Technology Scan: Wastewater Treatment and Renewable Energy Technologies for Rural Communities in Scotland

Published by CREW – Scotland’s Centre of Expertise for Waters. CREW connects research and policy,

delivering objective and robust research and expert opinion to support the development and

implementation of water policy in Scotland. CREW is a partnership between the James Hutton

Institute and all Scottish Higher Education Institutes supported by MASTS. The Centre is funded by

the Scottish Government.

This document was produced by:

Katina Tam

The James Hutton Institute

Craigiebuckler

Aberdeen AB15 8QH

Scotland, UK

Please reference this report as follows: Tam, K. (2013) Wastewater Treatment and Renewable

Energy Technologies for Rural Communities in Scotland. CREW report 2013, CD2013_20. Available at

www.crew.ac.uk/publications

Dissemination status: Unrestricted

All rights reserved. No part of this publication may be reproduced, modified or stored in a retrieval

system without the prior written permission of CREW management. While every effort is made to

ensure that the information given here is accurate, no legal responsibility is accepted for any errors,

omissions or misleading statements. All statements, views and opinions expressed in this paper are

attributable to the author(s) who contribute to the activities of CREW and do not necessarily

represent those of the host institutions or funders.

Cover photograph courtesy of: Katina Tam, James Hutton Institute

Contents

EXECUTIVE SUMMARY ..................................................................................................................................... 1

1.0 INTRODUCTION ................................................................................................................................... 2

2.0 TECHNOLOGIES FOR TREATING WASTEWATER .................................................................................... 2

2.1 ATLANTIC WATER FRESHWATER GENERATOR .................................................................................................. 2

2.2 ENDOSAN ................................................................................................................................................. 3

2.3 AQUALOGIX DRINKING WATER PROCESSOR ..................................................................................................... 4

2.4 DUTCH RAINMAKER .................................................................................................................................... 5

2.5 AQUALOOP ............................................................................................................................................ 6

2.6 BIOMATRIX WATER POND BASED PREFABRICATED SYSTEMS ............................................................................... 7

2.7 BIOMATRIX WATER LAND BASED MULTI-STAGE RECIRCULATING WETLAND .......................................................... 9

2.8 LIVING MACHINE ..................................................................................................................................... 10

2.9 MICROBAC PACKAGE SEWAGE TREATMENT PLANTS ........................................................................................ 11

2.10 SEPTIC WIZARD ....................................................................................................................................... 13

2.11 AQUACRITOX .......................................................................................................................................... 13

3.0 TECHNOLOGIES FOR RENEWABLE ENERGY PRODUCTION .................................................................. 14

3.1 CLEARFLEAU ANAEROBIC DIGESTION ............................................................................................................ 14

3.2 WILLOW SYSTEMS .................................................................................................................................... 15

.......................................................................................................................................................................... 16

4.0 CONCLUSIONS ................................................................................................................................... 17

4.1 LIMITATIONS OF THIS REPORT ..................................................................................................................... 17

4.2 NEXT STEPS ............................................................................................................................................. 17

5.0 REFERENCES ...................................................................................................................................... 18

Page | 1

Executive Summary Background to research

This report responds to a CREW call down request submitted by Scottish Water to carry out an initial

review of technologies for treating water and wastewater, and for producing renewable energy from

water in rural Scottish communities. The technologies included in this report are either on the

market or are close to market.

Objectives of research

1. To identify and summarise water and wastewater treatment systems that utilise

reclaimed effluent for drinking water, toilet flushing, irrigation, and other purposes.

2. To identify and summarise renewable energy systems that utilise water, wastewater,

and waste products.

Key findings

We include details of eleven technologies that reclaim rainwater and wastewater for household and

community uses:

Atlantic Freshwater Generator utilises a heat plate exchanger and concepts of evaporation and

condensation to produce freshwater.

EndoSan disinfects domestic water as an alternative to chlorine.

Aqualogix Drinking Water Processor uses ultrafiltration and activated carbon for purifying water.

Dutch Rainwater uses wind turbines to produce water.

AQUALOOP may be installed in households for greywater recycling, wastewater treatment, and

surface and groundwater treatment.

Biomatrix Water Pond Based Prefabricated Systems uses a cascade floating platform system for

treating wastewater.

Biomatrix Land Based Multi-Stage Recirculating Wetland utilises biofilms and principles of

wetland ecologies for treating wastewater.

Living Machine is similar to Biomatrix and builds natural ecosystems for treating wastewater.

Microbac Biomass Wastewater Treatment markets bioreactors and membrane bioreactors.

Septic Wizard uses principles of vermifiltration to treat wastewater.

AquaCritox uses principles of super critical water oxidation to treat wastewater and to produce

energy.

