Sewage Sludge Compost Research Articles

Long-term field fertilization experiment with energy willow (Salix sp.) − Elemental composition and chlorophyll fluorescence in the leaves

A small-plot long-term field fertilization experiment was set up in 2011 with willow (Salix triandra x Salix viminalis ’Inger’) grown as an energy crop in Nyíregyháza, Hungary. The brown forest soil was treated three times (in June 2011, May 2013, May 2016) with municipal biocompost (MBC), municipal sewage sludge compost (MSSC) or willow ash (WA), and twice (June 2011, May 2013) with rhyolite tuff (RT). In late May – early June 2016 urea (U) and sulphuric urea (SU) fertilizers were also applied to the soil as top-dressing (TD). These fertilizers and amendments were also applied to the soil in 2016 in the combinations; MBC+SU, RT+SU, WA+SU and MSSC+WA. All the treatments were repeated four times. In July 2016 the highest nitrogen concentrations in willow leaves were measured in the U (3.47 m/m%) and SU (3.01 m/m%) treatments, and these values were significantly higher than the control (2.46 m/m%). An excess of nitrogen considerably reduced the Zn uptake of the leaves, with values of 39.5 μg g-1 in the U treatment, 53.4 μg g-1 in the SU treatment, and 63.5 μg g-1 in the control. All other amendments or TDs, except for WA, enhanced the specific potassium concentrations in willow leaves compared to the control. No significant quantities of toxic elements (As, Ba, Cd, Pb) were transported from soil amendments or TDs to the willow leaves. In July 2016 the most intensive leaf chlorophyll fluorescence was observed in the MSSC and MSSC+WA treatments.

Impact of fertilization on the mineral nutrition and yield of Salix triandra x Salix viminalis and Robinia pseudoacacia L. bioenergy crops

Willow was cultivated as an energy crop in a field experiment. The brown forest soil was treated with an inorganic fertilizer (ammonium nitrate−AN: 100 kg ha-1) or with various organic or mineral soil amendments (municipal biocompost–MBC: 20 t ha−1; municipal sewage sludge compost–MSSC: 15 t ha−1; rhyolite tuff–RT: 30 t ha−1; willow ash−WA: 600 kg ha−1), or their combinations (AN+MBC; AN+RT; AN+WA, MSSC+WA) in four replications. Nineteen months after the soil treatments the macroelement-rich amendments (MBC, MSSC) enhanced the harvested fresh shoot yield most significantly (up to 41% as compared to the untreated control), and also the shoot diameter and shoot height of the willow plants. Most of the treatments enhanced the uptake of N (9.8-23.5%) and K in willow leaves, but the concentrations of P, Mg, Ca, Fe and Zn in the leaves were reduced. The toxic element (As, Cd, Pb) accumulation of willow shoots was negligible. In a 4-year field experiment the effects of the mineral fertilizers AN and AN+calcium-magnesium carbonate (CMC) were studied on the mineral nutrition of the leaves and wood yield of black locust trees cultivated as an energy crop. The brown forest soil was treated with 300 kg ha−1 annual doses of these fertilizers as top-dressing in June 2009, May 2010 and May 2011. Both fertilizers caused a three to four times increase in the nitrate content of the upper soil soon after their application in June. By the end of the vegetation period (in December) the nitrate concentration in the soil was similar to that in the control plots. The nitrogen content of the leaf stalks (petioles) and leaves, however, was only slightly higher in the treated plots. As a trend, fertilization increased the phosphorus and reduced the calcium uptake in the leaf stalks and leaves, while the magnesium content was not influenced. In March 2012, when the whole trees were harvested, 22% or 28% higher aboveground fresh shoot weight was detected in the AN or AN+CMC treatments than in the control.

