Comparison between pine bark and coconut husk sorption capacity of metals and nitrate when mixed with sewage sludge

Waste products such as biosolids and wood wastes have been frequently used in container production of plants. The use of biosolids in agriculture is a beneficial mean of recycling the by-products of waste-water treatment. However, care must be taken to avoid environmental or human health problems via run-off and leaching. The objective of this work is to compare the retention capacity of cadmium, lead, zinc and nitrate between pine bark (PB) and coconut fibre (F) when mixed with increasing amounts of composted sewage sludge (CSS) (0%, 15% and 30% (v/v)). Substrates were packed into leaching columns and irrigated with deionised water every 2 days. Leachates were collected during 1 month, and nitrate, Zn, Cd, Pb, EC and pH were monitored along the experiment. PB columns leached lower amount of nitrate than the coconut fibre ones. The same trend was observed for Zn, Cd and Pb. It could be said, that in order to minimize the environmental risks of using sewage sludges our results indicate that it is preferred to mix the sludge with pine bark instead than with coconut husk.     

Substitution of peat for municipal solid waste- and sewage sludge-based composts in nursery growing media: effects on growth and nutrition of the native shrub Pistacia lentiscus L

In this study, the effect of a partial substitution of peat for compost on the growth and nutrition of a native shrub (Pistacia lentiscus L.) was tested. Composts were prepared from pruning and municipal solid wastes or pruning waste and sewage sludge. For preparing growing media each compost was added at a rate of 40%, fresh pine bark at 20% or 40% and peat at 20%, 40% or 60%. Aqueous extracts from the substrates did not impair germination of cress (germination bioassay). In relation to plants growing in peat-based substrate (used as a control), plants of the compost-based substrates reached better growth and nutrition, especially when using the sewage sludge-based compost, and the P uptake was notably enhanced. The concentrations of trace elements were far lower than the ranges considered phytotoxic for vascular plants. Detrimental effect derived from using fresh pine bark was not observed.     

Use of composted sewage sludge in growth media for broccoli

In this study, the use of composted sewage sludge (CSS) as a binary component with peat (P) in growth media for a horticultural crop, broccoli (Brassica oleracea var. Botryti cv. Marathon), was evaluated. Four treatments were established, based on the addition of increasing quantities of composted sewage sludge to peat (0%, 15%, 30% and 50%, v/v). Physical, physico-chemical and chemical analyses of the different mixtures of CSS and P were made. Plant growth, biomass production and macronutrient (N, P, K, Ca, Mg), micronutrient (Fe, Cu, Mn, Zn) and heavy metal (Pb, Ni, Cd, Cr) contents of plants were determined. The addition of CSS to P increased plant nutrient and heavy metal contents of plants and electrical conductivity (EC) and bulk density values of the substrates. The use of CSS did not affect the germination rate, even at 50% compost. For broccoli growth, the highest yield was obtained with the medium prepared by mixing the peat with 30% of compost; however, the mixture with the most sewage sludge compost (50%) had the greatest contents of macro and micronutrients.     

Impact of application of organic waste materials on microbial and enzyme activities of mine soils in the Lusatian coal mining region

The objective of the present work was to study the short-term stimulation of microbial and enzyme activity in mine soils by application of organic waste materials in lysimeter and mesocosm studies. The mine soils derived from tertiary and quaternary deposits were ameliorated with brown coal filter ash (tertiary deposits) and lime (quaternary deposits). At the beginning of recultivation the soils were treated with varying amounts of sewage sludge, coal sludge, composted sewage sludge and compost to a depth of 30 cm. In the first 2 years after application of organic waste materials we found a very low level of microbial properties especially in the sandy materials from quaternary deposits but a significant increase in microbial respiration, substrate induced respiration and enzyme activities like invertase and alkaline phosphatase with increasing application rates of sewage sludge, compost and sewage sludge mixed with coal sludge. This can be explained by an increase in organic matter and nutrient content of the soils and an improvement of soil physical properties such as water and nutrient retention capacity. Additionally it can be assumed, that constituents of the coal admixtures of tertiary deposits can be mineralised or converted by the soil microorganisms. In the tertiary materials ameliorated with brown coal ash the highest amounts of microbial and enzyme activities were measured after application of nitrogen-rich sewage sludge or very high amounts of mature compost mainly consisting of green waste. Compared with sewage sludge the stimulating effects of composted sewage sludge were quite lower because of organic matter fragmentation and a reduced energy and nutrient supply to soil microorganisms. This revised version was published online in June 2006 with corrections to the Cover Date.     