We include details of three technologies that generate renewable energy from waste and

wastewater:

Clearfleau markets anaerobic digestion systems for biogas and electricity production.

A willow systems project is investigating wastewater treatment and biofuel production from

willow crops.

AquaCritox uses principles of super critical water oxidation to treat wastewater and produce

energy.

Independent evaluation of each technology is required to fully understand each of the products and

their suitability to use in rural communities in Scotland.

Key words: wastewater treatment; renewable energy; sustainable rural communities

Page | 2

1.0 INTRODUCTION

This report responds to a CREW call down request submitted by Scottish Water to carry out an initial

review of technologies for treating water and wastewater, and for producing renewable energy from

water. The technologies included in this report are either on the market or close to the market. This

scan feeds into Scottish Water’s strategic vision to develop Sustainable Rural Communities.

This report is presented in two parts:

1. Technologies for treating wastewater: an overview of eleven technologies that reclaim

rainwater and wastewater for household and community uses. Relevant case studies are

presented for certain technologies, where information was available.

2. Technologies for producing renewable energy: an overview of three technologies that

generate renewable energy from waste, water, and wastewater. Relevant case studies are

presented for certain technologies.

The information presented in this report is sourced directly from the company or product websites,

or is taken from product brochures and leaflets. The data presented is based on the research

conducted by the companies, and has not been verified externally.

2.0 TECHNOLOGIES FOR TREATING WASTEWATER

2.1 Atlantic Water Freshwater Generator

Company: Atlantic Water

Location: Newmachar, Aberdeenshire

Technology status: On the market

Output: Potable

The Atlantic Water (AW) Freshwater Generator uses a flat surface heat exchanger or a shell and tube

heat exchanger for producing drinking water standard freshwater from water and contaminated

water sources. Water is passed through the generator and is evaporated, while condensation of the

steam subsequently produces freshwater (Atlantic Water, 2013).

Further information on the operation of a standard freshwater generator is available through Alfa

Laval, which markets a similar generator called AQUA Freshwater Generator. Water flows through

the bottom evaporator section of a heated plate pack and is evaporated at 40-60°C. The vapour

rises between the plates into the separator section of the plate pack, which causes residual droplets

to fall into the bottom of the generator. The pure vapour enters the top condenser section of the

plate pack and the vapour is condensed into freshwater, which is released by a freshwater pump

(Alfa Laval, undated).

The AW Generator is available in varying capacities, producing 10 to 200 Tonnes of freshwater per

day. Power consumption is 240 kw per day for producing 10 Tonnes, and residual trace salt is less

than 4 ppm.

Page | 3

While the Generator targets seawater treatment, it treats river water, sewage water, flood water,

and private water supplies to produce drinking water. The Generator also treats oil well water and

industrial wastewater. The Generator is resistant to corrosion and is fully automatic (Atlantic Water,

2013). While high energy inputs are typically required for water evaporation, the Generator

recovers and recycles thermal energy for its own operation. The result is a reduction in the power

consumption of the Generator and energy savings of 95% as compared to conventional generators

(Atlantic Water, 2013). No information has been found on costs.

2.2 EndoSan

Company: EndoSan

Location: The Quays, Manchester

Technology status: On the market

Output: Potable

EndoSan, a product based on the Huwo-San TR50 technology, is a water disinfectant made of 50%

hydrogen peroxide, and activated silver-based stabiliser. It has been used to provide potable water

in buildings in the UK, and serves small communities. When reacting with water, EndoSan

decomposes to produce water and oxygen. It has a higher pH and a lower silver content than other

products, making it more stable and capable of remaining in water for longer periods of time for

thorough disinfection. It is effective against the formation of biofilms, biofouling, and legionella, and

is used for treating drinking water in buildings or for individual water supply tanks. It is an odourless,

tasteless, and colourless (it is unclear if the product itself is colourless or if it treats the water to

become colourless) alternative to chlorine (Endo Enterprises, 2012).

EndoSan is marketed as not requiring water temperatures to reach 60°C (the recommended

temperature for Legionella control), saving energy costs. Compared to chlorine, it does not form

chlorinated by-products, is less corrosive (does not hydrolyse to form an acid), is not pH dependent,

and performs well at both higher and lower temperatures (Endo Enterprises, 2012).

No information has been found on costs.

Page | 4

Case Study: Exchange House, Broadgate

A three-month trial was completed at The Exchange House, an office building in London. Source

water (Thames) entered the basement of the building and into the Cold Water Storage tank

(capacity of 72 tonnes). The water was then pumped to a 10 tonne tank on the tenth floor (the

highest level) of the building. The water also supplied two sets of storage calorifiers (Wilson, 2013).

