Removal of helminth eggs and fecal coliforms by anaerobic thermophilic sludge digestion

2002 ◽  
Vol 45 (10) ◽  
pp. 269-274 ◽  
Author(s):  
N. Cabirol ◽  
M. Rojas Oropeza ◽  
A. Noyola
Keyword(s):  
Primary Treatment ◽  
Fecal Coliforms ◽  
Volatile Fraction ◽  
Waste Sludge ◽  
Biological Sludge ◽  
Sludge Stabilization ◽  
Sludge Digestion ◽  
Helminth Eggs ◽  
Thermophilic Conditions ◽  
Thermophilic Digestion

Anaerobic digestion of two types of waste sludge was applied in order to assess the suitability of thermophilic conditions for the stabilization of organic matter and removal of fecal coliforms and helminth eggs. Feeding sludge was taken from an activated sludge municipal facility (BS) and from an enhanced primary treatment municipal plant (EPT). As an accompanying experiment, mesophilic digesters were also operated. The four digesters (M1, M2, T1, T2) had a 5 litre volume and an egg shape. A highly stabilized material was obtained at both temperatures with BS type of sludge, taking the reduction of volatile fraction of suspended solids (%RVSS) as indicator (84% for M1 and 74% for T1). In general, EPT sludge was a more difficult substrate, if compared with BS sludge; thermophilic condition was better adapted than mesophilic for this kind of sludge. Satisfactory reductions on counts of fecal coliforms and helminth eggs were achieved under thermophilic digestion for both types of feeding sludge. T1 digester, fed with biological sludge, removed fecal coliforms below 1000 MPN/gTS and helminth eggs down to 0.28 HELarval/gTS, at an HRT of 20 days. As a general conclusion, anaerobic thermophilic digestion may be an appropriate option for sludge stabilization, in order to meet EPA Class A biosolids final disposal regulations. However, further research is needed in order to consistently remove helminth eggs and fecal coliforms from waste sludge at shorter hydraulic retention times.

Biolixiviation des métaux lourds et stabilisation des boues d'épuration : essai en bioréacteur opéré en mode cuvée

1993 ◽  
Vol 20 (1) ◽  
pp. 57-64 ◽  
Author(s):  
R. D. Tyagi ◽  
J. F. Blais ◽  
N. Meunier ◽  
D. Kluepfel
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Suspended Solids ◽  
Elemental Sulfur ◽  
Batch Reactor ◽  
Fecal Coliforms ◽  
Sludge Stabilization ◽  
Sludge Digestion ◽  
Batch Time ◽  
Phosphorus And Potassium

A biological process of heavy metals solubilization and sewage sludge stabilization was studied in a batch reactor of 30-L capacity. The acclimatized leaching microflora was composed of two major groups of thiobacilli: less acidophilic and acidophilic. A batch time of 10 days allows a substantial metal solubilization: cadmium (100%), copper (80%), manganese (80%), nickel (46%), and zinc (100%). The bioleaching process also causes a significative decrease in sludge total suspended solids (25%) and volatile suspended solids (32%), and a considerable reduction (under the detection limit of 10 cfu∙mL−1) of indicator bacteria (total coliforms, fecal coliforms, fecal streptococci). After filtration or centrifugation of the leached sludge, the solubilized metals were precipitated by lime neutralization. The phosphorus and potassium sludge contents were not affected by bioleaching process. These results indicate that the process of sludge digestion and metal leaching can be conducted in parallel in the same reactor. Key words: sewage sludge, heavy metals, bioleaching, stabilization, thiobacilli, elemental sulfur.

