scholarly journals Heavy metal content of Swedish municipal wastewater sludge – status and goals

2017 ◽  
Vol 76 (4) ◽  
pp. 869-876 ◽  
Author(s):  
A. Mattsson ◽  
A. Finnson ◽  
D. I'Ons

In 2014, 25% of the sludge produced at Swedish municipal wastewater treatment plants was applied to agricultural land. Even though the Swedish heavy metal limits for sludge to be used in agriculture are amongst the most stringent in the EU, more stringent heavy metal limits are proposed. Most sludge applied to agricultural land is recycled within a certification system, Revaq. Revaq has targets for control at source management and improvement of sludge quality. Statistics based on data collected within the Revaq system was used to differentiate between local and general sources of heavy metals and assess the need to improve sludge quality. The analysis indicates that proposed future national limits on the quality of the sludge can be met by most of the sludge. The improvement needed for about 20% of the sludge is feasible through local control at source management. The levels of cadmium, copper and mercury need to be reduced if these metals are not to limit the amount of sludge that may be applied per unit area of arable land. Finally, the long term Revaq targets for cadmium and silver will be difficult to meet.

Author(s):  
Megan Abrahams ◽  
Mujahid Aziz ◽  
Godwill Kasongo

Abstract The minimization of sludge produced by municipal wastewater treatment plants (MWWTPs) is critical as its handling accounts for approximately 50% of the total operating cost. The challenges in predicting dewatering performance can be overcome by optimizing the sludge treatment process, especially conditioning and dewatering. This study aimed to investigate sludge dewaterability at four different MWWTPs, using a gravity drainage test unit and a bench-scale press. The effect of differently treated effluent used as a solvent to mix the flocculation polymers was observed during dewatering. The membrane bioreactor (MBR) treated effluent yielded the highest filtrate volume in the lowest amount of time, with the least polymer flocculant dosage. The Box Behnken Design model fitted the data and proved a relationship between polymer dosage, cake solids concentration, and cake height during the bench-scale press tests.


2017 ◽  
Vol 21 (3) ◽  
pp. 32-35
Author(s):  
P.V. Khoreva ◽  
I.M. Bernadiner

Current trends of improving of wastewater discharge regulation mechanisms in centralized municipal systems of sewage disposal and in water bodies, the tightening of the requirements for the quality of wastewater, stimulate the development of technologies for their treatment. While improving the quality characteristics of the treated water, problem of formation and subsequent disposal of large source of waste – wastewater sludge (WS) – remains unresolved to date. There were presented information confirming the increase in the volumes of WS produced at municipal wastewater treatment plants. There were presented results of experimental studies on the effect of the thermal characteristics of sludge on the process of their incineration.


2022 ◽  
Vol 42 ◽  
pp. 03001
Author(s):  
Irina Elshaeva ◽  
Vera Titova ◽  
Alexander Vetchinnikov ◽  
Anna Pinaeva ◽  
Oksana Vetchinnikova

Wastewater sludge from municipal wastewater treatment plants in Nizhny Novgorod and soils based on them, prepared with different ratios of sludge, sawdust and peat, have been investigated. Sewage sludge-based soils contain plant nutrients and are suitable for use as fertilizing materials in green building. Under the conditions of a three-year lysimetric experiment on cereal lawn grasses, a significant efficiency of organic soils was noted in comparison with traditional soils. The lawn maintenance regime revealed differences in the mixtures of fertilizing materials in terms of the effect on the productivity of the phytocenosis. Use of sewage sludge containing large amounts of heavy metals as one of the soil components undoubtedly leads to increase in the amount of these toxic elements in the soil as a whole.


