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Chemical and spectroscopic analysis of organic mattertransformation during composting of sewage sludge and

green plant waste

Abdelmajid Jouraiphya, Soumia Amirb, Mohamed El Gharousa, Jean-Claude Revelc,Mohamed Hafidib,�

aLabo. Fertilite des Sols, Centre Arido-Culture, INRA Settat, MoroccobDepartment de Biologie, Faculte des Sciences Semlalia, Unite Sol et Environnement (Eco-Veget.), BP : 2390, Marrakech 2390, Morocco

cEquipe Agronomie, Environnement et Ecotoxicologie (A2E), ENSAT-INP, Toulouse, France

Received 14 January 2005; accepted 6 June 2005

Available online 10 August 2005

Abstract

When a mixture of thick sewage sludge (10m3) and green waste (5m3) was composted, the thermogenic phase (72 1C) improved

the hygiene of the final product. After 135 days of composting, overall decomposition reached 60%, with percentage decomposition

of hemicellulose, cellulose and lignin 70%, 61% and 37%, respectively. The C/N ratio was 12 and the NH4+/NO3

� ratio was 0.24,

illustrating the maturity of the final product. During composting, the humification process resulted in an increase in humic acids

from 26 to 39.5mg g�1, and a decrease in fulvic acids from 38 to 18mg g�1. The different humification indices and the Fourrier

transform infra-red (FTIR) spectroscopic analysis revealed an increase in aromaticity and degree of polycondensation, with a

decrease in aliphatic groups and a reduction in the easily assimilated peptide and carbohydrate components. The germination index

for both lettuce (Lactuca sativa) and turnip seed (Brassica rapa) was 98% after 135 days of composting, showing that the final

compost was not phytotoxic.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Composting; Sewage sludge; Maturity index; Cellulose; Hemicellulose; Lignin; Humification; Germination tests; Infrared spectroscopy

1. Introduction

The necessity to preserve natural resources and theoptimisation of use of non-renewable energy hasencouraged the recycling and recovery of organic wasteas an alternative to dumping and incineration(ADEME, 1994). Among the organic waste recycled inagriculture, residual sludge generated by wastewatertreatment is a source of organic matter rich in bothphosphorus and nitrogen. It can contribute to therehabilitation of degraded soils by its fertilising andother soil-improving qualities. Nevertheless, directagricultural use of sewage sludge is limited by the

e front matter r 2005 Elsevier Ltd. All rights reserved.

iod.2005.06.002

ing author.

ess: hafidi@ucam.ac.ma (M. Hafidi).

presence of pathogens, by fermentation of any unstableorganic matter and by the organic and inorganicpollutants it contains (Lavoie and Marchand, 1997;Dudka and Muller, 1999). To overcome the risksincurred by the direct use of this waste in agriculture,treatment is required to minimise and eliminate theundesirable effects and to optimise the efficiency of thematerials once applied to the soil. Composting isconsidered to be the best pretreatment for overcomingthese problems (Ouatmane et al., 2000; Amir and Hafidi,2001), and the high temperatures reached, 50–70 1C,destroy almost all pathogens (Dumontet et al., 1999).Numerous bacteria degrade the readily availableorganic components or transform them into stablehumic components (Garcia et al., 1992; Diaz-Burgoset al., 1994; Tuomela et al., 2000; Amir et al., 2004).

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Table 1

Physico-chemical features of the sewage sludge and green waste used

for composting

Parameters Sewage sludge Green waste

Water (%) 55 64

pH 7.2 6

Total Kjeldahl nitrogen (g kg�1)a 13 15

Total organic carbon (g kg�1)a 367.5 528

C/N ratio 28.3 35.2

Ash (g kg�1)a 312 83.3

aResults expressed g kg�1 of dry matter.

102

A decrease in the content of organic pollutants and areduction in the bio-availability of metal trace elementshas also been reported during the composting of sewagesludge (Kastner and Mahro, 1996; Echab et al., 1998;Lau et al., 2003).The success of composting is linked to the quality of

the final product, especially its stability. Spreadingimmature or unstable compost can generate seriousproblems of hygiene and phytotoxicity (Deportes et al.,1995; Pascual et al., 1997). The reliability of individualindicators for the determination of compost maturity isdebatable, so several parameters are often consideredtogether. Numerous authors (Mathur et al., 1993;Ouatmane et al., 2000; Tomati et al., 2000) havesuggested the use of different maturity indices (C/Nratio, humification indices, and germination indices).The purpose of this investigation was to follow some

of the physico-chemical and microbiological modifica-tions occurring during the composting of activatedsludge when mixed with fresh green plants. Theevolution of compost maturity was assessed frommeasurement of various types of humification indices,by comparison with data obtained by Fourrier trans-form infra-red (FTIR) spectroscopy.

