Analysis of branched-chain fatty acids in humic substances as indices for compost maturity by pyrolysis–gas chromatography/mass spectrometry with tetramethylammonium hydroxide (TMAH-py–GC/MS)

Parameters that affect the degree of humification for humic substances (HSs) are deeply related to the maturity of the compost. In general, the matured composts contain HSs with a higher degree of humification. In addition, microbial activities during composting are also one of the indices for compost maturation. Branched-chain fatty acids are metabolites as the result of microbial activities in a soil environment. Such branched-chain fatty acids, regarded as humic precursors, are incorporated into HSs during the composting process. To determine whether branched-chain fatty acids in HSs can be used as biomarkers during composting processes or not, HSs were extracted from three types of composts with the different maturation, and the branched-chain fatty acids in the HSs were analyzed by pyrolysis–gas chromatography/mass spectrometry with tetramethylammonium hydroxide (TMAH-py–GC/MS). HSs with a higher degree of humification (higher aromaticity and lower molecular weight) contained higher levels of branched-chain fatty acids. These results show that branched-chain fatty acids in HSs from matured compost samples can be used as biomarkers, which indicate the history of microbial activities during overall composting process.     

Investigation on the humification of municipal solid waste incineration residue and its effect on the leaching behavior of dioxins

In this study, we investigated the humification of municipal solid waste incineration residue through identification of extracted humic substances, and examined the leachability of dioxins by batch leaching test. The samples were incineration residues excavated from lysimeters 6-8 years after being filled. The results of investigation of humic substances showed that the top layers from the surface to a depth of 30-70 cm contained more humic substances than the other layers judging from the color of the samples and optical characteristics of the extracts. In particular, humification in the lysimeter filled with a small amount of compost had progressed through all the layers, not only the top one. The tests revealed that the leaching concentrations of dioxins increased with advanced humification and showed relatively good correlation to dissolved organic carbon (DOC) of leachate at each lysimeter. Humification advances from the surface first, and DOC generated from the humification may preferentially carry down the highly chlorinated dioxin compounds such as O8CDD as DOC-dioxin complexes. Comparing the content and leaching concentration according to depth, we observed not only a decrease in dioxin content but also an increase in leaching of the highly chlorinated dioxins at deeper layers in the lysimeters with the compost. This tendency seemed to result from biological activities.     

腈纶污水处理厂污染物转化规律分析

对某腈纶污水处理厂的现有处理工艺进行了评估,考察了污染物的转化规律。结果表明,经一级生化处理后,废水中的COD、TOC和BOD₅去除率分别为51.1%、32.1%和98.1%,但二级生化处理对COD和TOC的去除没有贡献。一级生化处理过程中氨化作用显著,有机氮逐渐向氨氮和有机胺转化,含氰基的大分子逐渐降解为较小的分子,且可见光区类富里酸荧光物质向类腐殖酸荧光物质、紫外区类富里酸荧光物质转化,同时生化出水中新增溶解性微生物代谢产物。但一级生化出水中碳氮比很低,几乎没有可生化性,导致二级生化处理效果不佳。     

Use of biosurfactants from urban wastes compost in textile dyeing and soil remediation