Study of Total Bacteria and Ammonia-Oxidizing Bacteria and Ammonia-Oxidizing Archaea in Response to Irrigation with Sewage Sludge Compost Tea in Agricultural Soil

ABSTRACTOrganic amendments have been shown to improve the quality of agricultural soils. Thus, the use of sewage sludge compost tea as a fertilizer can be considered a worthy and environmentally friendly alternative as it also offers the option of recycling sludge at the same time. However, an in-depth knowledge of how the addition of this product affects soil microbial diversity is still necessary. As such, the main objective of this study was to evaluate, at a microcosm level, the effects of irrigation with sewage sludge compost tea in an olive grove soil, focusing on the changes in the total bacteria, ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA). For this purpose plastic pots were filled with olive grove soil, watered with different amounts of water and/or compost tea, and incubated at 21 and 35°C for a period of 90 days. Denaturing gradient gel electrophoresis (DGGE) fingerprinting, real-time PCR, and 454-pyrosequencing analysis were performed. Our results suggested that the addition of sewage sludge compost tea (liquid fertilizer) slightly increased the soil biological diversity during the incubation time which suggests that sewage sludge compost tea did not have any negative effects in the soil microbiota. Accordingly and regardless of the incubation temperature, significant changes in the soil community structure were not observed throughout the experiment, suggesting that the treated soils maintained their microbiological stability.

Visualization of Long-Term Quantitative Changes of Microelements in Soils Amended with Sewage Sludge Compost Evaluated with Two Extraction Solutions

ABSTRACTThis research deals with the effects of soil amendment with sewage sludge compost (SSC) on long–term quantitative changes of available microelements [iron (Fe), zinc (Zn), manganese (Mn), copper (Cu)] in two types of soils using various extraction solutions [diethylenetriaminepentaacetic acid (DTPA) and hydrochloric acid (HCl)]. These changes were visualized using principal component analysis (PCA) and hierarchical cluster analysis. A 3-year pot experiment was conducted in a randomized, factorial design with two soils (light vs. medium) and a treatment with SSC at the rate of 6 Mg ha−1. The application of SSC to the light soil increased the HCl-extractable Cu, Zn, Mn, and Fe. The effect of SSC application on the microelement quantitative changes was lower in the medium soil, as shown primarily by DTPA extraction. The results of the PCA highlighted that one can correctly conclude on the basis of the limited collection of data without loss of information, which is incorporated by individual microelements.

The Influence of Humification Degree of Humic Acid on Its Sorption of Norfloxacin During Sewage Sludge Composting

Norfloxacin (NOR), an antibiotic widely used in livestock and poultry production, has become ubiquitous in the aquatic and terrestrial ecosystems as a result of veterinary excretion of the parent compound or its active metabolites. The sorption of NOR onto humic acid (HA) may influence the fate of NOR in the environment. In the present study, HA was extracted from sewage sludge in different composting stages of days 0, 10, 30, and 70 to investigate the sorption of NOR onto HA as affected by the humification degree of HA. The results of elemental and Fourier transform infrared (FTIR) spectrum analyses showed that the contents of aromatic and carboxylic groups in HA increased with composting time, indicating an increase of humification degree. The result of sorption experiments demonstrated that the HA had a high sorption capacity for NOR with strong nonlinearity. A two-stage sorption was observed in the sorption process with an equilibration time of 48 h. Both the Freundlich model (Adj. R2 range 0.988–0.994) and Langmuir model (Adj. R 2 range 0.917–0.928) fitted well with all sorption isotherms of the HA samples of different humification degrees. Moreover, the increase of sorption distribution coefficient (K d ) value with composting time indicated that the sorption affinity of HA for NOR increased with increasing humification degree of HA. The major sorption mechanism was the interaction between NOR and rich aromatic moieties and carboxylic group in the HA.

