Search

The present investigation was carried out to evaluate the vermicomposting potential of two cruciferous vegetables' residual biomasses under laboratory conditions. Cabbage and cauliflower residual biomasses were spiked with 60% cow dung and vermicomposted for 90 days. The results showed a decrease in pH (5.3-9.8%), Total Organic Carbon (36.7-42.8%); increase in Electrical Conductivity (33-99.4%) and ash content (144.7-187.8%) after vermicomposting. Significant reduction in C:N ratio (49.5-76.4%) and C:P ratio (62.8-66.04%), increase in Total Kjeldahl Nitrogen (49.3-85.3%), Total Available Phosphorus (68.2-98.1%), Total Potassium (91.8-120.3%) were observed. FT-IR spectra of the vermicomposts had lesser band heights and peak intensities than raw materials. This evidenced decomposition of organic compounds and vermicompost stability. Germination Index values was calculated to determine the phytotoxicity level. Earthworms' growth and prolificacy was evaluated in terms of biomass gain, cocoons production and worm growth rate. Finally, it was inferred that cruciferous vegetables' biomass can be used for vermicomposting. The cauliflower residual biomass has shown better decomposition efficiency than cabbage residual biomass.

The aim of present work was to evaluate periodic changes in bakery industry sludge during vermicomposting. Six different blends of cow dung (CD) and bakery industry sludge (BIS) containing 10 to 50% of BIS were assessed in this study. Changes in physico-chemical parameters were evaluated at 21 days interval up to 105 days. Earthworms significantly increased NPK content and EC, while decreased pH, TOC and C: N ratio of BIS. After vermicomposting, TKN, TAP and TK contents increased 2.0–3.5, 1.2–1.9 and 1.2–1.4 times, respectively as compared to initial blends. A significant reduction (65.4–83.5%) in C: N ratio was observed in all blends. The concentrations of metals were found to be higher in the vermicomposts as compared initial blends. It was inferred that bakery industry sludge spiked with cow dung can be biotransformed into valuable manure employing earthworms.

Two systems were compared for medium-strength dairy wastewater treatment. The first comprised a methanogenic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic MBBR (AeMBBR), while the second an AnMBBR and a sequencing batch reactor (SBR) with Chlorella sorokiniana. The AnMBBR, under ambient conditions, achieves biogas production sufficient enough to attain energy autonomy. The produced energy was 0.538 kWh m−3, whereas the energy consumption 0.025 kWh m−3. Its coupling with the AeMBBR removed COD, NH4-N TKN, and PO4-P by 93 ± 4%, 97 ± 3%, 99 ± 1% and 49 ± 15%, respectively, while the use of the SBR as a second step eliminated totally COD but partially the other pollutants. The higher nitrogen removal in the first system was due to nitrification occurring in the AeMBBR. The acclimatization of microalgae to dairy wastewater enhanced their growth. Their protein content was 54.56%, while starch and lipids were 3.39% and 23.1%, respectively.

Mikania micrantha Kunth is an abhorrent weed that destroys agricultural output. It contains toxic compounds that are detrimental to the natural ecosystem and have negative impacts on the economic and aesthetic aspects of the environment. This study depicts the treatment and management of this plant by in-vessel composting using a 550 L rotary drum composter. Six different mix proportions of biomass, cow dung, and sawdust were used for the study. Rotary drum (RD2) with 2.71% has the highest Total Kjeldahl Nitrogen (TKN). Total Organic Carbon (TOC) decreased to 19.72% at the end of the 20th day. Final C/N ratio falls between 7 and 14 in all the reactors. The phytotoxicity test of Mikania was evaluated using Vigna radiata and Allium cepa. The findings of the study suggest that Mikania can be efficiently utilised to produce mature and stable compost that might be recommended for field application as the process can reduce toxicity.

The effectiveness of specific concentrations of bamboo biochar (BB) on nutrient conservation based on gaseous emissions during poultry manure composting was investigated. The results indicate that the total carbon and nitrogen losses were significantly reduced with elevated of biochar from 542.8 to 148.9% and 53.5 to 12.6% (correspondingly with an additive of 0%, 2%, 4%, 6% and 8% to 10% BB dry weight based). The primary contributor was CO2 and NH3 losses (542.3-148.8% and 47.8-10.81%). The enzyme activities related to carbon and nitrogen metabolism indicated a positive and significantly enhanced with high concentration biochar amended composting. Simultaneously, the alteration of total organic carbon and total Kjeldahl nitrogen as well as maturity indexes during ultimate compost also confirmed a high quality product under higher content biochar amended composting. Carbon and nitrogen were best preserved with 10%BB and produced a superior final product. The analysis of a network and heat map illustrated the correlation of gaseous and physicochemical elements as well as enzyme activities, with an intersection of 68.81%.

The objective of this study was to explore the changes in physicochemical properties and bacterial community during swine manure composting with a new compost tray (CT). The results showed that the organic matter (OM), moisture content (MC), and C/N decreased. The total Kjeldahl nitrogen (TKN), P2O5, K2O and humic acids (HAs) contents of the compost increased. The properties of the final compost product comply with the requirements of regulation except for the moisture according to NY/T 525-2012. Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes were the major phyla during the composting. Genus Terrisporobacter played a key role in degrading organic (OM). The content of K2O was main factors driving the succession of bacterial communities. These findings shed some novel lights into the dynamic changes of physicochemical propertied and their impact on bacterial community in a composting process.

