Toxicity of domestic wastewater pH to key species within an innovative decentralised vermifiltration system

Abstract

The development of innovative decentralised wastewater treatment systems is pertinent to environmental sustainability. However for their appropriate use they require significant research and design to ensure they can be relied upon in the future and in most cases they have received less attention and research than large-scale sewage systems. This study assessed the likelihood of biological inhibition and disruption from pH to key species for vermifiltration. The test firstly assessed the buffer capacity of a vermicompost + manure media finding it had a relatively high buffering capacity for pH. The toxicity after the buffer capacity experiment showed that the species would survive between pH levels of 6.2 and 9.7. At the higher and lower pH levels however the survival of juveniles was impaired, probably due to their ability to uptake greater amounts of soluble salts and inability to regulate them. Overall the study showed that the tolerance of the key vermifiltration species to pH was far less than their survival as previously proposed and further research assessing their long-term population dynamics in a vermifiltration system with pH is warranted.