2. Materials and methods

2.1. Composting

The sewage sludge used was taken from the waste-water aerobic treatment plant of Khouribga (Morocco).Thick sludge (10m3) was mixed with fresh green plantwaste (5m3) in a pile 8m long and 1.5m high on acomposting platform. The mixture was prepared so as tooptimise the composting parameters, i.e. 60% humidityand a C/N ratio of about 30. Table 1 lists the mainphysico-chemical characteristics of the raw materials.With the aim of maintaining aerobic conditions duringthe process, the pile was turned manually every 15 days.Temperature was measured daily at a depth of 50 cm atdifferent positions inside the pile. Samples were takenbefore composting (T0), after 15 days of composting(T15), and at T60, T90 and T135).

2.2. Physico-chemical analysis

The pH of a suspension of compost in water (1:2 v:v)was measured. Total organic carbon (TOC) wasdetermined by oxidation with potassium bichromate(Nelson and Sommers, 1982) and total nitrogen by theKjeldahl method. Ammonium was assayed by distilla-tion in alkaline medium, and nitrates after reduction byDewarda alloy (Ezelin De Souza, 1998) Ash content wasdetermined after calcination at 550 1C. Decomposition(Dec) was calculated according to the following formula

(Ezelin De Souza, 1998):

Decð%Þ ¼ 100� ½ðAf � AiÞ=Af � ð100� CiÞ� � 100,

where Af is final ash and Ai is initial ash.

2.3. Extraction and assay of humic substances

Before extracting the humic substances, the samples(15 g fresh weight) were defatted with a chloroform:-methanol mixture (2:1). After filtering, the defattedsample was evaporated under nitrogen to eliminate thesolvents (Lichtfouse et al., 1998; Amir et al., 2005). Theresidues were extracted with distilled water three timesto eliminate soluble non-humic substances (sugars,proteins) which can interact with humic substances(Amir et al., 2003). Extraction with 0.1M NaOH (40ml)was repeated several times until colourless solutionswere obtained after centrifugation at 5000 rpm (shouldbe as g). The humic substances (HS) obtained werefractionated into humic acids (HA) and fulvic acids(FA) by precipitation of HA by 1.5M H2SO4 (24 h at4 1C), which were separated HOW? from the FAsolution. Subsequently, the HA were redissolved inNaOH (0.1M). The HA and FA solutions obtainedwere dialysed through a Spectra-Por membrane(1000Da), freeze-dried, and then weighed. Differenthumification indices were calculated: humification ratio,HS/TOC� 100; humification index, HA/TOC� 100;percentage HA: HA/HS� 100, degree of polymerisa-tion: HA/FA (Sanchez-Monedero et al., 1999).

2.4. Fibre assay

The proportion of fibre (cellulose, hemicellulose andlignin) was determined according to the method of VanSoest (1963). The reduction in lignin, cellulose andhemicellulose (organic matter loss) was calculated fromthe initial and final ash levels, Ai and Af (Paredes et al.,1996)

OM� loss ðg Kg�1Þ

¼ ð100� 100½ðAið100� Af Þ�=½Af ð100� AiÞ�Þ � 100

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Table 2

Cultural conditions used to characterised the microbial population of the compost

Total aerobic mesophiles Sporulating, aerobic

(Bacilli)

Yeasts and moulds Clostridia

Culture medium PCA PCA PDA SPS

Incubation temperature 30 1C/48–72h 30 1C/48–72 h sample

heating at 80 1C/10min

30 1C/24 h 30 1C/48–72 h sample

heating at 80 1C/10min

PCA: plate count agar; PDA: potato dextrose agar; SPS: sodium-polymixin-sulphate.

70

80

taking into account the apparent increase in ash contentwhich results from the weight loss of dry matter(Nuntagij et al., 1989).