Ecophysiological Responses of Plants After Sewage Sludge Compost Applications

Composting is one of the most appropriate methods to recycle sewage sludge. Sewage sludge compost is a suitable solution for improving the quality of barren soil at landfill. Therefore, it is important to investigate the effects of sewage sludge compost on plants. Different compost application methods (mixing and scattering over reclaimed soil) on sawtooth oak (Quercus acutissima) and Japanese red pine (Pinus densiflora) have been tested. The application of sewage sludge compost markedly increased soil moisture and nitrogen content. Compost treatments resulted in significant increases in both plant height and biomass as compared to controls. Compost treatments led to a significant increase in the N content of plant leaves. Compost treatments resulted in significant increases in the chlorophyll content and photosynthetic rates of the plants. The scattering of compost over reclaimed soil (compost 2) resulted in lower total antioxidant activity and superoxide dismutase activity than mixing the compost with the reclaimed soil (compost 1), or in the control treatment. Since the growth rates, N content, and photosynthetic rates in compost 2 treatment were not markedly different from compost 1 treatment, it (compost 2) would be a better application method from both an ecological and economic perspective.     

Production of compost from marine waste: evaluation of the product for use in ecological agriculture

The sea contains large amounts of resources that are sometimes considered as waste. Such material includes the waste generated by the fish-processing industry and seaweed that is washed up on shores. In this study, these waste products were windrow composted, along with pine bark as a source of carbon and aeration. The final mix proportions were 20 % seaweed, 20 % fish waste, and 60 % pine bark (v/v). After 10 weeks, stable, well-structured, hygienic compost, which was rich in organic matter and nutrients and had a low metal content, was obtained. Tests for maturity, hygiene, and phytotoxicity, along with a detailed physical and chemical characterization, showed that this compost can be used as an organic amendment and/or growth substrate for use in ecological agriculture. The only limiting feature was the high salinity, which could easily be lowered prior to composting the material.     

The use of sewage sludge and horticultural waste to develop artificial soil for plant cultivation in Singapore

Greenhouse pot experiments were performed with Ipomoea aquatica (Kang Kong) to evaluate artificial soil produced from poor fertility subsoil, horticultural compost, and sewage sludge. The addition of horticultural compost and sewage sludge to subsoil substantially improved plant growth, improved the physical properties of subsoil and enriched subsoil by essential nutrients for plants. The effect was enhanced when the two ingredients were added to subsoil together. The highest yield of biomass of I. aquatica was observed in artificial soil prepared by mixing subsoil with 4% (wet weight/wet weight) of horticultural compost and 2% (dry weight/wet weight) of sewage sludge. The contents of heavy metals in plants, grown in the artificial soil, were significantly lower than toxic levels. The artificial soil could be recommended for urban landscaping and gardening in Singapore.     

Influence of bulking agent on sewage sludge composting process

Four types of compost, consisting of mixtures of Acacia dealbata (A) with sewage sludge (SS) were studied in a laboratory reactor. Composting time was 80 days and parameters monitored over this period included temperature, organic matter, pH, CO₂, O₂, C/N ratio, Kjeldahl-N, as well as maturity indexes. All the studied parameters were influenced by the bulking amount used. The highest profile temperature measured was for the A/SS 1/2 (w/w) mixture that reached a maxima temperature of 67 °C and lower maximum temperatures of 52, 48 and 46 °C were observed for A/SS 1/3, 1/1 and 1/0 composts, respectively. The kinetic model used showed that a descent of sewage sludge in the composting mixtures favored the enzyme–substrate affinity. However, an increase in depending on the parameters of the process factors was observed when the sewage sludge ratio was increased in mixtures. The optimal amounts of sewage sludge for co-composting with Acacia indicate that moderate amounts of sludge (1/1) would be the best compromise.     

