Occurrence and Fate of Selected Heavy Metals in a Conventional Municipal Wastewater Treatment Plant in Kisumu City, Kenya

Author(s):  
Victor Odhiambo Shikuku ◽  
George O. Achieng'

The objective of this work was to investigate the occurrence and fate of five heavy metals in water, sludge, and sediments from a conventional municipal wastewater treatment facility in Kisumu City, Kenya. The effluent quality was compared with the effluent quality parameters stipulated by the National Environmental Management Authority (NEMA) to assess the efficiency of the plant and potential effect of the discharged effluent on the recipient river. The levels of the heavy metals recorded in the sludge samples were significantly higher than those in the corresponding water samples. The order of the metal percentage removal efficiency (%R) from the treatment plant was Mg>Cu>Mn>Fe>Zn. It is concluded that the plant is a point source for Zn loading into the recipient waters which poses potential risk to end users downstream. The heavy metal-laden sludge was within permissible limits for utilization in agricultural lands.

1990 ◽  
Vol 22 (7-8) ◽  
pp. 225-232
Author(s):  
G. Petersen

The upgrading of an existing mechanical wastewater treatment plant to meet the new standards for effluent quality in the Municipality of Fredericia, Denmark, are presented. The Municipality has a lot of very big organic and inorganic industries, which leaves several different possibilities for treatment strategies. In 1987 pilot-scale tests were carried out to study the effects of various combinations of wastewater types on the treatment efficiency, and the tests resulted in two main solutions for the wastewater treatment system. The pilot-scale tests were run in a two - stage biology plant. The first stage was either a BIOSORPTION unit or a PRE-DENITRIFICATION unit. The second stage was a biological nitrogen and phosphorus removal unit (a BIO-DENIPHO unit).


2000 ◽  
Vol 41 (10-11) ◽  
pp. 287-293 ◽  
Author(s):  
M. Ogoshi ◽  
Y. Suzuki

An easily installed wastewater treatment plant was developed using an MBR process. The plant consists of inlet pumps, automatic fine screen, a main reactor in which aerator-mixer and MF membrane separators are installed and a control board. The main reactor is a sheeted pond which is easily constructed on-site by an excavation. As a result, the installation of this plant is easy and inexpensive, operation is easy, yet the effluent quality is high. The 50 m3/d pilot plant was constructed in our experimental facility in Ibaraki Pref., and operated from January 1997 to April 1998 to evaluate performance, stability and the ease of separation and installation of each unit. The results were satisfactory in all areas, except the durability of membrane permeability in the latter half of the experiment. For both hollow fibre type and plate type, membrane permeability immediately decreased due to the deposit of concentrated sludge cake on the surface, even though continuous bubble washing had been made. Hence,drastic improvement is needed in the way of sludge deposit control on the membrane surface. This is the key for the developed system to become a practical one.


2007 ◽  
pp. 227-237
Author(s):  
Nataliia Suchkova ◽  
Yuri Vergeles

The contamination of the sewage sludge fields of municipal wastewater treatment plants (WWTPs) by heavy metals, hydrocarbons or other pollutants is a major environmental problem. Sludge can retain up to 96% of all the metals entering the WWTPs in sewage, therefore, when it is disposed to land, heavy metals will be accumulated in the soil. Effects of heavy metal accumulation are long lasting and even permanent. Phytotoxicity is the main problem, although metals can be transferred directly to man via vegetables and other crops or indirectly via animals, primarily cattle, eating herbage (zootoxic). The common metals in sludge are Zn, Cu, Ni, Pb, Cr, and Cd which are generally the most toxic metal found in high concentration.Conventional treatment techniques of contaminated territory suffer from serious shortcomings which limit their applicability and efficiency. These include high cost and maintenance requirements, the need to transfer the contamination from one medium to another, and the extended duration of the operation. Alternatives to these treatments lie in in­situ phytoremediation. Plants are among the most tolerant organisms to pollution, which emphasizes their utility for the detoxification or degradation of pollutants. The concept of phytoremediation was inspired by the discovery of hyper-accumulators, most of which belong to the botanical families Brassicaceae, Poaceae, Papilionaceae, Caryophyllaceae, and Asteraceae, which provide most of the candidates for heavy metal phytoremediation. Two other families are important - the Salicaceae with the genera Salix and Populus, which are effective against a range of pollutants; and the Betaceae which contribute species effective against salt ions and small (few rings) polycyclic aromatic hydrocarbons (PAHs). Some Asteraceae species have been shown to be good phytoremediants of radionuclide pollution [ I ].This paper summarizes the results obtained from laboratory, as well as from in-situ experiments (sludge fields at Kharkiv's WWTP, total area is approx. 126 ha) which focused on phytoremediation methodologies for the removal of heavy metals from sewage sludge.


