Storage induced changes in coliform, heterotrophic groups of bacteria and nutrient levels of human urine for its safe use in biological production.

Human urine is a potential source of various nutrients, minerals and trace elements. Its use as a fertilizer is growing popular among farmers. Here, we examined the pattern of changes in the counts of coliform, heterotrophic bacteria as well as physico-chemical characteristics of human urine during different days of storage under closed conditions at ambient temperature. We observed that after 253 days of storage under closed condition, the coliform counts were reduced significantly and remained within the safe limit to be used as fertilizer. With increase in storage period, the concentration of phosphate showed decline coupled with rise in pH, alkalinity and electrical conductance. Our study revealed that human urine can be used as safe fertilizer after 8 months of storage under closed conditions at ambient temperature ranging 25-35ºC.

Responses of succinate dehydrogenase and non-specific alkaline phosphatases and mortality of tilapia to ambient pH stress in a sewage-fed aquaculture pond.

The fish, tilapia (Oreochromis mossambicus) of 50-60 g body weight was experimentally exposed to effluent gradients of highly alkaline pH in a sewage-fed aquaculture farm for examining the pH stress-induced responses of mortality and the stress marker enzyme succinate dehydrogenase and the non-specific alkaline phosphatases of fish prior to death at different hours of intoxication. A second trial was performed after two months when water quality changed along the sewage effluent gradient. An in situ experiment was also performed for better understanding of the responses of enzymatic activities attributable to different levels of pH conditions. Time required for 100% mortality of fish tended to increase from 30 min in pH 11.6 to 22 hr in pH 10.2. There was no mortality of fish when water quality improved significantly (with pH ranging between 9.6 to 8.0) after two months. The activities of succinate dehydrogenase and intracellular alkaline phosphatases assayed in gills and liver prior to death of fish tended to reduce with increase in survival hour, following a pattern of decay curve. On the other hand, percent of enzymatic inhibition of the exposed fish over the control increased as the survival hour increased following a pattern of exponential curve. It appears that the highest water pH of 11.6. maximum ratio for ammonium to ammonium hydroxide (1: 21) and reduced level of dissolved oxygen (2.62 mg/l) were perhaps responsible for the 100% mortality of fish within 30 min of their exposure and the enzymatic activities in the gills and liver assayed prior to death of fish tended to reduce as the acclimatization period of fish increased and vice-versa.