MALTENTO (PTY) LTD
ODOUR MANAGEMENT PLAN
PROPOSED EXPANSION OF THE
MALTENTO FACILITY, EPPING, CAPE TOWN
28 JANUARY 2022
ODOUR MANAGEMENT PLAN
PROPOSED EXPANSION OF THE MALTENTO
FACILITY, EPPING, CAPE TOWN
MALTENTO (PTY) LTD
REPORT (VERSION 01)
PROJECT NO.: 41101855 DATE: JANUARY 2022
WSP BUILDING C
KNIGHTSBRIDGE, 33 SLOANE STREET BRYANSTON, 2191
SOUTH AFRICA
T: +27 11 361 1372 F: +27 86 556 7189 WSP.COM
Q U A L I T Y M A N A G E M E N T
Issue/revision First issue Revision 1 Revision 2 Revision 3
Remarks Draft Report Final Report Final Report Final Report
Date 17 August 2021 31 August 2021 17 November 2021 28 January 2022
Prepared by N. Reddy N. Reddy N. Reddy N. Reddy
Signature
Checked by L. Ramsay L. Ramsay L. Ramsay L. Ramsay
Signature
Authorised by L. Ramsay L. Ramsay L. Ramsay L. Ramsay
Signature
Project number 41101855 41101855 41101855 41101855
Report number 1 of 1 1 of 1 1 of 1 1 of 1
File reference
A C R O N Y M S A N D A B B R E V I A T I O N S
AEL Atmospheric Emission License
APPA Atmospheric Pollution Prevention Act 45 of 1965
BA Basic Assessment
BAT best available technique
BATNEEC best available technique not entailing excessive cost
EA environmental authorisation
H2S hydrogen sulphide
HVAC heating, ventilation and air cooling
Maltento Maltento (Pty) Ltd
NAAQS National Ambient Air Quality Standards
NEMA National Environmental Management Act 107 of 1998
NEMAQA National Environmental Management: Air Quality Act 39 of 2004
NH3 ammonia
OMP Odour Management Plan
SANS South African National Standards SAWS South African Weather Service
UV ultraviolet
WDL whole dried larvae
WSP WSP Environmental (Pty) Ltd
E X E C U T I V E S U M M A R Y
Maltento (Pty) Ltd (Maltento), a biotech business located in Epping, Cape Town, South Africa, utilises the larvae of black soldier fly to convert the residual nutrients in brewer’s by-products (i.e., spent grain and yeast) into animal feed, including a premium grade pet food. Maltento propose to expand this facility from processing less than one ton of raw material a day to more than one ton of raw material per day, triggering the need for an Atmospheric Emission License (AEL) and associated Environmental Authorisation. A Basic Assessment process is underway in terms of the National Environmental Management Act (Act 107 of 1998) (NEMA).
The processing of fly larvae (more than one ton of raw material per day) at the Maltento facility will fall under Subcategory 10 Animal Matter Processing of Government Notice Regulation 893 of 2013, promulgated in line with Section 21 of the National Environmental Management: Air Quality act (NEM:AQA). Category 10, unlike other Listed Activities, does not stipulate emission limits for specific pollutants but rather requires a plan for the implementation of best practice measures for odour management. An AEL application with appended Odour Management Plan (OMP) is hence required. Maltento appointed WSP Group (Pty) Ltd to compile the OMP (this document) for their proposed expansion facility in Epping. The OMP describes measures to reduce, dilute and abate odours. These include:
— A reduction in the amount of odour produced by the site by:
— Cleaning all vehicles, equipment and surfaces on a continuous basis to remove old decomposing material;
— Carefully managing the breeding process;
— Ensuring the storage of frass in particular is stored within the warehouse building and not outdoors;
and
— Taking measures to reduce the likelihood of spills, and if these do occur, addressing them promptly and thoroughly.
— A reduction in odorous releases from the site by:
— Ensuring the manufacturing process remains within the warehouse and not outdoors (i.e. inclusive of storage of by-products, frass, etc);
— Venting the odorous emissions to an odour abatement system such as a condenser; and
— Using odour masking sprayers.
— Facilitation of odour dilution by:
— Maintaining adequate air exchanges.
In addition to the above measures there will be a need for regular monitoring (quarterly monitoring is
recommended) at the facility fenceline to verify the effectiveness of the mitigative measures. There should also be procedures in place for the unplanned events that lead to an increase in odour release from the facility. If all the above measures, monitoring and planning is implemented correctly, and there is a prompt response to any unforeseen incidents, WSP expects the odour impacts of the Maltento facility on surrounding receptors to be limited. However, should odour complaints arise despite the measures outlined above, the following should be considered:
— Increased use of the odour masking sprayers;
— An increase in the number of air exchanges per hour in some zones; and/or
— The installation of more effective abatement technologies such as activated carbon filters or as a last resort, a scrubber.