A compost isolated humic acid-like (cHAL) material was pointed out in previous work for its potential as auxiliary in chemical technology. Its potential is based on its relatively low 0.4gL(-1) critical micellar concentration (cmc) in water, which enables cHAL to enhance the water solubility of hydrophobic substances, like phenanthrene, when used at higher concentrations than 0.4gL(-1). This material could be obtained from a 1:1 v/v mixture of municipal solid and lignocellulosic wastes composted for 15 days. The compost, containing 69.3% volatile solids, 39.6% total organic C and 21C/N ratio, was extracted for 24h at 65 degrees C under N2 with aqueous 0.1molL(-1) NaOH and 0.1molL(-1) Na4P2O7, and the solution was acidified to separate the precipitated cHAL in 12% yield from soluble carbohydrates and other humic and non-humic substances. In this work two typical applications of surfactants, i.e., textile dyeing (TD) and soil remediation by washing (SW), were chosen as grounds for testing the performance of the cHAL biosurfactant against the one of sodium dodecylsulfate (SDS), which is a well established commercial synthetic surfactant. The TD trials were carried out with nylon 6 microfiber and a water insoluble dye, while the SW tests were performed with two soils contaminated by polycyclic aromatic hydrocarbons (PAH) for several decades. Performances were rated in the TD experiments based on the fabric colour intensity (DeltaE) and uniformity (sigmaDeltaE), and in the SW experiments based on the total hydrocarbons concentration (CWPAH) and on the residual surfactant (Cre) concentrations in the washing solution equilibrated with the contaminated soils. The results show that both cHAL and SDS exhibit enhanced performance when applied above their cmc values. However, while in the TD case a significant performance effect was observed at the surfactants cmc value, in the SW case the required surfactants concentration values were equivalent to 25-125xcmc for cHAL and to 4-22xcmc for SDS. The vis-a-vis comparison of the two surfactants gave the following results: in the TD case the cHAL biosurfactant at 0.4gL(-1) yields good colour intensity and equal colour uniformity as SDS at 5gL(-1), in the SW case cHAL was found to enhance CWPAH by a factor of 2-4 relative to SDS with one soil, whereas with the other soil the two surfactants behaved similarly. The Cre data, however, showed that both soils absorbed by far more SDS (68-95%) than cHAL (12-54%). The results point out intriguing technological and environmental perspectives deriving from the use of compost isolated biosurfactants in the place of synthetic surfactants.     

Evaluating compost maturity with a newly proposed index based on a germination test using Komatsuna (Brassica rapa var. peruviridis) seeds

A new index for evaluating compost maturity was developed based on a germination test of Komatsuna seeds using water extract from compost. Several compost samples were collected from a kitchen-garbage composting plant to determine an index to evaluate compost maturity. Firstly, some extraction conditions for extracting compost ingredients with water were evaluated using the time course of total organic carbon concentration in water extract. The water temperature of 60?°C, periodic mixing, and extraction period >1 were selected. Secondly, applying these conditions, the germination test was performed using the water extract solutions at several dilution ratios. The relationship between the germination rate and the dilution ratio was expressed using a logistic regression curve. The dilution ratio to give a germination rate of 0.5, defined as DG₅₀, was calculated with the parameters of the curve. Compared with other maturity indices, DG₅₀ was the most effective. Moreover, it has a unique feature in that maturity is quantified even for the compost from which water extract results in a germination rate of 0. This feature can be used to compare the maturity of different kinds of composts and quantify the change in the levels of inhibitory substances in a composting process.     

Waste paper and clinoptilolite as a bulking material with dewatered anaerobically stabilized primary sewage sludge (DASPSS) for compost production

Environmental problems associated with sewage sludge disposal have prompted strict legislative actions over the past few years. At the same time, the upgrading and expansion of wastewater treatment plants have greatly increased the volume of sludge generated. The major limitation of land application of sewage sludge compost is the potential for high heavy metal content in relation to the metal content of the original sludge. Composting of sewage sludge with natural zeolite (clinoptilolite) can enhance its quality and suitability for agricultural use. However, the dewatered anaerobically stabilized primary sewage sludge (DASPSS) contained a low concentration of humic substances (almost 2%), and the addition of the waste paper was necessary in order to produce a good soil conditioner with high concentrations of humics. The final results showed that the compost produced from DASPSS and 40-50% w/w of waste paper was a good soil fertilizer. Finally, in order to estimate the metal leachability of the final compost product, the generalized acid neutralization Capacity (GANC) procedure was used, and it was found that by increasing the leachate pH, the heavy metal concentration decreased. The application of the sequential chemical extraction indicated that metals were bound to the residual fraction characterized as a stabilize fractions.     

Composting olive mill pomace and other residues from rural southeastern Spain

The costly disposal of the semisolid residual pomace generated in the two phase extraction used in modern olive mills is causing serious problems to the small oil producers of rural southeastern Spain. Composting may be a viable alternative since complementary residues are usually available in these areas to prepare an adequate starting mixture. In this work, four different combinations of residues (pomace+rabbit manure, pomace+sheep manure, pomace+rabbit manure+rice straw, pomace+rabbit manure+almond shells) were composted in 3 ton piles aerated by turnings, using technology available to any small community of oil producers. During the four long processes (9-10 months), a steady decrease of organic matter and increases in the concentrations of nutrient and humic substances were observed, together with large increases in pH and salinity which may reduce the agronomic value of the final products.     