2014 ◽  
Vol 71 (3) ◽  
pp. 337-342 ◽  
Author(s):  
Shanel M. Raney ◽  
M. Catherine Eimers

Long-term trends (1975–2010) in total phosphorus (TP) concentrations were evaluated at 113 stream stations across southern Ontario. Declines in TP were evident at the majority of sites (68%), including those both with (n = 49) and without (n = 64) upstream municipal wastewater treatment plants (MWWTP). Although declines in TP at stream stations downstream of MWWTPs may be attributed to improvements in P removal from treated effluent, declines at the remaining streams must be attributed to other causes. During the same time period, increases in chloride (Cl−) were observed at almost all (95%) of the 64 MWWTP-free stations. Over the past 35 years, urban land cover has increased at the expense of agricultural land area in Ontario, with the majority of these changes occurring in southern Ontario. The coincidence of declines in TP and increases in Cl− at the 64 MWWTP-free streams suggests that the two may be related, with P-rich agricultural fields being replaced with impervious surfaces and therefore increased road salt applications.


2012 ◽  
Vol 178-181 ◽  
pp. 507-511
Author(s):  
Zhi Min Zhang

The concentration of heavy metals in excess sludge from municipal wastewater treatment plants has restricted its convertion to soil fertilizer, so it is necessary to remove the heavy metals from sludge. In this article, the effects of heavy metal removal by some mineral acids such as HCl, H2SO4, H3PO4, HNO3 were analysed, when treating excess sludge from a second sediment tank in municipal wastewater treatment plants. To improve the treatment, a combination of H2O2 and acid was also investigated. Consequently, the difference of heavy metal removal among those acids was showed. Its removal of Hg by HNO3 was better than by other acids. Lower pH enhanced the dissolving of heavy metal, yet the removal of Cr was insensitive to the pH. Aided by H2O2, the removal by the acid was enhanced. The suitable dosage of H2O2 was specially related to the solid content of sludge, pH and the acid kind.


2002 ◽  
Vol 46 (4-5) ◽  
pp. 421-425 ◽  
Author(s):  
I.T. Yeom ◽  
K.R. Lee ◽  
Y.H. Lee ◽  
K.H. Ahn ◽  
S.H. Lee

The effects of ozone pretreatment on the biodegradability of municipal wastewater sludge were determined. Three types of experiments were conducted: anaerobic digestion, aerobic biodegradation, and denitrification using ozone-treated sludge as a carbon source. For 5 days, ozonated sludge at 0.1 gO3/g-SS showed about 2-3 times greater biodegradation compared to the raw sludge in both aerobic and anaerobic conditions. In anaerobic experiments, biodegradation increased with ozone dosage up to 0.2 gO3/g-SS. Further increase of ozone dosage did not improve the biodegradation. In aerobic condition, about 77% of the ozonated sludge at 0.1 gO3/g-SS could be biodegraded after 15 days and is compared with 36% degradation of the untreated sludge. Most of the biodegradation of the ozonated sludge occurred within 5 days while the raw sludge was biodegraded steadily throughout the experimental period. The biodegradation enhancement of ozonated sludge was confirmed in batch denitrification experiments.


2012 ◽  
Vol 610-613 ◽  
pp. 198-202
Author(s):  
Ying Xie ◽  
Tao Zhang ◽  
Chong Li Xu ◽  
Yuan Feng Hui ◽  
Wen Jing Ou Yang

Application of sludge-to-energy is an important direction for disposal of sludge, and it is necessary to provide the contents change of heavy metals in sludge. Through sampling in situ and analysis in laboratory, distributions of seven heavy metals in five kinds of sludge, which were come from wastewater treatment plant of Jilin Petrochemical Company of Petro China, were studied, and contents change of heavy metals in the course of sludge-to-energy were analyzed. The results were compared with the other sludge in the factory and municipal wastewater treatment plants and the national standard. The results showed that the heavy metal contents are different in the different sludge, and the mean is Fe>Cu>Zn>Mn>Pb >Cr>Cd, the total content distributions from high to low is incinerated sludge, chemical sludge, activated sludge, neutralization sludge, digested sludge. Contents of Cu and Zn exceeded the the mean of 44 municipal wastewater treatment plants and GB18918-2002. After biogas of digested sludge and energy of incinerated sludge were recovered, heavy metal contents exceeded in varying degrees, which were paid more attention for treatment and utilization.


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