TABLE OF CONTENTS
1 INTRODUCTION ... 1
1.1 Terms of Reference ... 1
2 PROJECT BACKGROUND ... 2
2.1 Site Description ... 2
2.2 Process Description ... 2
3 LEGISLATION ... 7
3.1 South African Legislation ... 7
3.2 International Legislation and Guidelines ... 8
4 METEOROLOGICAL OVERVIEW ... 10
5 ODOUR MANAGEMENT PLAN ... 14
5.1 Good Housekeeping ... 19
5.2 Odour Dilution ... 19
5.3 Odour Abatement Technologies ... 19
5.4 Odour Masking and Control ... 20
5.5 Vent and Fenceline Monitoring ... 20
5.6 Abnormal Odour Response Procedures ... 21
6 CONCLUSIONS ... 21
TABLES
TABLE 1: PROCESS DESCRIPTION... 3
TABLE 2: ANIMAL MATTER PROCESSING
(CATEGORY 10) ... 8
TABLE 3: PERCENTAGE DATA RECOVERY
FOR THE CAPE TOWN INTERNATIONAL AIRPORT METEOROLOGICAL STATION FOR THE PERIOD JANUARY 2017 TO DECEMBER 2019 ... 10
TABLE 4: ODOUR MANAGEMENT PLAN BY
ZONE DURING NORMAL
OPERATIONS ... 15
FIGURES
FIGURE 1: LOCALITY MAP OF THE
PROPOSED EXPANDED
MALTENTO FACILITY, EPPING ... 2
FIGURE 2: BLOCK FLOW DIAGRAM OF
PROPOSED PROCESS ... 5
FIGURE 3: PROPOSED FACILITY DIAGRAM 6
FIGURE 4: TOTAL MONTHLY RAINFALL,
AVERAGE HUMIDITY AND AVERAGE MONTHLY
TEMPERATURE (2017 – 2019) AT THE CAPE TOWN
METEOROLOGICAL STATION .. 11
FIGURE 5: PERIOD SURFACE WIND ROSE
PLOTS FOR THE PERIOD JANUARY 2017 TO DECEMBER 2019 ... 11
FIGURE 6: SEASONAL AND DIURNAL WIND
ROSE PLOTS FOR THE PERIOD JANUARY 2017 TO DECEMBER 2019 ... 13
APPENDICES
A CITY OF CAPE TOWN PRE-COMPLIANCE NOTICE
1 INTRODUCTION
Maltento (Pty) Ltd (Maltento), a biotech business located in Epping, Cape Town, South Africa, utilises the larvae of black soldier fly to convert the residual nutrients in brewer’s by-products (i.e., spent grain and yeast) into animal feed, including a premium grade pet food. Maltento propose to expand this facility from processing less than one ton of raw material a day to more than one ton of raw material per day, triggering the need for an Atmospheric Emission License (AEL) and associated Environmental Authorisation. A Basic Assessment process is underway in terms of the National Environmental Management Act (Act 107 of 1998) (NEMA).
The processing of fly larvae (more than one ton of raw material per day) at the Maltento facility will fall under Subcategory 10 Animal Matter Processing of Government Notice Regulation 893 of 2013, promulgated in line with Section 21 of the National Environmental Management: Air Quality act (NEM:AQA). Category 10, unlike other Listed Activities, does not stipulate emission limits for specific pollutants but rather requires a plan for the implementation of best practice measures for odour management. An AEL application with appended Odour Management Plan (OMP) is hence required.
Maltento appointed WSP Group (Pty) Ltd (WSP) to compile the OMP (this document) for their proposed expansion facility in Epping. This document presents the principal odorous components associated with the proposed expansion Maltento facility and seeks to determine appropriate odour management mechanisms.
1.1 TERMS OF REFERENCE
An OMP is required for the licensing of facilities under Listed Activity Category 10 (GN 893 of 2013). The following methodology is proposed to best meet the requirements of the OMP:
— Identification of neighbouring sensitive receptors, including adjacent communities and residential areas;
— Identification of any neighbouring air pollution/odour sources;
— Assessment of meteorological conditions using available meteorological data;
— Review of air quality and odour legislation applicable to the operations;
— Assessment of existing odour conditions through the analysis of relevant ambient air quality monitoring data (if available);
— A summary of Best Available Techniques (BAT) to reduce / mitigate odour emissions from the facility;
and
— Recommendations and strategy development for odour abatement solutions, odour monitoring, incident reporting, community liaison and the development of an effective complaints database.
2 PROJECT BACKGROUND
2.1 SITE DESCRIPTION
Maltento set up a pilot facility within an existing warehouse located on Moody Avenue in Epping Industrial Area, Cape Town in November 2019. Maltento propose to expand their operations into an adjacent warehouse.
The site (Figure 1) is surrounded by light industrial activities to the north, east and south. These are small-scale enterprises such as First Cut (steel engineering), Castaway (floor tiles), Hitec Inks, Impressions (Printing and Signage Marketing), Food Forward (food redistribution), Blowplas, Gear Pump Manufacturing, Protours Bus Company and Optical Trade Links Group and various others. The railway line and Jan Smuts Drive run immediately adjacent to the west. The closest residential areas are Pinelands (approximately 1.3 km to the west) and Langa (approximately 1.3 km to the southwest).
Figure 1: Locality map of the proposed expanded Maltento Facility, Epping
2.2 PROCESS DESCRIPTION
2.2.1 CURRENT OPERATIONS
Maltento breed and grow black soldier larvae. Black soldier flies are a non-pathogenic, non-pest species of fly.
