Performance of Experimental Bio-Digestion for Pathological and Biodegradable Waste Management at Mwananyamala Regional Referral Hospital Tanzania

The aim of the experimental trial was to evaluate the performance of the designed placenta and other pathological waste digester system on the effectiveness of digesting the placenta and its energy recovery (bio-gas) process in Mwananyamala Referral Hospital in Dar es Salaam. A 32 m3 digester is constructed in Mwananyamala Referral Hospital, one inlet of which is to attach to the toilet of maternity ward, where the placentas are flushed directly into the digester, while food waste is fed through another inlet. The slurry of the digester is sent to a sewer/septic tank to avoid further handling. Most fraction of the waste fed into the digester is food waste. In general with the amount of 25.6 ± 4.5 kg/day of placenta and 83.1 ± 14.7 kg/day of food waste, 2.5 m3/d gas was produced. The pH throughout the study period (that is of 18 weeks) was found to be consistent within the range of 6.3 to 8.0, while the pressure ranged from 5 kPa - 33 kPa. Average temperature within the digester was found to be 30.3°C. With all the favorable condition, gas production was consistent and hence the system has been successful in management of the pathological waste along with the production of gas as an alternative source of energy for the hospital.

Integrated Application Technology of Feces Processing in Duck Farm at Scale Based on Configuration Technology

[Objective] The aim was to explore technology on processing feces in duck farms at scale, providing guiding method for effective control of environmental issues in breeding farms. [Methed] Bio-safety disposal and recovering processing of excrements in a duck farm were researched based on technology of configuration, detection, digestion, EM and poultry breeding. [Result] The integrated application technology is quite simple and the cost is not high. During breeding period, excellent organic fertilizers and high-protein forages could be obtained without any antibiotics. Furthermore, secondary wastes and pollution would not occur. In addition, ammonia was lower in excrements processed with earthworm and air pollution was reduced; the produced humus provided organic fertilizers and improved barren soils. [Conclusion] The research provides references of multi-technology integration for related industries.

Simulation of Biogas Production from Solid Organic Wastes

The design and building of new alternative fuel plants is an increasing necessity to replace old technology and non-renewable fossil fuels. To optimize the performance of these plants and to obtain an economically feasible production of these types of fuels, it is necessary to have a total control of each variable involved in the process of production and how these factors affect the yield of fuel production. In this paper it is proposed a model of a digester to generate gas using a Vensim software designed to generate simulations in dynamic state. This simulation was developed using differential equations to model the behavior at each stage of the process and auxiliary conditions to complement the mathematical description of the model. The main factors in the biogas production are the retention time and the methanogen mortality ratio. For retention time lower than 10 h the process loses effectiveness due to bacterial growth is not completed efficiently, but a high retention time involves a bigger reactor and the yield of production decreases considerably for retention time higher than 40 h. The best yields were obtained for a mortality ratio in methanogen and acidogenic bacteria lower than 0.2 and a retention time of 30 h with a final production of 3.33 L by each kilogram of biomass.