Removal of fecal indicator organisms and parasites (fecal coliforms and helminth eggs) from municipal biologic sludge by anaerobic mesophilic and thermophilic digestion

2001 ◽  
Vol 44 (4) ◽  
pp. 97-101 ◽  
Author(s):  
M. Rojas Oropeza ◽  
N. Cabirol ◽  
S. Ortega ◽  
L. P. Castro Ortiz ◽  
A. Noyola
Keyword(s):  
Treatment Plant ◽  
Anaerobic Treatment ◽  
Fecal Coliforms ◽  
Anaerobic Sludge ◽  
Indicator Organisms ◽  
Fecal Indicator ◽  
Class A ◽  
Helminth Eggs ◽  
Start Up ◽  
Thermophilic Digestion

In this work, two egg-shaped, 5L-volume, anaerobic sludge digesters were used, one under mesophilic conditions (35°C, M1), and the other under thermophilic conditions (55°C, T1). Both digesters were fed with the purged sludge from an anaerobic treatment plant (start-up period) and from an activated sludge plant (stabilization period), treating municipal wastewaters. The purpose of the study was to establish the technical feasibility of the anaerobic thermophilic sludge treatment comparatively, during the stages of start-up and stabilization of the process, for removing pathogenic microorganisms and parasites efficiently. The results show that, in both stages, the anaerobic thermophilic digester presents higher efficiency on the removal of pathogens and parasites, than the mesophilic digester. Anaerobic thermophilic digestion is close to complying with the EPA (1996) limits for “Class A” type biosolids, referring to the number of parasitic helminth eggs (0.25 HELarval/gTS), and to the pathogen indicator fecal coliforms (<1000 MPN/gTS). Therefore, the results show that thermophilic anaerobic digestion of biologic sludge may be considered as a suitable technology for the production of Class A biosolids, for further use in agriculture without restrictions.

Effect of biological additives and micronutrients on the anaerobic digestion of physicochemical sludge

2005 ◽  
Vol 52 (1-2) ◽  
pp. 275-281 ◽  
Author(s):  
A. Noyola ◽  
A. Tinajero
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Municipal Wastewater ◽  
Primary Treatment ◽  
Volatile Solid ◽  
The Third ◽  
Waste Sludge ◽  
Aluminium Sulfate ◽  
Batch Tests ◽  
Thermophilic Digestion

Two additives (lyophilized bacilli and enzymes) and a solution of micronutrients (Fe, Co, Ni and Mo) were tried separately and in combination, in order to assess their effect on the anaerobic digestion of waste sludge from an enhanced primary treatment (EPT) of municipal wastewater. Three batch tests were carried out in serological bottles. In the first test, addition of bacilli increased production of methane from day 11 and at day 17 the production was 95% greater than the control. In that experiment, the concentration of volatile fatty acids (VFAs) was 1,391 mg/L, 40% lower than the control. In the second test, the combination of micronutrients with bacilli, reached from the first days a better methane production than the control, 167% higher in day 17. At the end of the experiment, this combination achieved a lower concentration of VFAs and a greater percentage of volatile solid removal than the rest of the treatments. The third test was based on an experimental design in order to statistically determine the best doses of bacilli additive and micronutrients. The anaerobic thermophilic digestion of sludge from aluminium sulfate EPT will be improved with the addition of Fe: 4.5 mg/g VS, Ni: 0.75 mg/g VS, Co: 0.45 mg/g VS, Mo: 0.09 mg/g VS and bacilli additive: 12 mg/g VS.

Class B biosolids production from wastewater sludge with high pathogenic content generated in an advanced primary treatment

2000 ◽  
Vol 42 (9) ◽  
pp. 103-110 ◽  
Author(s):  
B. Jimenez ◽  
J. A. Barrios ◽  
C. Maya
Keyword(s):  
The United States ◽  
Primary Treatment ◽  
Land Application ◽  
Wastewater Sludge ◽  
Fecal Coliforms ◽  
Treatment Processes ◽  
Helminth Eggs ◽  
Class B ◽  
Us Epa ◽  
High Pathogenic