Biodegradation of nonylphenol during aerobic composting of sewage sludge under two intermittent aeration treatments in a full-scale plant

The urbanization and industrialization of cities around the coastal region of the Bohai Sea have produced large amounts of sewage sludge from sewage treatment plants. Research on the biodegradation of nonylphenol (NP) and the influencing factors of such biodegradation during sewage sludge composting is important to control pollution caused by land application of sewage sludge. The present study investigated the effect of aeration on NP biodegradation and the microbe community during aerobic composting under two intermittent aeration treatments in a full-scale plant of sewage sludge, sawdust, and returned compost at a ratio of 6:3:1. The results showed that 65% of NP was biodegraded and that Bacillus was the dominant bacterial species in the mesophilic phase. The amount of NP biodegraded in the mesophilic phase was 68.3%, which accounted for 64.6% of the total amount of biodegraded NP. The amount of NP biodegraded under high-volume aeration was 19.6% higher than that under low-volume aeration. Bacillus was dominant for 60.9% of the composting period under high-volume aeration, compared to 22.7% dominance under low-volume aeration. In the thermophilic phase, high-volume aeration promoted the biodegradation of NP and Bacillus remained the dominant bacterial species. In the cooling and stable phases, the contents of NP underwent insignificant change while different dominant bacteria were observed in the two treatments. NP was mostly biodegraded by Bacillus, and the rate of biodegradation was significantly correlated with the abundance of Bacillus (r = 0.63, p < 0.05). Under aeration, Bacillus remained the dominant bacteria, especially in the thermal phase; this phenomenon possibly increased the biodegradation efficiency of NP. High-volume aeration accelerated the activity and prolonged the survival of Bacillus. The risk of organic pollution could be decreased prior to sewage sludge reuse in soil by adjusting the ventilation strategies of aerobic compost measurements.

Influence of different sewage sludges and composts on growth, yield, and trace elements accumulation in rice and wheat

AbstractThe use of sewage sludge (SS) and solid waste composts in agriculture is considered as one of the best disposal options. In this study, impact of different composts and SS was evaluated on the soil quality, growth, and yield performance of rice and wheat crops. Four types of composts and SS were collected from different sources and applied in soil at 0.5% (5 g kg−1 soil) and 1.0% (10 g kg−1 soil) in comparison with chemical fertilizer (no SS/compost). The application of all types of composts at all the tested rates increased the straw and grain yields of both the crops compared with control. Nevertheless, application of Lahore compost and all SS (1.0%) resulted in a significant increase in the concentration of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in plant parts. The Cd concentration in rice grains with Lahore compost and Kasur SS applied at the rate of 1.0% was above the safe limit. The trace elements in wheat grains with all composts and SS at all the tested rates remained within safe limits. The release of amendment bound trace elements in soil solution was highly dependent upon dissolved organic carbon and concentration of these trace elements especially for Cu and Zn. Application of SS at low level (0.5%) and compost (except Lahore compost) at both levels could be a better strategy to exploit their benefits in terms of crop performance and soil quality. However, application of SS and compost at high rates may lead to accumulation of trace elements in rice grains limiting its suitability for human consumption.

Fractionation, Bioaccessibility, and Risk Assessment of Heavy Metals in the Soil of an Urban Recreational Area Amended with Composted Sewage Sludge.

A composted sewage sludge (CSS) was added to the soil of an urban garden at 5%, 10%, and 25% (w/w soil) and stabilised for 180 days. Samples were then collected and analysed for total heavy metal concentrations, chemical fractions, and bioaccessibility, together with some physicochemical properties. The results showed that the total chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) concentrations were increased with CSS addition rate. The CSS addition decreased the residual fractions of these four elements. The exchangeable Cr, Cu, and Pb fractions were very small or not detected, while Zn exhibited an increasing trend in its exchangeable fraction with CSS addition rate. The bioaccessibility of these four elements was increased with the CSS addition rate. Moreover, the Cr, Cu, and Zn bioaccessibility correlated positively with the total concentration, while the bioaccessibility of these four elements exhibited a negative correlation with the residual fraction. The fractionation and bioaccessibility of heavy metals may have also been influenced by pH, cation exchange capacity, and organic matter. The risk assessment code reflected the amended soil showed no or low environmental risks for Cr, Cu, and Pb and a medium risk for Zn. The hazardous index values and cancer risk levels indicated that the heavy metals in the soil amended with 25% CSS posed negligible potential noncarcinogenic and carcinogenic risks to children and adults via incidental ingestion.