Optimization of compost fermentation of glycerol by-product discharged from biodiesel fuel production process

Development of a cheap system for reuse of glycerol by-product discharged from the biodiesel fuel (BDF) production process is needed in parallel with development of a low-cost BDF production system. In this article, optimization of compost fermentation of glycerol by-product was studied. The type and amount of additive nitrogen source was studied, and good utilization of glycerol was observed when 0.5 g of urea was added to a mixture of 625 g dry sawdust, 25 g of microbial seed, and 50 g of glycerol by-product. To achieve efficient compost fermentation, repeated batch fermentation was applied and five batch cultures were repeated. Although the pH level and nitrogen and water contents were maintained at suitable levels for microbial growth, the glycerol consumption rate gradually decreased with accumulation of oily compounds in the compost. Finally, a material cost evaluation of the compost fermentation proposed in this study was performed. The total material cost decreased to ￥0.57 /l of BDF when employing an existing compost system for the fermentation process, although sawdust used for mushroom cultivation was used in this study at the very high cost of ￥123 /kg dry sawdust. However, the cost of disposal of the glycerol byproduct as an industrial waste was ￥5.2 /l of BDF produced; therefore, there might be an economical advantage to compost fermentation of glycerol by-product from BDF production.     

Study of the organic matter evolution during municipal solid waste composting aimed at identifying suitable parameters for the evaluation of compost maturity

In this work the composting process of municipal solid wastes was studied in order to characterize the transformations of organic matter, particularly humic acid (HA). A composting process, lasting three months, was monitored by chemical methods; the following parameters were measured: water-soluble carbon concentration (WSC) and humic substances content (humic and fulvic acid (FA)). The effects of humification on the molecular structure of humic acid (HA) were also evaluated by Fourier transform infrared (FT-IR) and (13)C NMR spectroscopy. WSC concentration rapidly increased reaching a maximum at day-14 of the composting process and then declined. The humic and fulvic acid content (HA and FA, respectively) slightly increased during the process. The FT-IR and (13)C NMR spectra of HA indicate a high rate of change in structure during composting. The groups containing aromatic and carboxylic C increased, while polysaccharides and other aliphatic structures degraded during composting, resulting in HA structures of higher aromaticity. Therefore, spectrometric measurements could provide information significantly correlated to conventional chemical parameters of compost maturity.     

Amelioration effect of humic acid extracted from solubilized excess sludge on saline-alkali soil

In this study, the main characteristics and soil amendment effects on the saline–alkali soil of humic acid extracted from solubilized excess sludge (SS-HA) were investigated. The excess sludge was solubilized prior to extraction to improve the humic acid recovery rate. The structural features of SS-HA were characterized by an elemental analysis, Fourier transform infrared spectroscopy, and ¹H-nuclear magnetic resonance spectroscopy, and compared with those of HA extracted from non-solubilized excess sludge (ES-HA). The results showed that extraction efficiency of humic acid was enhanced by using solubilization, although structural properties of humic acid extracted from solubilized excess sludge were almost the same as those of ES-HA. To study a utilization method of SS-HA, the soil amendment effects on saline–alkali soil by mixture of SS-HA were investigated with a model soil-column experiment. SS-HA reduced the pH of the saline–alkali soil, and the effect was immediately observed or faster than the case in which only peat is added. Moreover, the cation exchangeable capacity of the saline–alkali soil was enhanced by addition of SS-HA.     

Humification index of composts originating from three types of woody biomass

Composting is a good method for recycling surplus manure and stabilizing organic matter from biowastes. Compost is used as a soil amendment and recently, for restoration of vegetation in barren areas. We investigated the relationship between the type of woody biomass (using Robinia pseudoacacia, Japanese larch and apple) and the humification index (HI) of the resulting compost. This study evaluated the difference in HI between the three compost types, and the structural features of composts and extracted humic acids (HAs). The HIs for R. pseudoacacia and apple were larger than that for Japanese larch after composting for 11 months. The structural features of the Japanese larch compost were also different from the apple and R. pseudoacacia, with a very high carbon/nitrogen ratio. The average molecular weights and ultraviolet–visible spectra (A600/C) of HAs extracted from composting samples at 0 and 11 months indicate that the humification rate of Japanese larch was slower than that of R. pseudoacacia and apple. During composting, the average molecular weights of apple and R. pseudoacacia decreased, while their A600/C values increased, but the reverse was observed for Japanese larch. The humification rate was found to depend on the type of woody biomass being composted.     

