Wastewater Forum Meeting Notes 21/03/2013

Meeting 21st March 2013

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Informed the meeting that an optimisation tool is being developed for InfoWorks LS to assist in meeting compliance requirements, e.g. combined sewer overflows and conveyance, which is linked to property flooding.

HR Wallingford is working on an UKWIR guide to real time control of effluent that is intended to be intelligible at the grass roots level of the water industry. It involves very conservative nowcasting. Thames Water is getting into RTC. Cardiff in South Wales is an example of the potential benefits of RTC; runoff from “the valleys” surcharges combined sewers in the city centre resulting in flooding, but RTC could enable some of the flow to be held upstream either in tanks or by managed flooding. RTC could also be used for beach warnings (e.g. beach closed [until --] due to pollution) this would take the beach out of monitoring. SEPA has 26 electronic display signs costing £25k each; this would be much less expensive that building the infrastructure for managing and treating the stormwater, but the signage and the infrastructure are the responsibilities of the local authority and the water company respectively.

A second UKWIR project deals with the contentious subject of modelling runoff; a 2-d model is due to be finished in December 2013.

Brought members up to date with research at Loughborough:

Recovering phosphate from wastewaters is going to be important both to prevent eutrophication of water bodies and to slow the rate at which the planet’s resource is exhausted. Several companies are offering struvite (magnesium ammonium phosphate) recovery, which is best suited to BNR, but more widely applicable methods and ones that recover P directly from wastewater would be useful. Loughborough is looking at organic ligands to bind P and find nucleation is important.

Using algal ponds for nitrogen-stripping before groundwater recharge is being developed in Cyprus, where saline intrusion into coastal aquifers because of over-abstraction has been a problem for more than 20 years.

Algal bioreactors [RSC and SCI will hold a 1-day conference on sustainable chemicals from microalgae on 19th November 2013 at the Chemistry Centre, London]

A pilot plant for 50 p.e. of the Gates’ Foundation “reinvented toilet” that uses hydrothermal carbonisation is expected to be commissioned in April 2013. Corrosion and temperature are on-going areas of work.

Decentralised anaerobic digestion.

Discussed work on surface water management and billing. Basing charges on water consumption is inequitable as highlighted by parking lots that can generate large volumes of wastewater but use negligible potable water or an apartment in a block that does use potable water but generates very little surface water. One difficulty is assessing whether surfaces drain to sewers; fluorescence dye is expensive. Maybe cities that charge for surface water, e.g. in Germany or Philadelphia have answers.

Currently emphasis in flood prevention is getting people to protect themselves, i.e. to bring their local knowledge to the problem and “localism”. Kempsey, south of Worcester, is a salutary case. The Hatfield Brook, a small tributary of the River Severn flows through the village but when there is excess flow in the Severn the flow reverses and floods. The solution was a flood bank and a pump over back to the Severn; this worked well until the pump controls failed and rather than improve the reliability of the controls the scheme was abandoned and residents reverted to passive/reactive controls.

The Shellfish Directive is to be repealed in favour of the Water Framework Directive at the end of 2013, but the bacterial standards will remain the same. In the case of Norovirus, there is a question of differentiating viable from non-viable. A rapid test for Enterococci has been developed that gives a result in 2 hours “in a van” compared with the current 72 hours in a lab.

The EA is very interested in Smart Sponge® (which were used by Abtech so effectively in the BP Gulf of Mexico oil spill and featured at the BlueTech Forum 2010) and Antimicrobial Smart Sponge® Plus which achieve 2 log reductions.

The question of “disproportionate cost assessment” for the Water Framework Directive and shellfish and bathing waters may be subject to ministerial review.

Technical Presentations with members of CIWEM’s Wastewater Management Panel

Tom has just completed a prestigious EPSRC Dream Fellowship; the aim of Dream is to enable talented researchers to take time out from their everyday activities, to give them the freedom to gain new knowledge of novel creative problem solving techniques, explore new radical ideas and develop new ambitious research directions that enable discovery.

Bomb calorimetry shows domestic wastewater contains 7.6 kJ/L (2000 kWh/ML) but drying (even freeze-drying) loses volatiles. In 2010, Northumbrian Water Ltd., which sponsored much of the work, used 0.45 GWh/day to treat wastewater but the gross energy content in the wastewater was about 2.03 GWh/day if only it could be tapped.

In warm climates (e.g. northeast Brazil) methanogenic reactors (UASB) are treating wastewater successfully in installations without primary tanks for populations up to 600,000 producing lots of methane and very little sludge. Temperature is a key factor. Currently the activated sludge process dominates for treating municipal wastewater and it has done a fantastic job but electricity consumption is increasing inexorably; there must be room for an alternative, at least for warm climates, at least initially.

The voltages generated by microbial fuel cells are modest and therefore it does not take much electrical resistance to kill them. Most researchers give a false impression of the success that can be accomplished with MCFs; they use acetate or sucrose instead of wastewater, warm rooms instead of ambient, high conductivity buffer instead of wastewater, expensive materials instead of cheap ones and short runs at small scale instead of long ones at large scale. The team collected “extremophiles” in the arctic to see whether they would improve performance of MFCs in the UK at ambient temperature but there was no benefit, however a trial MFC performed throughout 2011/12 at a Northumbrian Water WwTW, it used an iron wool cathode.

Climate change is likely to result in slower flowing, warmer rivers and more sunlight hours; because of less in-stream dilution higher nutrient concentrations can be expected. These add up to better environmental conditions for phytoplankton blooms; and will favour potentially-toxic Cyanobacteria species however Zebra mussels are a confounding factor. They are very invasive which is a problem but they are also very effective filter feeders, which is a benefit. It appears Zebra mussels could filter 70% of the water in the Thames during summer low flows, but there is uncertainty about their population dynamics and over-winter survival. High flows can also account for flush-out of phytoplankton. Simulations derived from regional climate modelling applications appear reliable across the inter-quartile range (and to a large degree to 5th and 95th percentile levels); the most extreme conditions are not simulated reliably. Accelerated phytoplankton growth in future will lead to more limitation (including self-shading) and greater risk of blooms crashing, leading to possible dissolved oxygen sags.

The expected trends for wastewater are increasing chemical usage and increasing electricity use. Increasing EU river quality standards will result in additional waste sludges, increasing energy intensity and greenhouse gases. Required research outcomes are how to balance energy/water quality goals at a catchment scale and how to achieve zero energy or energy positive wastewater management and sustainable resource recovery. The results in the following research needs:

If it were to happen, end of waste (EoW) criteria at EU level would have significant consequences for Member States because they would replace national EoW for whatever materials that are in the scope of the EU EoW and they would tilt the playing field for whatever materials are outside the scope.

A fundamental problem with the exercise appears to be that the end of waste product/use has not been defined and nor has the risk pathway so there is no real foundation on which to build an objective set of criteria. Instead, people argue in something of a vacuum about what should be in-scope or out-of-scope, which compounds should be regulated and what concentrations are acceptable. There was no consideration of the beneficial constituents of that the treated biodegradable wastes might contain, which is of great relevance because for example a material with a phosphate:contaminant ratio of X will add much less contaminant than one with a ratio of 0.01X when used as a phosphate fertiliser replacement.

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