They are found throughout South Africa naturally but are not attracted to human areas unlike the house fly and blow fly. The fly itself does not have mouth parts and thus will not be found landing on human food.
The black soldier fly eggs are placed on the feedstock substrate to grow. The growth trays are stacked and placed in a chamber, with strict climate control. Once grown the trays are harvested, where the grown larvae are separated from the frass. The frass is a by-product of insect production and includes the undigested fibre, insect residue and exoskeletons. The frass is pelleted for sale to the agriculture sector as an organic soil amendment with further testing to see its applicability in animal diets due to its prebiotic nature. The larvae are taken for further product processing within the facility. Some of the grown larvae are allowed to pupate into flies and are
kept in cages in a climate-controlled room where they breed and lay eggs for use in the production process.
Total larvae processing is currently below one ton per day.
Black soldier larvae present an amazing source of nutrition for pet food and animal feeds alike. They have a highly digestible make-up including ~50% protein and 30% oils. The oils themselves can be used in feed and cosmetics. They are similar in nature to that of coconut oil (i.e. high lauric acid). By utilising these sources of nutrition, less sustainable forms of protein and oil such as fishmeal and soymeal can be replaced.
There are currently three product options being manufactured at the facility, namely:
Primary Product:
• Dried product – Dehydration in a surface dryer to whole dried larvae (WDL), which can also be pressed into a defatted meal and an oil.
Secondary Products in small scale production:
• Liquid Product – Mincing of the larvae and stabilisation through enzymatic and pH control for use in pet and aquaculture feed.
• Live product – Sale of live larvae to chicken farmers.
Current market demand has resulted in the production of WDL for export to the United States to be used as the main ingredients in Norwegian Dog Food. Our future strategy will be to supply the South African pet food and aquaculture industries in future.
Research is underway on the production of liquid solutions to process the larvae, thereby reducing the drying and electricity dependence of the product.
2.2.2 PROPOSED EXPANSION OPERATIONS
The proposed expansion of the Maltento facility will take place within the adjoining warehouse with no external construction or increase in building footprint planned. Given the surrounding industrial land use, the site has low environmental sensitivities.
The expansion will be phased with an initial increase in the on-site production of a grow out capacity of three to four tons of live larvae per day to be processed at the facility. Once stabilised, this on-site grow out capacity will be increased to eight to ten tons of larvae per day, in line with market demands, to be processed at the facility.
Maltento anticipate that in the medium to long term the market demand may increase to as much as 20 tons per day. To meet the increased market demand Maltento would then bring in additional live larvae per day, from another grow-out facility, to be processed at the facility (i.e. the facility will have a total processing capacity of up to 20 tons of live larvae per day).
A detailed description of the proposed expansion process is outlined below.
Table 1: Process description
Zone Zone Description Description of Process
1 Raw Material Receiving, Storage and Mixing
• Raw ingredients are received from various ‘clean’ sources of by- product via +/- 2 trucks per day
• All by-products / commodities are paid for and are not considered waste in anyway, these include:
o Spent grain and yeast from various craft Breweries come in daily
o Fruit pulp from the juice factory comes in daily o Dry bran, soy and maize come in bulk bags once per
week
o Broiler pellets (dry, 50kg bags) come once per week
• Raw feedstocks are kept in a combination of agri-bins and bulk bags in the factory and used within a few days of being on site. Spent grain / yeast is used on the day it is collected.
• Raw ingredients are weighed into batches and tipped into one of two paddle mixers. Water is added to adjust the moisture content
• Once ingredients are mixed they are discharged from the mixer into a secondary dosing mixer
Zone Zone Description Description of Process
• Dosing mixer discharges ~20kg of feed into a plastic grow bin on a conveyor belt
2 Growth Chambers
• Young larvae are then added to each growth bin
• The grow bins are stacked on a metal pallet and then taken into a climate-controlled chamber which holds a full day of growing bins
• Chambers are set to control for temperature, humidity, carbon dioxide and ammonia (low levels but monitored for safety)
• After seven days, the growth bins are removed from the chamber and taken to the harvesting section
3 Harvesting - Separation of Frass and Larvae
• Bins are discharged onto a conveyor belt which feeds a rotating screen separator to separate the frass and grown larvae
• The frass is polished and pelleted for sale into agriculture (i.e., no waste)
• Larvae is sent for further product processing
4 Breeding and Pupae Holding
• Larvae are allowed to pupate into flies and are then kept in cages in a climate-controlled room where they breed and lay eggs
• These eggs are then hatched which provide the young larvae for the production
5 Larvae Processing
• Total larvae processing is currently below one tonne per day and only includes a drying step
• Total larvae in the future will be ±20 tons per day
• Larvae processing includes:
o A portion of larvae are dried in a surface dryer (gas and electric operated) which reduces the moisture content in the larvae from 70% to 10%
o Some of these larvae are further pressed to separate oil and protein components – this process does not produce any odour
o Larvae is stored in bulks bags and sent to the US for pet food in a container
o Finished goods will usually not exceed 20 tons on the factory racks at any point in time but by this stage product is stable and is odourless
o Portion of larvae are minced and then put through digest process where enzymes are added to enhance flavour of the larvae
o In future Maltento might look to dry this product in a spray-type dryer
• Finished product is stored as wet liquid in “bag in a box” / “Flow Bin”
before sending to customers
6 Composting • A small amount of waste (i.e. from spills, etc) is created which is disposed of regularly to a local compost site
Figure 2: Block flow diagram of proposed process
Figure 3: Proposed facility diagram
3 LEGISLATION
3.1 SOUTH AFRICAN LEGISLATION
In 2004, South Africa’s approach to air pollution control (under the Atmospheric Pollution Prevention Act 45 of 1965 (APPA)), was repealed with the promulgation of the NEM:AQA Act 39 of 2004 which subsequently came into effect on the 11th of September 2005. NEM:AQA represents a shift in South Africa’s approach to air quality management, from source-based control to a more integrated approach that included ambient standards.