Modification of soil humic matter after 4 years of compost application

Two soil plots, 1 ha each, were amended yearly for 4 years, respectively, with 35.8 and 71.6 Mg ha(-1) yr(-1) of mature compost (CM) obtained from food and vegetable residues. The compost, amended soils, and a control soil plot after 4 years (S4), were analyzed for humin (HUC), humic acid (HAC), fulvic acid (FAC), and non-humic carbon (NHC) content. Compared to S4, the amended soil contained more humified C (HAC, FAC and HUC) and less NHC. Further evidence of the effect of compost on soil organic matter was obtained by the analysis of the humic acid (HA) fractions isolated from both the compost and the soils. These were characterized by elemental analyses and Diffuse Reflectance Infrared Fourier Transformed spectroscopy. The HAs isolated from CM and from S4 were significantly different. The HAs isolated from the amended plots were more similar to HA isolated from CM than to HA isolated from S4. The experimental data of this work indicate that the compost application may affect significantly the soil organic matter composition, and that the approach used in this work allows one to trace the fate of compost organic matter in soil.     

Physicochemical and biochemical changes during composting of different mixing ratios of biogas sludge with palm oil mill wastes and biogas effluent

Prior to composting, the composition of palm oil mill wastes were analyzed. Palm empty fruit bunches (PEFB) contained the highest total organic carbon (52.83 % dry weight) while palm oil mill biogas sludge (POMS) and decanter cake (DC) contained higher total nitrogen (3.6 and 2.37 % dry weight, respectively) than the others. In addition, palm oil fuel ash (POFA) had a high amount of phosphorus and potassium (2.17 and 1.93 % dry weight, respectively). The effect of mixture ratio of POMS and other palm oil mill wastes for composting was studied using the mixed culture Super LDD1 as an inoculum. All compost piles turned dark brown and attained an ambient temperature after 40 days incubation. The pH values were stable in the range of 6.9–7.8 throughout the process whereas the moisture content tended to decrease till the end with the final value around 30 %. After 60 days incubation, the mixture ratio of POMS:PEFB:DC at 2:1:1 with the addition of biogas effluent gave the highest quality of the compost. Its nitrogen content was 31.75 % higher than the other treatments that may be a result of growth of ink cap mushroom (Coprinus sp.). This is the first report on the occurrence of this mushroom during composting. In addition, its nutrients (3.26 % N, 0.84 % P and 2.03 % K) were higher than the level of the Organic Fertilizer Standard. The mixed culture Super LDD1 produced the highest activity of CMCase (6.18 Unit/g) and xylanase (11.68 Unit/g) at 9 days fermentation. Therefore, this solid-state fermentation could be employed for production of compost as well as enzymes.     

Extracting humic acids from digested sludge by alkaline treatment and ultrafiltration

The concentration of hardly biodegradable humic substances in sludge would relatively increase after anaerobic digestion due to the degradation of other organic substances. Thus, extracting humic substances from digested sludge as a liquid organic fertilizer was tested using alkaline treatment and ultrafiltration, and the dewaterability of the residual sludge was also tested. The results showed that the contents of humic acids and fulvic acids in digested sludge were 16.4 mg/g total solids and 88.9 mg/g total solids, respectively, and most of the humic acids had a molecular weight higher than 50 kDa. Hence, the membrane with a molecular weight cut-off of 50 kDa was used for humic acids recovery from the centrifugation supernatant after alkaline sludge disintegration with an optimum NaOH dose of 0.1 mol/L. Under these conditions, the total concentration of humic acids and fulvic acids was 4239 mg/L in the retention solution, which can be further concentrated and processed for liquid fertilizer. The total recovery rate of sludge humic acids and fulvic acids was about 25 %. The dewatering performance of the residual sludge was better than that of the untreated sludge when the residual sludge was diluted to a water content of 95–98 % and then conditioned with polyacrylamide at a dose of 10–30 mg/L.     