The objectives of the trial were to discover if:

1. EndoSan is capable of controlling legionella and maintaining sterile Domestic Hot Water

(DWH) conditions

2. Endosan is a system that is easy to dose and control

3. Microbiological control is unaffected by water temperature

4. Positive savings as a result of reducing DWH temperature could be made.

After the initial disinfection of the whole system at 200 ppm, the EndoSan system was installed by

nitrogen freezing of the water lines connected to the calorifiers. Two dosing tanks with top

mounted Smart pumps were added to the mains water supply, and the tanks contained diluted (2:1)

EndoSan with demineralised water (16% concentration). The pumps were set so that a dose was

given every 10 L of water passing a water meter installed in the system. Dosages of EndoSan were

set at 20 to 30 ppm during the three month period. Microbiological analyses were completed prior

to the dosing, and results from the trial showed that microbiological contamination was immediately

removed upon application of the doses and did not display any reoccurrence of microbial activity

(even when the dosage and water temperatures were reduced). The trial demonstrated that

continuous dosing at 20-30 ppm (upon an initial disinfection of 200 ppm) will maintain the sterility of

the water and the elimination of legionella. With a reduction in DWH temperature from 65°C to

50°C and the Exchange House ambient temperature at 20°C, the energy savings would be 30% as

compared to other disinfection products (such as chlorine or hydrogen peroxide products) (Wilson,

2013).

2.3 Aqualogix Drinking Water Processor

Company: R S Garrow Ltd

Location: Glasgow

Technology status: On the market

Output: Potable

Aqualogix is a compact, decentralised treatment for small-scale or individual household use. It uses

an ultrafiltration filter and activated carbon for purifying water in remote areas. The system consists

of a collection tank through which source water is fed. The water from the tank may pass through

an outlet if the water will be used for toilet flushing, gardening, car washing, and does not require

full treatment.

Page | 5

The water may pass through a second tank that has a particle filter, and is subsequently pushed

through activated carbon and an ultrafiltration membrane (0.01 um pores area). This water is

suitable for household use and drinking water. Chlorine tablets may be inserted in a chlorine cup

(between the activated carbon and the ultrafiltration membrane) for occasional disinfection

(Garrow, 2012). The Household Aqualogix treats 4,000 L of water per day, and is priced at £3,500

(Garrow, 2013).

2.4 Dutch Rainmaker

Company: Dutch Rainmaker

Location: Badhoevedorp, Netherlands

Technology status: On the market (very recently)

Output: Potable

Figure 1 Design of the Dutch Rainmaker (Dutch Rainmaker, undated).

Dutch Rainmaker is a new technology that markets water production from wind turbines, and

currently operates in Kuwait and the Netherlands. It produces up to 7,500 L of water per day. As

shown in Figure 1, the wind turbine drives air through a heat exchanger that condenses the air into

water and filters the water into a water storage compartment. No external energy sources are

required. It may be installed in a range of climates, and the quantity of water produced depends on

the ambient temperature and relative humidity (RH). At 20°C and 50% RH, 7.5 g water/kg air is

produced. At 30°C and 60% RH, 16 g water/kg air is produced. With further treatment, the water

may serve irrigation or drinking water purposes (Dutch Rainmaker, undated).

Though the Rainmaker is designed to produce water for more southern regions in the world, it is

undergoing trials in the Netherlands and may be useful given similar climatic conditions in Scotland

(Dutch Rainmaker, undated). No information has been found on costs of the technology.

Page | 6

2.5 AQUALOOP

Company: INTEWA

Location: Aachen, Germany

Technology status: On the market

Output: Non-potable and potable

AQUALOOP is used for greywater recycling and wastewater treatment to produce non-potable

water, and for surface and groundwater treatment to produce potable water. For greywater

recycling, the system can be installed in individual households, and contains one filtering membrane.

The system may be installed in internal or external storage tanks, and may be connected to a

rainwater tank if additional water is required. A single family household requires 2x300 L of storage

volume. A multiple family dwelling of up to 24 inhabitants requires 2x2,000 L. A multiple family

dwelling of up to 48 inhabitants requires 2x4,000 L. A large property of up to 192 inhabitants

requires 40,000 L (Intewa, 2013).

The system is comprised of five modular components that may be easily assembled and installed

into most types of storage tanks (Intewa, 2013):

1. Pre-filter – automatic extraction of bottom sediment and floating debris, such as hair and

organic contaminants in household greywater, from a collection tank

2. Growth bodies – biological degradation, supplied with oxygen

3. Membrane station with systems control – a fully automatic system controller for operating

and monitoring the pump and blower. The system contains up to 6 membranes and

different types of blowers, depending on the desirable volume of water to be recycled.

4. Membranes – the main pieces of the system - hollow fibres that retain bacteria and viruses

(do not contain chemicals), with a lifespan of up to 10 years with minimal maintenance

5. Blowers – membrane cleaning and oxygen supply

The system also requires a clean water storage tank and the Rainmaster Eco pump and control unit,

which supplies the system with water.