Key features of current legislation include:
— A decentralisation of air quality management responsibilities;
— The identification and quantification of significant emission sources that then need to be addressed;
— The development of ambient air quality targets as goals for driving emission reductions;
— The use of source-based (command-and-control) measures in addition to alternative measures, including market incentives and disincentives, voluntary programmes, and education and awareness;
— The promotion of cost-optimized mitigation and management measures;
— Stipulation of air quality management planning by authorities, and emission reduction and management planning by sources; and
— Access to information and public consultation.
The Act introduces a system based on ambient air quality standards and corresponding emission limits to achieve these. Two significant regulations stemming from NEM:AQA have been promulgated in this regard and are as follows:
— Government Notice 1210 on the 24th of December 2009 (Government Gazette 32816) National Environmental Management: Air Quality Act, 2004 (Act No. 39 of 2004) National Ambient Air Quality Standards (NAAQS).
— Government Notice 893 on the 22nd of December 2013 (Government Gazette 37054) National Environmental Management Air Quality Act, 2004 (Act No. 39 of 2004) List of Activities which result in Atmospheric Emissions which have or may have a significant detrimental effect on the environment, including health, social conditions, economic conditions, ecological conditions or cultural heritage.
The NAAQS were based primarily on guidance offered by two South African National Standards (SANS):
— SANS 69:2004 Framework for implementing national ambient air quality standards; and
— SANS 1929:2005 Ambient air quality – Limits for common pollutants.
SANS 69:2004 makes provision for the establishment of air quality objectives for the protection of human health and the environment as a whole. Such air quality objectives include limit values, alert thresholds and target values.
SANS1929:2005 uses the provisions in SANS 69 to establish air quality objectives for the protection of human health and the environment, and stipulates that limit values are initially set to protect human health. The setting of such limit values represents the first step in a process to manage air quality and initiate a process to ultimately achieve acceptable air quality nationally. The limit values presented in this standard are intended as information to be used in air quality management but have only become enforceable as revised under Government Notice 1210 since the 24th of December 2009. NAAQS for criteria pollutants generally have specific averaging periods; compliance dates (timeframes), permissible frequencies of exceedance and reference methods.
Listed activities and associated minimum emission standards (MES) were published in Government Notice 248, as amended by GNR 893, in line with Section 21 of NEM:AQA. The processes to be conducted at the Maltento facility fall under Category 10: Animal Matter Processing. Category 10, unlike other Listed Activities, does not stipulate emission limits for specific pollutants but rather requires a plan for the implementation of best practice measures for odour management (Table 1).
Table 2: Animal matter processing (category 10)
Description: Processes for the rendering cooking, drying, dehydrating, digesting, evaporating or protein concentrating of any animal matter not intended for human consumption
Applications: All installation handling more than 1 ton of raw materials per day
The following special arrangement shall apply: Best practice measures intended to minimize or avoid offensive odours must be implemented by all installations. These measures must be documented to the satisfaction of the Licencing Authority.
With respect to odour control, Section 35 of NEM:AQA (under Part 6: Control measures in respect of dust, noise and offensive odours) states the following:
1) The minister or MEC may prescribe measures for the control of offensive odours emanating from the specified activities; and
2) The occupier of any premises must take all reasonable steps to prevent the emission of any offensive odour caused by any activity on such premises.
Odour performance criteria guide decision makers on odour management can be used to assess whether odour control and management techniques need to be implemented. Since specific measures for the assessment and control of offensive odours in South Africa are yet to be promulgated, international guidance on best practice has been sourced as described in Section 3.2 below.
3.2 INTERNATIONAL LEGISLATION AND GUIDELINES
Maltento manufactures larvae-based protein feed for animal and pet market use, with key odorous activities from:
1) Grow Chambers –raw materials as the larvae feed and larval metabolism (e.g., ammonia and amides produced by the larvae themselves);
2) Frass produced and to be dispatched from the site largely due to high moisture content in the frass; and 3) Larvae Processing – drying.
Since there is no process specific local guidance on odour, international guidance was sought, particularly the United Kingdom’s Department of Environment, Food and Rural Affairs Process Guidance Note 6/-05(13):
Statutory Guidance for Maggot Breeding Installations and the Process Guidance Note 6/26(13): Statutory Guidance for Animal Feed Compounding for best practice.