Alleviation of heavy metal phytotoxicity in sewage sludge by vermicomposting with additive urban plant litter

The handling of sewage sludge (SS) and urban plant litter (UPL) has become an important concern. Immobilizing heavy metals (HMs) is regarded as a necessary process for recycling SS in agriculture and forestry. Here, HM removal and HM phytotoxicity in SS during vermicomposting with different additive UPLs was investigated. The results show that vermicomposting with additive UPL significantly reduced the content of HMs, and increased organic carbon content and the proportion of macroaggregates in SS. This process also significantly immobilized HMs by mainly transforming extractable and reducible HMs into residual products. The litters of Dracontomelon duperreanum and Bauhinia purpurea increased oxidizable HMs in SS and the accumulation capacity of HMs of earthworms during vermicomposting. The Cd content in vermicomposts with the B. purpurea litter addition was decreased by 31% relative to the initial SS. Maize in vermicomposts with UPL additions, especially with B. purpurea litter, exhibited significan5tly higher seed germination rates, seedling biomass, root activity, and a lower accumulation of HMs than in SS compost without UPL additions. These results suggest that vermicomposting with additive UPL can alleviate the phytotoxicity of HMs in SS and provides a new method for simultaneously recycling SS and UPL.

Effects of Medium-Term Amendment with Diversely Processed Sewage Sludge on Soil Humification-Mineralization Processes and on Cu, Pb, Ni, and Zn Bioavailability.

The organic fraction of sewage sludge administered to agricultural soil can contribute to slowing down the loss of soil’s organic carbon and, in some cases, can improve the physical and mechanical properties of the soil. One of the main constraints to the agricultural use of sewage sludge is its heavy metals content. In the long term, agricultural administration of sewage sludge to soil could enhance the concentration of soil heavy metals (as total and bioavailable fractions). The aim of this research was to evaluate the effects of medium-term fertilization with diversely processed sewage sludge on the soil’s organic carbon content and humification–mineralization processes, on the physical–mechanical properties of soil and their influence on the pool of potentially bioavailable heavy metals, in order to assess their effectiveness as soil organic amendments. After eight years of sludge administration; an increase in the concentrations of bioavailable form was evidenced in all the heavy metals analyzed; independently of the type of sludge administered. The form of sludge administration (liquid, dehydrated, composted) has differently influenced the soil humification–mineralization processes and the physical–mechanical properties of soil. The prolonged amendment with composted sewage sludge contributed to keeping the soil humification–mineralization process in equilibrium and to improving the physical and mechanical qualities of the treated soil.

Leaching characteristic of toxic trace elements in soils amended by sewage sludge compost: A comparison of field and laboratory investigations

A 3-years field test and laboratory leaching test have been conducted to assess the environmental impact of land application of sewage sludge compost in conjunction with wheat and rice crops. Considering the complexity and variability of field conditions, we compared the result of laboratory test with the field test to understand the accuracy and uncertainty associated with using the laboratory test to evaluate the field scenario. The laboratory test with cycling of compost additions and water percolation was a high time-efficient and feasible method to simulate the annually repeated additions of compost in the field application scenario. The results of laboratory test were congruent to the 3-years field test regarding the leaching characteristics and geochemical speciation of toxic trace elements. Both the laboratory and the field test showed that repeated additions of compost to soils can increase leaching concentrations of toxic trace elements at neutral to alkaline pH. Increased toxic trace elements leaching was caused by the increase of organic matter from compost application and organic matter dissolution at alkaline pH. Uncertainties of the laboratory test mainly included the negligibility of crop growth and the strongly reducing condition formed with continuous percolation procedure.