Similar designs are available for wastewater treatment and for surface and groundwater treatment.

AQUALOOP can be installed in rural and urban areas (including camping sites and private homes).

Treated water may be used for toilet flushing, washing machines, gardening and irrigation, or

drinking water (Intewa, 2013). No information is available on energy requirements..

No information has been found on costs of the technology.

Page | 7

2.6 Biomatrix Water Pond Based Prefabricated Systems

Company: Biomatrix Water

Location: Forres, Moray

Technology status: On the market

Output: Non-potable

The Biomatrix Water Pond Based Prefabricated Systems is an on-site cascade floating platform

system that requires minimal assembly and can be constructed in a matter of weeks. Its central

objective is to create a visually and ecologically attractive solution for treating wastewater

(Biomatrix Water, undated).

Figure 2 Overview of the Biomatrix Water Pond Based Prefabricated System (Biomatrix Water,

undated)

The system, as shown in Figure 2, has six stages:

Stage 1 – Headworks (the initial stages of wastewater treatment) are designed according to the

specific characteristics of the influent, and may include functions such as screening, degritting, and

dissolved air flotation.

Stage 2 – Anaerobic, anoxic, and aerobic treatment, including phosphorus removal and

denitrification. This is a closed stage which also treats odours.

Stage 3 – Aerobic treatment, including Biological Oxygen Demand (BOD) and Chemical Oxygen

Demand (COD) removal, and nitrification.

Stage 4 – Precipitation of bacterial flocs and biofilms, and settled sludge treatment and removal.

Stage 5 – Polishing in the form of micro filtration or sand filtration, if higher levels of treatment are

required.

Stage 6 – Disinfection (optional) if the effluent will be used for landscape irrigation or toilet flushing.

Page | 8

The system is built within a tank or lagoon that is lined with an impermeable membrane. High

strength geotextile baffles separate the aerobic stages, while each stage contains a floating matrix of

biological components and planted ecologies within a floating High-Density Polyethylene (HDPE)

structure. The HDPE structure supports other components of the system, including attached growth

treatment media, walkways, aeration systems, and process controls. An air distribution system

(fine bubble membrane diffusers or submersible aerators) oxygenates and controls water

movement. The system treats 10-5000 m3/day of wastewater (Biomatrix Water, undated). There is

presently no available information on energy requirements or costs.

Figure 3 Performance of the Biomatrix Water Pond Based Prefabricated System (Biomatrix Water,

undated)

Due to its modular design, the system is suitable for a range of treatment requirements, including re-

use in landscape irrigation and toilet flushing. It is flexible and is made of individual sections that

may be adjusted according to the retention times required. The system may also be used to

upgrade existing treatment plants. Minimal maintenance is required, and recycle rates, dissolved

oxygen levels, and sludge retention times may be manually or automatically controlled. Figure 3

displays the performance of Biomatrix, according to its website. The concentrations of BOD

(300mg/L to 15mg/L), TSS (250mg/L to less than 8mg/L), ammonia (50mg/L to 2-5mg/L), and faecal

coliform (FC) (10^8mg/L to 10^3mg/L) are drastically reduced following the six treatment stages.

Minimal sludge is produced, due to a long hydraulic retention time and the presence of plants and

live substrate attached to the growth treatment surface that allow for further removal of the sludge

(Biomatrix Water, undated).

Page | 9

2.7 Biomatrix Water Land Based Multi-Stage Recirculating Wetland

Company: Biomatrix Water

Location: Forres, Moray

Technology status: On the market

Output: Non-potable

Biomatrix offer a wetland-based subsurface flow system for treating wastewater. While the Pond

Based Prefabricated System has a modular design with movable baffles, and may be added as an

extension to existing treatment systems, the Land Based Multi-Stage Recirculating Wetland is a

completely new system (not an extension) that utilises biofilms and principles of wetland ecologies

for treating wastewater. The system allows for the growth of plants that provide a surface area for

microorganisms to thrive, and gravel for biofilms to form (Biomatrix Water, undated).

Figure 4 Overview of the Biomatrix Water Land Based Multi-Stage Recirculating Wetland (Biomatrix

Water, undated)

The system, as shown in Figure 4, consists of six stages:

Stage 1 – The anaerobic stage; a multiple compartment baffle tank removes up to 30-40% Total

Suspended Solids (TSS).

Stage 2 – The wetland stage; a high surface area attached growth treatment is used for establishing

biofilms and removing BOD.

Stage 3 – The aerobic stage; nitrification and denitrification.

Stage 4 – The polishing stage; effluent is recirculated up to six times through a fine pore treatment

media, before UV disinfection.