Study on the quality and stability of compost through a Demo Compost Plant

This study is concerned with the performance of a Demo Compost Plant for the development of acceptable composting technology in Bangladesh. The Demo Compost Plant was setup at the adjacent area of an existing compost plant located at Khulna city in Bangladesh. Four different composting technologies were considered, where Municipal Solid Waste (MSW) were used as a raw material for composting, collected from the adjacent areas of the plant. Initially the whole composting system was conducted through two experimental setups. In the 1st setup three different types of aerators (horizontal and vertical passively aerator and forced aerator) were selected. For a necessary observation four piles, using only MSW as the input materials in the first three compost pile, the fourth one was the existing Samadhan’s compost pile. Based on the analysis of the experimental findings, the horizontal passively aerated composting technique is suitable for Bangladesh as it had better performance for reducing composting period than that of the others. It was being observed from the quality parameters of compost in the both 1st and 2nd setup that as the waste directly come from kitchen, degradation rate of waste shows a positive result for reducing this waste and there is no possibility of toxic contamination, when it would be used as a soil conditioner. Though there is no significant improvement in the quality of the final product in the 2nd setup as comparing with the 1st setup but it fulfills one of the main objectives of this study is to reduce the whole composting period as well as immediate management of the increasing amount of waste and reducing load on landfill. Selfheating tests reveal that degree of stability of compost with respect to maturation period was remained in the acceptable level, which was further accelerated due to the use of organic additives.     

Change of the chemical composition and biodegradability of the Van Soest soluble fraction during composting: A study using a novel extraction method

Van Soest fractionation is widely employed to characterize exogenous organic matter. The soluble fraction of Van Soest fractionation (SOL, extracted using hot water and then neutral detergent) often increases in line with compost maturity, although it is generally considered as labile. We have developed an alternative extraction method that comprises four successive steps (extraction using hot water, sodium tetraborate, dichloromethane/methanol and chelating resin) in order to clarify the chemical nature of the SOL fraction and explain its biodegradability. This method was tested on municipal solid waste compost sampled during the thermophilic phase (MSWi) and after 8 months of composting (MSWm). Both methods extracted similar proportions of organic matter. The composition of the residues was similar in MSWm although differences were noted for the extraction of polysaccharides and lipids in the case of MSWi. The hot water extractable fraction decreased during composting. Its high biodegradability in MSWi was linked to the high polysaccharide content revealed by pyrolysis–GC/MS and FTIR spectroscopy. The increase in the sodium tetraborate extractable fraction mainly explained the increase in the SOL fraction during composting. This was made up of N-containing compounds, polysaccharides and lipids in the immature compost, and a majority of N-containing compounds in the mature compost. During composting, the stabilization of organic matter in the SOL fraction extractable by sodium tetraborate and EDTA might principally involve N-containing structures through the formation of complexes of organic matter with metal ions, especially Ca²⁺, which may be broken down during extraction of the Van Soest soluble fraction. These mechanisms still need to be investigated.     

Assessment of municipal solid waste compost quality using standardized methods before preparation of plant growth media.

The quality of compost and its suitability for agricultural application depend upon physical and chemical parameters such as water-holding capacity, porosity, pH, electrical conductivity, C/N ratio, available nutrients and the absence of toxic substances. In the present study a complete characterization of an industrial municipal solid waste compost (MSWC) based on standardized European methods (CEN) for soil improvers and growing media was obtained, and compared with the quality of other Spanish composted biowaste and conventional substrates such as peat and pine bark. The MSWC was obtained from the main composting plant in Galicia (Spain), which processes organic waste that has been separated at origin and collected from more than 100 000 inhabitants. The MSWC presented a lower C/N ratio (15) than peat (84) and composted pine bark (CPB) (211), but had a similar ratio to other marketed MSWC. The nutrients and heavy metals were extracted using different recommended solvents (water, CaCl2 + diethylen triamin pentaacetic acid, and aqua regia). The nutrient concentrations of composted urban waste or manure were much higher than those of peat, CPB or pine bark. On the basis of the results of the plant tolerance test, the MSWC could be employed directly as a soil improver, but would need to be diluted with other low-salt components such as peat or CPB before being used as a growing media.     