Composting of Sewage Sludge with a Simple Aeration Method and its Utilization as a Soil Fertilizer.

The objective of this study was to examine the feasibility of sewage sludge composting using a simple aeration method. Two consecutive composting trials (run A and run B) using Japanese sludge and woodchips (1:1, v/v) were conducted in cubic boxes (0.45 × 0.45 × 0.45 m3) made by plywood at Okayama University. Air was forced up through small holes perforated on two open-ended parallel PVC pipes (ø 16 mm, 0.25 m apart) laid at the base. The results show that compost temperatures were rapidly increased to the peak points of 47.4 °C (run A) and 74.8 °C (run B) within the first 2-3 days and varied depending on each composting run and vertical locations. The changes in physicochemical properties with particular attention to inorganic nitrogen (NH4-N, NO3-N) and free amino acid nitrogen (FAA-N) indicated that the biodegradation took place by different mineralization pathways during the composting process. The degradation of organic matter into amino acids followed by ammonification was predominant in run B, whereas the nitrification was greater in run A. A pot experiment using the two finished composts and their raw materials was carried out to study their effectiveness as fertilizer to Komatsuna (Brassica rapa var. perviridis). The total plant biomass produced by the composts was similar to chemical fertilizer. The lowering proportions of FAA-N/T-N, NH4-N/NO3-N, and C/N ratios in the composts compared to those in raw materials was found to correlate with the increase in plant biomass.

Composting of sewage sludge with solid fraction of digested pulp from agricultural biogas plant

Sewage sludge management is an important element of environmental protection. Composting and anaerobic digestion are the biological conversion methods for sewage sludge management. Mass and volume reduction is a result of a properly composted process. Solid fraction of digested pulp can be use as co-substrate, because it is good structural material. The aim of the study was to determine the possibility of composting sewage sludge with a solid fraction of digestate. The compost mix consisted of 25 kilograms of sewage sludge and 20 kilograms solid fraction of digestate in fresh mass. The experiment was carried out in laboratory conditions. Bioreactors of 165 dm3 volume were used. The experiment included two stages. Stage I took place in bioreactors and lasted until the cooling phase of the compost was complete. Stage II included compost maturation for a period of eight months (to 287 day of composting). The reduction of mass obtained at the end of Stage I amounted 30.2%. At the end of Stage II, it was 86.7% relative to the initial weight of the compost. The maximum value of temperature was 75.1°C. Studies have shown that sludge with a solid fraction of digestate can be a suitable substrate for composting with sewage sludge.

Скрининг активных штаммов микроорганизмов для компостирования илового осадка сточных вод

Скрининг активных штаммов микроорганизмов для компостирования илового осадка сточных вод

CARACTERIZAÇÃO E POTENCIAL DE SUBSTRATOS FORMULADOS COM BIOSSÓLIDO NA PRODUÇÃO DE MUDAS DE &lt;i&gt;Schinus terebinthifolius&lt;/i&gt; Raddi. e &lt;i&gt;Handroanthus heptaphyllus&lt;/i&gt; (Vell.) Mattos