Page | 10

Figure 5 Performance of the Biomatrix Water Land Based Multi-Stage Recirculating Wetland

(Biomatrix Water, undated)

The Multi-Stage Recirculating Wetland requires little energy, using a trickling filter system during the

aerobic phase. There is presently no available information on specific energy requirements or costs.

Local materials are used, so the cost of building and maintaining the system will depend on the

specific region. The system relies principally on photosynthesis for its operations, so little

maintenance is required. The system is flexible, and the number of polishing cycles may be adjusted

according to specific site requirements and the nature of the influent. Figure 5 shows that like the

Pond Based Prefabricated System, concentrations of BOD (300mg/L to less than 5mg/L), TSS

(250mg/L to less than 8mg/L), ammonia (40mg/L to less than 2.5mg/L), and FC (10^8mg/L to less

than 500mg/L) are reduced considerably (Figure 5). The effluent may be used for the application of

fertilizers through an irrigation system (fertigation) or landscape irrigation activities (Biomatrix

Water, undated)

2.8 Living Machine

Company: Living Machine

Location: Charlottesville, Virginia (U.S.)

Technology status: On the market

Output: Non-potable

Living Machine is a wetland-based system that pumps wastewater into a series of gravel-filled

wetland cells which are alternately flooded and drained, creating tidal cycles. It operates very

similarly to the Biomatrix MSR Wetland, effectively removing contaminants to produce reclaimed

effluent that is suitable for safe discharge into water bodies, toilet flushing, or irrigation purposes

(Living Machine, 2012).

Living Machine has an extensive portfolio. It has been designed for schools and universities for

natural on-site wastewater and rainwater treatment, and reclaimed effluent is used for irrigating

athletic fields, toilet flushing, and re-charging aquifers. Similar systems have been designed as on-

site alternatives to transporting wastewater to centralised municipal wastewater treatment plants.

Page | 11

Case Study: Kwan Lamah Subdivision, San Juan Island, Washington (U.S.)

The new housing development contains 240 housing units. Living Machine is producing a system for

the primary treatment of wastewater and flow equalization (solids removal). It will contain five Tidal

Flow Wetland cells for biological treatment, followed by polishing and disinfection. The effluent is

stored in a holding tank, and is used for landscape irrigation within the development. Future plans

also include using the effluent for toilet flushing. With the expansion and development of the

housing development (capacity of 7,000 gallons per day to 40,000 gallons per day), the modular

nature of the system will be useful for easily increasing its capacity (Living Machine, 2012).

2.9 Microbac Package Sewage Treatment Plants

Company: Microbac Biomass Wastewater Treatment

Location: Consett, County Durham

Technology status: On the market

Output: Non-potable

Figure 6 Overview of the Microbac Bioreactor (Microbac, 2010)

Microbac produces bioreactors designed for treating industrial and municipal wastewater. As shown

in Figure 6, the Bioreactor unit is a steel-coated or concrete tank that contains a submerged plastic

matrix and a membrane air distribution system. It has alternating vertical columns that allow for air

and water circulation through the system. The influent first enters the system and reaches the

surface through up-flow columns and is aerated, then flows horizontally to the next vertical column

and flows down. The aerated influent supplies oxygen for the bacteria in the down-flow column

(Microbac, 2010).

Bacteria obtain energy from organic substrates in the influent. The bacteria grow and secrete polysaccharides that allow them to adhere and form biofilms. A high surface area to volume ratio (150 m2 per m3) in the system allows for the accumulation of bacteria and a thicker biofilm. The

Page | 12

bacteria absorb organic chemicals and nutrients as the influent passes through the matrix (Microbac, 2010).

Figure 7 Microbac Bioreactor growth and sloughing process (Microbac, 2010)

As the biofilm becomes thicker and less permeable, the diffusion of oxygen and nutrients decreases,

and the bacterial organisms in the inner layer are less able to adhere to the surface of the matrix

(Figure 8). The shear forces of water and air bubbles cause sloughing (shedding of biofilm layers).

The sloughed solids become part of the effluent, which is free of organic chemicals. The quality of

the effluent depends on the quantity of suspended solids and the concentrations of BOD and COD in

the influent (Microbac, 2010).

Microbac markets a package sewage treatment plant for treating domestic and commercial

wastewater in small communities. The treatment plant can be designed to withstand a range of

temperatures (as low as -50°C and as high as 60°C).

Microbac also markets a membrane bioreactor, which adds hollow fibre filtration membranes to the

standard bioreactor. This improves the quality of the effluent by further breaking down organics,

ammonia, and suspended solids. The system disinfects the wastewater so that it may be safely

discharged or recycled. It is useful for treating municipal sewage or industrial wastewater

(Microbac, 2010). There is presently no available information on specific energy requirements or

costs.

