Testing decentralised treatment solutions for portable home toilet waste - Kumasi, Ghana

Water and Sanitation for the Urban Poor (WSUP) and Unilever have developed Clean Team, a business providing portable home toilets that are attractive and branded. Customers pay for their waste to be collected two to four times per week. Three “off-the-shelf” technologies are being tested to treat this waste and allow Clean Team to scale up to other cities. The three technologies are Sistema Biobolsa, which uses flexible tubes as anaerobic digesters, and aerobic planted gravel filter; Biorock, where an anaerobic pre-treatment tank is followed by an aerobic tank containing synthetic filtration media, pretreated with enzymes that stimulate the growth of aerobic bacteria and ventilation executed by natural draft; and Biofil, which will receive the sludge from the Biorock system, and digest it using macrofauna. The paper will present the initial trial results

Use of dispersion modelling for Environmental Impact Assessment of biological air pollution from composting: Progress, problems and prospects

© 2017 The Authors With the increase in composting as a sustainable waste management option, biological air pollution (bioaerosols) from composting facilities have become a cause of increasing concern due to their potential health impacts. Estimating community exposure to bioaerosols is problematic due to limitations in current monitoring methods. Atmospheric dispersion modelling can be used to estimate exposure concentrations, however several issues arise from the lack of appropriate bioaerosol data to use as inputs into models, and the complexity of the emission sources at composting facilities. This paper analyses current progress in using dispersion models for bioaerosols, examines the remaining problems and provides recommendations for future prospects in this area. A key finding is the urgent need for guidance for model users to ensure consistent bioaerosol modelling practices

Effects of cattle manure on erosion rates and runoff water pollution by faecal coliforms.

The large quantities of slurry and manure that are produced annually in many areas in which cattle are raised could be an important source of organic matter and nutrients for agriculture. However, the benefits of waste recycling may be partially offset by the risk of water pollution associated with runoff from the fields to which slurry or manure has been applied. In this paper, the effects of cattle manure application on soil erosion rates and runoff and on surface water pollution by faecal coliforms are analysed. Rainfall simulations at a rate of 70 mm h−1 were conducted in a sandy loam soil packed into soil flumes (2.5 m long×1 m wide) at a bulk density of 1400 kg m−3, with and without cattle slurry manure applied on the surface. For each simulation, sediment and runoff rates were analysed and in those simulations with applied slurry, presumptive faecal coliform (PFC) concentrations in the runoff were evaluated. The application of slurry on the soil surface appeared to have a protective effect on the soils, reducing soil detachment by up to 70% but increasing runoff volume by up to 30%. This practice implies an important source of pollution for surface waters especially if rainfall takes place within a short period after application. The concentrations of micro-organisms (presumptive faecal coliforms (PFCs)) found in water runoff ranged from 1.9×104 to 1.1×106 PFC 100 mL−1, depending on the initial concentration in the slurry, and they were particularly high during the first phases of the rainfall event. The result indicates a strong relationship between the faecal coliforms transported by runoff and the organic matter in the sediment

Two strategies for improving animal farm wastewater treatment in reed beds

In this study, dewatered alum sludge cakes were used as substrate in a laboratory scale tidal vertical flow reed bed system treating animal farm wastewater. The “tidal flow” operation was employed to enhance oxygen transfer into the reed bed system, while dewatered alum sludge cake was used to enhance phosphorus (P) removal in the system through ligand exchange. Except for the removal of P which was consistently high throughout the experiment, the removal of organics (BOD5, COD) exhibited a trend of gradual and increasing removal. This highlights the obvious advantage of the use of the dewatered alum sludge cake in the reed bed. For the removal of organics, a mean removal percentage of 82.3 ± 3.5 % was obtained for BOD5 at an average loading of 84.6 g/m2.d. In addition, the first-order kinetics constant for BOD5 removal (KBOD, m/d) obtained in the system was about 9 times the rate constant commonly obtained in conventional horizontal flow systems. The mean level of dissolved aluminium (Al) monitored in the effluent was 0.04 ± 0.01 mg/l and this is well below the discharge limit of 0.2 mg/l for Al discharge into all waters.Other funderEnvironmental Protection Agency12M embargo: release on 23/09/2011 - AV 25/8/201

Studies of removal of chromium by model constructed wetland

Chromium is a pollutant present in tannery wastewater, its removal is necessary for protection of the environment. Penisetum purpureum, Brancharia decumbens and Phragmites australis were grown hydroponically in experimental gravel beds to determine their potential for the phytoremediation of solutions containing 10 and 20 mg Cr dm-3. These concentrations, similar to tannery wastewater after initial physico-chemical treatment were used with the aim of developing an economic secondary treatment to protect the environment. All the systems achieved removal efficiencies of 97 - 99.6% within 24 hours. P. purpureum and B. decumbens removed 78.1% and 68.5% respectively within the first hour. Both P. purpureum and B. decumbens were tolerant of the concentrations of chromium applied, but P. purpureum showed the greatest potential because its faster growth and larger biomass achieved a much greater chromium removal over the whole length of time of the experiment

Does soil biology hold the key to optimized slurry management? A manifesto for research

The application of agricultural biosolids to land is likely to increase on farms as pressures intensify to manage nutrients and carbon, especially with regard to slurry. Although much work has been carried out in this area, it has tended to focus on specific aspects of the application-use cycle, without a coherent framework and notably the role of soil biology has been little studied in this context, or considered appropriately in the development and application of slurry management systems. In this review article we present a hypothesis that the configuration of the soil microbial community is determined by the history of long-term inputs to which the community has been subjected and that the resultant configuration determines the instantaneous responses of the associated soil to the presence of slurries, and posit a set of critical questions which would effectively test this.</p