The effects of spent mushroom substrate (SMS) and sucrose (S) amendment on emissions of nitrogenous gas (mainly NH3 and N2O) and end products quality of sewage sludge (SS) composting were evaluated. Five treatments were composted for 20 days in laboratory-scale using SS with different dosages of SMS and S, without additive amended treatment used as control. The results indicated that SMS amendments especially combination with S promoted dehydrogenase activity, CO2 production, organic matter degradation and humification in the composting, and maturity indices of composting also showed that the 30%SMS+2%S treatment could be much more appropriate to improve the composting process, such as total Kjeldahl nitrogen, nitrification index, humic acids/fulvic acids ratio and germination index, while the emissions of NH3 and N2O were reduced by 34.1% and 86.2%, respectively. These results shown that the moderate addition of SMS and S could improve the compost maturity and reduce nitrogenous gas emission.

In this study, the removal efficiency of nitrogen, specific nitrification rate (SNR), specific denitrification rate (SDNR) and compliance rate of the novel tapered variable diameter biological fluidized bed (TVDBFB) and anoxic/oxic (AO) process were compared at different temperatures. The results showed that the optimal TN, NH4+-N, and TKN removal efficiencies of the TVDBFB were 76%, 89% and 88%, respectively, and those of AO were 65%, 67% and 69%, respectively. The SNR and SDNR of the TVDBFB were significantly higher than those of AO. The TVDBFB had a smaller footprint than AO. The alkalinity/NH4+-N, BOD5/TN and temperature play important roles in the compliance rate. Increasing the carrier packing rate has emerged as a new strategy for enhancing the compliance rate. Mathematical models were developed and determined to be well-fitted with the experimental values, which can be employed to predict the SNR and SDNR of the TVDBFB.

Digesters fed on food waste (high nitrogen content) were operated successfully over an extended period using sidestream biogas stripping to control total ammonia nitrogen (TAN) below inhibitory concentrations. This is the first time biogas stripping has been used to achieve stable thermophilic operation with undiluted substrate of this type. Stripping columns operated batch-wise treated the equivalent of 1.7–4.1% of digester contents daily at pH >10 and 70 °C, with no detrimental effect on digestion. TKN removal was 54%, with potential to recover 3.5 kg N tonne −1 substrate. When stripping was stopped in one digester TAN increased, accompanied by rising propionic acid concentrations with progressive instability observed from 2.5 g N L −1 . Eventual failure as TAN approached 5 g N L −1 was due to rapid acetic acid accumulation, resulting in a fall in pH to below 6.5. The pattern of VFA accumulation indicated failure of both acetoclastic methanogenesis and acetate oxidation.

Solid-liquid (S/L) separation of digestate (D) represents a simple technology able to produce two fractions having different composition. The aim of this work was to study the effect of S/L separation on dry matter (DM), nitrogen (TKN), phosphorus (P2O5) and heavy metals (HM) repartition into these two fractions and to characterize them. Therefore, thirteen full-scale digestion plants were studied and D, LF and SF were collected during three seasons of the year. Results obtained indicated that unexpectedly, on a mass balance, the liquid fraction still contains the majority of DM, i.e. 67% of the total of D. LF also contained 87% and 71% of TKN and P2O5 respectively. HM contents were in line with typical NP-organic fertilizers. Chemical characterization suggested that the LF can be used as a substitute for mineral N fertilizers because of its high N content, while SF can be proposed as an NP-organic fertilizer.

Three-layered feedforward backpropagation (BP) artificial neural networks (ANN) and multiple nonlinear regression (MnLR) models were developed to estimate biogas and methane yield in an upflow anaerobic sludge blanket (UASB) reactor treating potato starch processing wastewater (PSPW). Anaerobic process parameters were optimized to identify their importance on methanation. pH, total chemical oxygen demand, ammonium, alkalinity, total Kjeldahl nitrogen, total phosphorus, volatile fatty acids and hydraulic retention time selected based on principal component analysis were used as input variables, whiles biogas and methane yield were employed as target variables. Quasi-Newton method and conjugate gradient backpropagation algorithms were best among eleven training algorithms. Coefficient of determination (R2) of the BP-ANN reached 98.72% and 97.93% whiles MnLR model attained 93.9% and 91.08% for biogas and methane yield, respectively. Compared with the MnLR model, BP-ANN model demonstrated significant performance, suggesting possible control of the anaerobic digestion process with the BP-ANN model.

The study was carried out to gain insight into the effect of pretreatment on enzymatic hydrolysis of kitchen waste (KW) for xanthan fermentation. Herein, various pretreatments were applied and it was found that chemical pretreatment had positive effect on the following enzymatic or overall hydrolysis process. The highest reducing sugar concentration was obtained as 51.87g/L from 2% HCl (90°C) pretreated sample, while the Kjeldahl nitrogen (KDN) concentration was 7.79g/L. Kinetic study showed that first order kinetic model was suitable to describe the enzymatic hydrolysis process. The obtained kitchen waste hydrolysate (KWH) was successfully applied for xanthan fermentation. Xanthan concentration reached 4.09-6.46g/L when KWH with 2% HCl (90°C) pretreatment was applied as medium. In comparison, a xanthan concentration of 3.25-5.57g/L was obtained from KWH without pretreatment. Therefore, pretreatment of KW using diluted acid is favorable for the overall hydrolysis process and effective for xanthan fermentation.