Page | 13

Case Study: Ministry of Defence, Scotland

Microbac installed a bioreactor at a transit training camp, which is occupied by as few as 12 and up

to 2000 people at a time. The bioreactor was designed in such a way that minimal operation and

maintenance is required, and that minimal disturbance to the surrounding environment would be

made. The bioreactor was pre-assembled and was installed on a concrete base at the camp. Within

hours of its installation, the bioreactor had wastewater (including food and sewage) flowing through

the system. The system is capable of degrading high levels of grease and fats. The bioreactor may

easily be relocated if the training camp requires a different site (Microbac, 2010).

2.10 Septic Wizard

Company: Wastewater Wizard

Location: East Watergate, Fortrose, UK.

Technology status: On the market

Output: Non-potable

Septic Wizard designs wastewater treatment systems that using vermifiltration, a worm-based

technology. The system is appropriate for treating household sewage. Sewage flows from the

household to a filter surface, and trickles through a vermifilter that traps the organic matter. Worms

break down the organic matter, and the treated effluent passes to a soakaway, local water course,

or may be used for gardening (Wastewater Wizard, 2012).

Tiger and California Black worms are used for their abilities to digest large amounts of organic

matter and thrive in aquatic environments. Coconut coir and sawdust (waste) support the habitat

for the worms. In contrast to anaerobic digestion systems which utilise bacteria that produce

sludge, worms break down organic matter to produce casts, which are filtered and do not contribute

to sludge production (desludging is required every 4-5 years, as compared to every year for

conventional anaerobic digestion systems). The casts may be used as organic garden fertiliser.

Septic Wizard is capable of converting an anaerobic environment to an aerobic environment within

48 hours. Inputs of oxygen are not required, as worms naturally burrow and aerate the system,

reducing foul odours. The worms are capable of thriving for long periods of time without food.

Research by the company has found that Septic Wizard reduces BOD from 386mg/L to 24mg/L, COD

from 786mg/L to 124mg/L, and suspended solids from 180mg/L to 44mg/L (Wastewater Wizard,

2012). There is presently no available information on specific energy requirements or costs.

2.11 AquaCritox

Company: SCFI Group

Location: Cork, Ireland

Technology status: On the market

Output: Unknown

AquaCritox uses principles of super critical water oxidation to treat wastewater and to produce

energy. The temperature of the water is heated to above 374°C and the pressure is elevated to 221

bar, transforming water to a supercritical phase that is neither liquid nor gas (SCFI, undated); under

Page | 14

this phase, the water is a solvent for gases and organic compounds; its density becomes lower than

that of its original liquid phase, its viscosity is the same as gas, and its diffusivity is mid-way between

its original liquid phase and gas. The solubility of gases and organic compounds increases to almost

100%, and inorganic compounds become mostly insoluble. The result is that instead of the

production of sewage sludge that must be recycled or discarded, nearly 100% of organic compounds

are converted to carbon dioxide and nitrogen gas. The carbon dioxide may be recovered and sold

for industrial applications or dry ice production (Taylor 2011). The nitrogen gas is released to the

atmosphere. Inorganic compounds can be further treated, and phosphorus may be recovered.

Super critical water oxidation, being an exothermic reaction, also results in the production of

thermal energy. There is presently no available information on specific energy requirements or costs

(SCFI, undated).

Four sizes are available, with hydraulic loads ranging from 1 to 20 tons per hour. AquaCritox has

been used by the military (Taylor, 2011), as well as for processing waste streams in the U.S. and

Australia (SCFI, undated).

3.0 TECHNOLOGIES FOR RENEWABLE ENERGY PRODUCTION

3.1 Clearfleau Anaerobic Digestion

Company: Clearfleau

Location: Bracknell, Berkshire, UK.

Technology status: On the market

Clearfleau offers anaerobic digestion systems that treat liquid bio wastes to generate renewable

energy; the usage of Combined Heat and Power (CHP) engines produce electricity from biogas. The

electricity may be used on-site or sold to the national power grid. To date, the systems are designed

primarily for livestock (diary) farms, and food and industrial facilities (Clearfleau, undated).

Clearfleau’s anaerobic digestion systems reduce the load of residual solids by at least 95%, as

compared to conventional anaerobic digestion systems. The residual solids from the digestion

process are rich in nutrients that may be applied to the land, subject to complying with current

legislation and standards, notably for agricultural land. The system’s dewatering technologies

produce a cake that is more compact (up to 18% dry matter), easier and less costly (haulage costs

are reduced up to 80% as compared to conventional systems). There is presently no available

information on specific energy requirements or costs. Clearfleau is currently developing advanced

membrane-based solids removal systems, which are used pre or post-digestion for producing cakes.