Assessment of chemical and biochemical stabilization of organic C in soils from the long-term experiments at Rothamsted (UK)

Biological and chemical stabilization of organic C was assessed in soils sampled from the long-term experiments at Rothamsted (UK), representing a wide range of carbon inputs and managements by extracting labile, non-humified organic matter (NH) and humic substances (HS). Four sequentially extracted humic substances fractions of soil organic matter (SOM) were extracted and characterized before and after a 215-day laboratory incubation at 25 degrees C from two arable soils, a woodland soil and an occasionally stubbed soil. The fractions corresponded to biochemically stabilised SOM extracted in 0.5M NaOH (free fulvic acids (FA) and humic acids (HA)) and chemically plus biochemically stabilised SOM extracted from the residue with 0.1M Na4P2O7 plus 0.1M NaOH (bound FA and HA). Our aim was to investigate the effects of chemical and biochemical stabilization on carbon sequestration. The non-humic to humic (NH/H) C ratio separated the soils into two distinct groups: arable soils (unless fertilised with farmyard manure) had an NH/H C ratio between 1.05 and 0.71, about twice that of the other soils (0.51-0.26). During incubation a slow, but detectable, decrease in the NH/H C ratio occurred in soils of C input equivalent or lower to 4Mgha(-1)y(-1), whereas the ratio remained practically constant in the other soils. Before incubation the free to bound humic C ratio increased linearly (R2=0.91) with C inputs in the soils from the Broadbalk experiment and decreased during incubation, showing that biochemical stabilization is less effective than chemical stabilization in preserving humic C. Changes in delta13C and delta15N after incubation were confined to the free FA fractions. The delta13C of free FA increased by 1.48 and 0.80 per thousand, respectively, in the stubbed and woodland soils, indicating a progressive biological transformation. On the contrary, a decrease was observed for the bound FA of both soils. Concomitantly, a Deltadelta15N of up to +3.52 per thousand was measured after incubation in the free FA fraction and a -2.58 Deltadelta15N in the bound FA. These changes, which occurred during soil incubation in the absence of C inputs, indicate that free FA fractions were utilised by soil microorganisms, and bound FA were decomposed and replaced, in part, by newly synthesized FA. The 13CPMAS-TOSS NMR spectra of free HA extracted before and after 215 days of incubation were mostly unchanged. In contrast, changes were evident in bound HA and showed an increase in aromatic C after incubation.     

Characterization of iron elution for seaweed bed restoration using a steelmaking slag and compost method

Coastal areas in Japan and other parts of the world have serious problems with barren grounds. A method has been developed that uses a mixture of steelmaking slag and compost including humic substances supplied in seawater, for restoring seaweed beds. The effects of this method have been previously confirmed in field tests. It was found that the mixture of steelmaking slag and compost was effective for extending the lifetime of iron elution as well as increasing iron concentrations in seawater. In this study, the effect of the mixing composts with steelmaking slag was evaluated additionally for increasing dissolved iron concentrations in seawater. The characteristics of iron elution were also studied using this method. In particular, the mechanism of Fe elution and dissolved Fe oxidation was examined in detail. The iron elution of actual seawaters was tested using three kinds of samples which involved steelmaking slag, compost, and a mixture of steelmaking slag and compost. These samples were used to understand the mechanism of Fe elution and oxidation in seawater. It was found that the mixture of steelmaking slag and compost was the most effective, which also confirmed the validity of the proposed Fe elution process in seawater.     

Characterization and removal of dissolved organic matter (DOM) from landfill leachate rejected by nanofiltration

Dissolved organic matter (DOM) from wastewater rejected by nanofiltration from a landfill leachate treatment plant was fractionated into humic acid (HA), fulvic acid (FA) and hydrophilic (HyI) fractions. It was found that humic substances (HA and FA) composed 75% of the total dissolved organic carbon (DOC) concentration of the DOM, with an average molecular weight of about 1000 Da. Elemental analysis, infrared spectroscopy, UV-visible spectroscopy and acid-base titration observations showed that the HA and FA of the DOM exhibited lower fractions of condensed aromatic functional groups but larger fractions of acidic groups compared with other aquatic DOMs. The properties of HA and FA were similar, but HA exhibited more complete humification, while the HyI fraction had more acidic groups. An aminated polymeric adsorbent NDA-8 was used to adsorb the DOM in the wastewater along with primary coagulation. Results of bench-scale experiments indicated that the treatment process could effectively remove the DOM and heavy metals while desorption liquid was 10 times more condensed than raw wastewater. Results of desorption and reproducibility tests consolidated the strong application potential of this treatment process as an advanced landfill leachate treatment technology.