This research investigated the influence of biochar (B) and bean dregs (BD) amendments on carbon and nitrogen losses through greenhouse gas (GHG) emissions during pig manure (PM) composting. The treatments included 15% BD, 10% B and 15% BD+10% B (w/w dry basis of PM) amendments in the compost, whereas the CK (control) lacked any additives. The NH4+-N, C/N and germination index (GI) of the end products ensured compost maturity. Compared with the CK, the 15% BD amendment increased the total nitrogen content (TKN) of the final product by 8.05% but also increased NH3 (54.98%) and GHG emissions (40.35%) as well as nitrogen loss (25.62%). Furthermore, the combined treatment of 15% BD+10% B improved the TKN (2.83%) of the end product and controlled NH3 emissions (33.71%), GHG emissions (29.56%) and nitrogen loss (24.26%) while increasing CO2 only with the 15% BD amendment. Therefore, the combination of BD+B was recommended.

The objective of this study was to explore the relationships among physico-chemical parameters, dissolved organic matters (DOM), and bacterial community during composting to better understand composting performances. The results showed total Kjeldahl nitrogen (TKN) (57%), temperature (39%), and pH (3%) were main factors driving the succession of bacterial communities. Firmicutes was a crucial phylum degrading organic matters for DOM formation, whereas the aromaticity and humification of DOM were closely related to Luteimonas (R2 = 0.971, p 80%), indicating that compost reached maturity and could be safely applied for soil amendment.

This work studied the nitrogen transformation and bacterial dynamics in the co-composting of bean dregs (BD) and pig manure (PM). Four treatments were performed with BD at 0% (CK), 5%, 10% and 15% (w/w dry basis of PM) amended for 49-days aerobic compost. Results revealed that the temperature, NH4+-N and pH of end product all met the maturity requirement. The BD-amendment increased nitrogen losses (8.55%-55.92%) during composting compared to CK. However, this amendment also enhanced total nitrogen content (TKN) of end products (1.86%-12%). The highest content of TKN was in 10%BD-amended treatment with relatively lower nitrogen loss compared to 15%BD. Furthermore, the results of 16S rDNA showed that BD-amended changed the bacterial community composition compared with CK. Especially, 10%BD-amended was the optimum in promoting the diversity and abundance of bacteria. Additionally, Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes and Chloroflexi were dominant phyla and Bacilli was dominant class in BD-amended compost.

Process instability commonly encountered in anaerobic co-digestion (AcoD) of organic fractions of municipal solid wastes (OFMSWs) is addressed by utilizing hydrochar (CB-HTC) and activated hydrochar (ACB-HTC) derived from coffee ground biomass. Addition of CB-HTC or ACB-HTC shortened the lag phase resulting in high biogas yield of 68.57 Nl/kg oTS or 102.86 Nl/kg oTS, respectively within the first week. Improvement in biogas yield (~5% higher than the control) was due to unique properties which prevented washout of consortia of bacteria useful for AcoD and subsequently led to a more stable process. An increase in either OLR [1.0 kg oTS/(m3*d) to 1.5 kg oTS/(m3*d)] or temperature (36.5 °C to 42.5 °C) did not lead to increase in ammonium-nitrogen or TKN in reactors amended with hydrochars. Likewise, ratio of VFA/TA was within 0.2–0.3 after the fourth week in ACB-HTC treated reactor. Addition of ACB-HTC greatly improved nutrient retention in the digestate.

Effect of bamboo biochar (BC) combined with two bacterial powders (B) on gaseous emission and variety of bacterial community during pig manure (PM) composting was investigated. The results showed that treatments of BC, BC + B1 and BC + B2 can reduce peak gaseous emission by 54%, 80% and 69% for CH4, respectively, while 37%, 45% and 45% for N2O, respectively, and 13%, 19% and 26% for NH3, respectively. The evolution of the bacterial community quantified with 16S rDNA analysis showed that in the thermophile stage, total relative abundance percentage of bacterial phyla of Firmicutes and Proteobacteria reached 97%, 97%, 93% and 96% for CK, BC, BC + B1 and BC + B2, respectively. Effects of BC on the compost bacterial community variation analysis proved bacterial activity in the thermophile stage was controlled by the content of dissolved organic carbon and temperature of the compost mixture, while electrical conductivity and total kjeldahl nitrogen also influenced compost maturity stage.

The aim of this study was to determine how the treatment of the HTL AP with activated carbon would affect both growth and chemical composition of the microalgae. Tetraselmis MUR233 was grown in HTL AP (filtered and unfiltered) at 500×, 1000×, and 2000× dilutions in hyper saline conditions. The organic nitrogen and carbon component of the HTL AP was greatly reduced with the activated carbon treatment (TKN 52,000 ± 520 mg/L to 5900 ± 59 mg/L; TOC 19,000 ± 190 mg/L to 13,000 ± 130 mg/L). Growth of Tetraselmis MUR233 was achieved on all dilutions of HTL AP, with a maximum growth observed in the AP filtered 1000× dilution treatment (0.41 ± 0.09 g/L), this compares to a yield of 0.49 ± 0.10 g/L when grown in traditional culture media.

Three mono-digestion experiments treating slaughterhouse waste with high TKN concentration (∼11g/kg) were applied in lab-scale at mesophilic and psychrophilic conditions to study the impact of high ammonia concentrations and additives. Precipitation of sulphur by addition of ferrous chloride did not influence process behaviour, whereas supplementation of trace elements significantly improved process stability by reducing volatile fatty acid concentration towards zero. The limit of NH4-N concentration causing a rise of VFAs to 19,000mg/l and reduction of methane by 25% was found between 7.7 and 9.1g/kg which correspond to NH3 concentrations of 830-1060mg/l. Psychrophilic operation (25°C) lowered inhibitory NH3 concentration to 140mg/l, but process performance was stable only at low OLR of 0.4kgVS/m(3)d. Robust performance at highest possible NH4-N concentration (7.7g/kg), low VFA accumulation and satisfying methane yield of about 280Nm(3)/t COD was observed at OLR of 2.5kgVS/m(3)d at 37°C.