The Statutory Guidance for Maggot Breeding Installations applies specifically to facilities “that utilise fish, animal and bird matter for the purpose of breeding maggots (the larval stage of the order Diptera)” (page 6). As such, this guideline cannot be directly applied to the proposed facility given that the raw feedstock does not contain fish, animal or bird matter but can be used as best practice where relevant within the breeding of insects’
process.
The dominant feed components received at the Maltento site will be spent grains, yeast, pulp and broiler pellets, thus distinguishing Maltento from conventional breeding facilities. Based on this it is expected that odour production from Maltento would be significantly lower than such facilities, thus requiring the lower levels of odour management (e.g. number of air exchanges) recommended in the Defra guidelines.
This document is one of a series of notes giving guidance on BAT and best available techniques not entailing excessive cost (BATNEEC) for specific facility categories and provides a strong framework for consistent and transparent regulation of installations in the United Kingdom.
As stated in the guidelines, the intention is to limit the occurrence of odour beyond the boundary of the facility.
An assessment of the potential for odour impact beyond the site boundary should take account all predicted wind directions and weather conditions typical of the location in question. Should odours be detected at or beyond the site boundary (as perceived by the regulator) and should this have impact on receptors, further
process controls, management controls and arrestment provisions are required to the satisfaction of the regulator. The locality of a site will influence the assessment of the potential for odour impact. In cases where the site has a low odour impact due to its remoteness from sensitive receptors, escape of offensive odour beyond the site boundary would be unlikely to cause harm. It may not be necessary to demonstrate BAT in isolated cases, in contrast to cases where there are adjacent residential receptors and investments in BAT will be necessary. As explicit in the guidelines, offsite odour impacts are significantly reduced when air is effectively contained within the processing equipment and/or within a ventilation system for treatment. This key principle guides the odour management plan for Maltento.
4 METEOROLOGICAL OVERVIEW
Since meteorological conditions affect how pollutants emitted into the air are directed, diluted and dispersed within the atmosphere, the incorporation of reliable data into an air quality assessment is of the utmost
importance. Dispersion comprises vertical and horizontal components of motion. The stability of the atmosphere and the depth of the atmospheric mixing layer control the vertical component. The horizontal dispersion of pollution in the boundary layer is primarily a function of the wind field. The wind speed determines both the distance of downwind transport and the rate of dilution as the plume 'stretches'. Mechanical turbulence is influenced by wind speed in combination with surface roughness.
Parameters that need to be taken into account in the characterisation of dispersion potential include wind speed, wind direction, atmospheric stability, ambient air temperature and mixing depth. To accurately represent meteorological conditions at Maltento, meteorological data for the 2017 to 2019 period from the South African Weather Service’s (SAWS) meteorological station located at Cape Town International Airport (33.9630 °S;
18.6020 °E) for the period January 2017 – December 2019 was sourced. This station is located approximately 10 km south east of Maltento, and as such is considered to be representative of the prevailing meteorological conditions at the site. The percentage data recovery for each meteorological variable is given in Table 3.
Table 3: Percentage data recovery for the Cape Town International Airport meteorological station for the period January 2017 to December 2019
Parameter Data Recovery (%)
Wind speed (m/s) 99.7
Wind direction (°) 94.0
Temperature (°C) 100
Relative Humidity (%) 100
Rainfall (mm) 100
Figure 4 presents the average temperature, humidity and total monthly rainfall recorded at the Cape Town station for the 2017 to 2019 period.
Clear seasonal variations are evident in the temperature and rainfall values for the area. The region typically receives higher levels of rainfall during the winter months, with the highest rainfall recorded during June 2018.
Average summer temperatures range from 18.2 to 21.9°C with average winter temperatures ranging from 12.1 to 14.0°C. Relative humidity is generally stable throughout the year (70% average), as would be expected for a coastal location.
Figure 4: Total monthly rainfall, average humidity and average monthly temperature (2017 – 2019) at the Cape Town meteorological station
Wind roses are useful for illustrating the prevailing meteorological conditions of an area, indicating wind speeds and directional frequency distributions. In the following wind roses, the colour of the bar indicates the wind speed while the length of the bar represents the frequency (as a percentage) of winds blowing from a certain direction.
Period wind rose plots from the Cape Town meteorological station data is presented in Figure 5. Winds recorded in the area originate predominantly from south and north, with smaller north-westerly, south-south- easterly, south-south-westerly and north-north-westerly components. Wind speeds are light to gale force, with 16% of winds exceeding 8 m/s. Calm conditions (wind speeds < 1 m/s) are experienced 4.15% of the time.
Cape Town (SAWS)
Figure 5: Period surface wind rose plots for the period January 2017 to December 2019
Seasonal variations in winds are depicted in Figure 6. During summer (December to February) winds originate predominantly from the south. Highest average wind speeds are recorded during this time. During autumn (March to May), winds from the south continue to dominate, however, winds from the northerly sector start to increase in frequency. During winter (June to August), winds from the northerly sector dominate. During spring (September to November), winds from the north continue to dominate in the SAWS dataset, but with increasing frequency from the southerly sector.
Diurnal variations in winds are depicted in Figure 6. During the early morning (00:00 – 06:00) winds originate predominantly from the north and south. During this time winds are much gentler than during the daytime hours.