Alkaline post-stabilization of wastewater sludge with high pathogenic content (up to 1010 NMP/g TS of Salmonella sp. and up to 89.8 helminth eggs/g TS) was studied to evaluate the feasibility of producing Class B biosolids. The sludge was produced in pilot systems using different advanced primary treatment processes treating wastewater generated in Mexico City. Samples were dewatered to different dryness ranging from 11.5 to 29.0% TS and stabilized using quicklime in doses ranging from 15 to 40% (w/w). The levels of pathogens found in dewatered sludge were up to 8 log and 1.95 log higher than those found in primary sludge generated in the United States for Salmonella sp. and helminth eggs respectively. Distribution of genera of helminths indicated that more than 90% of the eggs found were Ascaris, while the rest were Hymenolepis, Trichuris, Toxocara and Taenia. Minimum and maximum removals ranged between 3.6 to 9.5 log for fecal coliforms; 3.7 to 7.9 log for Salmonella sp.; and 0.1 to 1.3 log for helminths. The recommended quicklime dose was determined for different solids contents in order to achieve the pH-time criteria and the levels of microorganisms required by the US EPA. Metal concentrations were below the maximum levels established for land application of biosolids.

Alternative Treatment for Wastewater Destined for Agricultural Use

1999 ◽  
Vol 40 (4-5) ◽  
pp. 355-362 ◽  
Author(s):  
B Jinénez ◽  
A. Chávez ◽  
C. Hernández
Keyword(s):  
Water Quality ◽  
Alternative Treatment ◽  
Drainage System ◽  
Primary Treatment ◽  
Fecal Coliforms ◽  
Filter Media ◽  
Helminth Eggs ◽  
Start Up ◽  
Agricultural Use ◽  
Water Quality And Quantity

An Advanced Primary Treatment (APT) system commercially known as ACTIFLO®, coupled with a system of filtration and chlorination are described. The system used microsand grains in the coagulation phase. This allowed an almost immediate start-up as well as an increase in loading in the sedimentation tank to rates far higher than those previously described (up to 180 m/h). The process was shown capable of treating wastewater from a combined drainage system, which typically varies in water quality and quantity. The ACTIFLO® process reduced TSS from 354 to 27 mg/L, helminth eggs from 24.8 to 1.2 HE/L, COD from 460 to 198 mg/L, TKN from 21.7 to 18.3 mg/L, and TP-P from 8.7 to 3.2 mg/L. To comply with WHO, 1989 recommendations regarding HE quality in water destined for irrigation of crops eaten raw it is necessary to add to the APT a system of filtration. In the paper two types of filter media are compared. In both cases the HE were reduced to <1.0 HE/L for filtration rates of up to 40 m/h. In the disinfection phase 10 mg Cl2/L were used to reduce the number of fecal coliforms from 6.5 × 108 to 340 MPN/100 mL.

Wastewater Treatment by Stabilization Ponds with and without Macrophytes under Arid Climate

1993 ◽  
Vol 28 (10) ◽  
pp. 177-181 ◽  
Author(s):  
L. Mandi ◽  
N. Ouazzani ◽  
K. Bouhoum ◽  
A. Boussaid
Keyword(s):  
Bacterial Load ◽  
Fecal Coliforms ◽  
Arid Climate ◽  
Organic Load ◽  
Experimental Systems ◽  
Helminth Eggs ◽  
Stabilization Ponds ◽  
Treated Effluents ◽  
Summer Time ◽  
Influent Flow

This paper presents a comparative study of two experimental systems, stabilization ponds without macrophytes and macrophytic ponds, to purify wastewater under arid climate of Marrakesh. Organic load (COD, TSS), bacterial load (SF, CF) and parasitical load (helminth eggs) are significantly reduced in both systems. Even though water loss was more important at the macrophytic ponds (evapotranspiration reaches 60% of influent flow), this system shows generally the best efficiency in purifying wastewater. In summer time, TSS and COD depletion is better on macrophytic ponds (TSS: 95%, COD: 87%). The stabilization ponds are more efficient to reduce nutrients: NH4+: 72%. PO4: 63% at the same period. Fecal streptococci and fecal coliforms are reduced more in stabilization ponds (CF: 99.4%, SF: 99.7%) than macrophytic ponds (CF: 96.2%, SF: 94.7%). No helminth eggs were found in the effluent from either system. The two systems ensure optimal removal of parasites allowing the eventual reuse of the treated effluents for agricultural purposes.

