Treatment of dairy milking parlour wastewater using the Magnetic Activated Sludge (MAS) process was investigated. The experiment was carried out for 150 days without withdrawal of excess sludge and without addition of ferromagnetic powder. During the experimental period, three different CODcr loading rate; 527.7mg/l/d, 852.0mg/l/d and 1541.9mg/l/d for hydraulic retention times of 3 days, 2 days and 1 day were used, respectively. The average CODcr removal efficiency of 93% was maintained in the experimenteal period. High biomass concentration in aeration tank was achieved by magnetic separation.
This study aimed at evaluating the efficacy of anaerobic methane fermentation on shochu wastewater treatment and collecting the performance data for this system. The performance data studied include Chemical oxygen demand (CODcr) removal efficiency, methane production rate (MPR) and biogas production rate (BPR). Shochu wastewater contained 43, 000mg/l and 36, 800mg/l as total CODcr and suspended solids, respectively. Approximately CODcr removal efficiency of 98% could be achieved after 120h of fermentation in a batch reactor. The optimal biogas production was attained at the shochu wastewater to seed ratio of 1:4 (v/v). Undiluted shochu wastewater sample gave the best results indicating that its dilution is unnecessary. Initial material pH value of 6.5 to 7.5 for the shochu wastewater-seed mixture was effective and the pH outside this range resulted in reduced biogas production. Methane (CH4) content in biogas was on average 65.5% regardless of the initial pH value, with exception of pH 5.5 where no CH4 gas was detected. The BPR of 0.95l/l d and MPR of 0.43l/l d were realized with undiluted shochu wastewater at 1:4 (v/v) shochu wastewater to seed ratio. A large fraction of organic matter was effectively degraded.
The stability of Slightly Acidic Electrolyzed Water (SAEW) on storage was evaluated. SAEW samples of known initial Oxidation Reduction Potential (ORP, mV), pH and available chlorine concentration (ACC, mg/L) were stored at 25°C in different containers and changes of ORP, pH and ACC were monitored daily for a period of 10 days. ORP, pH and ACC were respectively maintained at 900-1000mV, 5-6.5 and 10-30mg/L. SAEW was further evaluated for its microbial inactivation effectiveness on the aerobic microflora present on spinach (Spinacia oleracea L.) expressed as aerobic plate count (APC) and was compared to Sodium hypochlorite (NaOCl) solution. The decontamination was done by dipping spinach samples with or without a pre-washing step into treatment solution for 5min. SAEW (pH 5.5, 25mg/L ACC) achieved a significantly higher microbial reduction than NaOCl solution (pH 9.9, 103mg/L ACC). While pre-washing of spinach in running tap water for 5min increased the microbial reduction by SAEW from 1.3log10 colony forming units (CFU)/g to more than 2log10 CFU/g at 5min contact time, increasing exposure time did not significantly affect its antimicrobial effectiveness on spinach aerobic microflora.
We examined the effect of ethylene on sex differentiation in balsam pear (Momordica charantia L.) flowers, two cultivars ‘Abashi’ and ‘Chofuku’ (only autumn cropping) with different pistillate flower differentiation characteristics were treated with silver nitrate (AgNO3) and ethrel. AgNO3 induced hermaphroditic flower differentiation in the main vines of ‘Chofuku’ near the 20th node. The concentration and the frequency of treatment were correlated with hermaphroditic sex differentiation. Frequent treatments with high concentrations of AgNO3 inhibited ethylene action in the plants. AgNO3 had no effect on pistillate flower differentiation in the spring cropping of ‘Abashi’, but increased the number of pistillate flowers in the fall cropping when applied at high concentrations. Repeated high concentration applications markedly increased the effect. Treatment with low concentrations of ethrel tended to lower the position of pistillate flower nodes in ‘Abashi’. Repeated treatment with low concentrations of ethrel somewhat increased the ratio of pistillate flower differentiation in the main vines, and a single low concentration treatment of ethrel somewhat increased the ratio in secondary vines. However, the ratio remained low near the 15th node and above. Sensitivity to AgNO3 thus varies by cultivar and by season. As well the effect of ethrel on flower bud sex differentiation was less pronounced in balsam pear than in other Cucurbitiaceae, suggesting that balsam pear is unusually sensitivity to ethylene.