Immobilization and phytoavailability of cadmium in variable charge soils. III. Effect of biosolid compost addition

We examined the effect of biosolid compost on the adsorption and complexation of cadmium (Cd) in two soils (Egmont and Manawatu) which varied in their organic matter content. The effect of biosolid compost on the uptake of Cd from the Manawatu soil, treated with various levels of Cd (0–10 mg Cd kg^–1 soil), was also examined using mustard (Brassica juncea L.) plants. The transformation of Cd in soil was evaluated by a chemical fractionation scheme. Addition of biosolid compost increased negative charge in soil. The effect of biosolid compost on Cd adsorption varied between the soils, with a large portion of the sorbed Cd remaining in solution as an organic complex. Increasing addition of Cd increased Cd concentration in plants, resulting in decreased plant growth at high levels of Cd (i.e., phytotoxicity). Addition of biosolid compost was effective in reducing the phytotoxicity of Cd as indicated by the decrease in the concentration of NH₄OAc extractable-Cd and soil solution-Cd. The solid-phase fractionation study indicated that the addition of biosolid compost decreased the concentration of the soluble and exchangeable Cd fraction but increased the concentration of organic-bound Cd fraction in soil. Alleviation of Cd phytotoxicity by biosolid compost can be attributed primarily to complexation of Cd by the organic matter in the biosolid compost.     

Adsorption, absorption, and biological degradation of ammonia in different biofilter organic media

A tailor-made apparatus called ammoniometer, which is a batch mode respirometer applied to the study of ammonia biodegradation in biofilter media, has been used to evaluate adsorption, absorption, and biodegradation in five different organic materials (compost, coconut fibre, bark, pruning wastes, and peat) obtained from full-scale biofilters in operation in several waste treatment plants. The results showed that absorption could be represented by a Henry's law linear equation, with values of the Henry coefficient significantly higher (from 1,866 to 15,320) than that of pure water (1,498). Adsorption data were successfully fitted to Langmuir and Freundlich isotherms and maximum adsorption capacity varies from 1.06 to 1.81 mg NH(3)/g dry media. Ammonia biodegradation rates for each organic material were also calculated. Biodegradation rates varied from 0.67 to 7.82 mg NH(3)/kg media/d depending on the material tested. The data obtained showed important differences in the behaviour of the biofilter organic media, which has important implications in the design and modelling of these systems.     

Nitrogen transformation during organic waste composting by the Rutgers system and its effects on pH, EC and maturity of the composting mixtures

The evolution of the different forms of nitrogen during the composting of several wastes was studied, as well as its relation to the pH, electrical conductivity and parameters of maturity of the composts obtained. Four mixtures were prepared from different organic materials: sewage sludge, municipal solid waste, brewery sludge, sorghum bagasse, cotton waste and pine bark. The evolution of the different forms of nitrogen during composting depended on the material which supplied the nitrogen to the mixtures and the organic matter (OM) degradation rate during composting. The greatest concentration of ammonium was observed during the first weeks of composting, coinciding with the most intense period of OM degradation, and ammonium then decreased gradually to reach final values of below 0.04%. The use of urea as a nitrogen source in the mixtures led to high ammonium levels during the first weeks as a result of its rapid hydrolysis. The nitrification process began only when the temperature of the mixtures had dropped below 40 degrees C and its intensity depended on the quantity of ammonium present when the process began. The highest concentrations of NO3-N were always produced at the end of maturation, reaching values of 0.52%, 0.53%, 0.12% and 0.20% in the four mixtures studied. Nitrogen losses during composting depended on the materials used and on the pH values of the mixtures. Mixtures with the highest lignocellulose content showed the lowest losses (below 25%), while those containing municipal solid waste lost more than 40% of the initial content. Statistically significant correlations at a high probability level were found between the NO3-N concentration and pH and electrical conductivity. confirming that nitrification was responsible for the falling pH values and increasing electrical conductivity. The ratio of NH4-N and NO3-N concentrations was shown to be a clear indicator of the maturity of the mixtures during composting, the final values of 0.08, 0.04, 0,16 and 0.11 for the four mixtures being equal to, or below the maximum value established as a maturity index in other materials.     