1501002000

10

20

30

40

50

60

Composting time (days)

Tem

pera

ture

(°C

)

2.5. Fourrier transform infra-red analysis

KBr pellets of each sample to be analysed wereprepared by compression under vacuum of a mixture of2mg dry sample (105 1C, 24 h) with 400mg KBr. Spectrawere obtained with a FTIR Perkin Elmer 1600 spectro-photometer by subjecting the pellet to a frequency of4000–400 cm�1 at 16 nmsec�1.

Fig. 1. Variation of temperature during composting of sewage sludge

and green waste.

2.6. Microbiological analyses

The following bacterial groups were quantified: (i) totalaerobic mesophiles (TAM), (ii) clostridia, (iii) bacilli and(iv) yeasts and moulds. Each 10g sample was ground in90ml solvent in an Ultraturrax and left to stand for10–15min to allow the microorganisms to migrate into thesolution. Serial dilutions (102–10�6) were prepared fromthis in sterile water. Microorganisms were counted afterseeding sterile Petri dishes with 1ml of dilutions from10�1 to 10�[were these pour or spread plates?] and incubation atthe temperatures and times indicated in Table 2.

2.7. Germination test

Germination tests were performed with lettuce(Lactuca sativa) and turnip (Brassica rapa) seed. Eightseeds, three replicates for each sample of the compost,were left to germinate in a water extract of the compost,at 25 1C for 72 h. The germination index (GI) Zucconiet al. (1985) was computed by the formula:

GI ¼ ðpercentage viable seeds

� percentage root lengthÞ=100,

where percentage viable seeds ¼ (number of viableseeds in the sample/in the control)� 100, percentageroot length ¼ (root length in the sample/ in thecontrol)� 100.

3. Results and discussion

3.1. The composting process

The variation in temperature recorded during theprocess (Fig. 1) was typical of a two-phase compostingprocess (Mustin, 1987; Tomati and Galli, 1995). Aninitial stabilisation phase is characterised by an increasein temperature which can reach 72 1C within 4 days.This temperature rise results from intense microbialactivities favoured by the high concentration of easilydecomposable organic molecules. Afterwards, duringthe maturation phase, the temperature decreased stea-dily to reach an ambient 25 1C at the end of the process.During composting, microbial activities are diverse

(Finstein and Morris, 1975; De Bertoldi et al., 1979).Microbiological analysis of the initial mixture (sewagesludge/green waste) showed TAM (6� 106CFUg�1

fresh compost), bacilli (4.6� 108CFUg�1 fresh com-post) and yeasts and moulds (2� 106CFUg�1), andclostridia (22� 106CFUg�1 fresh compost) (Table 3).The microbial density was significantly reduced after 135days of composting to reach 1.5� 102 bacilli ando10CFUg�1 of TAM, yeasts, moulds and clostridia.This drop can be attributed to the exhaustion ofnutrients from the medium and/or to the temperaturepeak during the thermogenic phase (72 1C at 4 days).

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Table 3

Bacterial counts (expressed as colony forming units g�1 fresh material) during the composting process

Samples Total aerobic mesophiles

(CFUg�1)

Sporulating, aerobic

(Bacilli) (CFUg�1)

Yeasts and moulds

(CFUg�1)

Clostridia (CFUg�1)

Initial sewage sludge 6� 106 4.6� 108 2� 106 22� 106

T0 5.2� 106 3.4� 109 4.3� 106 2� 106

T15 d 2.1� 105 7.6� 108 3.2� 103 86� 105

T60 d 3.3� 104 1.6� 106 o 10 18� 106

T90 d 9.5� 102 6.5� 105 o 10 44� 102

T135 d o 10 1.5� 102 o 10 o 10

Table 4

Evolution of physico-chemical parameters during composting of a sewage sludge and green waste mix

pH Corga TKNb C/N Asha Dec %c NH4

+ ppm NO3� ppm NH4

+/NO3�

T0 6.4a 35.770.5a 1.270.2b 29.8a 33.670.5e — 24.670.05a 9.470.2e 2.6

T15 d 5.7c 35.370.8a 1.470.1b 26ab 35.170.1d 6.6 19.671.09b 11.470.1d 1.7

T60 d 6.1bc 30.970.7b 1.370.08b 23.8bc 41.77 0.2c 29.3 15.970.6c 19.770.09c 0.8

T90 d 6.1bc 28.270.3c 1.470.2b 20.4c 45.770.1b 39.9 12.070.55d 24.970.1b 0.5

T135 d 6.2ab 20.570.3d 1.770.1a 12.2d 56.370.2a 60.8 9.770.28e 40.270.2a 0.2

All values are reported as mean7standard deviation between four replicates; values in the same column with different letters are significantlydifferent (ao0.05).aResults expressed in % dry weight.bTKN: total Kjeldahl nitrogen.cDec %: degree of decomposition.