Anaerobic co-digestion of multiple substrates has the potential to enhance biogas productivity by making use of the complementary characteristics of different substrates. A blending strategy based on a linear programming optimisation method is proposed aiming at maximising COD conversion into methane, but simultaneously maintaining a digestate and biogas quality. The method incorporates experimental and heuristic information to define the objective function and the linear restrictions. The active constraints are continuously adapted (by relaxing the restriction boundaries) such that further optimisations in terms of methane productivity can be achieved. The feasibility of the blends calculated with this methodology was previously tested and accurately predicted with an ADM1-based co-digestion model. This was validated in a continuously operated pilot plant, treating for several months different mixtures of glycerine, gelatine and pig manure at organic loading rates from 1.50 to 4.93 gCOD/Ld and hydraulic retention times between 32 and 40 days at mesophilic conditions.

The objective of this study was to determine the effects of cow dung (CD) (at 0%, 20%, and 35%) and/or spent coffee grounds (SCGs) (at 0%, 30%, and 45%) as amendments in the two-stage co-composting of green waste (GW); the percentages refer to grams of amendment per 100g of GW based on dry weights. The combined addition of CD and SCGs improved the conditions during co-composting and the quality of the compost product in terms of composting temperature; particle-size distribution; mechanical properties; nitrogen changes; low-molecular weight compounds; humic substances; the degradation of lignin, cellulose, and hemicellulose; enzyme activities; the contents of total Kjeldahl nitrogen, total phosphorus, and total potassium; and the toxicity to germinating seeds. The combined addition of 20% CD and 45% SCGs to GW resulted in the production of the highest quality compost product and did so in only 21days.

This study evaluated the amelioration of pressmud (PM) and bagasse (BG) wastes by the vermiremediation process. The wastes were spiked with cattle dung (CD) in different concentrations to find out the best proportion supporting maximum earthworm growth and nutrients availability. The highest growth rate was observed in PMBG50 (282.2mg/d/worm) feed mixture. Response surface design of earthworm growth parameters enumerated best concentration of wastes in CD with maximum value of 21.81% for earthworm number, 30.86% for earthworm weight, 27.09% for cocoons, 29.71% for hatchlings and 34.0% for hatchlings weight. Vermicomposting enhanced nutrient parameters like pH (6-8%), total kjeldahl nitrogen (19-48%), total phosphorus (9-67%), total calcium (13-111%), while decrease in total organic carbon (14-32%), electrical conductivity (21-30%), C:N ratio (36-51%), total potassium (9-19%) and total sodium (3-21%). Heavy metals in the final products were found to be under safe limits. SEM micrographs were more fragmented which indicated maturity and stability.

Throughout the sugarcane harvest, it is common for sulfate to accumulate in the vinasse of sugar and ethanol plants. However, little is known regarding the influence of sulfate on the anaerobic digestion (AD) of vinasse, which may lead to severe performance losses. This study assessed the influence of various COD/sulfate ratios (12.0, 10.0 and 7.5) on both COD removal and methane (CH4) production from sugarcane vinasse AD. Batch assays were conducted in thermophilic conditions. At a COD/sulfate ratio of 7.5, CH4 production was 35% lower compared with a ratio of 12.0, considering a diversion of approximately 13.6% of the electron flow to sulfidogenesis. The diversion of electrons to sulfidogenesis was negligible at COD/sulfate ratios higher than 25, considering the exponential increase in CH4 production. Organic matter degradation was not greatly affected by sulfidogenesis, with COD removal levels higher than 80%, regardless of the initial COD/sulfate ratio.

A sixth-generation down-flow hanging sponge reactor (DHS-G6), using rigid sponge media, was developed as a novel aerobic post-treatment unit for upflow anaerobic sludge blanket (UASB) treating municipal sewage. The rigid sponge media were manufactured by copolymerizing polyurethane with epoxy resin. The UASB and DHS system had a hydraulic retention time (HRT) of 10.6 h (8.6 h for UASB and 2 h for DHS) when operated at 10–28 °C. The system gave reasonable organic and nitrogen removal efficiencies. The final effluent had a total biochemical oxygen demand of only 12 mg/L and a total Kjeldahl nitrogen content of 6 mg/L. The DHS reactor gave particularly good nitrification performance, which was attributed to the new rigid sponge media. The sponge media helped to provide a sufficient HRT, and retained a high biomass concentration, extending the solids retention time. The DHS reactor maintained a high dissolved oxygen concentration under natural ventilation.

Four different additives of Medical stone (MS), Zeolite (ZL), Bamboo biochar (BC), and Wood vinegar (WV) were investigated in pig manure composting. The four additives reduced the peak CH4 emission from 54% to 74%, while reduced N2O loss from 36% to 69%, compared with control (CK). WV and ZL showed better ability in N2O loss reduction, yet MS with the efficient inhibition both on CH4 and NH3 emissions. The bacterial community analysis indicated that bacterial diversity in the maturity phase was higher than that in the thermophilic phase, especially with treatments of ZL, BC and WV. The selected factors of pH, temperature, TOC and DOC could influence the thermophilic phase, while EC and TKN related closely with maturity phase in pig manure composting.

