Sulfonamide antibiotic removal and nitrogen recovery from synthetic urine by the combination of rotating advanced oxidation contactor and methylene urea synthesis process.

The combination of nitrogen recovery and pharmaceutical removal processes for livestock urine treatment were investigated to suppress the discharge of pollutants and recover nitrogen as resources. We combined methylene urea synthesis from urea and adsorption and photocatalytic decomposition of sulfonamide antibiotic using rotating advanced oxidation contactor (RAOC) contained for obtaining both safe fertilizer and reclaimed water. The methylene urea synthesis could recover urea in synthetic urine, however, almost all sulfonamide antibiotic was also incorporated, which is unfavorable from a safety aspect if the methylene urea is to be used as fertilizer. Conversely, RAOC could remove sulfonamide antibiotic without consuming urea. It was also confirmed that the methylene urea could be synthesized from synthetic urine treated by RAOC. Thus, we concluded that RAOC should be inserted prior to the nitrogen recovery process for effective treatment of urine and safe use of methylene urea as fertilizer.

Toilet compost and human urine used in agriculture: fertilizer value assessment and effect on cultivated soil properties.

Toilet compost (TC) and human urine are among natural fertilizers, which raise interest due to their double advantages to combine sanitation and nutrient recovery. However, combination of urine and TC is not so spread probably because the best ratio (urine/TC) is still an issue and urine effect on soil chemical properties remains poorly documented. This study aims to determine the best ratio of urine and TC in okra cultivation, by targeting higher fertilization effect combined with lower impact on soil chemical properties. Based on Nitrogen requirement of okra, seven treatments were compared: (T0) no fertilizer, (T1) chemical fertilizer (NPK: 14-23-14), (T2) 100% urine, (T3) 100% TC, (T4) ratio of 75% urine+25% TC, (T5) 50% urine+50% TC and (T6) 25% urine+75% TC. Results indicated that T4 (75% urine+25% TC) gave the highest plant height and yield. In contrast, T2 (100% urine) gave the lowest results among all treatments, indicating toxicity effects on plant growth and associated final yield. Such toxicity is confirmed by soil chemical properties at T2 with soil acidification and significant increase in soil salinity. In contrast, application of urine together with TC mitigates soil acidification and salinity, highlighting the efficiency of urine and TC combination on soil chemical properties. However, further investigation is necessary to refine better urine/TC ratio for okra production.

Designing slanted soil system for greywater treatment for irrigation purposes in rural area of arid regions.

To solve the unpleasant disposal of greywater in rural area and allow its collection for reuse in gardening, a slanted soil treatment system (SSTS) was designed and installed in two households. Granitic gravel of 1-9 mm size was used as the filter medium. The aim of this study was to design a SSTS and assess its suitability as a treatment system allowing greywater reuse in gardening. The efficiency of the SSTS was assessed based on organic matter and bacterial pollution removal. The developed SSTS allowed the collection of greywater from three main sources (shower, dishwashing and laundry) in rural area. The SSTS is efficient in removing at least 50% of suspended solids, chemical oxygen demand and biological oxygen demand. The study highlighted that, contrary to the common perception, greywater streams in rural area are heavily polluted with faecal indicators. The removal efficiency of faecal indicators was lower than 2 log units, and the bacteriological quality of the effluents is generally higher than the WHO reuse guidelines for restricted irrigation. Longer retention time is required to increase the efficiency. The possibility of reusing the treated greywater as irrigation water is discussed on the basis of various qualitative parameters. The SSTS is a promising greywater treatment system for small communities in the rural area in the Sahelian region. To increase the treatment efficiency, future research will focus on the characteristics of the SSTS, the grain size and the establishment of a pretreatment step.

Inactivation mechanisms of pathogenic bacteria in several matrixes during the composting process in a composting toilet.

