concentrations and toxicity of PCDFs were reduced for all carbonization temperatures. In hydrochar from HTC at 240 °C, the limit values for the application of SS in German agriculture have been exceeded. The results indicate that the process conditions for HTC should be controlled also for SS with average contamination if the hydrochar is to be used as material, especially in agriculture.


2009 ◽  
Vol 29 (2) ◽  
pp. 590-597 ◽  
Author(s):  
He Miaomiao ◽  
Li Wenhong ◽  
Liang Xinqiang ◽  
Wu Donglei ◽  
Tian Guangming

2021 ◽  
Vol 23 ◽  
pp. 580-593
Author(s):  
Robert Sidełko

This paper pertains to the influence of decreasing supplementation to transformation of chemical forms of Ni. Zn and Cu during composting of sewage sludge. A universally used supplementing material constituting a rich source of organic carbon is straw. Addition of straw to sewage sludge is aimed at increasing C/N proportion up to at least 15 due to the risk of formation of toxic forms of nitrogen, concentration of which in sewage sludge is exceptionally high. We have presented in this paper the results of speciation research of three elements applying Tessier’s sequential extraction. It’s been proven that decreasing of straw share in the composted mixture with sewage sludge down to the level of C/N value below the admissible value, has a beneficial effect on the allocation of tested heavy metals towards the forms that are permanently bound in compost matrix. A systematic increase of organic (IV) and residual (V) fractions share and decrease of mobile forms of heavy metals content in bioavailable fractions i.e. ion-exchange (I) and carbonate (II) has been ascertained.


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