A Rottiers

Adaptation of the CAS test system and synthetic sewage for biological nutrient removal: Part I: Development of a new synthetic sewage

A new synthetic medium has been developed for routine use in laboratory-scale sewage treatment simulation and biodegradation tests, such as OECD guideline 302A & 303A or ISO method 11733. The new medium, Syntho, was designed to meet the following objectives: 1) to be more representative of real sewage than the existing standard OECD synthetic sewage, 2) the COD:N:P ratio and mineral composition must allow a good degree of biological nutrient (N, P) removal, and 3) the medium should result in stable unit operation, including good sludge settling and minimal need for control actions. The IAWQ Activated Sludge Model No. 2 (ASM2,) was used to help design the medium and predict reactor performance for different possible media compositions. The results obtained with Syntho indicate that Continuous Activated Sludge (CAS) units with or without nutrient removal can be operated routinely on this feed. The new medium was also characterized by means of a respiration test. The different influent fractions applied in the model were validated, and a respiration profile indicated that Syntho is a close approximation of real sewage.

AIS/CESIO Environmental Surfactant Monitoring Programme. Part 1: LAS Monitoring study in "de Meern" sewage treatment plant and receiving river "Leidsche Rijn".

Abstract This manuscript reports on the outcome of a 7-day pilot monitoring study on the anionic surfactant linear alkyl benzene sulfonate (LAS) at the “de Meem” municipal sewage treatment plant. The receiving surface water, the Leidsche Rijn is a straight river — about 20 m wide and 1.5 m deep — and dilutes the sewage discharge by a factor 3. The monitoring study illustrates an effective removal of LAS of 99.9% during dry weather and normal operating conditions. The LAS concentrations in daily composite raw sewage samples varied between 3.1 and 7.2 mg/L, with corresponding effluent concentrations generally under the analytical detection limit of 8.1 ug/L. During this same period, total LAS concentrations in the river varied between

LAS degradability by marine biofilms derived from seawater in Spain and Sweden

Marine biofilms were established on glass beads with or without deliberate pre-exposure to LAS (20 μg/L) in Spain (Cadiz) and Sweden (Kristineberg). The ability of each community to mineralize LAS (100 μg/L) was then assessed in biometers at four experimental temperatures (between 6 and 21°C). Genetic diversity and biomass of the biofilms were assessed by genetic fingerprinting (DGGE) and direct bacterial counts. With biofilms from Sweden, where LAS was not detected in seawater (n = 3), deliberate pre-exposure to LAS resulted in lower genetic diversity and higher mineralization rate constant; however, with biofilms from Spain, where 6.4 ± 3.9 μgLAS/L (n = 3) was measured during the colonization, pre-exposure did not affect the bacterial community. Bacterial acclimation therefore appeared to have been induced at environmental concentrations < 6 μgLAS/L. Environmental pre-exposure was not a pre-requisite for featuring the full consortia of LAS degraders in the biometers. The mineralization rate was described using an Arrhenius equation at experimental temperatures within the typical annual range; however, they departed from this model below this range.