2013 ◽  
Vol 807-809 ◽  
pp. 1245-1250
Author(s):  
Jing Li Gu ◽  
Jun Hong ◽  
Ling Wan ◽  
Fan Zhang ◽  
Nan Nan Yuan

A process of CAST, designing parameters and characteristics in the water treatment technology was introduced in this paper. The CAST was adopted to treat a scale of 3300m3/d of municipal wastewater and industrial effluent coming from a small town of Huojia county in Henan province. It is an innovative attempt to applied the CAST to a rural sewage treatment in the traditional water treatment field. What is more , after the chemical phosphorus removal and a sufficient reaction in the CAST tank, the effluent quality would ultimately meet level A while others could only meet level B in the state standard discharge standard of pollutants for municipal wastewater treatment plant (GB 18919-2002).


1994 ◽  
Vol 29 (12) ◽  
pp. 283-289
Author(s):  
O. Burica ◽  
R. Vodopivec ◽  
M. Stražar

The paper describes the upgrading of an existing conventional two-stage municipal wastewater treatment plant for 200,000 PE to meet the EEC and Slovenian high effluent quality demands for nitrogen. The incoming wastewater is highly loaded with industrial waste and specifically with effluent from anaerobic pretreatment of piggery sludge. The low-cost concept of extensive wastewater treatment is based on integrating appropriate technologies into an existing treatment facility, preserving as much of the technical infrastructure as possible. The proposed concept uses a predenitrification system for the elimination of nitrogen.


2011 ◽  
Vol 356-360 ◽  
pp. 2908-2913
Author(s):  
Si Ruo Zhang ◽  
Tie Jian Zhang ◽  
Jun Liang Liu ◽  
Yan Li

To solve the problem of huge investment and high difficulty of individually treating landfill leachate, the experiment adopted A2O simulated wastewater treatment plant to treat landfill leachate combined with municipal sewage.Under the conditions of 11h HRT, 1.0-2.0mg/L DO concentration, 200% mixture reflux proportion, 80% sludge reflux proportion and 20d sludge age, adding langdfill leachate to municipal sewage with the proportion of 1:1500, 1:1000 and 1:600, the effluent concentration can achieve the first order A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant. When the proportions come to 1:400 and 1:200,the effluent quality can’t reach the standard. After a comprehensive consideration of water quality and landfill leachate treatment amount in practice, we can draw a conclusion that the 1:600 proportion is the most suitable one of adding landfill leachate to municipal sewage.


2011 ◽  
Vol 365 ◽  
pp. 361-366
Author(s):  
Mei Yan Xing ◽  
Ya Nan Lin ◽  
Hao Wang ◽  
Jian Yang ◽  
Zhi Dong Huang

A Pilot-scale study was conducted to treat municipal wastewater by Biological-Ecological filter (BEF), which is composed by anaerobic hydrolysis pool (AHP), high load biological filter (BF) and vermifilter (VF). The results demonstrated that when the influent concentrations of COD and NH3-N were in the range of 190~300 mg/L and 25~35 mg/L, respectively, the effluent concentration of them ranged from 45 to 65 mg/L and 8 to 20 mg/L with the average removal efficiency of 73.6% and 50%, respectively. Meanwhile, the effluent average SS concentration was less than 15 mg/L. The effluent quality could steadily meet the second level criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002) in China. The removal performance of fine zeolite was significantly better than the coarse one and heightening packing layer had little effect on the removal of COD and NH3-N. This study verified that BEF system for municipal wastewater treatment was feasible.


Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6953
Author(s):  
Ewa Neczaj ◽  
Anna Grosser ◽  
Anna Grobelak ◽  
Piotr Celary ◽  
Bal Ram Singh

Resource recovery from biodegradable waste is essential in order to reach the goals of zero circular economy waste generation and zero greenhouse gas emissions from the waste sector. Waste whose management is a real challenge is sewage sludge, mainly because of high concentrations of heavy metals. The aim of this study was to compare the effectiveness of material stabilization during aerobic stabilization of two feedstocks with sewage sludge obtained from different sources, namely, digestate from a municipal wastewater treatment plant and digestate from a co-digestion process. Moreover, the goal of the experiment was to assess the quality of compost in terms of remediation potential. The composting process was carried out for four different mixtures consisting of the mentioned digestates, municipal solid waste, and grass. A better composting efficiency with digestate from the co-digestion process was observed. In that case, a higher temperature in the thermophilic phase (>55 °C) and a higher organic matter loss ratio (60%) were obtained as compared to the process with digestate from wastewater treatment plant. Taking into account the fertilizing properties and the concentration of heavy metals, all obtained composts met the requirements set out in the Polish Regulation for organic fertilizers. Only the content of Helminth eggs in the composts produced with the digestate from the wastewater treatment plant was above the acceptable level. The research also proved that the produced composts can be used in the phytoremediation process of the degraded area. It was found that all composts caused a significant increase in fescue biomass. The highest yield was achieved for compost produced from a mixture with the addition of 30% sewage sludge from the co-digestion process.


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