Specific organic and nutrient loads in stabilized sludge from municipal treatment plants

1996 ◽  
Vol 33 (12) ◽  
pp. 243-250 ◽  
Author(s):  
O. Nowak ◽  
A. Franz ◽  
K. Svardal ◽  
V. Müller
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Single Stage ◽  
Nutrient Loads ◽  
Activated Sludge Process ◽  
Waste Sludge ◽  
Sludge Stabilization ◽  
Nitrogen Loads ◽  
Theoretical Considerations ◽  
P Removal

By means of theoretical considerations and of statistical evaluations, specific organic and nitrogen loads in separately stabilized sludge have been found to be in the range of 16 to 20g VSS/PE/d and of 1.1 to 1.5 g N/PE/d respectively. About 0.6g P/PE/d are removed from the wastewater in activated sludge plants without chemical or enhanced biological P removal. By using the single-stage activated sludge process without primary sedimentation and without separate sludge stabilization, almost complete nitrogen removal can be achieved, but specific organic and nitrogen loads in the waste sludge are up to two times higher than in separately stabilized sludge.

Biodegradation of PAH and DEHP micro-pollutants in mesophilic and thermophilic anaerobic sewage sludge digestion

2006 ◽  
Vol 53 (8) ◽  
pp. 99-107 ◽  
Author(s):  
T. Benabdallah El-Hadj ◽  
J. Dosta ◽  
J. Mata-Álvarez
Keyword(s):  
Anaerobic Digestion ◽  
Wastewater Treatment Plants ◽  
Economic Cost ◽  
Process Efficiency ◽  
Sludge Digestion ◽  
Thermophilic Conditions ◽  
Polycyclic Aromatic ◽  
Positive Effect ◽  
Process Product ◽  
Micro Pollutants

Anaerobic digestion for the treatment of sludge in wastewater treatment plants has been reported to produce a low organic loaded effluent with an acceptable economic cost. But in the last years, new regulations and the increasing sludge production invite us to find an alternative and/or to improve the process efficiency. Moreover, the use of the effluent as fertilizer in agriculture imposes more restrictions on digestion process product and its micropollutant contents to protect the environment. In this study, a performance of the anaerobic digestion under mesophilic and thermophilic conditions at different hydraulic retention times (HRT) is assessed and the removal efficiencies of two important compounds or family compounds (Polycyclic Aromatic Hydrocarbons, PAH, and Di-2-(Ethyl-Hexyl)-Phthalate, DEHP) are evaluated. A positive effect of thermophilic temperature was observed on both micropollutants' biodegradation. However, HRT effect also had an important role for DEHP and low molecular weighted PAH removal.

Sludge digestion enhancement and nutrient removal from anaerobic supernatant by Mg(OH)2 application

2001 ◽  
Vol 44 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Q. Wu ◽  
P. L. Bishop ◽  
T. C. Keener ◽  
J. Stallard ◽  
L. Stile
Keyword(s):  
Biogas Production ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Ammonia Nitrogen ◽  
Phosphate Removal ◽  
Anaerobic Sludge ◽  
Phosphorus Concentration ◽  
Sludge Stabilization ◽  
Sludge Digestion ◽  
Anaerobic Sludge Digestion

Anaerobic sludge digestion is a widely adopted process for sludge stabilization. Phosphate removal from anaerobic supernatant is necessary to limit the phosphate returned to the head of the treatment plant, thereby improving the overall treatment efficiency. In this study, magnesium hydroxide (Mg(OH)2) was used to improve the sludge digestion efficiency and to remove phosphorus from anaerobic supernatant. The anaerobic sludge digestion experiment was conducted at a pilot scale, and the results showed that applying Mg(OH)2 to anaerobic sludge digester resulted in a larger reduction in SS and COD, a higher biogas production rate, a lower level of phosphate and ammonia nitrogen concentrations in the sludge supernatant and an improved sludge dewaterability. Research results at both lab scale and pilot scale on phosphorus removal from anaerobic supernatant using Mg(OH)2 showed that a high removal of phosphorus can be achieved through the addition of Mg(OH)2. The required reaction time depends on the initial phosphorus concentration and the Mg(OH)2 dosage.

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