O lodo de esgoto devidamente compostado (biossólido) apresenta em sua composição quantidades significantes de matéria orgânica e nutrientes para o crescimento vegetal. Desta forma, sua utilização na composição de substratos para produção de mudas florestais passa a representar não apenas um benefício ambiental, mas também uma ótima escolha do ponto de vista técnico e econômico. O objetivo deste trabalho foi caracterizar química e fisicamente substratos à base de biossólido e substrato comercial e verificar o potencial destes para produção de mudas de Schinus terebinthifolius e Handroanthus heptaphyllus. Foram testadas diferentes proporções volumétricas de biossólido (BIO) misturadas ao substrato comercial (SC) para a produção das mudas em tubetes, consistindo nas seguintes formulações: T1 = 0% BIO + 100% SC; T2 = 25% de BIO + 75% SC; T3 = 50% de BIO + 50% SC; T4 = 100% de BIO + 0% SC. Aos 134 dias após a semeadura, foram avaliados os parâmetros morfológicos, altura da parte aérea (H) e diâmetro do coleto (D), matéria seca da parte aérea (MSPA) e da matéria seca das raízes (MSR), relação altura diâmetro (H/D), relação entre a matéria seca da parte aérea e da matéria seca das raízes (MSA/MSR), e o Índice de Qualidade de Dickson (IQD). Quanto maior a proporção de biossólido no substrato, maior foi o teor de nutrientes, principalmente N, P e K, e maior foi a capacidade de retenção de água. O biossólido apresentou elevado potencial para composição de substratos na produção de mudas das espécies estudadas. Para Schinus terebinthifolius os melhores resultados de crescimento foram observados nos tratamentos T3 e T4, já para Handroanthus heptaphyllus, no tratamento T3.

FUZZY MODELING ON WHEAT PRODUCTIVITY UNDER DIFFERENT DOSES OF SLUDGE AND SEWAGE EFFLUENT

This study aimed to evaluate the effects of fertilization with composted sewage sludge and irrigation with treated effluent in wheat crop using fuzzy rule-based system. The experiment was conducted in the Department of Soil and Environmental Resources, of FCA, UNESP - Botucatu, with factorial 6 × 2, which were applied 6 doses of sewage sludge (0, 50, 100 , 150, 200 and 250% of nitrogen recommendation) and two types of effluents (treated water and sewage). In the developing of the system based in fuzzy rules, it was used the Mandani inference method, where the input variables were sewage sludge doses and water types and the output variables used were the number of tillers, length and number spike per plant; number of spikelet per plant, grain mass per spike and dry mass of the aerial parts. It can be seen that the sewage sludge and the effluent contributed to the higher increase of production, and at 150% sludge dose occurred higher production.

The impact of sewage sludge and compost on winter triticale.

There is an increasing interest in the agricultural application of organic waste such as soil amendment, due to the possibility of recycling valuable components, organic matter, and nutrient elements necessary for plant growth. The present study was carried out to evaluate the effects of sewage sludge, and green waste compost application, on a forage crop, triticale "X Triticosecale Wittmack" compared to unfertilized control. The experimental design was installed in the glasshouse conditions at the Regional Field Crop Research Center in Beja, Tunisia. Sewage sludge and green waste compost were added by four rates (0, 5, 10, and 20t/ha) in soil, 15days before triticale sowing. The main results showed that plant response differs depending on the type of adding fertilizer. Indeed, compost inputs decreased shoot length and production of triticale, among all sewage sludge rates, by average values of 26 and 60% respectively at final harvest, as compared to unamended soil. However, amendment with different rates of sewage sludge significantly (p<0.05) increased different plant growth and yield attributes.

PCDD/F determination in sewage sludge composting. Influence of aeration and the presence of PCP

Composting of sewage sludge is a common practice for sludge disposal. Some previous studies found high levels of polychorodibenzo-p-dioxins and polychorodibenzofurans (PCDD/Fs) after composting, especially octachlorodibenzo-p-dioxin (OCDD) but also 1234678-heptachlorodibenzo-p-dioxin (1234678-HpCDD) to a lesser extent. In this work, the concentrations of OCDD, 1234678-HpCDD and the rest of the 17 toxic congeners of PCDD/Fs were determined in compost obtained under different conditions. Although the toxicity of the two compounds mentioned above is small, their generation may reach undesirable levels. The PCDD/F content was analyzed in a composting plant and in a laboratory test. In both cases, the composted material was a mixture of sewage sludge, straw and sawdust. The composting plant was a tunnel with air turbine aeration and with a turner to homogenize and move the mixture upwards. The laboratory tests were carried out with Dewar vessels (with air dispersion at the bottom and controlled temperature) and with small vessels inside a controlled oven with non-forced aeration. The laboratory runs were also carried out with the addition of pentachlorophenol in some runs, as a dioxin precursor. The highest OCDD levels were found in three samples of the composting plant (30000–90000pg/g dry matter or dm), with toxicity values surpassing the limit level for soil amendment (17pgI-TEQ/gdm). Their formation was analyzed considering their concentration vs. that of octachorodibenzofuran (OCDF), which is not formed during composting. In the laboratory, in experiments carried out in a vessel with non-forced aeration conditions and with the addition of pentachlorophenol, the formation of OCDD was significant (e.g. from 80 to 1500pg/gdm). That means that these two factors, non-forced aeration and the presence of pentachlorophenol, can cause the OCDD formation.