A general methodology to implement fermentable soluble substrates in the IWA Anaerobic Digestion Model No. 1 (ADM1) that extends its application to anaerobic co-digestion of multiple substrates is presented. The approach considers the fermentation of new soluble substrates, not originally described in ADM1, as channelled through mass- and electron-balanced sugar fermentation equivalent reactions, and that fermentable substrates are degraded by a generic group of fermenters instead of the original ADM1 sugar fermenters. Therefore, no additional microbial group state is required. An additional term that modifies the ADM1 sugar fermentation kinetics equation was included to account for the competition among multiple substrates to be degraded by a particular biomass group. The model was validated at pilot scale treating a blend of pig manure (soluble fraction), wine and gelatine at mesophilic conditions. Only the ADM1 acetoclastic ammonia inhibition parameter was calibrated to obtain consistent model prediction of gas and liquid composition.

This study aimed to develop an ectopic fermentation system (EFS) to reduce the pollution of cow wastewater and to provide a basis for the production of biofertilizer with fermentation residues. Six thermophilic strains, three of which have efficient cellulose-degrading abilities and the other have good ammonia-N utilizing abilities, were chosen as the microbial inocula. The results showed that EFS inoculated with microbial consortium brought higher temperature and more wastewater was needed to ensure continuous fermentation. The pH values decreased in the early stage of fermentation, and then increased during the process. It caused increases in total Kjeldahl nitrogen, total phosphorous, and total potassium content. Decreases in organic matter content and C/N ratio were also observed. The high level of nutrients indicated the suitability of the paddings after fermentation for agronomic uses. It firstly attempted to combine cow wastewater treatment and bio-organic fertilizer production by EFS with mixed microbial culture.

In this study, an innovative aerobic/anoxic sludge bed bioreactor with two feeding regimes, continuous-fed (an up-flow sludge bed reactor (USBR)) and batch fed (sequencing batch reactor (SBR)), was evaluated for the treatment of an industrial estate wastewater with low BOD5/COD ratio. The process performance in the two regimes was compared. Two numerical independent variables (retention/react time and aeration time) were selected to analyze, model and optimize the process. Response surface methodology with central composite design (CCD) was used with five levels of hydraulic retention time (HRT)/react time (12–36 h) and aeration time (40–60 min/h). In order to analyze the process, ten dependent parameters as the process responses were studied. As a result, HRT/react time showed a decreasing impact on the responses measured in both hydraulic regimes, USBR and SBR. The USBR showed better performance than the SBR in removal of total COD, slowly biodegradable COD, total nitrogen and total Kjeldahl nitrogen.

This work aimed to evaluate the influence of different amounts of bentonite on nutrients transformation during pig manure composting process. The results showed that bentonite had no significant effects on compost temperature and pH changes. While, EC, moisture, OM, TN and NO(3)(-)-N were notably influenced by BT addition. The adding of BT could facilitate OM degradation, increase TKN content and decrease the C/N ratio. Increasing the proportion of bentonite in pig manure compost to reduce extractable heavy metal content is feasible. However, potherb mustard seed GI decreased with the proportion of added bentonite increasing. The results suggest that a proportion of less than 2.5% bentonite is recommended for addition to pig manure compost, and examining the additive ratio in a comprehensive waste composting project is a worthwhile direction for future research.

A bioreactor cascade with a submerged biofilm is proposed to treat young landfill leachate of jbel chakir landfill site south west from capital Tunis, Tunisia. The prototype was run under different organic loading charges varying from 0.6 to 16.3 kg TOC m−3 day−1. Without initial pH adjustment total organic carbon (TOC) removal rate varied between 65% and 97%. The total reduction of COD reached 92% at a hydraulic retention time of 36 h. However, the removal of total kjeldahl nitrogen for loading charges of 0.5 kg N m−3 day−1 reached 75%. The adjustment of pH to 7.5 improved nitrogen removal to a rate of 85% for loading charge of 1 kg N m−3 day−1. The main bacterial groups responsible for a simultaneous removal of organic carbon and nitrogen belonged to Bacillus, Actinomyces, Pseudomonas and Burkholderia genera. These selected isolates showed a great capacity of degradation at different leachate concentrations of total organic carbon.

In this study, a promising system consisting of up-flow anaerobic sludge blanket (UASB) reactor followed by down-flow hanging sponge (DHS) reactor was investigated for onion dehydration wastewater treatment. Laboratory experiments were conducted at two different phases, i.e., phase (1) at overall hydraulic retention time (HRT) of 11h (UASB reactor: 6h and DHS reactor: 5h) and phase (2) at overall HRT of 9.4h (UASB reactor: 5.2h and DHS reactor: 4.2h). Long-term operation results of the proposed system showed that its overall TCOD, TBOD, TSS, TKN and NH(4)-N removal efficiencies were 92 ± 5, 95 ± 2, 95 ± 2, 72 ± 6 and 99 ± 1.3%, respectively (phase 1). Corresponding values for the 2nd phase were 85.4 ± 5, 86 ± 3, 87 ± 6, 65 ± 8 and 95 ± 2.8%. Based on the available results, the proposed system could be more viable option for treatment of wastewater generated from onion dehydration industry in regions with tropical or sub-tropical climates and with stringent discharge standards.

This study focuses on the enhancement of an Austrian anaerobic digestion plant at a slaughterhouse site which exclusively uses animal by-products as substrate. High ammonia concentrations from protein degradation cause severe inhibitions of anaerobic microorganisms. For improving the current situation the COD:TKN ratio is widened by (a) ammonia stripping directly out of the process and (b) addition of a C source to the substrate. Different OLR and HRT were tested in continuous experiments to simulate new operating conditions. The results show that the addition of carbon cannot improve fermentation capacity. The reduction of ammonia boosts the degradation: After reduction of TKN from 7.5 to 4.0 g kg −1 the initially high VFA concentration decreased and the COD degradation was improved by 55.5%. Hence, the implementation of the new N reduction process facilitates either the increase of the OLR by 61% or the reduction of the HRT by 25%.