This study aimed to compare the inactivation rate and the mechanisms of pathogenic bacteria in three matrixes (sawdust, rice husk and charcoal) during the composting process. The inactivation rate was evaluated with Escherichia coli strain and the damaged parts and/or functions were evaluated with three different media. Normalized inactivation rate constant in three media and from three matrixes had no significant difference in each process (pure, 1 month and 2 months). The value in rice husk was relatively increased during 2 months but there was no significant difference. The inactivation rate constants of Tryptic Soy Agar (TSA) and Compact Dry E. coli/Coliform in pure sawdust and rice husk were relatively lower than that of Desoxycholate Agar, but increased in 2 months. This indicated that damaging part was changed from outer membrane to enzymes and metabolisms during the 2-month composting process. In the case of charcoal, only the TSA value in apure matrix was relatively lower than that of others, but it increased in 2 months. This indicated that damaging part was changed from outer membrane and enzyme to metabolisms during the composting process. Composting matrix and composting process did not significantly affect inactivation rate of pathogenic bacteria during the process but affected the damaging part of the bacteria.

Adsorptive removal of sulfonamide antibiotics in livestock urine using the high-silica zeolite HSZ-385.

The adsorptive removal of seven sulfonamide antibiotics using the high-silica zeolite HSZ-385 from distilled water, synthetic urine and real porcine urine was investigated. The pH greatly affected the adsorption efficiency, and the amounts of all sulfonamide antibiotics adsorbed on HSZ-385 decreased at alkaline conditions compared with that at neutral conditions. During storage, the pH and ammonium-ion concentration increased with urea hydrolysis for porcine urine. We clarified that the adsorption efficiency of sulfonamides in synthetic urine was equivalent to that in distilled water, suggesting that adsorption behavior was not affected by coexistent ions. HSZ-385 could adsorb sulfonamide antibiotics in real porcine urine even though the non-purgeable organic carbon concentration of porcine urine was 4-7 g/L and was two orders of magnitude higher than those of sulfonamides (10 mg/L each). Moreover, the adsorption of sulfonamides reached equilibrium within 15 min, suggesting that HSZ-385 is a promising adsorbent for removing sulfonamides from porcine urine.

Assessment of wastewater-irrigated soil containing heavy metals and establishment of specific biomarkers.

Irrigation with treated wastewater (TWW) is a vital alternative for arid and semi-arid lands but it poses pollution-risk to soil, vegetation and groundwater. Therefore, in the present study, in vitro bioassays were used to evaluate the adverse effects of TWW and irrigated-soil extract sample, on mammalian cells, with respect to heavy metal--Ni, Cd, Pb, Fe, Al-content. The heat shock protein (HSP) 47, E-screen, and transepithelial electrical resistance (TEER) assays served to investigate the stress response of treated-HSP47-transfected Chinese hamster ovary (CHO) cells, the estrogenic activity of the samples in MCF-7 breast cancer cells, and the barrier function (BF) of Caco-2 cells. Furthermore, proteomics analyses were performed to shed light on involved mechanisms and to establish pollution biomarkers. Results showed that the TWW elicited a stress response on HSP cells from 0.1% concentration while soil extract samples exhibited a stress at 1%. TWW induced an estrogenic activity at 10%; up-regulating cell proliferation and tumor-related proteins. Soil extract triggered the enhanced expression of HSP70 family proteins as survival mechanisms against their cytotoxicity toward MCF-7 cells. Moreover, depending on the concentration, 1% of soil extract from 20 cm depth (T20) resulted in a disruption of BF in Caco-2 cells involving cell metabolism, protein synthesis and tumor marker proteins, whereas, 5% of T20 induced the expression of BF-related proteins associated to heat shock, oxidative stress, cell proliferation and glycolytic metabolic pathway. These biological techniques were found to be extremely useful to evaluate the impact of wastewater reuse and to establish specific biomarkers that are common proteins for humans, other mammals and plants. Future studies should focus on exposure quantifications.

Fate of nitrogen during volume reduction of human urine using an on-site volume reduction system.

This study was carried to assess the effect of a mixture of salts, urea and creatinine on water evaporation from urine using an on-site volume reduction system in long-term experiments. Subsequently, the fate of nitrogen during volume reduction of urine was also assessed. The water evaporation rate, salt accumulation in the gauze sheet, concentrations of urea and ammonia-N, and pH of urine were measured periodically. Based on the results, a mass balance of nitrogen in concentrated urine was calculated for a moderate evaporating condition. The results revealed that steady-state evaporation was observed throughout the experiment period without any inhibition due to salt accumulation. Salt concentration in the gauze sheet reached steady-state illustrating the possibility of salt falling back to the tank from the sheet. No significant reduction of urea was observed for a moderate evaporating condition, which indicates inhibition of urea hydrolysis by the high concentration of the mixture of salts, urea and creatinine in the urine. In contrast, for a low evaporating condition, the pH of the urine increased to 8.9, which indicates early urea hydrolysis, causing an offensive odour and ammonia loss to the air. In simple storage experiments, a mixture of salts, urea and creatinine amounting to 227-334 g L(-1) in urine inhibited urea hydrolysis, even with faecal contamination, at 25 degrees C, while urine samples containing a mixture of salts, urea and creatinine at less than 227 g L(-1) did not provide strong inhibition of hydrolysis.