Table 5

Levels of fibre and percentage decomposition estimated during sewage sludge–green waste composting

Stage Fibre (g kg�1 dry matter) % Decomposition

Lignin Cellulose Hemicellulose Lignin Cellulose Hemicellulose

T0 254.971.3c 64.072.8a 108.971.6a 0 0 0

T15 d 231.070.2e 66.673a 137.072a 13.376.4 5.171.1 —

T60 d 250.070.8d 45.071.1b 100.672.4b 21.470.4 43.572.8 26.074.3T90 d 261.470.5b 45.071.6b 65.572.1b 24.672.7 48.672.1 56.075.7T135 d 270.871a 41.070.8c 55.370.7c 36.771.0 61.471.1 69.574.7

All values are reported as mean7standard deviation between four replicates; values in the same column with different letters are significantlydifferent (ao0:05).

104

Maintaining the temperature at 60 and 70 1C for the firstmonths of composting caused a significant eliminationof clostridia (pathogenic agents). At this temperature,only a few days are required to eliminate almost allpathogens and nematodes according to Lavoie andMarchand (1997) and Dumontet et al. (1999). Althoughaerobic sporulating bacteria (bacilli) are very oftenactive between 60 and 65 1C, temperatures cannotexceed 75 1C, which would irreversibly denature thebacterial enzymes (De Bertoldi et al., 1985; Tuomelaet al., 2000).The intense microbial activity induced very significant

transformations of the mixture of sewage sludge andgreen waste, the main characteristics of which are

presented in Table 4. After 135 days, decomposition ofthe mixture reached 60% and the C/N ratio 12. Theslight acidification of the mixture after the first 15 dayswas the combined result of the production of organicacids during composting and the production of CO2during the aerobic decomposition of organic matter.Then the pH stabilised at 6.1–6.2 following thegeneration of ammonia (Bernal et al., 1996; Zorpaset al., 2000) and/or the buffer action of the HS producedduring the process (Hafidi et al., 2005).The changes in the proportions of fibre during

composting are reported in Table 5. After 135 daysbiodegradation reached 61%, 70% and 37%, respec-tively for cellulose, hemicellulose and lignin. This is

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Table 6

Humic and fulvic acid levels and humification indexes during sewage sludge green waste composting

Stage Humic acids (g kg�1 dry matter) Fulvic acids (g kg�1 dry matter) HR HI PH DP

T0 26.571.5 38.271.0 18.1 7.4 40.9 0.69

T15 d 30.071.4 22.271.5 14.8 8.5 57.6 1.36

T60 d 39.770.5 11.472.4 16.5 12.9 77.8 3.49

T135 d 39.570.3 17.871.3 27.9 19.2 68.9 2.21

All values are reported as mean7standard deviation between four replicates.HR (humification ratio) ¼ EX/TC� 100; HI (humification index) ¼ HA/TC� 100; PH (percentage humic acids) ¼ HA/EX� 100; DP (degree of

polymerisation) ¼ HA/FA� 100.

Table 7

Evolution of lettuce and turnip germination index in the water extract

of sewage sludge and green waste composted for different durations

Stage Germination index (%)

Lettuce Turnip

T0 10.170.1 12.270.5T15 d 17.070.9 20.272.1T60 d 36.673.0 48.272.3T90 d 64.274.3 72.172.0T135 d 98.572.1 98.570.7

All values are reported as mean7standard deviation between five

replicates.

explained by microorganisms making rapid use of thecarbohydrate oligomers released during the degradationof cellulose as a source of energy (Sanchez-Monedero etal., 1999). Lignins resist biodegradation and onlyundergo partial biotransformation (Lynch, 1993; Tuo-mela et al., 2000). Hemicellulose is the component whichunderwent the most extensive degradation. According toEiland et al. (2001), xylans and other hemicellulosecomponents tend to be degraded more easily thancellulose components or lignin. Nevertheless, the lowrates of cellulose and hemicellulose decomposition,observed at the beginning of the composting process(T60) can be due to inhibition of the activity of themicroorganisms involved by high temperatures, whichlargely exceeded the threshold of 57 1C (Godden andPenninckx, 1984), and/or by the high ammoniumcontent of the initial mixture (Ko et al., 1974;Sanchez-Monedero et al., 1999).The nitrate increase, linked to nitrification during