After sunrise, both the northerly and southerly components strengthen in speed and frequency. Winds are at their strongest during the afternoon (12:00 – 18:00), with the southerly component dominating and the northerly component diminishing. From 18:00 – 24:00, winds speeds decrease on average, with both the southerly and northerly components significant once again.
Cape Town (SAWS) – Seasonal Cape Town (SAWS) – Diurnal
Autumn
Summer
Winter
00:00 – 06:00
06:00 – 12:00
12:00 – 18:00
Figure 6: Seasonal and diurnal wind rose plots for the period January 2017 to December 2019
Spring 18:00 – 24:00
5 ODOUR MANAGEMENT PLAN
Currently, Maltento is implementing a multi-pronged approach to limit odour impact. These include looking at odour control through chemical sprays to be added to all ducting to mask odour and bind with odorous molecules to control odours. Additionally, Maltento are investigating the use of a condenser to reduce odour from the drying step.
To date only one odour-related complaint has been received by the City of Cape Town regarding this facility.
This complaint occurred when frass was being removed from site (Refer to Appendix A for the City of Cape Town Pre-Compliance Notice). As such, the aim of the OMP is to reduce or eliminate nuisance odour beyond the fenceline of the Maltento facility. There is no single solution to odour management but rather a combination of measures to achieve this goal. These measures fall into three main categories:
— Those that reduce the production of odour (e.g., substituting inputs for less odorous alternatives);
— Those that reduce the amount of odour ultimately emitted to ambient air (e.g. air treatment with a condenser); and
— Those that facilitate the dilution of odour when emitted to air (e.g. high air flows through a ventilation system).
Mitigation measures are presented in Table 4 for each zone of the facility. This is followed by a more detailed description of various management and abatement strategies recommended for the site, including good housekeeping, odour dilution, odour abatement technological options, and fenceline monitoring. Finally, an odour response procedure is presented for unforeseen odour incidents.
Table 4: Odour management plan by zone during normal operations
Zone Potential Odour Source Odour Potential Actions to Reduce Odour
Production Odour Abatement
Zone 1: Receiving and Storage Feedstock (spent grain, yeast, pulp, etc) Low
• It is noted that the raw materials received are fresh, coming in daily or weekly. This process should be continued as the age of the raw materials are important (i.e.
receive only fresh raw materials) to ensure a negligible/low potential of odours
• Use refrigerated trucks if the raw materials are traveling for more than one day to prevent raw material generating odours in warm weather conditions
• Trucks should be cleaned in the Maltento yard via a wet sweeper before leaving the Maltento facility
• Transport raw materials in the early morning during lower ambient temperatures
• Keep the area as cool as possible
• Reduce the possibility of odour escaping to ambient air during truck offloading (i.e material is offloaded in bulk bags or agri- bins via
forklift/automatic auger to increase efficiency and reduce odour escaping in to the ambient air)by opening the door only once a truck is ready to enter, keeping the truck sealed until it has entered the receiving area, offloadingthe materials into the receiving area as quickly as possible, closing the receiving area as soon as a truck has completed offloading and closing the door as soon as the truck has left
• A register of trucks, their contents and their arrival times should be kept to correlate with an odour complaints
Zone Potential Odour Source Odour Potential Actions to Reduce Odour
Production Odour Abatement register and monitoring register
• Odour masking sprayers should be turned on when trucks are onsite
• Odour in this zone should be diluted by means of adequate air exchanges
• This zone should be sealed when a delivery is not taking place
Zone 1: Mixing Feedstock Low
• Ensure that raw materials are in sealed bags/
containers at all times and only opened for use
• Ensure that all containers, and equipment used are easily cleanable and impervious
• Clean the area on a continuous basis to remove any feed
• Reduce the possibility of spills by applying good materials handling practices.
• Clean spills promptly
• Odour in this zone should be diluted by means of adequate air exchanges
Zone Potential Odour Source Odour Potential Actions to Reduce Odour
Production Odour Abatement
Zone 2: Growth Chambers Larvae feeding on spent grains/ Larval metabolism Medium
• Ensure that all containers and equipment used are easily cleanable and impervious
• Air in this zone should be ducted with a mister system
• Odour in this zone should be diluted by means of adequate air exchanges
• Ensure chambers are sealed
• Mobile floor scrubbers should be installed in this area if a mess occurs
Zone 3: Frass Separation, Handling and Removal Frass Medium
• Ensure the frass is stored indoors within a sealed room and collected on a regular basis (e.g multiple times per week)
• Keep the frass storage/separation/
handling area as cool as possible
• Ensure that when the frass is moved, it is sealed within bulk bags
• Reduce the possibility of spills by applying good materials handling practices
• Mobile scrubbers should be installed in this area
• If a spill occurs, it should be diluted and drained immediately
Zone 4: Breeding None - the flies do not feed; their sole purpose is to breed Low • None • None
Zone 4: Pupae None – the pupae do not feed Low
• None • Installation of self-
sealing doors
Zone Potential Odour Source Odour Potential Actions to Reduce Odour
Production Odour Abatement
Zone 5: Processing
Larvae within the hot dryer Medium • None • Air in this zone
should be ducted to an odour abatement system
• Odour in this zone should be diluted by means of adequate air exchanges
Mincing of the larvae Low
• None
5.1 GOOD HOUSEKEEPING
Good housekeeping will be a vital component of the day to day routine at Maltento. Good cleaning and working practices must be practiced at all times and in all areas of the facility. A daily cleaning regime must be instituted at the facility. The regime should cover all structures, equipment, internal surfaces and containers used for collection and storage. This will reduce odour production within the facility. All yards and corridors must be swept/disinfected at least once a week. Spills of all feed inputs and products (including those not considered odorous) must be addressed immediately. Water usage for cleaning purposes should be minimised, where practical.