Effects of different soil ameliorants on karee trees (Searsia lancea) growing on mine tailings dump soil-part I: pot trials

Rehabilitation of mine tailings dams is often a challenge due to a lack of nutrients and a poor humus reservoir prevailing in tailings soils. This is especially true for establishing longer lived species such as trees. For these reasons the effects of different soil ameliorants (woodchips compost, vermicompost, mature sewage sludge), added to the root system of Karee (Searsia lancea) saplings were tested in pot trials. Those pots were filled with platinum and gold tailings substrate as well as red clay soil, respectively. For three months plants remained in a greenhouse and were subsequently moved to a test field outside. Throughout the test period regular chl a fluorescence measurements were taken and subjected to JIP-test quantifying changes in photosynthetic vitality status. Additionally, growth measurements and one-off leaf analysis were carried out. Test plants growing on mine tailings experienced an up to 35% higher average photosynthetic vitality (PI(ABS)) and improved nutrient supply, when treated with mature sewage sludge. Consequently, sewage sludge treated plants showed a higher biomass build-up rate and an up to 55% higher diameter growth, compared to control. In summary the experiments present a low cost alternative for reforestation enterprises on platinum and gold tailings dams in South Africa.     

Soil microcosm experiments to study the effects of waste material application on nitrogen and carbon turnover of lignite mine spoils in Lusatia (Germany)

The lignite and pyrite containing spoil substrates of the Lusatian mining district are marked by very high acidity and salt concentrations due to pyrite oxidation and by a very low content of pedogenic organic matter and nutrients. The effects of fly ash application to neutralize the produced acid and of organic waste material application to improve the ecological soil functions were studied considering the carbon and nitrogen cycling. Nineteen, 38 and 57 t ha⁻¹ sewage sludge and 22, 44 and 66 t ha⁻¹ compost were applied to ameliorated lignite and pyrite containing substrate. An automated soil microcosm system was used to analyse the solid, gaseous and liquid phases. Almost 9% of total N applied with sewage sludge (620, 1240 and 1860 t N ha⁻¹ applied) were lost over a period of 150 days mainly as NO₃-N. The total N losses from compost treatments were three times lower (2.8–3.1% of applied Nt) and occurred in similar quantities as NH4-N and NO₃-N. Only sewage sludge treatments showed slightly increased N₂O emissions at the beginning of the experiment. CO₂ emissions determined the carbon losses of all treatments. The C losses amounted to 3.2–4.7% and 1.5–2.7% of C_t applied with sewage sludge and with compost, respectively. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