Comparison between treatment of kitchen-sink wastewater and a mixture of kitchen-sink and washing-machine wastewaters.

In this paper, a submerged membrane bioreactor was used to treat 'higher-load' grey water: (a) kitchen-sink wastewater only, and (b) a mixture of kitchen-sink wastewater and washing-machine wastewater. For each type of wastewater, three systems operated at different hydraulic retention times (HRTs) were investigated. In the mixture of kitchen-sink wastewater and washing-machine wastewater, the reactor with a short HRT of four hours was stopped due to foaming. It has been observed that for both types of wastewater, an HRT of eight hours or longer can be used for the treatment. However, it has been observed that a higher COD in the permeate of the mixture can be obtained compared with that of the kitchen-sink wastewater only. This indicated that washing-machine wastewater has some component that is not easily biodegradable. The total linear akylbenzene sulfonate (LAS) removal was > 99% even at a concentration of 10-23 mg 1(-1).

Inhibition factor of ammonification in stored urine with fecal contamination.

Inhibition factors of urea hydrolysis caused by fecal contamination as source of urease were investigated. The urea hydrolysis was described by initial ammonification rate (IAR). Three factors for the inhibition (pH, free ammonia nitrogen (FAN) and salinity) were investigated in this study. It was found that the optimum pH value for the urea hydrolysis was obtained at pH 7 (30 degrees C). Similar results were obtained from pH 5 to pH 8 whereas pH 9 provided a little amount of negative effect on the hydrolysis. Significant effect of the FAN as inhibition factor on the urea hydrolysis was obtained in the urea solution: the hydrolysis was observed within 120 mg-N/l of the FAN level in artificial urea solution with fecal contamination. However in storage process of real urine the urea hydrolysis was observed until the FAN level increased up to 2,000 mg-N/l. Salinity obviously provided negative effect on the urea hydrolysis in stored urine with fecal contamination at 30 degrees C. It was assumed that high concentration of the NaCl (150 g/l) was required to achieve 50% reduction of the IAR.

Experimental study on nitrogen components during composting process of feces.

We measured nitrogen components during composting process of feces in a batch test in which sawdust was used as a matrix. Further decomposition rates of fecal nitrogen and carbon were obtained in the batch tests of different feces loading. In composting material that was a mixture of sawdust and fresh feces, fecal organic matter decomposed to CO2 and fecal nitrogen mineralized to ammonia during the composting process. The biological response of organic matter and nitrogen in the composting material was evaluated by oxygen consumption (OUR) and ammonia production that was a sum of volatilized ammonia gas and ammonia remaining in the composting material. Since composting material contains two different sources of organic matter from feces and sawdust, the OUR by using the sawdust matrix only was evaluated in preliminary tests. The fecal contribution to the OUR in the composting material was therefore calculated by subtraction of the result in the preliminary tests from the one in the composting material. The ammonia production from the fecal nitrogen was obtained by the same procedure. The decomposition rates of input organic matter in feces were approximately 83 and 70% respectively, whereas ammonia production rates were approximately 73 and 58% of input fecal nitrogen. There was an interesting time lag of the peak time between volatilisation rates of ammonia and CO2 during the composting process while fecal carbon and nitrogen simultaneously decomposed to ammonia and CO2 in the composting material.

Toxicity assessment of the extract of compost as a final product from Bio-Toilet.