composting, resulted in NH4+/NO3

� ratio o1 at the endof the process (Table 4), suggesting that the finalcompost had reached maturity (Garcia et al., 1992).Likewise, the drop in C/N ratio from 30 at T0 to 12 atT135 supports this hypothesis (Dorfmann and Batsch,1985; Bernal et al., 1996; Amir and Hafidi, 2001; AitBaddi et al., 2004a). The germination index of lettuceand turnip exceeded 50% at 90 days and reached 98%after 135 days of composting, revealing loss ofphytotoxicity and achievement of compost maturity(Table 7).

3.2. Humification during the composting

At T0, there was 26.5mg HAg�1 compost and38mgFAg�1 compost, while at T135, these levels wererespectively 39.5 and 17.8, (Table 6). According toTuomela et al. (2000), this profile clearly shows theevolution of the compost from immaturity towardsmaturation. This was assessed from the humificationratio (HR or HS/TOC) of nearly 28%; from thepercentage of HA (PH or HA/HS) being 69% and fromthe humification index (HI or HA/TOC) of 19% after135 days (Table 7). The degree of polymerisation (DP orHA/FA) underwent a very significant increase from 0.69

to 2.2. This ratio appears to be the most sensitive way tomonitor the humification process and has been proposedby numerous authors as an index of maturity, e.g.Sanchez-Monedero et al. (1999) and Tomati et al.(2000). The increase in this ratio is explained either bythe formation of complex molecules (HA) as a result ofpolymerisation of simple molecules (FA); or by thebiodegradation of non-humic or easily decomposablecomponents of the FA fraction, followed by theformation of more polycondensed humic structures.

3.3. Infrared spectra (FTIR)

The infrared spectra of the compost at the differentphases of treatment (Fig. 2) show similar areas ofabsorbance, the differences lying in the intensity ofcertain bands. The interpretation of the spectra is basedon numerous works, notably Schnitzer (1972), Gerasi-mowisz and Byler (1985), Hernandez et al. (1990), Inbaret al. (1991), Ouatmane et al. (2000), Ait Baddi et al.(2004b), Amir et al. (2005). The main absorbance bandsare now considered. There is a very large band locatedbetween 3700 and 2800 cm�1 centred around 3400 cm�1,

which is due to hydrogen vibrations of the OH groups ofalcohols, phenols or carboxylic acids, as well as to amidehydrogen vibrations. The peak at 2922 cm�1 is due toCH vibrations of aliphatic groups. The band centred on1650 cm�1 is due to COO� and CQO of amides,ketones and/or quinones. The absorbance around

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4000 3500 3000 2500 2000 1500 1000 500

cm-1

-340

0.1

-282

7.0

-165

1.6

-142

8.2

1036

.1

-873

.8-8

74.8

1040

.1

-142

8.1

-165

1.5

-285

6.3

-292

4.7

-342

3.9

-342

6.4

-252

6.4

-155

3.1

-153

3.3

-143

0.2

-124

4.4

1032

.1

-874

.0-8

74.0

1035

.0

-122

6.0

-142

0.1

-154

0.0

-164

6.0

-285

3.5

-342

6.5

-292

6.9

T0 d

T15 d

T60 d

T135 d

Fig. 2. Infrared spectra showing the evolution of a sewage sludge and green waste mix compost.

106

1540 cm�1 is characteristic of secondary amides. Theband at 1420–1430 cm�1 is caused by the absorbance ofseveral aliphatic structures, phenolic OH groups, COO�

groups, stretch vibrations of aromatic rings andcarbonates. The band at 1230–1240 cm�1 is generallylinked to the absorbance of ethers and aromatic esters

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and to the N–H of amides. In the area 1200–900 cm�1

there is absorption by silicates, and around1180–1050 cm�1 by polysaccharides. The ether andaromatic ester band is at about 1034 cm�1. The bandat 874 cm�1 is linked to the presence of calcite.During composting, a drop occurred in the abun-

dance of structures absorbing at around 2926, 1650,1100 cm�1 and a rise in the abundance of structureswhich absorb at around 1420 cm�1 and 1034 cm�1. Thiscan be explained by the microbes using aliphatic andpeptide structures and carbohydrates such as polysac-charides, cellulose and hemicellulose to meet theirenergy needs. In parallel, there was an increase in therelative intensity of the aromatic polycondensed struc-tures, which are mainly aromatic ethers–esters. Theintensity of these structures is linked both to aconcentration effect, following the disappearance ofthe components most easily degraded, and to theincrease of oxidised lignin derivatives that are involvedin the humification process.