Estimation of phosphorus bioavailability from composted organic wastes

Sewage sludge derived from municipal sewage treatment plants is an important source of macronutrients, micronutrients and organic matter. For this reason composting of sewage sludge, along with combustion and co-combustion, is a new management priority in Poland. In this study six composts of different origin and composition were evaluated in terms of their abundance in phosphorus, because it is an essential nutrient for all living organisms. Analyses were conducted on the samples at the initial and at the maturation phase of composting. The bioavailability of phosphorus was estimated on the basis of amounts of the nutrient in isolated fractions using the sequential extraction method. First of all quantitative changes of the total nutrient content and its amounts in separated fractions were dependent on the mixture composition. Irrespective of compost type, 34.5–75.0% of the total amounts of phosphorus were found in hardly available combinations (Fr. III), while available phosphorus forms (Fr. I) accounted for only 6.6–21.6%. As a result of composting together different organic wastes an increase was observed both in the total content and the amounts of this nutrient in separated fractions. This phenomenon was observed particularly in composts with smaller levels of sewage sludge (30–40%), characterised by rapid organic matter decomposition, which was indicated by higher bioavailable amounts of phosphorus. Under such conditions the content of P ranged between 3.68 and 7.4 g kg^?1. In comparison to the labile pool of P obtained for matured composts C5 and C6 (65 and 75% of sewage sludge in their composition) amounting to 2.45–3.0 g kg^?1 the above values were considerable. Bioavailable phosphorus contents potentially introduced to soil with composts doses calculated at 170 kg total N/ha/yr ranged from 69.8 to 80.2 kg for compost with the lowest share of sewage sludge and from 11.2 to 20.7 kg for compost with the highest share of sewage sludge.     

构树的污泥适应性及养分和重金属吸收累积特征

构树是我国重要速生经济树种,具有适应性强、生物量大和重金属富集能力强等优点,而污泥中含有大量养分和重金属,在污泥中种植构树有望同时实现污泥生态修复和构树资源生产。本研究通过盆栽试验,分析在对照(赤红壤)、50%污泥(污泥、赤红壤混合基质,重量比各50%)和100%污泥基质中构树生长及不同部位(根、茎、叶)养分和重金属吸收累积特征,并通过主成分分析和隶属度函数对吸收累积能力进行综合评价。结果表明: 构树在50%和100%污泥中均可正常生长且株高、生物量显著高于对照,在100%污泥中长势最好,质量指数(1.02)分别是对照和50%污泥处理的4.3和2.4倍。50%和100%污泥处理构树各部位N含量和茎P含量显著高于对照,100%污泥处理构树茎、叶K含量显著低于对照。构树对Cu、Zn、Pb、Cd、Ni的吸收部位以根为主,根系重金属含量与污泥比例呈正相关,叶Pb、Cd含量符合《饲料卫生标准》(GB 13078—2017)。构树对Cd的吸收累积效果好于其他重金属元素。与对照相比,50%和100%污泥处理构树根部Zn、Pb、Cd滞留率显著提高(57.8%~85.8%),100%污泥处理构树根部Cu、Ni滞留率显著提高(67.5%和74.8%)。污泥处理全株养分和重金属累积量均显著大于对照,其中100%污泥处理显著大于50%污泥处理。与50%污泥处理相比,100%污泥处理构树各部位及全株养分和重金属累积量大幅提高。不同处理下构树污泥适应性和元素吸收累积的综合评价得分为100%污泥(0.848)>50%污泥(0.344)>对照(0.080)。构树对污泥具有良好的适应性,在纯污泥中能够正常生长并具有较强的吸收累积养分和重金属能力,可在修复污泥的同时进行构树资源生产。     

Compost-based growing media: influence on growth and nutrient use of bedding plants

The agronomic performance and the mineral composition and trace element content in Begonia semperflorens "Bellavista F1", Mimulus "Magic x hybridus", Salvia splendens "maestro", and Tagete patula xerecta "Zenith Lemon Yellow", were tested by growing the plants on substrates of white peat and 25-50-75-100% green waste and sewage sludge (80%+20%v/v) compost (CP). A commercial peat medium of black and white peat (2:1v/v) was used as control. At flowering, the agronomic parameters were compared by ANOVA and plant nutritional status was compared by vector analysis. Substrate-species interactions (P<0.001) were evident for all measured parameters. In the 25% CP medium all the species showed an increase or preservation of the studied agronomic parameters. Begonia grown in 25% CP, showed the highest dry weight (DW) and number of flowers. Other treatments were comparable to the control. Mimulus and Salvia showed the highest DW in the 25-50% CP. Mimulus, after a DW increase up to 50% CP, showed the steepest reduction as the CP increased further. Tagete showed no differences in DW up to 50% CP, or in flower number up to 25% CP, compared to the control. The additional increases of CP in the medium showed a DW decrease similar to that of Salvia. Vector analysis showed the use of compost mainly induced a decrease of P concentration in tissues, except for Begonia which remained unchanged. Plant tissues showed a general P reduction due to a dilution effect in the low compost mixtures (25-50%) and a deficiency in the higher CP mixtures. In contrast, an increase of Mg in the aboveground tissues of all species was detectable as compost usage increased, with the exception of Salvia which suffered a Mg deficiency. Vector analysis also highlighted a Ni and partial Fe deficiency in Tagete and Salvia.     