This study compares organic and nitrogen removals of thermophilic and mesophilic aerobic processes. The experiments were performed in three 7.2 L sequential batch reactors (SBRs) operated at 30, 47 and 60 °C. Molasses based synthetic wastewater consisting chemical oxygen demand (COD): 11,200 mg/L, total kheljal nitrogen (TKN): 770 mg/L, ammonical nitrogen (NH4): 560 mg/L was the feed medium. Biokinetic parameters, COD, NH 4 + and TKN removal efficiencies were compared under six different operating conditions. Five times lower sludge production and similar COD removal were observed in thermophilic SBRs compared to mesophilic SBR under 8.25 kg COD/m3 d loading rate. However at 24.75 kg COD/m3 d there were no differences in terms of sludge production while COD removals were varied as 59%, 80% and 82% at 30, 47 and 60 °C respectively. A mechanism was developed to understand the varying behaviors of thermophilic aerobic process. Stripping is the major mechanism for nitrogen removal in thermophilic SBRs.

This investigation examined the effects of nitrogen source and concentration on the ash free dry biomass (AFDB) and oil accumulation and productivity of a Scenedesmusrubescens like alga cultivated in indoor photo-bioreactors and outdoor raceway ponds. Among the nitrogen sources ((NH4)2CO3, urea, NaNO3, urea and NaNO3 mixture), the algae fed with the mixture of urea-N and NaNO3-N had the highest AFDB productivity of 0.539±0.040 g/L/d and the content of fatty acid methyl esters (FAME) (%) fed with (NH4)2CO3-N increased continuously for 17 days and reached 42.94±2.05% in the indoor photo-bioreactors. The content of C18 series (as % of total FAME) was high in all the treatments of nitrogen sources. The algae fed with (NH4)2CO3-N had the highest FAME productivity of 0.133 g/L/d (P

Anaerobic digestion of tomato, cucumber, common reed and grass silage was studied in four separate two-stage reactor configuration consisting of leach bed reactor (LBR) and upflow anaerobic sludge blanket reactor (UASB). LBR studies showed that COD solubilization for cucumber and grass silage was higher (50%) than tomato (35%) and common reed (15%). Results also showed that 31–39% of initial TKN present in tomato and cucumber was solubilized in the leachates and 47–54% of the solubilized TKN was converted to NH4-N. The corresponding values for common reed and grass silage were 38–50% and 18–36%, respectively. Biomethanation of the leachates in UASB reactors resulted in methane yields of 0.03–0.14 m3 CH4 kg−1VSfed for the studied crop materials. Thus, high COD solubilization, high nitrogen mineralization and solubilization rates were feasible during anaerobic digestion of lignocellulosic materials in a two-stage LBR–UASB reactor system.

Composting has been identified as a viable means of reducing the environmental impact of antibiotics in manure. The focus of the present study is the potential use of composting on the degradation of salinomycin in manure prior to its field application. Manure contaminated with salinomycin was collected from a poultry farm and adjusted to a C:N ratio of 25:1 with hay material. The manure was composted in three identical 120 L plastic containers, 0.95 m height x 0.40 m in diameter. The degradation potential for salinomycin was also ascertained under open heap conditions for comparison (control). Salinomycin was quantified on HPLC with a Charged Aerosol Detector, at an interval of every 3 days. The salinomycin level in the compost treatment decreased from 22 mg kg(-1) to 2 x 10(-5) microg kg(-1) over 38 days. The corresponding decrease in the control was from 27.5 mg kg(-1) to 24 microg kg(-1). The changes in pH, EC (dS m(-1)), temperature, total kjeldahl nitrogen (TKN), total potassium (TK), total phosphorus (TP) and carbon content in both the composting and the control samples were monitored and found to be different in compost as compared to the control. During the composting process, the loss of TKN was 36%, which was substantially lower than corresponding loss of 60% in the control. The loss of carbon was 10% during composting, whereas the loss in the control was 2%. In composting, the temperature modulated from 27 degrees C (initially) to a high of 62.8 degrees C (after 4 days), and then declined to 27.8 degrees C at the end of 38 days. On the basis of the results obtained in this study, it appears that the composting technique is effective in reducing salinomycin in manure.

This study investigates for the first time, on laboratory scale, the possible exploitation of the advantages of two-phase anaerobic digestion for treating a mixture of olive mill wastewater (OMW) and olive mill solid waste (OMSW) using two sequencing semi-continuous digesters operated at mesophilic temperature (37+/-2 degrees C). The experiments were conducted at hydraulic retention times (HRTs) of 14 and 24 days corresponding to organic loading rates (OLRs) ranging from 5.54 to 14 g COD/L/day in the first stage (acidifier) and at HRTs of 18, 24 and 36 days corresponding to OLRs ranging from 2.28 to 9.17 g COD/L/day in the second stage (methanizer). The results indicated that volatile fatty acids (VFA) concentrations increased with the increase of either HRT or feed concentration and their high values were obtained with the most concentrated influent (196+/-5 g COD/L) digested at the longest HRT (24 days) corresponded to an OLR of 8.17 g COD/L/d. Furthermore, two-phase anaerobic digestion system has given the best performances concerning methane productivity, soluble COD (SCOD) and phenol removal efficiencies and effluent quality compared to those given by conventional one-phase anaerobic digestion (AD) reactors.