Greywater may be recycled and discharged, re-used onsite (such as for irrigation) or further treated

for other uses. Greywater recycling equipment for industrial re-use may qualify for Enhanced Capital

Allowances (ECAs), as part of the UK Government’s tax relief scheme for investments in equipment

that is energy-saving (DECC, 2013).

Page | 15

Table 1 Performance of the Clearfleau Mobile Trials Unit (Clearfleau, undated)

Waste Source Treatment Results

Bio-Diesel Refinery

Dairy 1 Dairy 2 Food

Waste water COD (mg/l) 64,000 27,000 120,000 25,000

COD removal (%) 98 99 98 99

CH4 content (%) 78 68 50 50

CH4 yield (m3CH4/Kg COD) 0.36 0.39 0.32 0.3

Hydraulic retention time (days) 10 6 16 7

Clearfleau also operates a smaller-scale mobile trials unit, the Small Scale Production Plant (SSPP).

The unit requires a 15m by 15m site, and can accommodate 200-2000 L/day. It requires power and

water on-site, and uses a mixed balance tank and a biogas flare. It has been used for treating liquid

waste, and has reduced COD and biosolids, produced a yield of biogas, and is simple to install and

operate (Clearfleau, undated). Table 1 displays the waste treatment results of a bio-diesel refinery,

dairy farm waste, and food waste in a SSPP; all four cases saw a 98-99% removal of COD, a 50-78%

removal of methane, a methane yield of 0.3-0.39 m3CH4/kg COD, and a hydraulic retention time of

6-16 days. The cases show that the system does not require a long period of time to adequately

treat the system.

Clearfleau is in the process of designing a small-scale anaerobic digestion modular unit suitable for

small sites, the Small Anaerobic Treatment Plant (SATP). The SATP treats liquid residues (sugars, oils,

fats) which are broken down and produce biogas. The system qualifies for the Feed-In Tariff (FIT)

and Renewable Heat Incentive (RHI) payments from the UK Government’s Energy Savings Trust

scheme. The SATP processes up to 70m3/day of influent. It arrives at the site pre-assembled and

pre-tested, making it convenient to operate. At this time, it is being tested at a brewery site in

Oxfordshire (Clearfleau, undated).

Clearfleau has found success with installing its systems in several dairy farms, including BV Dairy in

Dorset, but no cases have been found where it has installed systems designed for household waste

digestion. There is presently no available information on specific energy requirements or costs.

3.2 Willow Systems

Company: James Hutton Institute

Location: Aberdeen

Technology status: Not on the market

Willows, grown as short rotation coppice (SRC) are viewed as being effective bioenergy crops due to

their fast-growing nature (depending on the species). They can be grown in high density and

intensively for energy production, replacing fossil fuels.

A project currently conducted by the James Hutton Institute involves planting willow crops (Salix

viminalis and St. burjatica) and irrigating them with the wastewater, utilising the nutrients and

facilitating phytoremediation of the pollutants found in the water. The efficiencies of the crops for

Page | 16

treating water quality will be compared to the performance of an existing wetland. The project is

based on a successful willow cultivation and wastewater treatment in Sweden (Avery, 2012). There

is presently no available information on specific energy requirements or costs.

Case Study: Willow cultivation for biomass production in Sweden

Sweden cultivates 16,000 ha of short-rotation willow crops (Salix viminalis, S. dasyclados, and S.

schwerinii) for bioenergy, producing approximately 6-12 tonnes per ha per year. The crops are

planted in double rows for convenient weeding, fertilization, and harvesting. Harvest is completed

every three to five years, during the wintertime. The biomass is chipped on-site, stored, or directly

used in district heating plants for heat and power production. Replanting is not required, with the

approximate lifespan of the short-rotation willow coppice stand being 20 to 25 years (Dimitriou

and Aronsson, undated).

In Enköping, Sweden (population 20,000), the village’s wastewater (post sedimentation and

centrifugation) is used for irrigating a 75 ha willow plantation. The wastewater provides 800 mg of

nitrogen/L, 25% of the total nitrogen normally treated in the wastewater plant. Irrigation takes

place over the summer (a 120 day period of irrigation), and the water is stored in storage ponds

over the winter. Every year, the system treats 11 tonnes of nitrogen and 0.2 tonnes of phosphorus

in 200,000 m3 of wastewater. Researchers note that there are some risks that accompany the

system, including nitrogen leaching and nitrous oxide emissions from the wastewater (Dimitriou

and Aronsson, undated).