4. Conclusion

The trial industrial-scale composting of sewage sludgewith green (fresh plant) waste, under an arid climate,reached maturity after 135 days. The two classic phasesof composting resulting from microbiological activitywere identified as biodegradation followed by matura-tion. Various indices showed the maturity of the finalproduct, including the NH4

+/NO3� ratio of 0.2, the C/N

ratio of 12, a germination index of 98%, as well as thehumification indices. Indeed, spectroscopic analysisFTIR revealed the biodegradation of components thatcan be easily assimilated by microorganisms, such ascertain aliphatic and peptide structures, and carbohy-drates including celluloses and hemicelluloses. A de-crease in the degree of aliphaticity and an increase inaromaticity occurred. The direct measurement of theratio of aliphatics to aromatics would make a rapid andreliable index of compost maturity rather than thecommonly used ratio HA/FA, which involves tediousextraction steps.

Acknowledgements

The authors thank P. Winterton (UPS Toulouse-Fr),for his help with the English language in writingthis paper. The authors also thank Dr. A. Chraay(Laboratory of Fodder CRPA-INRA, Settat, Morocco)and Dr. M. Faid (Food Microbiology and Biotech-nology Department, Hassan II Institute of Agronomyand Veterinary Medicine, Rabat-Instituts, Morocco)for their assistance in providing their material foranalyses.

References

ADEME, 1994. La collecte et le traitement des dechets, Guide pratique

pour les elus de Midi—Pyrenees.

Ait Baddi, G., Alburquerque, J.A., Gonzalvez, J., Cegarra, J., Hafidi,

M., 2004a. Chemical and spectroscopic analyses of organic matter

transformations during composting of olive mill wastes. Interna-

tional Biodeterioration and Biodegradation 54, 39–44.

Ait Baddi, G., Hafidi, M., Cegarra, J., Alburquerque, J.A., Gonzalvez,

J., Gilard, V., Revel, J.-C., 2004b. Characterization of fulvic acids

by elemental and spectroscopic (FTIR and 13C-NMR) analyses

during composting of olive mill wastes plus straw. Bioresource

Technology 93, 217–323.

Amir, S., Hafidi, M., 2001. Valorisation de boues de stations

d’epuration des eaux usees par un bioprocede aerobie ‘‘compo-

stage’’. Annale de Chimie-Sciences des Materiaux 26, S409–S414.

Amir, S., Hafidi, M., Bailly, J.-R., Revel, J.-C., 2003. Characterization

of humic acids extracted from sewage sludge during composting

and of their Sephadex gel fractions. Agronomie 23, 269–275.

Amir, S., Hafidi, M., Merlina, G., Hamdi, H., Revel, J.C., 2004.

Elemental analysis, FTIR, 13C-NMR of HA from sewage sludge

composting. Agronomie 24, 13–18.

Amir, S., Hafidi, M., Merlina, G., Revel, J.-C., 2005. Structural

characterization of fulvic acids during composting of sewage

sludge. Process Biochemistry 40, 1693–1700.

Bernal, M.P., Navarro, A.F., Roig, A., Cegarra, J., Garcia, D., 1996.

Carbon and nitrogen transformation during composting of sweet

sorghum bagasse. Biology and Fertility of Soils 22, 141–148.

De Bertoldi, M., Citerneci, U., Greselli, M., 1979. Microbiological

studies on sludge processing. In: Alexandre, D., Ott, H. (Eds.),

Treatment and Use of Sewage Sludge, Proceedings of C.E.C. First

European Symposium. C.E.C., Brussels, Belgium, p. 77.

De Bertoldi, M., Frassinetti, S., Bianchin, L., Pera, A., 1985. Sludge

hygienization with different compost systems. In: Strauch, D.,

Havelaaar, A.H., L’Hermite, P. (Eds.), Inactivation of Micro-

organisms in Sewage Sludge by Stabilisation Processes. Elsevier

Applied Sciences Publishers, London, pp. 64–76.

