Combined compact anaerobic reactors and lamella settlers for decentralized sewage treatment

This work presents a compact plant's development and performance evaluation for the decentralized treatment of domestic sewage. The plant was conceived and installed in a house with four residents in Vicente Pires, Federal District, Brazil. Its purpose was to remove organic matter and solids using a low-cost biological treatment process that was simple to operate. The plant was essentially anaerobic, composed of an up-flow anaerobic reactor and an anaerobic filter, both associated with lamella settlers. It was operated under real conditions and monitored for nineteen months, with removal efficiencies (calculated over the medians) of 81% for COD, 83% for BOD, 51% for Total Solids, 55% for Total Volatile Solids, 87% for Total Suspended Solids, and 100% for Settleable Solids. The plant performed adequately, with no clogging between the plates of the lamella settlers or no offensive odours, and limited amounts of sludge and scum.

Performance Evaluation of Laboratory Scale Vegetated Vermifilter for Domestic Wastewater

Locally as well as globally, the Collection and treatment of wastewater are seen to have an impact on the environment and economy in one way or the other. Designing a system that minimizes this effect to the best possible scenario is of paramount importance, adding to greater sustainability in terms of economic, environmental, and social terms. The solutions such as on-site treatment of wastewater, local recycling, and reuse of resources contained in domestic wastewater (predominantly water itself) can be best summed up as Decentralized treatment of sewage which appears to be a coherent solution to address sustainability. Vermifiltration is a low-cost aerobic decentralized wastewater treatment option. Two lab-scale vertical flow filters are designed in this project, with both being assisted by Canna indica (MAVF), but only one introduced with Eisenia fetida. The experimental phase continued for 5 weeks with a hydraulic loading rate of 0.14 m3 m -2 day-1 with an acclimatization period of 15 days. The results depicted that MAVF has a better organic degradation capacity than the one without earthworms alone. The quality of wastewater is determined by Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) to a great extent. Removal efficiencies of COD were 67 % for MAVF and 55 % for MAF, while for BOD, it was 80 % for MAVF and 69 % for MAF, respectively. The BOD and COD tests were assisted by other parameters like pH, and turbidity. Keywords: Domestic wastewater, Decentralized treatment, Aerobic treatment, Macrophyte Assisted Vermifilter (MAVF), Macrophyte Assisted Filter (MAF), Sustainability, Low-Cost Treatment, Canna Indica, Eisenia Fetida

Water denitrification by displacement biofiltration

This work was aimed creating a simple and reliable submersed biofilter for the decentralized treatment of nitrate-contaminated water. Denitrification of water was studied by the method of displacement (piston) bio-filtration in specially designed devices intended for home application. At certain sizes of grains of bio-filtration bed and filtration flow directions in it, the change in operating mode of denitrifying biofilter from direct flow to displacement mode offers the following advantages. There is no need to maintain a continuous and slow flow of water through the biofilter. The consumers have the opportunity to feed big portions of water into the bio-filter in one gulp (pulse) and nevertheless get the same quantity of denitrified water. The design of created biofilters is simple. Assembling these bio-filters implies the use of materials with a minimum carbon footprint.

Water denitrification by displacement biofiltration: transition of designed biofilter to the stationary mode

This work was aimed at creating a simple and reliable submersed biofilter for the decentralized treatment of nitrate-contaminated water. Denitrification of water was performed by the method of displacement (piston) biofiltration in specially designed U-shaped devices intended for residential use. The efficiency of biofiltration in these devices was evaluated under the conditions of their continuous service. The biofilter exhibited an essential increase in the rate of denitrification when transferring to the stationary mode. Hence, the consumer will have the opportunity of supplying big portions of nitrate-contaminated water into the biofilter in one gulp (pulse) and simultaneously getting the same amount of deeply denitrified water. This mode of biofilters exploitation prevents the clogging of the filtration bed and the channeling in it. The design of the created biofilters is rather simple. Materials with a minimum carbon footprint can be used to fabricate these devices.

Phosphorus Recovery from Wastewater: Bioavailability of P Bound to Calcareous Material for Maize (Zea mays L.) Growth

(1) Phosphorus (P) is an essential plant nutrient, and P deficiency negatively affects plant growth and development. Furthermore, P is a finite and nonrenewable resource, and there is an urgent need to recover P from some of the important waste streams in society. Newly engineered calcareous materials (sol–gel coated cat litter (CATSAN®)) can bind P from wastewater in decentralized treatment systems and potentially enable P recycling into agricultural production by direct addition of the P saturated material. (2) The effects of the addition of two P-enriched calcareous materials as fertilizers for maize (Zea mays L.) growth were investigated in a mesocosm experiment. We compared fertilization with the P-enriched materials at rates of 6, 12, 25, 50, 100 kg P ha−1 yr−1 with fertilization with commercial NPK fertilizer. (3) The P fertilization by the P-enriched materials had a significant positive effect on plant height, biomass, maximum light-saturated photosynthetic rate, respiration rate, and total P content in biomass. However, plants fertilized by the commercial NPK fertilizer performed significantly better in the majority of measured parameters at identical fertilization rates. (4) The bioavailability of the P bound to the calcareous material was very low. However, the studied material has the potential to be used as part of a decentralized treatment solution to remove and subsequently recover and recycle P from wastewater.