The aim of this study was to determine the effectiveness of natural flocculants to reduce solids and nutrient loads in dairy cow wastewater using solid-liquid separation; chitosan was used as a model. Its use efficiency and optimum application rate were determined using flushed dairy cow manure of varied strengths - 0.4%, 0.8%, 1.6%, and 3.2% total solids (TS) content. Treatments consisted of nine rates of chitosan. The flocculated manure was dewatered using 1-mm and 0.25-mm screens. Separation by screening alone was not effective; average efficiencies were about 60% for total suspended solids (TSS), 22% for total Kjeldahl nitrogen (TKN), and 26% for total phosphorus (TP). Mixing with chitosan before screening substantially increased separation. At optimum chitosan rate (0.5g/L for the highest strength effluent), separation efficiencies were >95% for TSS, >73% for TKN, and >54% for TP. The results of this study indicate that natural flocculants such as chitosan are useful for the solid-liquid separation treatment of livestock wastewater.

Fewer and fewer municipal solid wastes are treated by composting in China because of the disadvantages of enormous investment, long processing cycle and unstable products in a conventional composting treatment. In this study, a continuous thermophilic composting (CTC) method, only a thermophilic phase within the process, has been applied to four bench-scale composting runs, and further compared with a conventional composting run by assessing the indexes of pH, total organic carbon (TOC), total Kjeldahl nitrogen (TKN), C/N ratio, germination index (GI), specific oxygen uptake rate (SOUR), dissolved organic carbon (DOC) and dehydrogenase activity. After composting for 14 days, 16 days, 18 days and 19 days in the four CTC runs, respectively, mature compost products were obtained, with quality similar to or better than which had been stabilized for 28 days in run A. The products from the CTC runs also showed favorable stability in room temperature environment after the short-term composting at high temperature. The study suggested CTC as a novel method for rapid degradation and maturation of organic municipal solid wastes.

In view of the pressing problem that appears in our region (Asturias, north of Spain) with the residues from the cider production, it was decided to test this kind of material as a co-substrate joint with slaughterhouse waste in a laboratory unit. The anaerobic digestion of apple pulp was investigated for biogas production. This paper presents the results where apple pulp was co-digested with slaughterhouse waste (pig intestine and bovine stomach content) in a biogas laboratory unit (10 l CSTR reactor). The production of biogas has reached very satisfactory values during the whole test (0.8m(3)kg(-1)OTS), verifying that the process is kept in stable conditions of pH (near 8.0), and the volatile fatty acids was always underneath 3000 mg/l, when the pulp amount was lower than 100g in mesophilic conditions. The fat concentration into the digester remained always below the value that causes inhibition of the methanogenic bacteria, 500 mg/l. Finally, methane concentration (77-80%) and H(2)S concentration (400 ppm) in the biogas, they were similar to those obtained when the test was run out in the absence of apple pulp. The process efficiency with respect to COD removal was high, near 80% of the total COD. Finally, inhibitory effects of methanogenic bacteria were observed when pulp concentration was around 10% in the input material.

The aim of this work was to develop simple and fast tests to predict anaerobic biogasification potential (ABP) of ingestates and digestates from a biogas plant. Forty-six samples of both ingestates and digestates were collected within an eight-month observation period and were analyzed in terms of biological and chemical parameters, namely, ABP test, oxygen demand in a 20-h respirometric test (OD20), total solids (TS), volatile solids (VS), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonia, cell solubles (CS), acid detergent fibers (ADF), lignin (ADL), cellulose, and hemicellulose. Considering both quantitative (VS and TOC) and qualitative aspects (OD20 and CS) of organic matter (OM), four models (linear regressions; 0.80 < R 2 < 0.913; 16% < standard errors < 23%) were proposed to predict ABP. The models were chosen according to the needed accuracy of the evaluation in terms of time schedule and the availability of the required laboratory analyses.

A correct separation of solids from liquid fraction is crucial for a successful treatment of swine manure. For this reason an in-depth study of flocculant addition on different livestock wastewaters was carried out. Two flushed swine manure matrices, namely the mixture from nursery and feeder-to-finish pigs and the feeder-to-finish slurry alone, were tested for solids and nutrients removals from liquid fractions. The separation techniques applied were sieving and flocculation. A range of 80-200 ppm of polyacrylamide (PAM) followed by screening was employed in the case of flocculation treatment. The best results were observed when using the highest PAM dose in the matrix correspondent to the mixture of slurries. The removal rates in the liquid fraction were 73% for total solids, 87% for volatile solids, 98% for suspended total and volatile solids, 71% for chemical oxygen demand, 40% for total Kjeldahl nitrogen, and 34% for soluble phosphorus. Once the best PAM dose (120 ppm) was chosen, an anaerobic biodegradability study was performed in order to check the increase of methane production in the separated fractions by using the flocculant and the screen. The assay determined that the solid fractions biodegradability was constant at 79%. Meanwhile for the liquid fractions, an increase of 9% points was achieved with PAM-amendment when compared with 82% reached for the liquid fraction obtained by screening.