Deportes, I., Benoit, J.L., Zmirou, D., 1995. Hazard to man and the

environment posed by the use of urban waste compost: a review.

Science of the Total Environment 172, 197–222.

Diaz-Burgos, M.A., Polo, A., Calcinai, M., Masciandaro, G.,

Ceccanti, B., 1994. Use of pyrolysis-gas chromatography to

evaluate sludge humification. In: Senesi, N., Miano, T.M. (Eds.),

Humic Substances in the Global Environment and Implications on

Human Health. Elsevier, Amsterdam, pp. 1285–1289.

Dorfmann, R., Batsch, G., 1985. Les residus urbains: traitement et

valorisation. Technique et Documentation, Paris, 437pp.

Dudka, S., Muller, W.P., 1999. Accumulation of potentially toxic

elements in plants and their transfer to human food chain. Journal

of Environmental Science and Health B 34, 681–708.

Dumontet, S., Dinel, H., Baloda, S.B., 1999. Pathogen reduction in

sewage sludge by composting and other biological treatment: a

review. Biological Agriculture and Horticulture 16, 409–430.

Echab, A., Nejmeddine, A., Hafidi, M., Kaemmerer, M., Revel, J.-C.,

1998. Evolution de la fraction echangeable des metaux lourds

(Pb, Cu, Zn et Cd) lors du compostage des boues. Agrochimica 33,

310–318.

Eiland, F., Leith, M., Klamer, M., Lind, A.M., Jensen, H.E.K.,

Iversen, J.J.L., 2001. C, N turnover and lignin-cellulose degrada-

tion during composting ofMiscanthus straw and liquid pig manure.

Compost Science and Utilization 9, 186–196.

Ezelin De Souza, K., 1998. Contribution a la valorisation de la bagasse

par transformation biologique et chimique. Valeur agronomique des

composts et proprietes suppressives vis-a-vis du champignon phyto-

pathogene Fusarium solanum. Doctoral thesis, Institut National

Polytechnique de Toulouse, 386pp.

ARTICLE IN PRESS108

Finstein, M.S., Morris, M.L., 1975. Microbiology of municipal solid

waste composting. Advances in Applied Microbiology 19, 113–151.

Garcia, C., Hernandez, T., Costa, F., 1992. Characterization of humic

acids from uncomposted and composted sewage sludge by

degradative and non-degradative techniques. Bioresource Technol-

ogy 41, 53–57.

Gerasimowisz, W.V., Byler, D.M., 1985. Carbon-13 CPMAS NMR

and FTIR spectroscopic studies of humic acids. Soil Science 139,

270–278.

Godden, B., Penninckx, M.J., 1984. Biochemistry of manure

composting lignin biotransformation and humification. Annale de

Microbiologie (Institut Pasteur) 135B, 69–78.

Hafidi, M., Amir, S., Revel, J.C., 2005. Structural characterization of

olive mill wastewater after aerobic digestion using elemental

analysis, FTIR and 13C-NMR. Process Biochemistry 40,

2615–2622.

Hernandez, M.T., Moreno, J.I., Costa, F., Gonzalez-Vila, F.J., Frund,

R., 1990. Structural features of humic acid-like substances from

sewage sludge. Soil Science 149, 63–68.

Inbar, Y., Chen, Y., Hadar, Y., 1991. Carbon-13 CPMAS NMR and

FTIR spectroscopic analysis of organic matter transformations

during composting of solid wastes from wineries. Soil Science 152,

272–281.

Kastner, M., Mahro, B., 1996. Microbial degradation of polycyclic

aromatic hydrocarbons in soil affected by the organic matrix of

compost. Applied Microbiology and Biotechnology 44, 668–675.

Ko, W.H., Hora, F.K., Herlicksa, E., 1974. Isolation and identification

of a volatile fungistatic substance from alkaline soil. Phytopathol-

ogy 64, 1398–1400.

Lau, K.L., Tsang, Y.Y., Chiu, S.W., 2003. Use of spent mushroom

compost to bioremediate PAH-contaminated samples. Chemo-

sphere 52, 1539–1546.

Lavoie, J., Marchand, G., 1997. Determination des caracteristiques a

considerer d’un point de vue de sante et de securite des travailleurs

dans les centres de compostage des dechets domestiques. Etudes et

Recherches : Rapport R-159. Institut de Recherche en Sante et en

Securite du Travail du Quebec, 37pp.