Municipal sewage sludge compost promotes Mangifera persiciforma tree growth with no risk of heavy metal contamination of soil

Application of sewage sludge compost (SSC) as a fertilizer on landscaping provides a potential way for the effective disposal of sludge. However, the response of landscape trees to SSC application and the impacts of heavy metals from SSC on soil are poorly understood. We conducted a pot experiment to investigate the effects of SSC addition on Mangifera persiciforma growth and quantified its uptake of heavy metals from SSC by setting five treatments with mass ratios of SSC to lateritic soil as 0%:100% (CK), 15%:85% (S15), 30%:70% (S30), 60%:40% (S60), and 100%:0% (S100). As expected, the fertility and heavy metal concentrations (Cu, Zn, Pb and Cd) in substrate significantly increased with SSC addition. The best performance in terms of plant height, ground diameter, biomass and N, P, K uptake were found in S30, implying a reasonable amount of SSC could benefit the growth of M. persiciforma. The concentrations of Cu, Pb and Cd in S30 were insignificantly different from CK after harvest, indicating that M. persiciforma reduced the risk of heavy metal contamination of soil arising from SSC application. This study suggests that a reasonable rate of SSC addition can enhance M. persiciforma growth without causing the contamination of landscaping soil by heavy metals.

Fate of sulfamethoxazole, its main metabolite N-ac-sulfamethoxazole and ciprofloxacin in agricultural soils amended or not by organic waste products

Spreading organic waste products (OWP) issued from sewage sludge or manures into soil may disseminate antibiotics with unknown risks for human health and environment. Our objectives were to compare the fate of two sulfonamides, sulfamethoxazole (SMX) and its metabolite N-acetyl-sulfamethoxazole (N-ac-SMX), and one fluoroquinolone, ciprofloxacin (CIP), in an unamended soil, and two soils regularly amended since 1998 with a sewage sludge and green waste compost and with farmyard manure respectively. Incubations of soil spiked with 14C labelled SMX or N-ac-SMX (0.02 mg kg−1) or CIP (0.15 mg kg−1) allowed a quantification of radiolabeled molecules in the mineralized, easily, hardly and non-extractable fractions after 3 and 156 days. Nature of 14C molecules was also analyzed by HPLC in extractable fractions after 3 and 156 days.SMX and N-ac-SMX dissipation was fast and due to i) mineralization (∼10% of recovered 14C after 156 days) or incomplete degradation (production of metabolites), ii) adsorption, even if both sulfonamides present low Kd (<3 L kg−1) and iii) formation of non-extractable residues (NER), representing more than 50% of recovered radioactivity.N-ac-SMX was more mineralized than SMX, and formed more progressively NER, after a step of deacetylation. Adsorption of CIP was fast and formed mainly NER (>72%) whereas its mineralization was negligible. Repeated applications of OWP tend to enhance adsorption of antibiotics and lower their degradation, through the quantity and quality of the built up soil organic matter. If applications of sewage sludge compost favor adsorption and inhibit mineralization, applications of manure boost the formation of non-extractable residues.