The objective of this study was to determine the properties of food waste composting in relation to pH influence on microbial activity. Acidic wastes slowed down the composting process, while alkaline wastes rapidly increased the composting temperature to 70°C resulting to higher degradation of organic material. The difference in the rate of composting is largely due to growth response of compost microorganisms on pH. Mesophiles were found to grow in acidic as well as alkaline condition. On the contrary, thermophiles can hardly grow in acidic condition. The inhibition of the composting process for acidic wastes was caused by unsuccessful shift from mesophilic to thermophilic stage. In addition, acid-tolerant thermophiles with a growth under acidic condition and at about 55°C were found. However, the biodegradation capacity of acid-tolerant thermophiles is less than that of thermophiles found during composting of alkaline material.
This paper describes the determination of the appropriate moisture content for composting of food wastes. Commercial composting equipment was fed with food wastes from a university cafeteria everyday except weekend. The moisture content of the compost was controlled at 20, 25, 30, 35 and 40% (wet basis) by regulating the amount of food wastes fed to the equipment. Composting at moisture content of 40% exhibited the highest solid degradation rate. However, composting was very difficult to perform at moisture content of more than 40% because of higher plasticity of the material. Mechanical agitation caused kneading of food wastes into ball shape. In addition, material characteristics were different with agitation systems even if it was the same moisture content. A horizontal shaft-type agitation prevented formation of ball-shaped food wastes in comparison with a vertical shaft-type agitation. Consequently, the composting rate can be accelerated by improving the design of mechanical agitation system. It is recommended that moisture content should be maintained at 35 to 40% to achieve practical food waste composting.
The effect of turning frequency during composting on heat recovery and concentration of carbon dioxide yield on hydrolysis was investigated for utilization in greenhouse crop production. Composting was carried out with turning frequency of once a week (T1) and twice a week (T2) using vacuum-induced aeration system. Results showed that T2 had a consistently high heat recovery and CO2 concentration of effluent gas in comparison with T1. The increase in turning frequency from T1 to T2 enhanced the recovered heat energy from 141W·m-3 to 216W·m-3, and mean CO2 concentration from 1.5% to 1.8%. Further, T2 maintained and improved the microaerobic condition which might promote hydrolysis reaction of the compost. The use of induced aeration together with frequent agitation enabled the microaerobic condition to be maintained and improved and inhibited the production of hydrogen sulfide during composting.
For horticultural purposes, plastic greenhouses are used during the summer season in the Hokkaido Sorachi region. We studied the effect of moderating the hot environment of the greenhouse by introducing an openable roof. Thus, the environment of inside the openable roof greenhouse was compared with that inside a conventional greenhouse. The temperature in the openable roof greenhouse was occasionally at least 5°C below that in the conventional greenhouse. The total time required for the temperature within the openable roof greenhouse to exceed 30°C was reduced to about one third that required for the same temperature to be reached within the conventional greenhouse. The wet bulb globe temperature (WBGT) is used as an index of for hyperthermia prevention in working environments. In terms of the total time for the WBGT to exceed 28°C, as defined by the Ministry of Health, Labour, and Welfare for the work of involving the picking of fruits and the vegetables under warm conditions for the persons accustomed to hot environments, the openable roof greenhouse has the advantage of shortening this time to about one third that of the conventional greenhouse. The low-cost option of introducing of an openable roof greenhouse can be achieved by easy remodeling a conventional greenhouse. The cost of materials for remodeling is about 200, 000yen for a greenhouse that is 50m in length.