Page | 17

4.0 CONCLUSIONS

4.1 Limitations of this report

While some of the companies have well-developed websites and information available online

pertaining to the details of the products, costs, and energy costs, many of the website lack sufficient

information that allow for a complete analysis of the products. Furthermore, a number of the

technologies reported have only very recently entered the market (such as Dutch Rainwater, which

is still completing trials), and have few available examples or case studies that may be reviewed. A

few of the companies present data, such as Biomatrix Water and Clearfleau, yet it is unclear as to

how, where and when the data were gathered. It is also unclear as to how relevant the data are to

rural communities (smaller populations, resources available, reduced infrastructure, etc).

4.2 Next steps

Additional technologies will be added as we become aware of them. Further research into the

technologies might include:

contacting company representatives to obtain more information on the products

Requesting expert opinion on the pros and cons of the technologies

Page | 18

5.0 REFERENCES Alfa Laval (n.d.) AQUA Freshwater Generator, http://www.alfalaval.com/solution-finder/products/aqua-

freshwater-generator/pages/aqua-freshwater-generator.aspx (accessed 25 May 2013)

Avery, L (2012) Willows Systems In Wastewater Treatment (powerpoint)

Atlantic Water (2013) The AW Freshwater Generator, http://atlanticwaterco.com/freshwater.htm (accessed

25 May 2013)

Biomatrix Water (n.d.) Land Based Treatment, http://www.biomatrixwater.com/wastewater-treatment/land-

based-treatment/ (accessed 25 May 2013)

Biomatrix Water (n.d.) Pond Based Treatment, http://www.biomatrixwater.com/wastewater-

treatment/pond-based-treatment/ (accessed 25 May 2013)

Clearfleau (n.d.) Mobile Trials Unit, http://www.clearfleau.com/page/mobile-trials-unit (accessed 29 May

2013)

Clearfleau (n.d.) Small Scale Anaerobic Digeston For Businesses With Liquid Bio Waste Streams,

http://www.clearfleau.com/page/small-scale-anaerobic-digestion (accessed 29 May 2013)

Dimitriou, I., and Aronsson, P (n.d.) Willows For Energy And Phytoremediation In Sweden,

http://www.fao.org/docrep/008/a0026e/a0026e11.htm (accessed 1 June 2013)

Dutch Rainmaker (n.d.) Air To Water Production, http://www.dutchrainmaker.nl/wp-

content/uploads/Productsheet%20DRM%20AW75%20(2013).pdf (accessed 29 May 2013)

Endo Enterprises (2012) EndoSan, http://endoenterprises.com/index.php/our-products/endo-san/ (accessed 2

June 2013)

Endo Enterprises (2012) EndoSan, http://endoenterprises.com/wp-

content/uploads/PDF/EndoSanBrochure.pdf (accessed 2 June 2013)

Garrow, B (2012) Activated Carbon and UF Filter Drinking Water Plant (pdf)

Garrow, B (2013) Aqualogix Activated Carbon and UF Filter Drinking Water Plant From Ashton Industrial,

http://www.abcfluidtechnologysolutions.com/Documents/BillBorlandAqualogixHouse.pdf (accessed 23 May

2013)

Indewa (2013) Grey water recycling,

http://www.intewa.de/en/products/aqualoop/applications/greywaterrecycling/ (accessed June 2013)

Living Machine (2012) Kwan Lamah Subdivision, San Juan Island, WA,

http://www.livingmachines.com/Portfolio/Developments/Kwan-Lamah-Subdivision,-San-Juan-Island,-WA.aspx

(accessed 25 May 2013)

Living Machine (2012) Living Machine Components, http://www.livingmachines.com/About-Living-

Machine/How-it-Works/Living-Machine-Components.aspx (accessed 25 May 2013)

Microbac (2010) Bioreactor Installation, Ministry of Defence Site, UK,

http://www.microbac.co.uk/CaseStudies/MODsiteScotland.aspx (accessed 26 May 2013)

Microbac (2010) Microbac Bioreactors, http://www.microbac.co.uk/Wastewater/MicrobacBioreactors.aspx

(accessed May 26 2013)

SCFI (n.d.) AquaCritox, http://www.scfi.eu/products/ (accessed 12 June 2013)

Taylor, J (2011) SCFI’s AquaCritox: Sustainable Sludge Destruction,

http://www.waterandwastewater.com/www_services/newsletter/april_4_2011.htm (accessed June 2013)

Wastwater Wizard (2012) Frequently Asked Questions, http://www.wastewaterwizard.co.uk/faqs/ (accessed

13 June 2013)

Wet Salt (n.d.) Participerende bedrijven, http://www.wetsalt.nl/participanten.htm (accessed 29 May 2013)

Wilson, R (2013) Domestic Hot Water Treatment At Exchange House, Broadgate (pdf)

CREW Facilitation Team

James Hutton Institute

Craigiebuckler

Aberdeen AB15 8QH

Scotland UK

Tel: +44 (0) 844 928 5428

Email: enquiries@crew.ac.uk

www.crew.ac.uk