Bio-Toilet is the name of a dry closet or composting toilet using sawdust as an artificial soil matrix for bioconversion of human excrement into compost. Since feces and urine contain several chemicals such as pharmaceutical residues and endocrine disruptors and they may still remain in compost after biological reaction in the Bio-Toilet, it is required to examine the possibility of soil and/or groundwater pollution by applying compost to a soil system in farmland. In this study, toxicity of Bio-Toilet compost was evaluated by measuring the viability of human neuroblast (NB-1). The bio-assay was applied to the water extract of compost from the Bio-Toilets which are in practical use in Japan. The assay results showed that (1) the extract of feces showed no toxicity, and the extracts of unused sawdust had no or low level toxicity and (2) the extracts of composts had heavier toxicity than unused sawdust. These results implied that some chemicals that have toxicity were generated by biological reactions or accumulated in toilet system. The bioassay results with fractionated organic matter by its molecular weight showed that the small molecular weight fraction had stronger toxicity than other fractions. The effect of inorganic matter on toxicity was examined by comparing the dose-response relationship of the extracts of compost with positive control with 1M of sodium chloride solution. The comparison showed that sodium concentration in the extract was too low to develop the toxicity and the effect of inorganic matter could be neglected in this study.

Biological activity in the composting reactor of the bio-toilet system.

The bio-toilet is becoming commercially available and it is actually used in Japan in public parks, sightseeing areas, and households; however, the biological activity in the system during degradation of toilet wastes, particularly faeces, is unknown. Thus, in this study activity of microorganisms in the bio-toilet system during degradation of faeces was assessed through the quantification of reductions in total solids (TS), volatile solids (VS), and chemical oxygen demand (COD) during batch tests in laboratory-scale composting reactors. Additionally, the fate of nitrogen and its transformation processes in such reactors were evaluated. TS, VS, and COD reductions were on the order of 56%, 70%, and 75%, respectively, irrespective of the organic loading regarded. Total nitrogen (T-N) reductions quantified 94%, regardless of the organic loading. Furthermore, all T-N reductions observed during composting were equivalent to the NH(3)-N released from the reactor, i.e., 94% of ammonia was lost.

Role of hydrophilic organic matter on developing toxicity in decay process of activated sludge.

It is known that the toxicity of effluent is more intensive than that of influent in the activated sludge process. In this study, we applied bioassay using cultured human cell lines to the decay process of activated sludge to evaluate the toxicity of organic matter generated and/or released from activated sludge bacteria. We also applied this bioassay to hydrophilic fraction of samples. The bioassay results showed that: (1) the variation in the dose-response relation obtained from assay with original samples was observed during decay; (2) on the other hand, the response curves of only hydrophilic fraction at each time show the same relationship between TOC and viability of MCF7 cells; (3) this trend was confirmed by plotting the time course of EC50. These results imply that: (1) the hydrophilic organic matter controlled for developing toxicity during decay process of activated sludge; and (2) the character of hydrophilic organic matter is not changed during the experimental period.

Organic matter released from activated sludge bacteria cells during their decay process.

Organic matter released from activated sludge bacteria is a considerable issue in the wastewater reclamation process. In this study, we focused 2-keto-3-deoxyoctulosonic acid in the Lipopolysaccharide existed in the gram-negative bacterial cell wall as an index of organic matter released from bacteria, and investigated the fate of 2-keto-3-deoxyoctulosonic acid in the aerated and ultrasonicated activated sludge samples. The results shows 1) 2-keto-3-deoxyoctulosonic acid concentration in the hydrolyzed sample was higher than non-hydrolyzed sample, and this implied that 2-keto-3-deoxyoctulosonic acid existed in the water phase as a monomer and also as a polymer such as Lipopolysaccharide form and their fragments; 2) the value of (2-keto-3-deoxyoctulosonic acid)/(dissolved organic carbon) ratio did not change in the sludge sonication process and was approximately 0.0006, on the other hand, in the bacteria decay process, the ratio varied from zero to approximately 0.0012; 3) the linear relationship was observed between the degraded heterotrophic biomass and the generated 2-keto-3-deoxyoctulosonic acid; and 4) 2-keto-3-deoxyoctulosonic acid might be considered as an index of organic matter originated from activated sludge bacteria cell.

Mathematical model for describing reactions of residual chlorine with organic matter in reclaimed wastewater.