Lichtfouse, E., Chenu, C., Baudin, F., Leblond, C., Da Silva, M.,

Behar, F., Derenne, S., Largeau, C., Wehrung, P., Albrecht, P.,

1998. A novel pathway of soil organic matter formation by

selective preservation of resistant straight-chain biopolymers:

chemical and isotope evidence. Organic Geochemistry 28, 411–415.

Lynch, J.M., 1993. Substrate availability in the production of

composts. In: Hoitink, H.A.J., Keener, H.M. (Eds.), Science and

Engineering of Composting: Design, Environmental, Microbiolo-

gical and Utilization Aspects. Renaissance Publications, OH, pp.

24–35.

Mathur, S.P., Dowen, G., Dinel, H., Shnitzer, M., 1993. Determina-

tion of compost biomaturity. A literature review. Biological

Agriculture and Horticulture 10, 65–85.

Mustin, M., 1987. Le composte, gestion de la matiere organique.

Edition Franc-ais Dubus, Paris.

Nelson, D.W., Sommers, L.E., 1982. Total carbon, organic carbon and

organic matter. In: Page, A.L. (Ed.), Methods of Soil Analysis,

Part 2, Agronomical, second ed. Monograph 9 ASA at SSSA,

Madison, WI, pp. 539–579.

Nuntagij, A., De Lassus, C., Saya, G.D., Andre, L., 1989. Aerobic

nitrogen fixation during biodegradation of lignocellulosic wastes.

Journal of Biological Wastes 29, 3–61.

Ouatmane, A., Provenzano, M.R., Hafidi, M., Senesi, N., 2000.

Compost maturity assessment using calorimetry, spectroscopy and

chemical analysis. Compost Science and Utilisation 8, 135–146.

Paredes, C., Bernal, M.P., Cegarra, J., Roig, A., Navarro, A.F., 1996.

Nitrogen transformation during the composting of different organic

wastes. In: Van Cleemput, O., Hofman, G., Vermoesen, A.

(Eds.), Progress in Nitrogen Cycling Studies. Kluwer, Dordrecht,

pp. 121–125.

Pascual, J.A., Ayuso, M., Garcia, C., Hernandez, T., 1997. Char-

acterization of urban wastes according to fertility and phytotoxicity

parameters. Waste Management and Research 15, 103–112.

Sanchez-Monedero, M.A., Roig, A., Cegerra, J., Bernal, M.P., 1999.

Relationships between water soluble carbohydrate and phenol

fractions and the humification indices of different organic wastes

during composting. Bioresource Technology 70, 193–201.

Schnitzer, M., 1972. Chemical, spectroscopic and thermal methods

for the classification and characterization of humic substances.

In: Povoledo, D., Golterman, H.L. (Eds.), Humic Substances,

their Structure and Function in the Biosphere. Proceedings of

an International Meeting at Nieuwersluis. Wageningen, Pudoc,

pp. 293–310.

Tomati, U., Galli, E., 1995. Bioremediation of olive waste waters by

composting. Waste Management and Research 13, 509–518.

Tomati, U., Madejon, E., Galli, E., 2000. Evaluation of humic acid

molecular weight as an index of compost stability. Compost

Science and Utilization 8, 108–115.

Tuomela, M., Vikman, M., Hatakka, A., Itavaara, M., 2000.

Biodegradation of lignin in a compost environment: a review.

Bioresource Technology 72, 169–183.

Van Soest, P.J., 1963. Use of detergents in the analysis of fibrous feeds.

II. A rapid method for the determination of fiber and lignin.

Journal of the Association of Official Agricultural Chemists 46,

829–835.

Zorpas, A.A., Constantinides, T., Vlyssides, A.G., Haralambous, I.,

Loizidou, M., 2000. Heavy metal uptake by natural zeolite and

metal partitioning in sewage sludge compost. Bioresource Technol-

ogy 72, 113–119.

Zucconi, F., Monaco, A., Forte, M., De Bertoldi, M., 1985.

Phytotoxins during the stabilization of organic matter. In: Gasser,

J.K.R. (Ed.), Composting of Agricultural and Other Wastes.

Elsevier Applied Science Barking, Essex, UK, pp. 73–85.

Further reading

Garcia, C., Moreno, J.L., Hernandez, T., Costa, F., Polo, A., 1995.

Effect of composting on sewage sludges contaminated with heavy

metals. Bioresource Technology 53, 13–19.