5.2 ODOUR DILUTION
The dilution of odorous air is an effective method of reducing the concentration of odour and thus its ambient impact. Dilution is achieved by constantly cycling air through a heating, ventilation, and air cooling (HVAC) system. According to the Statutory Guidance for Maggot Breeding Installations (page 24), the necessary rate of ventilation depends on a multitude of factors including:
— The environmental conditions, most importantly the temperature;
— The quality and quantity of raw materials;
— The intensity of larvae breeding; and
— The design of the building and ventilation system.
The Maltento process consists largely of clean feedstock in terms of odour generating potential. The growth cycle is also much slower than that for blowfly facilities. Hence when assessing international guidance on odour dilution and minimum air exchanges we are of the opinion that the lower end of the recommended range (It is understood that Maltento use 4 air changes per hour which has been adequate) should be more than adequate.
With the provision of abatement measures, it may be feasible to operate at lower air exchange rates without adverse odour impacts in the receiving environment.
5.3 ODOUR ABATEMENT TECHNOLOGIES
There are various options available to treat odour containing air before it is emitted to the ambient environment.
These options along with their applicability to the Maltento facility are listed below;
— Wet Scrubber: the odorous air is passed through various liquid chemicals that remove the odorous compounds. This is an effective process but has a high initial capital investment and requires regular maintenance. It is better suited to larger scale facilities but would be a consideration for Maltento if odour issues persist at the site despite the application of one of the technologies below.
— Condenser – used to pull the steam out of the air in the dryer to reduce smell. This is an economical solution and is one of the preferred options for Maltento.
— Activated carbon filter: the odorous air is passed through activated carbon granules that adsorb odorous chemicals. This is a more cost effective option (relative to the above two mentioned options) and requires little maintenance. WSP suggests this as one of the preferred options for Maltento.
— Bio-filters: a blower sends odorous air through a humidifier and then into vessels that hold a filter media such as soil, peat, or chipped bark that is porous enough to allow the odorous air to pass through and be degraded by micro-organisms before it is emitted. This is a less expensive odour abatement option. WSP suggests that this is one of the preferred options for Maltento.
— Ozonisation: odour is limited through a process of oxidation. This technology is most appropriate for organic odours (generally from decay) and is less effective for inorganic odours (e.g. ammonia). It can be a cost-effective approach to organic odours. WSP suggests this as one of the preferred options for Maltento, possibly in combination with either activated carbon filters or bio-filters to treat inorganic odours.
— Ultraviolet (UV) germicidal irradiation: this is a disinfectant method using shortwave light to kill microorganisms. UV light also acts as a catalyst in breaking down ambient oxygen and water vapour molecules into oxygen and hydroxyl free radicals. These are then used in the process of oxidizing more complex molecules. The process works by photolysis (decomposition of molecules by action of light), creating carbon dioxide, water vapour and ozone as end products, by the principal of photolytic oxidation. The technology can be mounted in the ventilation ducting and works well in conjunction with ozonation to control organic odours. This is a costly option and is better suited to larger facilities.
Should abatement technology be installed at Maltento, the guideline document offers extensive guidance for management and maintenance of such systems to ensure their effective and sustainable usage. In the case of thermal oxidisers, for example, continuous monitoring of carbon monoxide levels or temperature indicate effective functioning. In the case of scrubbers, pH is an effective measure, while in the case of biofilters, pressure changes across the filter offers guidance. Criteria values can be linked to an alarm system that would sound should the technology begin to fail. Such failure would trigger the Odour Response Procedure outlined in Section 5.6 below.
5.4 ODOUR MASKING AND CONTROL
Odour masking agents (otherwise known as deodorants) are chemicals that cover bad odours with a stronger but more pleasant fragrance. Odour masking agents are sprayed into the air and can be varied in intensity depending on the amount of source odour being released, as well as the presiding meteorological conditions. The odour control Maltento are considering are chemical sprays to be added to all ducting which changes the molecule and smell and further does not just mask the odour. Maltento has installed odour masking sprays in the front of the facility, spraying into the yard as well as in the ducts. It is also recommended that these sprays be installed in the following locations:
— Along the perimeter of the Maltento site in the vicinity of the dryer;
— Along the perimeter of the Maltento site in the vicinity of the grow chambers; and
— Along the perimeter of the Maltento site adjacent to the frass removal.