Potential utilisation of sewage sludge and paper mill waste for biosorption of metals from polluted waterways

The adsorption of cadmium, copper(II), lead and zinc ions from aqueous solution by sewage sludge, paper mill waste (PMW) and composted PMW was investigated along with the influence of pre-treatment on composted PMW. Langmuir adsorption isotherms were fitted where appropriate. Sewage sludge was the most effective biosorbent of the waste products for all metal ions examined, adsorbing, for example, up to 39.3 mg/g of Pb at an initial concentration of 77.8 mg/l. PMW was a less effective biosorbent than sewage sludge. However, it was found that composting the PMW resulted in an increase in metal uptake capacity and both sewage sludge and composted PMW have potential for low-cost remediation of high leachate wastewaters. The desorption of metal ions from PMW compost was most effective using 0.1 N H2SO4 and 1 mM nitrilotriacetic acid (NTA).     

Survival of fecal coliforms in dry-composting toilets

The dry-composting toilet, which uses neither water nor sewage infrastructure, is a practical solution in areas with inadequate sewage disposal and where water is limited. These systems are becoming increasingly popular and are promoted to sanitize human excreta and to recycle them into fertilizer for nonedible plants, yet there are few data on the safety of this technology. This study analyzed fecal coliform reduction in approximately 90 prefabricated, dry-composting toilets (Sistema Integral de Reciclamiento de Desechos Orgánicos [SIRDOs]) that were installed on the U.S.-Mexico border in Ciudad Juárez, Chihuahua, Mexico. The purpose of this study was to determine fecal coliform reduction over time and the most probable method of this reduction. Biosolid waste samples were collected and analyzed at approximately 3 and 6 months and were classified based on U.S. Environmental Protection Agency standards. Results showed that class A compost (high grade) was present in only 35.8% of SIRDOs after 6 months. The primary mechanism for fecal coliform reduction was found to be desiccation rather than biodegradation. There was a significant correlation (P = 0.008) between classification rating and percent moisture categories of the biosolid samples: drier samples had a greater proportion of class A samples. Solar exposure was critical for maximal class A biosolid end products (P = 0.001). This study only addressed fecal coliforms as an indicator organism, and further research is necessary to determine the safety of composting toilets with respect to other pathogenic microorganisms, some of which are more resistant to desiccation.     

The Challenge of Peat Substitution in Organic Seedling Production: Optimization of Growing Media Formulation through Mixture Design and Response Surface Analysis

Peat replacement is an increasing demand in containerized and transplant production, due to the environmental constraints associated to peat use. However, despite the wide information concerning the use of alternative materials as substrates, it is very complex to establish the best materials and mixtures. This work evaluates the use of mixture design and surface response methodology in a peat substitution experiment using two alternative materials (green compost and palm fibre trunk waste) for transplant production of tomato (Lycopersicon esculentum Mill.); melon, (Cucumis melo L.); and lettuce (Lactuca sativa L.) in organic farming conditions. In general, the substrates showed suitable properties for their use in seedling production, showing the best plant response the mixture of 20% green compost, 39% palm fibre and 31% peat. The mixture design and applied response surface methodology has shown to be an useful approach to optimize substrate formulations in peat substitution experiments to standardize plant responses.