The feasibility of recirculation of currant-finishing wastewater in a currant-wash process was investigated in a laboratory scale plant. Recycle ratios from 0% to 95% were examined. By increasing the recycle ratio, effluent BOD increased from 681 to 5378 mg/l, effluent COD from 3808 to 43,722 mg/l, total suspended solids from 12.3 to 57.7 g/l, total sugars from 2.57 to 42.13 g/l, total phosphorus from 0.79 to 5.14 mg/l, total Kjeldahl nitrogen from 7.36 to 51.9 mg/l and total phenolic compounds from 0.095 to 1.13 g/l, while fresh water addition decreased from 6 to 0.3 kg/kg of currants processed and total sugars loss from 15.43 to 12.64 g/kg of currants processed. For a recycle ratio of 95%, the mass of currants recovered as a final product increased by 10% due to the proportional decrease in the sugars wasted per kg of currants processed.

This work examined 19 carbon samples prepared by acid and thermal activation of various agro-residues viz. bagasse, bagasse flyash, sawdust, wood ash and rice husk ash for color removal from biomethanated distillery effluent. Phosphoric acid carbonized bagasse B (PH) showed the maximum color removal (50%). However, commercial activated carbons AC (ME) and AC (LB) showed better performance of over 80% color removal. Besides color removal, activated carbon treatment also showed reduction in chemical oxygen demand (COD), total organic carbon (TOC), phenol and total Kjeldahl nitrogen (TKN). The performance was related to the characteristics of the investigated samples. Further, adsorption isotherms for melanoidins, which is the primary coloring compound in distillery spentwash, followed the Langmuir isotherm implying monolayer adsorption.

Dairy manure with a total solids content of 77.2 g TS/l was separated by means of screening and coagulation–flocculation treatments, using CaO as coagulant and a cationic polyacrylamide as flocculant, obtaining liquid and solid fractions. The solid fraction separated contained 33.4% of the initial total mass of dairy manure plus chemical solutions, containing also 75.2% of the TS, 80.4% of the VS, 58.5% of the total Kjeldahl nitrogen (TKN) and 87.4% of the total phosphorus (P T ) present in the initial dairy manure. 83.7% of the liquid fraction chemical oxygen demand (COD) was anaerobically biodegradable (COD BD ). Methane production for the separated liquid fraction was 0.604 l CH 4 NCTP/g VS added, being 0.307 and 0.371 l CH 4 NCTP/g VS added for dairy manure and screened dairy manure, respectively. The characteristics of this liquid fraction would allow its treatment in high loading anaerobic reactors having shorter hydraulic retention times, smaller reactor size and a higher methane volumetric production rate than conventional anaerobic reactors treating either manure or screened manure.

A study (100 days duration) was conducted to evaluate the efficiency of an exotic earthworm species (epigeic-Eisenia foetida) for decomposition of different types of organic substrates (kitchen waste, agro-residues, institutional and industrial wastes including textile industry sludge and fibres) into valuable vermicompost. The percentage of, nitrogen, phosphorous and potassium in vermicompost was found to increase while pH and total organic carbon declined as a function of the vermicomposting period. 4.4-5.8-fold increases in TKN was observed in different feed mixtures at the end of vermicomposting period. The increase in TKN for different feed substrates was found in the order: textile sludge>textile fibre=institutional waste>agro-residues>kitchen waste. Available Phosphorus increased 1.4 to 6.5-fold in different feed mixtures in comparison to control. Reduction in TOC was highest in agro-residues (3-fold) followed by kitchen waste (2.2-fold), institutional waste (1.7-fold) and textile industrial wastes (sludge, 1.5-fold and fibre, 1.68-fold) in earthworm-inoculated pots than control. The data reveals that vermicomposting (using E. foetida) is a suitable technology for the decomposition of different types of organic wastes (domestic as well as industrial) into value-added material.

The study reports the effects of irrigation of a sodic soil with post methanation effluent (PME) of a distillery. Impact of long term effluent irrigation in the field (10 years) and short term effluent irrigation using different doses of PME in the laboratory (30 days) was studied in combination with three bioamendments i.e. farmyard manure, brassica residues and rice husk. Impact on various soil properties like EC, pH, total organic carbon (TOC), total Kjeldahl nitrogen (TKN), available phosphorus, exchangeable K, Na, Ca, Cl, microbial population and soil enzyme activities were studied. Long term application of PME proved useful in significantly increasing TOC, TKN, K, P and soil enzymatic activities in the soil but tended to build up harmful concentration of Na, that could be chelated by bioamendments. In short terms studies, application of 50% PME along with bioamendments proved to be the most useful in improving the properties of sodic soil and also favoured successful germination and improved seedling growth of pearl millet.

This paper reports the results of a study of vermicomposting with Eisenia foetida of solid textile mill sludge mixed with cow dung in different ratios in a 90 days composting experiment. Vermicomposting resulted in significant reduction in C:N ratio and increase in TKN. Total K and Ca were lower in the final cast than the initial feed mixture. Microbial activity measured as dehydrogenase activity increased up to 75 days and decreased on further incubation. Total P was higher in the final product than the initial feed mixture. Total heavy metal contents were lower in the final product than initial feed mixture. Solid textile mill sludge can be potentially useful as raw substrate in vermicomposting if mixed with up to 30% cow dung (on dry weight basis). The growth and cocoon production of the worm species in different feed mixtures were also investigated.

A comparative study was conducted between exotic and local (epigeic--Eisenia fetida and anaecic--Lempito mauritii, respectively) species of earthworms for the evaluation of their efficacy in vermicomposting of municipal solid waste (MSW). Vermicomposting of MSW for 42 days resulted in significant difference between the two species in their performance measured as loss in total organic carbon, carbon-nitrogen ratio (C:N) and increase in total Kjeldahl nitrogen, electrical conductivity and total potassium and weight loss of MSW. The change in pH and increase in number of earthworms and cocoons and weight of earthworms were non-significant.