5.5 VENT AND FENCELINE MONITORING
Odour is difficult to accurately monitor since it is made up of a combination of different chemicals and it is not possible to test for all of these. It is understood that Maltento undertake ammonia (NH3) monitoring in the growth chambers, but WSP suggests that passive monitoring of NH3 at the ventilation exit vents and at the fenceline (particularly where the frass is being dispatched) be conducted on a quarterly basis. NH3 has a sharp odour and is excreted by the larvae as part of their metabolic processes. Should complaints increase and odours be above the acceptable limits, this can be increased to a monthly basis and the necessary measures taken to mitigate such odours.
Olfactory monitoring (‘sniff testing’) should be conducted on a daily basis (preferably two to three times per day to cover various site operations and changes in ambient temperature and wind direction). This is a cost effective monitoring approach that involves a team walking along the facility’s fenceline and independently documenting their perceptions of odour at specified points. The offensiveness of an odour is highly subjective, so it is suggested that where possible more than one person is assigned this task. An odour register should be updated daily, documenting olfactory monitoring results. If it is found that there is an offensive odour at the fenceline, an investigation into the cause should be initiated immediately while response procedures are actioned (as outlined below). A stock of essential spare parts should be kept on site for equipment that is susceptible to failure and critical to odour management.
There are multiple scenarios that could lead to an abnormal production and/or release of odour. Some of these scenarios are outlined below along with appropriate response procedures.
5.6 ABNORMAL ODOUR RESPONSE PROCEDURES
An odour response procedure is a written summary highlighting (i) foreseeable situation that can compromise the prevention or minimisation of odorous releases from the process, and (ii) actions to be taken to minimise the impact. Details should be included of the person responsible for initiating the odour response procedure and the person responsible for liaison with the regulator and members of the general public. There are four main reasons for releases which may lead to emissions of offensive odour:
— Changes in process conditions leading to odour generation or a change in the odour characteristics (e.g., seasonal variation in weather may affect odour of materials , or periods of high throughputs);
— Conditions which result in fugitive releases due to reduced odour containment (building damage, failure of HVAC, failure of door seals, or human error e.g., leaving doors open);
— Failures or reduced performance of odour plant (power failure, HVAC failure, or abatement technology failure e.g. scrubber saturation, or biofilter failure due to flooding during high rainfall); or
— Factors affecting the dispersion between the source and the receptor (e.g., inversion conditions).
Point 1 above can be limited by careful management of material inputs and outputs and increased understanding of key odour sources such that these materials can be given specific focus for odour management. A daily record of arrivals, use of inputs, product movements and dispatches can be used to determine any relationship between specific materials and/or processes and complaints received.
Points 2 and 3 above can be limited through compliance with an effective plant maintenance programme.
With regards to Point 4 certain wind directions are likely to correlate with complaints, such as a wind trajectory from the facility to a receptor. During high windy conditions, additional precautions to prevent odour (e.g.
checks that bags are sealed, cleaning of surfaces, and increase dilution of emission) should be considered.
If the odour vent/plant/abatement system has shut down due to power or mechanical failure, the following procedure should be undertaken;
— In the case of a power issue, an emergency generator must be turned on; and
— If the emergency generator fails or the system is experiencing a mechanical failure:
— All surfaces should be cleaned thoroughly and disinfected;
— No raw materials should be received while the system is shut down;
— Surrounding neighbours should be notified; and
— The introduction of new larvae to grow-out should cease.
Once normal operations have been restored, the incident should be thoroughly investigated and procedures put in place to limit a repeat incident. A comprehensive record of the incident/complaint must be kept. Should community complaints have occurred, feedback to complainants is required. A senior staff member must be available at all times to receive calls from the regulator should an emergency complaint from the public be received. Details of this person must be made available to the regulator.
6 CONCLUSIONS
With the proposed expansion of the Maltento facility odours are likely to be more contained on site, within the warehouse, but it will still be necessary to institute measures to reduce, dilute and abate odours. These should include:
— A reduction in the amount of odour produced by the site by:
— Cleaning all vehicles, equipment and surfaces on a continuous basis to remove old decomposing material;
— Carefully managing the breeding process;
— Ensuring the storage of frass in particular is stored within the warehouse building and not outdoors;
and
— Taking measures to reduce the likelihood of spills, and if these do occur, addressing them promptly and thoroughly.
— A reduction in odorous releases from the site by:
— Ensuring the manufacturing process remains within the warehouse and not outdoors (i.e. inclusive of storage of by-products, frass, etc);
— Venting the odorous emissions to an odour abatement system such as a condenser; and
— Using odour masking sprayers.
— Facilitation of odour dilution by:
— Maintaining adequate air exchanges.
In addition to the above measures there will be a need for regular monitoring at the facility fenceline
(recommended quarterly monitoring) to verify the effectiveness of the mitigative measures. There should also be procedures in place for the unplanned events that lead to an increase in odour release from the facility. If all the above measures, monitoring and planning is implemented correctly, and there is a prompt response to any unforeseen incidents, WSP expects the odour impacts of the Maltento facility on surrounding receptors to be limited. However, should odour complaints arise despite the measures outlined above, the following should be considered:
— Increased use of the odour masking sprayers;
— An increase in the number of air exchanges per hour in some zones; and/or
— The installation of more effective abatement technologies such as activated carbon filters or as a last resort, a scrubber.