Among several applications of urban wastewater reuse, use of reclaimed wastewater to sustain stream flows has become attractive in the urban area. Since these rivers are used for recreational purposes and for restoring aquatic eco-system, the adequate control of residual chlorine is essential. Mathematical model for describing reactions between residual chlorine and organic matter in reclaimed wastewater has been developed. The model considers the effect of molecular weight distribution of organic matter on the reaction rate. Lab-scale experiments were performed to estimate reaction rates constants and to examine their temperature dependency. The experiments showed that 1) the smaller organic matter gave the larger reaction rate; 2) temperature effect on reaction rate was described by the Arrhenius formula; 3) decline of free chlorine had more temperature dependency than combined chlorine. The comparison of computed results with data from lab-scale experiments confirmed the validity of the model. We used the one-dimensional dispersion model with proposed reaction model and examined the seasonal variation of residual chlorine profile along the river sustained by reclaimed wastewater in Sapporo. Simulation showed that seasonal variation of nitrification performance in secondary treatment as well as change in temperature caused seasonal variation in residual chlorine profile along the river.

Reuse of heat energy in wastewater: implementation examples in Japan.

Sewage and treated water can be a heat source in urban area due to large heat capacity, thus recovery and reuse of its energy is one of the most desirable plans for the sewerage system. In this paper, characteristics of heat energy in wastewater, reuse plans, and some experiences in Japan are presented. Full-scale reuse projects for heating and cooling in the Tokyo Metropolitan Districts and project for melting snow in Sapporo City are discussed. The key factors found in experience of Tokyo were setting the heat pumps near the demand points and the technical developments of equipment to prevent system from clogging, corrosion, and decrease in the heat transfer efficiency. It was also found through the project for melting snow in Sapporo that the key factor in public acceptance was the multi-purpose use of the sewerage system both for melting snow in winter and retaining rain water in summer.

Onsite wastewater differential treatment system: modeling approach.

In this paper, the Onsite Wastewater Differential Treatment System (OWDTS), a new approach for improving the traditional onsite wastewater treatment systems (OWTS), is proposed based on differential management and treatment of household wastewater effluents. Three fractions of household wastewater have been differentiated, reduced-volume blackwater, higher-load graywater and lower-load graywater. Based on this differentiation, different treatment processes required for each fraction are discussed. The procedure adopted for treatment of toilet wastes (reduced-volume blackwater) is shown. In the case of graywater, a sketch of treatment processes is provided. The OWDTS seems to be a new approach with higher potential for improvement of traditional OWTS, dry ecological sanitation, recycling of resources (toilet wastes and water), conservation of water resources, etc. Aerobic biodegradation of toilet wastes by using sawdust as a matrix is an essential treatment process of the OWDTS. Membrane technology seems to be the most effective process to treat higher-load gray water. Natural biodegradation of lower-load gray water by soil bacteria needs to be deeply studied.

Toxicity assessment of treated wastewater using cultured human cell lines.

Bioassay using cultured human cell lines was applied to an effluent of a wastewater treatment plant (WWTP) in Sapporo to assess their toxicity, and in order to investigate the fate of toxicity in the WWTP, bioassay of the water samples from several points in WWTP (influent, effluent, return flow from thickener, from dewatering process and from incineration process) was performed. We also applied bioassay to the mixture of the activated sludge from the investigated plant and artificial sewage. These results showed that the toxicity of the effluent was more intensive than the influent, and organic matter released from activated sludge bacteria during their decay process contributed to the increase of toxicity in the effluent.

Measurement of bacterial growth potential in a reclaimed water.

The objectives of this paper are to show a bio-assay method using direct total microbial count (DTMC) and to demonstrate the applicability of this method to reclaimed water for evaluating its potential of bacterial growth. We have applied our method to four types of reclaimed water, measuring the time course of DTMC and dissolved organic carbon in a bio-assay process. The experimental findings are summarised as follows: 1) By regulating organic carbon, bacteria growth could be controlled. 2) Reduction of the initial concentration of bacteria was effective to delay their growth, but this operation could not control their maximum level. This implies that the retention time of the storage and distribution system of reclaimed water should be considered in design and operation of the disinfection process. 3) Ozonation increased the growth potential. Carbon adsorption process reduced it, but the ozone plus carbon adsorption process could not improve the biological stability. 4) A linear relationship between DTMC and biodegradable organic carbon has been observed, the gradient of this linear correlation, however, depended on the source of reclaimed water.